A TAXONOMIC STUDY ON THE SOUTH ASIAN
CYPRINID GENERA HORADANDIA AND RASBOROIDES
(OSTARIOPHYSI: CYPRINIDAE: DANIONINAE) AND
EVALUATION OF THE PRESENT DISTRIBUTION PATTERN
OF RASBOROIDES VATERIFLORIS PALLIDUS IN GIN RIVER.
BATUWITA ACHARIGE SUDESH GRESHANA
2016
i
ABSTRACT
A taxonomic study was conducted to evaluate the systematic status of two cyprinid genera,
Horadandia and Rasboroides. Comparison of all congeners of Horadandia and Rasboroides
confirmed as two distinct genera in the tribe Rasborini by means of morphology (external
morphology and osteology) and morphometry. Horadandia (i.e.brittani+atukorali) differs
from Rasboroides (vaterifloris+nigromarginatus+pallidus+a new species) by a consistent set
of autoapomorphies: (a) absence/ presence of bifurcation at posterior end of kinethmoid; (b)
anterior boarder of cleithrum in ventral view either concave/ convex; (c) absence/ presence of
sensory canals in infraorbital bones; (d) absence/ presence of a concavity before the coronoid
process of dentary; (e) pharyngeal teeth surface ornamentation, either with grooves/ cusps; (f)
absence/ presence of 6th hypural. In addition to those, following characters, which have been
used to diagnose these two genera were repeated and confirmed in the present study: (a)
absence/presence of a bowl-shaped depression on the supraethmoid; (b) attachment of
Baudelot’s ligament on the dorsal part of the cleithrum, to distal end or not at the distal end;
(c) number of rows of pharyngeal teeth either two/ three; and (d) lateral line absent or present
(when present, incomplete).
Comparisons of putative topotypes of Rasboroides vaterifloris with materials collected from
several locations including the locations of Deraniyagala’s subspecies of Rasboroides in the
southwestern wet zone quarter of Sri Lanka (including Rakwana hills) revealed that R.
vaterifloris actually represents four different species.
Present study uncovered, two
subspecies of Rasboroides identified as distinct species and described a new species of
Rasboroides as well. Horadandia atukorali brittani is resurrected as a distinct species. Thus,
Horadandia atukorali, Rasboroides nigromarginatus and R. pallidus are three new additions
ii
to the endemic freshwater fish list of Sri Lanka. Rasboroides vaterifloris appears to be a
relatively uncommon fish in Gilimale forest. Rasboroides nigromarginatus is restricted to
the Atweltota (near Matugama), whereas R. pallidus has a stable population in the Bentara,
Gin, Polatumodera and Nilwala rivers. The new species found from Walawe River is the first
record of the genus from Walawe river. Horadandia atukorali is a widespread species in the
low land (North-western, Western and Southern Provinces) areas of Sri Lanka, whereas
Horadandia brittani is endemic to South India (Kottayam and Pondicherry areas).
To investigate the physico-chemical parameters suitable for distribution of Rasboroides
pallidus, five sites were selected in the Gin River, of which R. pallidus was recorded only
from two sites (i.e., Kottawa and Kanneliya). Physico-chemical parameters of both Kottawa
and Kanneliya were showed more or less similar values. Except Kosmulla (in the Sinharaja
forest), the other locations in which R. pallidus was not observed were within secondary
forests and/ or polluted. Kosmulla site was a torrent, but similar to the type locality of R.
vaterifloris.
Physico-chemical parameters of Kosmulla might not be favourable for
Rasboroides. Results on the velocity (flow rate), substrate and depth were in accordance with
the previous study of R. vaterifloris conducted at Ginigathhena (a locality in the Mahaweli
River). Present study concludes that Rasboroides pallidus is a habitat specialist, confined to
Kanneliya and Kottawa in the Gin River.
Rasboroides pallidus was observed.
With the onset of monsoon, breeding of
iii
ACKNOWLEDGEMENTS
I am grateful to Professor Udeni Edirisinghe (Program Coordinator, M. Sc. in Aquatic Bioresources Management & Aquaculture of the Postgraduate Institute of Agriculture (PGIA),
University of Peradeniya) and to Mr. Rohan Pethiyagoda (Ichthyological Section, Australian
Museum, Sydney (AMS)), under whose supervision and guidance this work has been carried
out. I am also grateful to Dr. A. R. S. B. Athauda for his guidance and support to continue
this research. I am deeply indebted to them for improvement of the manuscript and their
patience and friendly support, especially during the preparation of the manuscript, greatly
appreciated.
I would like to thank staff members of Board of Animal Science of PGIA, Prof. Mahinda B.
Dematawewa, Prof. Nimal Perera, Prof. Kalyani Perera, Prof. G. L. L. Pradeepa Silva, Dr. M.
P. B. Mahipala; Dr. Vajira P. Jayawardene, Dr. Thusith S. Samarakone, Dr. Janaka K.
Vidanachchi, Dr. Barana C. Jayawardana, and late Dr. S. Nathaneal (Rajarata University).
Thank to Mr. K. G. Nandasena, Mr. S. Leelaratne and all my colleagues of the PGIA for their
exceptional assistance in various ways.
I am also grateful to Dr. Tissa Devendra, Ms. Soma Nullaperuma (St. Aloysius College
Galle), Mr. Dharma Sri Kandamby (National Maritime Museum- Galle, Sri Lanka), Mr.
Hemantha V. Situge and late Mr. J. Alahendra for their guidance, encouragement and
enormous support for my studies.
I would like to acknowledge Mr. Sudath Nanayakkara (former Manager, WHT) for giving me
access to WHT collection (now in the National Museum, Colombo); and to Dr. Nanda
iv
Wickramasinghe (former Director, National Museum Colombo (NMSL)), Ms. Manori
Goonatilake (NMSL) and Ms. Chandrika Munasinghe (NMSL) for giving me to access the
WHT material in their care and for providing laboratory facilities.
I thank to Mr. Madura de Silva (President, Wildlife Conservation Society- Galle, [WCSG])
for giving me access to their recent fish collection and providing photographs of specimens;
Dr. Kalana Maduwage (University of Peradeniya), Dr. Suwin Hewage (University of
Peradeniya) and Mr. Sampath Udugampala (WCSG) for technical assistance and discussions
about fish osteology; and to Dr. Roshan Fernandupulle (University of Peradeniya) for his
help throughout this research in various ways.
I would like to thank Dr. Madhava
Meegaskumbura (University of Peradeniya) and Dr. Suresh P. Benjamin (National Institute
of Fundamental Studies [NIFS]) for laboratory facilities; to Dr. Eric Wickramanayake for
providing literature. My thanks also go to Ms. M. B. U. Perera (NIFS) for her assistance and
companionship.
I am also grateful to Dr. Gerhard Ott for providing photos of Horadandia atukorali from Sri
Lanka; and to Dr. Frank Schäfer (Editor, AQUALOG) for giving me photos of H. atukorali
brittani from India.
I am indebt to my beloved father, and my elder brother and younger brother for their
immense help and encouragement throughout my studies.
Finally, I would like to thank to my beloved family members who gave me much strength in
the completion of this research. I express my in-depth love to my wife, sweet little son &
sweet
little
daughter
for
their
affection
and
care.
v
Dedication
In memory of my beloved mother
Swarna Batuwita
vi
TABLE OF CONTENTS
ABSTRACT................................................................................................................................... i
ACKNOWLEDGEMENTS ......................................................................................................... iii
TABLE OF CONTENTS ............................................................................................................. vi
LIST OF TABLES ....................................................................................................................... xi
LIST OF FIGURES .................................................................................................................... xii
LIST OF ABBREVIATIONS ................................................................................................... xvii
CHAPTER I. INTRODUCTION ...................................................................................................1
1.1 Importance of taxonomic studies .......................................................................................1
1.2 History of fish taxonomy ...................................................................................................2
1.3 Fish as vertebrates ..............................................................................................................3
1.4 Importance of fish ..............................................................................................................3
1.5 Importance of study of fish taxonomy in Sri Lanka ..........................................................3
1.6 Origin of Cyprinidae ..........................................................................................................4
1.7 The discovery of the genus Horadandia ............................................................................5
1.8 The discovery, synonymy and resurrection of the genus Rasboroides ..............................6
1.9 Biogeography .....................................................................................................................7
1.10 Objectives ........................................................................................................................7
CHAPTER II. REVIEW OF LITERATURE ................................................................................8
2.1 History of taxonomy of fish .............................................................................................. 8
2.2 History of the taxonomy of fishes of Sri Lanka ................................................................ 9
2.3 Species in the subfamily Danioninae of Sri Lanka ......................................................... 10
2.4 Riverine eco-systems of the world and Sri Lanka .......................................................... 11
vii
2.5 The Gin River ................................................................................................................. 11
2.6 Previous studies on the Freshwater fish distribution pattern in Sri Lanka ..................... 12
CHAPTER III. MATERIAL AND METHODS ..........................................................................13
3.1 Experiment 01: Taxonomic study on the comparative morphology of Cyprinid genera
Horadandia and Rasboroides and evaluate the interspecific and intraspecific variations of
each species from both genera .................................................................................................... 13
3.1.1. Methodology for the osteological study ................................................................. 13
3.1.1.1. Clearing and staining of specimens .................................................................. 14
3.1.1.2. Meristic data (Osteological) .............................................................................. 14
3.1.2. External morphological study ................................................................................ 15
3.1.2.1. Meristic (Counts) and Mensural data (Measurements) ..................................... 15
3.1.2.2. Statistical data analysis (Principal component analysis)................................... 19
3.2 Experiment 02: Evaluation of the present distribution pattern of Rasboroides vaterifloris
pallida in the Gin River basin ............................................................................................... 20
3.2.1. Fish sampling ......................................................................................................... 21
3.2.2 Physico-chemical characteristics ............................................................................. 23
CHAPTER IV. RESULTS AND DISCUSSION.........................................................................24
4.1.Experiment 01: Taxonomic study on the comparative morphology of Cyprinid genera
Horadandia and Rasboroides and evaluate the interspecific and intraspecific variations of
each species from both genera ...............................................................................................24
4.1.1. Comparative morphology of Horadandia and Rasboroides ..................................24
4.1.1.1. Genus Horadandia Deraniyagala, 1943.............................................................24
4.1.1.1.1. Diagnosis of Horadandia ............................................................................25
4.1.1.2. Genus Rasboroides Brittan, 1954 ......................................................................30
viii
4.1.1.2.1. Diagnosis of Rasboroides ............................................................................30
4.1.1.3. Statistical analysis (Principal Component Analysis) .........................................34
4.1.2. Interspecific and intraspecific variations of Horadandia and Rasboroides ............39
4.1.2.1. Interspecific and intraspecific variations of Horadandia ..................................39
4.1.2.1.1. Horadandia atukorali Deraniyagala, 1943 .................................................39
4.1.2.1.1.1. Description (external morphology) ...................................................40
4.1.2.1.1.2. Description (Osteology). ...................................................................44
4.1.2.1.1.3. Distribution .......................................................................................46
4.1.2.1.2. Horadandia brittani Rema Devi & Menon, 1992 .......................................47
4.1.2.1.2.1. Description (external morphology) ...................................................47
4.1.2.1.2.2. Description (Osteology). ...................................................................48
4.1.2.1.2.3. Distribution .......................................................................................50
4.1.2.1.3. Statistical analysis (Principal Component Analysis)...................................50
4.1.2.2. Interspecific and intraspecific variations of Rasboroides ..................................51
4.1.2.2.1. Rasboroides vaterifloris (Deraniyagala, 1930) ...........................................52
4.1.2.2.1.1. Description (external morphology) ...................................................52
4.1.2.2.1.2. Description (Osteology). ...................................................................57
4.1.2.2.1.3. Distribution .......................................................................................59
4.1.2.2.2. Rasboroides nigromarginatus (Meinken, 1957) .........................................60
4.1.2.2.2.1. Description (external morphology) ...................................................60
4.1.2.2.2.2. Description (Osteology). ...................................................................62
4.1.2.2.2.3. Distribution .......................................................................................64
4.1.2.2.3. Rasboroides pallidus Deraniyagala, 1958 ...................................................65
4.1.2.2.3.1. Description (external morphology) ...................................................65
4.1.2.2.3.2. Description (Osteology). ...................................................................70
ix
4.1.2.2.3.3. Distribution .......................................................................................72
4.1.2.2.4. Rasboroides new species .............................................................................73
4.1.2.2.4.1. Description (external morphology) .............................................73
4.1.2.2.4.2. Description (Osteology). .............................................................75
4.1.2.2.4.3. Distribution .................................................................................76
4.1.2.2. 5. Statistical analysis (Principal Component Analysis)..................................78
4.1.3 Key to the species of the genera Horadandia and Rasboroides...............................82
4.2 Experiment 02: Evaluation of the present distribution pattern of Rasboroides vaterifloris
pallidus in the Gin River.......................................................................................................84
4.2.1. Fish sampling and distribution ................................................................................85
4.2.2. Physico-chemical characteristics .............................................................................90
4.2.2.1. Water temperature ..............................................................................................90
4.2.2.2. Stream pH ..........................................................................................................91
4.2.2.3. Depth of water column .......................................................................................92
4.2.2.4. Stream flow rate (velocity) ................................................................................93
4.2.2.5. Percentage of canopy cover ...............................................................................94
4.2.2.6. Substrate .............................................................................................................95
4.2.2.7. Turbidity.............................................................................................................96
CHAPTER V. CONCLUSIONS .................................................................................................97
CHAPTER VI. REFERENCES ...................................................................................................99
x
APPENDIX 1: Materials referred to this study .........................................................................115
APPENDIX 2: Principal Component Analysis of continuous variables of genera Horadandia
and Rasboroides ...............................................................................................117
APPENDIX 3: Principal Component Analysis of continuous variables of Horadandia
atukorali and H. brittani ...................................................................................118
APPENDIX 4: Principal Component Analysis of continuous variables of Rasboroides
vaterifloris, R. nigromaginatus, R. pallidus and Rasboroides new species ..119
APPENDIX 5: New character states used in this study.............................................................120
APPENDIX 6: Selected character states of Liao et al. (2010) used for this study ....................121
APPENDIX 7: Summary of physico-chemical parameters measured during the study ............126
APPENDIX 8: Publications based on the thesis ........................................................................127
xi
LIST OF TABLES
Tables
Table 3.1. Coordinates, elevation, adjoining forest, sources of pollution, presence of
waterfalls, substrate and adjoining vegetation of the selected sites .........................................22
Table 4.1. Cranium, pectoral girdle and pelvic girdle character states of, Rasboroides
vaterifloris; R. nigromarginatus; R. pallidus; Rasboroides new species; Horadandi atukorali;
and H. brittani ..........................................................................................................................38
Table 4.2. Morphometric data of Horadandia atukorali and H. brittani.. ..............................41
Table 4.3.Meristics of Horadandia atukorali and H. brittani. ................................................43
Table 4.4. Meristics of Rasboroides vaterifloris and R. nigromarginatus. .............................54
Table 4.5. Morphometric data of Rasboroides vaterifloris and R. nigromarginatus... ...........57
Table 4.6. Morphometric data of Rasboroides pallidus and Rasboroides new species.. ........67
Table 4.7. Canopy cover percentage and substrate categories of selected sites. .....................95
xii
LIST OF FIGURES
Figure 3.1.Methodology for taking meristic data ....................................................................16
Figure 3.2.Methodology for taking mensural data...................................................................18
Figure 3.3. Selected sites along the Gin River, Sri Lanka. .....................................................20
Figure 4.1. Osteology of Horadandia atukorali ......................................................................26
Figure 4.2. Osteology of Horadandia atukorali(contd.). ........................................................27
Figure 4.3. Osteology of Horadandia brittani .........................................................................28
Figure 4.4. Osteology of Horadandia brittani(contd.) ............................................................29
Figure 4.5. Osteology of Rasboroides pallidus. .....................................................................31
Figure 4.6. Osteology of Rasboroides pallidus (contd.) ..........................................................32
Figure 4.7. Osteology of Rasboroides nigromarginatus .........................................................33
Fig. 4.8. First principal component vs. second principal component of the principal
component analysis of Horadandia and Rasboroides .............................................................35
xiii
Fig. 4.9. Horadandia atukorali, living specimen, from Hamilton canal, Sri Lanka (Courtesy
of Gerhard Ott). ........................................................................................................................42
Fig. 4.10. Horadandia atukorali: A, dorsal view of kineethmid; B, lateral view of left dentary
(co, coronoid process); C, lateral view of left maxillae (pp, palatine process); D, dorsal view
of cranium (so, supraocular; f, frontal). ...................................................................................44
Fig. 4.11. Ventral views of dentary showing presence (arrows) and absence of Danionin
notch: A, Horadandia atukorali; B, Horadandia brittani; C, Rasboroides vaterifloris; D,
Rasboroides nigromarginatus; E, Rasboroides pallidus; F, Rasboroides new species (Scale
bars 1.0 mm). ...........................................................................................................................45
Fig. 4.12. Records of Horadandia species from India and Sri Lanka; H. atukorali (closed
circles); H. brittani (open circles). ...........................................................................................46
Fig. 4.13. Horadandia brittani, Kerala, India (Courtesy of Frank Schäfer). ...........................47
Fig. 4.14. Horadandia brittani: A, dorsal view of kineethmid; B, lateral view of left dentary
(co, coronoid process); C, lateral view of left maxillae (pp, palatine process);; D, dorsal view
of cranium (so, supraocular; f, frontal). ...................................................................................49
Fig. 4.15. First Principal Component vs. Second Principal Component of the Principal
Component Analysis of Horadandia atukorali and H. brittani...............................................51
xiv
Fig. 4.16. Rasboroides vaterifloris. A (male), B (female), living specimens, from Gilimale (in
the Induruwa Forest), Sri Lanka (Courtesy of WCSG); C, BMNH 1930.10.8.1, 25.7 mm SL,
syntypes, male (above) and female (below); Sri Lanka: Kalu River: Illukwatta (Courtesy of
Rohan Pethiyagoda). ................................................................................................................53
Fig. 4.17. Rasboroides vaterifloris. A, Lateral views of dentary (co, coronoid process); B,
Right operculum.......................................................................................................................58
Fig. 4.18. Distribution of Rasboroides vaterifloris (type locality, closed circle) in Sri Lanka.
..................................................................................................................................................59
Fig. 4.19. Rasboroides nigromarginatus. A, living male specimen, from Atweltota, Sri Lanka
(Courtesy of WCSG; B, ZMH 1207, male holotype (Courtesy of Ralf Thiel); C, living female
specimen, from Atweltota, Sri Lanka (Courtesy of WCSG); D, ZMH 1208, female paratype
(Courtesy of Ralf Thiel).. ........................................................................................................61
Fig. 4.20. Rasboroides nigromarginatus. A, Lateral views of dentary (co, coronoid process);
B, Right operculum (showing indentation). .............................................................................63
Fig. 4.21. Distribution of Rasboroides nigromarginatus in Sri Lanka ....................................64
Fig. 4.22. Rasboroides pallidus; A, not preserved, male, in life; Gin River basin: KottawaKombala forest reserve; B, not preserved, male, in life; Bentara River basin, Pituwala; C,
WHT 9703, 24.3 mm SL, male; Sri Lanka: Kottawa forest reserve (All photographs,
Courtesy of WCSG). ................................................................................................................66
xv
Fig. 4.23. Rasboroides pallidus. A, Lateral views of dentary (co, coronoid process); B, Right
operculum (arrows-lateral process). ........................................................................................71
Fig. 4.24. Distribution of Rasboroides pallidus (type locality, closed circle) in Sri Lanka. ..72
Fig. 4.25. Rasboroides new species. A, Lateral views of dentary (co, coronoid process); B,
Right operculum (arrow-lateral process). ...............................................................................74
Fig. 4.26. Rasboroides new species; A , WHT 9711, 31.3 mm SL, male; B, WHT 9720, 34.1
mm SL, female, in life; Sri Lanka: Walawe River basin: Suriyakanda (Photographs, Courtesy
of WCSG).. ..............................................................................................................................76
Fig. 4.27. Distribution of Rasboroides new speciesin Sri Lanka.. ..........................................77
Fig. 4.28. First principal component vs. second principal component of the principal
components analysis of four species of Rasboroides identified by the present study ............79
Fig. 4.29. Distribution of Rasboroides pallidus in the study sites of Gin River: Kottawa
(below) and Kanneliya (above) in red colour (Rasboroides pallidus present). Madola (below),
Homadola (middle), and Kosmulla (above) in black colour (Rasboroides pallidus absent). .84
Fig. 4.30. Cumulative number of individuals observed during the study period at each site .85
Fig. 4.31. Distribution of species richness and abundance in all the sites. .............................87
xvi
Fig. 4.32. Mean abundance of R pallidus in the two sites during the study period ................88
Fig. 4.33: Number of individuals (including juveniles) of Rasboroides pallidus observed in
the Kottawa and Kanneliya.. ....................................................................................................89
Fig. 4.34. Variation of water temperature in the sites throughout the study period (JanuaryDecember). ...............................................................................................................................91
Fig. 4.35. Fluctuation of pH in the selected sites (from January to December). ....................92
Fig. 4.36. Fluctuations of water depth in the selected sites (January-December) ..................93
Fig. 4.37. Variation of flow rate in different sites throughout the study period (JanuaryDecember) ................................................................................................................................94
Fig. 4.38. Variation of turbidity throughout the study period (January-December) ...............96
xvii
List of Abbreviations
CBD
Convention on Biological Diversity
DWC
Department of Wildlife Conservation
FAO
Food and Agriculture Organization of UN
GEF
Global Environment Facility
GTI
Global Taxonomy Initiative
NIFS
National Institute of Fundamental Studies
NMSL
National Museum of Sri Lanka
ICZN
International Commission on Zoological Nomenclature
IUCN
International Union for Conservation of Nature
PGIA
Postgraduate Institute of Agriculture
STAP
Scientific and Technical Advisory Panel
TRI
Tea Research Institute.
WCSG
Wildlife Conservation Society
WHT
Wildlife Heritage Trust
WWF
World Wildlife Fund
ZMH
Zoological Museum Hamburg
ZSI
Zoological Survey of India
1
CHAPTER I
1.0 INTRODUCTION
1.1.
Importance of taxonomic studies
Global biodiversity is being lost at an unprecedented rate because of human activities and
decisions have to be taken to prevent this enormous loss of biodiversity (WWF, 2015).
However, decision-makers have to decide where to establish protected areas. Hence, they
should have a sound knowledge on the fauna and flora of the world (Convention on
Biological Diversity [CBD], 2015).
Gathering data on known (or previously described
species) and exploring and describing unknown is the base for taxonomy.
Taxonomy
provides basic understanding about the components of biodiversity, which is necessary for
effective decision-making about conservation and sustainable use. Study of taxonomy will
bring benefits of biodiversity to the whole world by using their biological values and decision
makers or regulators can identify and take necessary measures to control or eradicate harmful
invasive species (CBD, 2015).
Ultimately, taxonomists classify organisms to better
understand how all living thing are interconnected.
Information arising from properly identified specimens includes data that can be used outside
taxonomy (Global Taxonomy Initiative [GTI], 2015). As an example, these data will provide
information to predict distributions of species, both actual and potential (e.g. as a response to
climate change or if the organism is introduced into a new geographic area), and they can
provide information with respect to most urgent areas to protect these species. In addition,
they can provide baseline data to plot the changing fortunes of taxa and ecosystems under
anthropogenic influence, predictions of interactions between species which come into contact
2
through natural or artificial changes in distribution, linkages between different life stages of
organisms where these look dissimilar (GTI, 2015).
1.2.
History of fish taxonomy
The study of fish dates from the Upper Paleolithic Revolution (with the advent of 'high
culture') (Nelson, 2006; FishBase, 2015). The science of ichthyology was developed in
several interconnecting eras, each with various significant advancements. The study of fish
received its origins from human's desire to feed, clothe and equip themselves with useful
implements (Nelson, 2006). According to Michael Barton, a prominent ichthyologist, "the
earliest ichthyologists were hunters and gatherers who learned how to obtain the most useful
fish, where to obtain them in abundance and at what times they might be most available"
(Nelson, 2006). Early cultures manifested these insights in abstract and identifiable artistic
expressions (FishBase, 2015).
Georg Marcgrave of Saxony composed the ‘Naturalis Brasilae’ in 1648 (Oregon Piranha
Exotic Fish Exhibit [OPEFE], 2016). This document contained a description of 100 species
of fish indigenous to Brazil. In 1686, John Ray and Francis Willughby published ‘Historia
Piscium’, a manuscript containing 420 species of fish, ~180 discovered, while those fish
contained within this informative literature were arranged in a provisional system of
classification (OPEFE, 2016).
Though a large number of species have been discovered and described, approximately 250
new species are officially described each year. According to FishBase (2015), 34300 species
of fish had been described by October 2015.
3
1.3.
Fish as vertebrates
Fishes are one of the major classes of vertebrates, which are widespread in freshwater,
brackish water as well as in marine waters (Nelson, 2006). Occupancy of a wide variety of
habitats and niches may be the reason for their high diversity among the other vertebrates.
Three-fourths of world’s surface is covered with water and fish are found in most of these
areas. Fish can live even in hostile environs, such as hot springs, volcanic seas, deep seas and
very cold areas (Nelson, 2006).
1.4.
Importance of fish
Fish are an important resource for humans worldwide, especially as a source of food.
Commercial and subsistence fishers hunt fish or farm them in ponds or in cages in different
aquatic resources. Some people keep fish as pets and exhibit in public aquaria. Fish have
had a role in culture through the ages, serving as deities, religious symbols and as the subjects
of art, books as well as movies (FishBase, 2015).
1.5.
Importance of study of fish taxonomy in Sri Lanka
Sri Lanka is a continental island, having ~65 610 km2 of land area (Somasekaram, 1997),
which during a greater part of its geological history had been a part of the Indian subcontinent
(Erdelen, 1989). Sri Lanka also possesses a highly diverse endemic fauna and flora (Myers et
al., 2000; Bossuyt et al., 2004). Studies on the Sri Lankan ichthyofauna is handful and most
of the large taxonomic studies had been published during the colonial period and are
4
concentrated to whole south Indian region or South Asia including some south-east Asian
regions (Günther, 1868; Day, 1888,1889); because at that time this whole region had been
managed by the East India Company. Thus, lack of comprehensive studies on the Sri Lanka
fishes is obvious, except the attempts made by P. E. P. Deraniyagala and I. S. R. Munro
(Deraniyagala, 1952; Munro, 1955).
Deraniyagala published many papers on Sri Lankan ichtthyofauna (Deraniyagala, 1929a, b, c;
1930; 1932; 1933; 1936; 1937a, b) and subsequently in 1952 published his classical work as
‘The Colored Atlas of Some Vertebrates from Ceylon: Fishes (volume one)’ (Deraniyagala,
1952). Munro (1955) published ‘Marine and freshwater fishes of Sri Lanka’, which included
almost all fish reported then from Sri Lanka and might be the first near-complete taxonomic
study in Sri Lanka. Recently, a few colour guides to the freshwater fishes of Sri Lanka were
published (Goonatilake, 2007; De Silva et al., 2015) but they have not addressed in depth, the
taxonomy of Sri Lankan fishes.
However, Pethiyagoda (1991) alone described and
uncovered many obscure literature in Sri Lankan ichthyofauna in his book, ‘Freshwater fishes
of Sri Lanka’ and gave several clues about potentially new species and described some of
them (with Maurice Kottelat, three new freshwater fishes from Sri Lanka). Unarguably,
Pethiyagoda’s (1991) work is the stepping-stone for the future studies on the freshwater
fishes of Sri Lanka (e.g. Goonatilake, 2007; De Silva et al., 2015).
1.6.
Origin of Cyprinidae
Thirty percent of fishes of the world are represented by Otophysi (one of the Series of
Superorder Ostariophysi); 64% of all freshwater species including Cypriniformes also belong
to Otophysi (Nelson, 2006). Freshwater fishes of the world comprise about 60 orders, of
5
which Cypriniformes
comprises of six families, i.e., Cyprinidae, Catostomidae,
Gyrinocheilidae, Psilorhynchidae, Cobitidae, and Balitoridae and it is the largest group of
freshwater fishes (Nelson, 2006). Cyprinidae is the largest vertebrate family with ~3000
currently recognized species (FishBase, 2016).
Many zoogeographers believed that the
centre of the origin for the Cyprinidae is the Oriental region, where almost all the major
groups and subgroups of cyprinids now live (Darlington, 1957; Bănărescu, 1972; Briggs,
1979). These scientists assume that the family Cyprinidae has dispersed to other geographic
regions from the Oriental region. Fossil records also confirmed this hypothesis since fewer
groups of cyprinids are present beyond the Asian-Oriental region, i.e., in Europe, Africa and
North America (Cavender, 1991).
1.7.
The discovery of the genus Horadandia
Horadandia was first described based on the discovery of a diminutive cyprinid fish
Horadandia atukorali (Deraniyagala, 1943). This species was first collected by a Sri Lankan
naturalist, Victor (Vicky) Atukorale, who collected it from Western coast of Sri Lanka and
drew the attention of Deraniyagala. According to folklore, Deraniyagala called and named
this species as Hora (= thief) + dandia (= Rasbora-like species) and thereby named the genus
epithet and the species epithet as atukorali in honour of the collector. Deraniyagala had a
doubt about the affinity of this new genus; either to Rasborinae (now classified in the
Danioninae) or to Cyprininae (Deraniyagala, 1943).
Horadandia remained as a monotypic genus until the discovery of a subspecies, Horadandia
atukorali brittani from India (Rema Devi and Menon, 1992). This subspecies is currently
considered as a junior synonym of H. atukorali. Horadandia atukorali is a widespread fish
6
in Sri Lanka, distributed from Puttalam to Colombo, and extends to Galle (i.e., Hiyare and
Wakwella). It is hitherto not recorded from the eastern coast of Sri Lanka.
1.8.
The discovery, synonymy and resurrection of the genus Rasboroides
Rasboroides vaterifloris (earlier Rasbora vaterifloris) was originally described from Gilimale
in the Sabaragamuwa Province of Sri Lanka (Deraniyagala, 1930). Brittan (1954) was the
first reviser, who recognized the uniqueness of Rasbora vaterifloris and proposed a new
subgenus, Rasbora (Rasboroides).
Later, another species, R. nigromarginatus (then
described as a Rasbora sp.) was discovered (Meinken, 1957). The exact locality of this rare
species has long been a mystery until simultaneously it was found in the Wildlife Heritage
Trust materials (present study) (now deposited in the National Museum Sri Lanka) and from
freshly collected specimens by the Wildlife Conservation Society, Galle (live fishes from the
same locality, Atweltota).
Wildlife Heritage Trust of Sri Lanka (WHT) had collected
Rasboroides nigromarginatus from Atweltota and they tentatively identified it as R.
vaterifloris. During the museum reference work in 2011, fourteen specimens of Rasboroides
nigromarginatus were found in the National Museum Sri Lanka (bearing the catalogue
number WHT 0528).
Deraniyagala (1958) considered this species (Rasboroides
nigromarginatus) as a yet another subspecies of Rasboroides vaterifloris. Deraniyagala (1958)
also described four subspecies of Rasboroides vaterifloris from Sri Lanka (then in the genus
Rasbora): the forma typica (i.e., Rasboroides vaterifloris vaterifloris) from Sabaragamuwa
Province (Gilimale and Parakaduwa), Rasboroides vaterifloris ruber from Western Province
(Meegahatenna to Vallallavita), and two subspecies from Southern Province, i.e.,
Rasboroides vaterifloris rubrioculis (from Akuressa) and Rasboroides vaterifloris pallidus
(from Kottawa).
7
1.9.
Biogeography
Alfred Wegener introduced the Theory of Continental Drift in 1912, though it was not widely
accepted until the 1960s (Cox et al., 1963). This theory was revolutionary, because it
changed the way that everyone thought about species and their distribution around the globe.
MacArthur and Wilson (1967) showed that the species richness of an area could be predicted
in terms of habitat area, immigration rate and extinction rate. This was added to the longstanding interest in island biogeography. Classical biogeography has been expanded by the
development of molecular systematics, creating a new discipline known as phylogeography.
This development allowed scientists to test theories about the origin and dispersal of
populations, such as island endemics (Avise et al., 1987).
1.10.
Objectives
The main objectives of this study are:
(1) to study the taxonomy of two closely related Rasborini genera Rasboroides and
Horadandia, i.e.,
a. to study the comparative morphology of two Rasborini genera, Rasboroides
and Horadandia
b. to evaluate interspecific and intraspecific variation of congeners of both
genera, and
(2) to study the present distribution pattern of Rasboroides vaterifloris pallidus in Gin
River.
8
CHAPTER II
2.0 REVIEW OF LITERATURE
2.1. History of taxonomy of fish
Ichthyology (from Greek: ἰχθύς, ikhthus, "fish"; and λόγος, logos, "study"), also known as
Fish Science, is the branch of biology devoted to the study of fish. This includes bony fishes
(Osteichthyes), cartilaginous fishes (Chondrichthyes) and jawless fish (Agnatha).
According to Oregon Piranha Exotic Fish Exhibit [OPEFE] (2016), classification used in the
‘Historia Piscium’ was further developed by Carl Linnaeus, the "father of modern taxonomy".
His taxonomic approach became the systematic approach to the study of organisms, including
fish. One of his colleagues, Peter Artedi known as "father of ichthyology" through his
indispensable advancements recognized five orders of fish: Malacopterygii, Acanthopterygii,
Branchiostegi, Chondropterygii, and Plagiuri (OPEFE, 2016). Artedi developed standard
methods for making counts and measurements of anatomical features that are currently
exploited. Another associate of Linnaeus, Albertus Seba, assembled a cabinet, or collection
of fish (OPEFE, 2016).
During the nineteenth century, Marcus Elieser Bloch of Berlin and Georges Cuvier of Paris
made attempts to strengthen the knowledge of ichthyology (OPEFE, 2016). Cuvier had
summarized all of the available information in his monumental ‘Histoire Naturelle des
Poissons’. This manuscript had been published between 1828 and 1849 in a 22 volume series
(OPEFE, 2016). This document describes ~4500 species of fish, of which 2311 are new to
9
science, which remains one of the most ambitious treatises of the modern world (OPEFE,
2016).
2.2. History of the taxonomy of fishes of Sri Lanka
The first freshwater fish species described from Sri Lanka appears to be the endemic
carnivorous fish, Channa orientalis (Bloch & Schneider, 1801). Secondly, Gronow in Gray
(1854) had described a very rare fish, Mastacembulus pentopthalmus (Pethiyagoda et al.,
2008d; De Silva et al., 2015). However, the most remarkable fish collection had been
performed by A. A. M. Reynaud in 1828 from Kanniyai, a hot spring of Sri Lanka (now a
popular place for tourists) (pers. obs.). George Cuvier of Paris museum described several
new species based on Reynaud’s collection (Cuvier & Valenciennes, 1844) (Pethiyagoda,
1991). According to Pethiyagoda (1999), some of these species are a mystery to science and
have not reported thereafter. In an extensive collection of A. Cumming, Albert Günther of
British Museum of Natural History had described many new species especially in the wet
zone area, whereby added several new species to science (Günther, 1868). Peter Bleeker had
come to historical port city, Galle also in 1860s and had collected several freshwater fish
from Sri Lanka (Bleeker, 1859, 1863). However, the most enigmatic fish collection from Sri
Lanka was owned by E. F. Kelaart, who sent those specimens to Zoological Survey of India
(ZSI) (Pethiyagoda, 1991). These hill country stream fishes have not been reported from Sri
Lanka. Hence, there are two possible explanations for it, these fishes might have been very
sensitive to their niches and thereby got extinct during the colonial period due to the massive
deforestation in the hill country or these fishes had been originally not collected from Sri
Lanka but from India.
10
The most classical and comprehensive work on fishes of the south Asian region was
published by Francis Day, which included several new species from Sri Lanka (Day, 1878).
Duncker (1910, 1912) also made an extensive collection from Sri Lanka.
2.3. Species in the subfamily Danioninae of Sri Lanka
Within the Cyprinidae, Danioninae is one of the diverse subfamilies and a widespread group
of fish. Species of Danioninae are distributed across Africa, through southern and south-east
Asia (Indonesia and Philippines), and into eastern Asia (Howes, 1991).
Only Barilius
mesopotamicus collected in the Middle East (Coad and Krupp, 1983; Liao et al., 2011).
Among the Rasborini in the subfamily Danioninae, other than the Horadandia atukorali and
Rasboroides vaterifloris, two other genera occur in Sri Lanka, i.e., Rasbora and
Amblypharyngodon.
Recently, Silva et al. (2010) reviewed the genus Rasbora and
recognized five species from Sri Lanka: R. dandia, R. microcephala, R. wilpita, R. armitagei
and R. naggsi. Amblypharyngodon represents two species from Sri Lanka (Pethiyagoda,
1991).
Kottelat and Vidthayanon (1993) accepted Brittan’s classification of the identity of the genus
Rasboroides and resurrected.
Kottelat and Vidthayanon (1993) also suggested that
Rasboroides could be a synonym of Horadandia. Very recently, Liao et al. (2010) provided
some evidence to separate these two genera (Horadandia and Raboroides). However, Tang
et al. (2010) again showed a possibility to synonym Rasboroides under Horadandia.
11
2.4. Riverine ecosystems of Sri Lanka
Drainage systems are the patterns formed by the streams, rivers, and lakes in a particular
basin. Geomorphologists and hydrologists often view streams as parts of drainage basins
(Pidwirny, 2006). A drainage basin is the topographic region from which a stream receives
runoff and groundwater flow (Pidwirny, 2006). Drainage basins are divided from each other
by topographic barriers called watersheds, which represent all the stream tributaries that flow
to some location along the stream channel (Pidwirny, 2006).
Dendritic systems are the most common form of drainage systems often found in Sri Lanka.
In a dendritic system, there are many contributing streams (analogous to the twigs of a tree),
which are then joined together into the tributaries of the main river (the branches and the
trunk of the tree respectively). They develop where the river channel follows the slope of the
terrain. Dendritic systems form in V-shaped valleys and as a result, the rock types must be
impervious and non-porous (David, 1998).
2.5. The Gin River
The Gin River is ~116 km long (Wickramaarachchi et al., 2013) and situated in Galle District
of Sri Lanka. It has a catchment area of about 932 km2 and is located approximately between
the longitudes 80°08” E and 80°40” E, and latitudes 6°04” N and 6°30” N. The Baddegama
River gauging station (6°11’23” N, 80°11’53” E) covers an upstream catchment area of 780
km2 (Wickramaarachchi et al., 2013). Catchment of the Gin river includes Galle (83 % of the
basin area), Matara (9 % of the basin area), Rathnapura (7 % of the basin area), and Kalutara
(1 % of the basin area) administrative districts (Wickramaarachchi et al., 2013).
12
Gin River originates from the Gongala mountains in Deniyaya, which has an elevation of
over 1300 m and flows to the Indian Ocean at Gintota in Galle District (Wickramaarachchi et
al., 2013). Rainfall pattern in the catchment is bi-modal, falling between May and September
(south-west monsoon, which is the major rainfall season), and again between November and
February (north-east monsoon) followed by inter-monsoon rains during the remaining months
of the year (Wickramaarachchi et al., 2013). Rainfall varies with altitude with a mean annual
rainfall above 3500 mm in the upper reaches, to less than 2500 mm in the lower reaches of
the catchment while it annually discharges about 1268 million cubic meters of water to the
sea (Wickramaarachchi et al., 2013). The Gin River is one of the main sources of water
supply in the southern region of Sri Lanka (Wickramaarachchi et al., 2013). Galle is the
capital city in Southern Sri Lanka and the city’s pipe-borne water supply system depends on
the water resources in the Gin river basin.
2.6. Previous studies on the freshwater fish distribution pattern in Sri Lanka
Ichthyofauna of Sri Lanka has a great diversity (either freshwater or brackish water or marine)
(Deraniyagala, 1952; Munro, 1955; Pethiyagoda, 1991; De Silva et al., 2015). Although
taxonomy of Sri Lankan fish has been published, the studies on their biology and ethology
are limited (Costa and Fernando, 1967; Kortmulder, 1972, 1986; De Silva and Kortmulder,
1977; De Silva et al., 1977; Wickramanayake, 1990). Ecology of freshwater fishes of Sri
Lanka is poorly studied. During the 1980s, some studies on the physico-chemical parameters
that affected the distribution of fish have been reported from Sri Lanka (Radda, 1973; Moyle
and Senanayake, 1984; Schut et al., 1984; Wickramanayake and Moyle, 1989).
13
CHAPTER III
3.0 MATERIALS AND METHODS
3.1.
Experiment 1: Taxonomic study on the comparative morphology of Cyprinid
genera Horadandia and Rasboroides and evaluation of the interspecific and intraspecific
variations of each genera.
Materials referred in this experiment were deposited in the collection of the Wildlife Heritage
Trust of Sri Lanka (WHT), which are now housed in the National Museum Colombo
(NMSL), the Zoological Museum Hamburg (ZMH), or at the Wildlife Conservation SocietyGalle (WCSG). The materials in the WCSG collection (bearing WHT catalogue numbers)
used in this study were collected in the course of a national freshwater-fish survey
commissioned by the Department of Wildlife Conservation (DWC) during 2010 to 2014
period.
3.1.1. Methodology for the osteological study
For osteological terminology Fang (2003) was followed, as described in Appendix 2. One to
six examples from each species from the genera Horadandia and Rasboroides were cleared
and stained using alizarin red S dye by a slightly modified procedure of Taylor & Van Dyke
(1985) as described below.
14
3.1.1.1. Clearing and staining of specimens
Preparation of Alizarin Red S solution: 2.0 g of Alizarin red S were mixed in 100.0 mL of
distilled water and the pH were adjusted to 4.1-4.3 using 0.5% potassium hydroxide.
Each fish specimen was de-scaled and skins were removed before cleaning and staining them.
Then these specimens were hydrated in 70% alcohol and were rinsed rapidly in distilled
water and placed in Alizarin red S solution for about 1-2 days depending on the size of each
specimen. The excess dyes were poured into another container and the specimens were
rinsed with distilled water. Then the specimens were transferred to following concentrations
of glycerin solutions respectively, 25%, 50% and 75%.
Finally, cleared and stained
specimens were stored in 100% glycerin solution.
3.1.1.2. Meristic data (Osteological)
Abdominal vertebrae were counted including the Weberian apparatus. Caudal vertebrae were
counted from the first haemal-spine bearing vertebra to the last half-centrum supporting the
hypural series.
All cleared and stained specimens were observed under a stereomicroscope and photographed
with an Olympus E 330 digital camera. Drawings were made using a Motic dissecting
microscope fitted with a camera lucida.
Pharyngeal teeth were photographed using an
Olympus BX 51 microscope and Olympus E330 digital camera; 2-5 photographs at different
depths of field were subsequently stacked using Helicon Focus software (Version 5.1) and
edited using Photoshop software (CS 5).
15
3.1.2. External morphological studies
Specimens were collected by using hand nets and drag nets. Freshly collected specimens
were fixed in 5% formalin and within two weeks, they were transferred to 70% ethyl alcohol.
Measurements were made with an aid of a dial Vernier calliper to the nearest 0.1 mm under a
stereoscope. Sexes of Rasboroides were determined by the finely serrated anterior edge of
the pectoral fins of males.
3.1.2.1. Meristic (Counts) and Mensural data (Measurements)
Counts were always made on the left side of the body for bilaterally symmetric features (Fig.
3.1). Dorsal fin rays were either spines or undivided simple rays and branched (divided) rays.
Since the posterior two rays of the dorsal and anal fins are branches of the same ray that unite
internally, they were counted as a single ray (last branch was denoted as a half-ray, e.g. 5½).
Anal fin rays were either simple rays or branched rays as indicated above. Caudal fin rays
were all branched rays excluding unbranched rays that formed the dorsal and ventral borders
of the caudal fin. Pectoral fin rays including simple rays and branched-rays were counted.
Pelvic fin rays were counted including simple rays and branched-rays.
16
Fig. 3.1. Methodology for taking meristic data (after Armbruster, 2012).
17
Lateral line or lateral rows of scales were counted from the scale bearing the lateral line canal
at the anterior edge of body (close to opercle edge in Rasboroides) to the end of the vertebral
column (end of the hypural plate). For Horadandia (lateral line is absent), counted from the
scale at the anterior edge of body (close to opercle edge) in a continuous row of scales to the
last scale at the end of vertebral column. Body scales in transverse line were counted
diagonally from the dorsal fin origin postero-ventral to the scale anterior to the anal fin origin,
with the scales straddling the fin origins counted as half (½).
Pre-dorsal scales were counted in a row between the supra-occipital and the origin of the
dorsal fin. Pre-ventral scales were counted from the origin of ventral fins to the isthmus.
Circumpedicular scales were counted at narrowest portion of caudal peduncle from anteriodorsalmost scale to posterio-ventral direction (counted at an angle from anterio-dorsal to
posterio-ventral).
Methodology for measurements were shown in Fig. 3.2. Standard length (SL) was measured
from the snout-tip to the hypural notch. Head length was measured from the snout-tip to the
bony edge of the opercle. Body depth was measured at greatest body depth (at origin of
dorsal fin). Caudal-peduncle depth was measured at least depth of caudal peduncle. Caudalpeduncle length was measured from the point of the anal fin end to the line at hypural notch.
Pre-dorsal length was measured at the origin of dorsal fin to the snout-tip. Dorsal fin base
length was measured from the origin of dorsal fin to posterior end of fin base. Anal fin base
length was measured as dorsal fin, from origin of fin to the posterior end of fin base.
18
Fig. 3.2. Methodology for taking mensural data (modified Conway et al., 2011).
19
Dorsal fin height was measured from origin of dorsal fin to tip of anterior lobe (greatest
height). Anal fin height was measured from origin of anal fin to tip of anterior lobe (greatest
height). Pectoral fin length was measured at origin of fin to tip of longest ray. Pelvic fin
length was measured at origin of pelvic fin to tip of longest ray. Upper and lower caudal fin
lobes lengths were measured from the origin of caudal fin to tip of lobe (greatest length).
Median caudal fin ray length was measured from origin of caudal fin to fork. Snout length
was measured from snout-tip to anterior border of orbit. Inter-orbital width was measured as
the least width between orbits. Eye diameter was measured as the greatest length of the orbit.
Inter-narial width was measured as the width between nostrils.
3.1.2.2. Statistical analysis (Principal component analysis)
Principal components analysis of the character correlation matrix was used to reduce
dimensionality of the continuous morphological variables (Fig. 3.2 [excluding mensural data
numbers 6, 18, 19 & 20]) of both Horadandia and Rasboroides. The first two principal
components explained 92.5% of the variance. Hundred and sixteen specimens (Horadandia,
n= 18; Rasboroides, n= 98) were used in the multivariate morphological analysis. Similar
analyses (PCA) were performed to confirm the identity of recognized all species in each
genera, Horadandia and Rasboroides. For Horadandia (H. atukorali, n= 8; H. brittani, n=
8), first two principal component explained 69.1% of the variance, whereas Rasboroides (R.
vaterifloris, n= 8; R. nigromarginatus, n= 12; R. pallidus, n= 15; Rasboroides new species,
n= 13) confirmed 90.1% variance. Minitab® (Version 16.0 for Windows) was used for
statistical analysis.
20
3.2. Experiment 2: Evaluation of the present distribution pattern of R.vaterifloris
pallidus in Gin River.
This study was conducted in Gin River at five different sampling sites (Fig. 3.3). Three study
sites were in the higher elevation (80–300 m) and the other two sites were in the lower
elevation (0–50 m). Madola (Site 1) is very close to Hiyare forest reserve at Kurundugaha in
Galle District. Kottawa site is within the Kottawa forest reserve. It was a very small forest
patch in Galle District. Site 3 (Kanneliya forest) was within a rain forest. Site 4 (Homadola)
was located close to Kanneliya forest. The fifth site (Site 5), Kosmulla located in the
Sinharaja World Heritage Site.
Fig. 3.3. Selected sites along the Gin River, Sri Lanka
21
Site selection was made systematically along the Gin River almost equidistant from site to
site and within rain forest areas, because, according to previous literature (Deraniyagala,
1958) R. vaterifloris pallidus is a rain forest dwelling fish.
Kottawa harboured many fish species, such as Pethia nigrofasciata, Rasboroides pallidus,
Belontia signata, Malpulutta kretseri. Although several streams were found in Kanneliya,
Rasboroides vaterifloris was observed only in a few streams. Homadola received water from
Udugama Ela.
Several fish species were reported from Homadola, i.e., Devario sp.,
Dawkinsia singhala, Sicyopterus halei and Sicyopus jonklaasi. Kosmulla stream had a fast
flow. Species found in this stream were Garra ceylonensis, Devario sp. and Schistura
notostigma.
3.2.1. Fish sampling
Five metre stretches of the river at each site were sampled. Fishes were sampled using a
variety of fishing nets of 5 mm mesh sizes (e.g., gill nets and dragnets) for a period of one
year (January 2015– December 2015). Fish specimens were identified by using the keys and
descriptions given in Deraniyagala (1952), Munro (1955) and Pethiyagoda (1991).
22
Table 3.1. Coordinates, elevation, adjoining forest, sources of pollution, presence of waterfalls, substrate and adjoining vegetation of the
selected sites
SITE
Coordinates
Elevation
Adjoining
Sources of
(metres)
Forest
pollution
KombalaSITE 1: Ma Dola
06º03’N, 80º19’E
40 m
Kottawa
(Hiyare)
SITE 2: Kottawa
SITE 3:
Homadola
06º06’N, 80º20’E
06º13’N, 80º20’E
50 m
80 m
KombalaKottawa
Kanneliya
Sewage,
pesticides
Moderate
Sewage,
Waterfalls
(Height in
metres)
–
Substrate
type
Adjoining vegetation
Sandy,
Rain forest (submerged
more leaf
vegetation, Aponogeton sp.)
litter
–
–
Sandy, less
Rain forest (submerged
leaf litter
vegetation, Aponogeton sp.)
Rocky,
gravels and
pesticides
pebbles
Disturbed rain forest, rubber
plantation
Sandy, less
SITE 4:
Kanneliya
06º15’N, 80º20’E
100 m
Kanneliya
Minimal
Kabbale Ella
leaf litter,
Rain forest (submerged
Falls, ~50 m
submerged
vegetation, Aponogeton sp.)
logs
SITE 5:
Kosmulla
Sinharaja
06º24’N, 80º23’E
300 m
World
Heritage Site
Minimal
Duwili Ella
Falls, ~80 m
Rocky
Rain forest
23
3.2.2. Physico-chemical characteristics
Physico-chemical parameters were measured between 1000 hours to 1200 hours and the
recorded parameters are as follows:
(A)
Water temperature: (Oregon Digital LCD water thermometer was used to
record the temperature),
(B)
Stream pH: (digital pH meter),
(C)
Stream depth: (maximum depth: using a pole and a measuring tape at the
selected site).
(D)
Stream flow rate at the point of maximum flow. The stream flow rate was
determined by measuring the time taken for a cork to cover a unit distance (ms-1),
(E)
Percentage of canopy cover (based on a visual estimation of sky visibility
from the centre of the stream). The % canopy cover values were divided into
five categories – 0–20% (category 1), 20–40% (category 2), 40–60% (category
3), 60–80% (category 4) and 80–100% (category 5).
(F)
Substrate types found in the sampling sites were classified under categories:
(a) Rocks,
(b) Pebbles & gravel and
(c) Sand and silt.
(G)
Turbidity was also estimated by categorizing the state of visibility of the
stream (1= Poor, 2= Average, 3= Good).
Samples were collected from each sampling point and mean values were plotted against
sampling period.
Geographic co-ordinates and altitudes were taken using a Magellan 12–channel GPS
(geodetic datumWGS-84: World Geodetic System of 1984).
24
CHAPTER IV
4.0 RESULTS AND DISCUSSION
4.1. Experiment 1:
Taxonomic study on the comparative morphology of Cyprinid genera Horadandia and
Rasboroides and evaluation of the interspecific and intraspecific variations of each
genera.
4.1.1. Comparative morphology of Horadandia and Rasboroides
Comparison of all congeners of Horadandia (two spp.) and Rasboroides (four spp.)
confirmed the identity of two distinct genera in the tribe Rasborini by means of morphology
(external morphology and osteology) and morphometry.
Horadandia (i.e., brittani +
atukorali) differs from Rasboroides (vaterifloris+nigromarginatus+pallidus+a new species)
by a consistent set of autoapomorphies.
4.1.1.1. Genus Horadandia Deraniyagala, 1943
The genus Horadandia erected with the description of H. atukorali from Sri Lanka
(Deraniyagala, 1943).
Thus far, Horadandia was considered as a monotypic genera
(Pethiyagoda, 1991, Goonatilake, 2007; Liao et al., 2010).
25
4.1.1.1.1 Diagnosis of Horadandia.
Horadandia differs from Rasboroides by its smaller maximum size (20.4 mm vs. 35.5 mm
SL in Rasboroides), presence of indistinct symphyseal knob (Fig. 4.1A), reduced
supraorbitals (Fig. 4.1B), presence (vs. absence) of bifurcation at posterior end of kinethmoid,
having (vs. absence) a concavity before the coronoid process of dentary (Fig. 1F).
It
(Horadandia) also differs from Rasboroides by the absence of lateral line (vs. present, but
incomplete), having two (vs. three) rows of pharyngeal teeth, having the pharyngeal teeth
with minute cusps terminally (Fig. 4.1J, K) and presence of 24-26 (vs. 28-30) vertebrae.
26
Fig. 4.1. Osteology of Horadandia atukorali, 17.8 mm SL, WHT 11104. A, lateral view of A.
Head showing symphyseal knob (sn); B, Cranium showing fontanel (fo) (so,
supraocular); C, arrangement of caudal vertebra and anal fin; D, Weberian apparatus
(wb); E, right infra-orbital (without sensory canals); F, lateral view of left dentary and
anguloarticular (co, coronoid process); G, premaxillae (ap, acending process); H, left
lateral view of maxillae (pp, palatine process); I, lingual view of left operculum; J,
lingual view of left 5th ceratobranchial (pt, phyrangeal teeth; pr, process); K, close up of
phyrangeal teeth showing minute cusps (cu).
27
Horadandia distinguished from Rasboroides in having the attachment of Baudelot’s ligament
to the lateral tip of the supracleithrum (vs. to the distal end of dorsal part of the
supracleithrum) and lacking 6th hypural (Fig. 4.2C).
Fig. 4.2. Osteology of Horadandia atukorali, 15.4 mm SL, WHT 11017. A, dorsal fin; B,
anal fin, C, caudal fin (caudal skeleton: pls, pleurostyle; parhy, parhypural; hyp 1, first
hypural [parhy & hyp1 fused posteriorly]); D, lingual view of right pectoral girdle
(broken at apex; lacking coracoid foramen); E, dorsal view of pelvic girdle; F, dorsal
view of pelvic girdle of WHT11104, 17.8 mm SL (with deeply bifurcate basipterygium
[bp]).
Horadandia differs from Rasboroides by possessing 9-12 (vs. 13-16) pre-ventral scales and
lacking sensory canals in the infraorbital bones (Fig. 4.3E).
28
Fig. 4.3. Osteology of Horadandia brittani, 14.4 mm SL, WHT 11110. A, lateral view of
snout showing symphyseal knob (sn); B, lateral view of head; C, cranium showing
fontanel (fo) (so, supraocular); D, left lateral view of maxillae; E, left infraorbitals
without sensory canals (only 1st, 2nd & 3rd); F, dorsal view of premaxillae (ap,
ascending process); G, lateral view of left dentary and anguloarticular (co, coronoid
process); H, lateral view of left operculum; I, lingual view of left 5th ceratobranchial
(pt, phyrangeal teeth; pr, process); J, close up of phyrangeal teeth showing minute
cusps (cu).
29
Horadandia is further distinguished from other genera of subfamily Danioninae by the
presence of a bowl-shaped depression on the supraethmoid. It also differs from Rasboroides
by having caoncave (vs. convex) anterior boarder of cleithrum in ventral view (Fig. 4.4D).
Fig. 4.4. Osteology of Horadandia brittani, 14.4 mm SL, WHT 11110. A, dorsal fin; B, anal
fin, C, caudal fin; D, dorsal view of pectoral girdle; E, dorsal view of pelvic girdle
showing deeply bifurcate basipterygium (bp); F, lateral view of Weberian apparatus (wb)
and first abdominal vertebrae.
Horadandia is distinguished from the two genera most closely related to it, viz.,
Trigonostigma and Rasboroides due to following reasons. It differs from Trigonostigma by
being a free spawner, scattering its eggs freely in the water column (eggs of Trigonostigma
are spawned on the undersides of broad leaves and similar structures) and lacking the
conspicuous black stripe below the dorsal fin origin to middle of the caudal fin base (hatchet
shape).
30
4.1.1.2. Genus Rasboroides Brittan, 1954
Rasboroides Brittan was first described as subgenus of Rasbora. Later this subgenus was
elevated to generic rank by Kottelat & Vidthayanon (1993). Kottelat & Vidthayanon (1993)
and subsequent authors (Tang et al., 2010) suggest to synonym this genus with Horadandia.
Liao et al. (2010) provided several characters to diagnose two genera, however, some
characters mentioned by them were not suitable to distinguish the two genera.
4.1.1.2.1. Diagnosis of Rasboroides.
Rasboroides differs from Horadandia by its greater maximum size (35.5 mm vs. 20.4 mm SL
in Horadandia), presence of well-developed symphyseal knob (Fig. 4.5A), absence of
bifurcation at posterior end of kinethmoid (Fig. 4.5H), absence of a concavity before the
coronoid process of dentary (4.5J) and presence of sensory canals in infraorbital bones (4.5K).
It also distinguished from Horadandia by having the lateral line incomplete, with 1-6 pored
scales (vs. lateral line absent), possessing 13-16 (vs. 9-12) pre-ventral scales, three (vs. two)
rows of pharyngeal teeth and having the pharyngeal teeth terminally smooth, Fig. 4.5M (vs.
bearing minute cusps).
31
Fig. 4.5. Osteology of Rasboroides pallidus (A, B & E, F of WHT 11101, 20.0 mm SL; C, D, GK of WHT 11113, 17.7 mm SL). A, lateral view of head showing symphyseal knob (sn); B,
dorsal view of snout showing articulation of premaxillae-maxillae (ke, kinethmoid; mp,
maxillary process); C, cranium showing fontanel (fo); D, dorsal view of Weberain apparatus
(tri, tripus); E, lateral view of Weberian apparatus (wb); F, lateral view of Weberian
apparatus and anterior abdominal vertebrates; G, lateral view of left operculum; H, dorsal
view of premaxillae (ap, ascending process, ke, kinethmoid [below]); I, lateral view of left
maxillae (pp, palatine process); J, lateral view of right dentary and anguloarticular (co,
coronoid process); K, left infraorbitals (sc, sensory canals); L, lingual view of right 5th
ceratobranchial (pt, phyrangeal teeth; pr, process); M, close up of phyrangeal teeth showing
grooves (gr).
32
Rasboroides also differs from Horadandia by possessing 28-30 (vs. 24-25) vertebrae, having
six hypurals (vs. five in Horadandia) (Fig. 4.6C) and presence of convex/ striaght anterior
boarder of cleithrum in ventral view (Fig. 4.6D).
Fig. 4.6. Osteology of Rasboroides pallidus (A-C of WHT 11101, 20.0 mm SL; D-F of WHT
11113, 17.7 mm SL). A, dorsal fin; B, anal fin, C, caudal fin (caudal skeleton: pls,
pleurostyle; parhy, parhypural; hyp 1, first hypural [parhy & hyp1 fused posteriorly]); D,
ventral view of pectoral girdle (cl, cleithrum) showing coracoid foramen (cf); E, presence
of coracoid foramen (cf) of pectoral girdle when view posteriorly; F, ventral view of
pelvic girdle, with deeply bifurcate basipterygium (bp).
Rasboroides also differs from Horadandia in having the attachment of Baudelot’s ligament to
the dorsal part of the supracleithrum at the distal end (vs. lateral tip of supracleithrum).
Rasboroides is further distinguished from other genera of Danioninae by having the leading
edge of the pectoral fin tuberculated in males (Fig. 4.7L).
33
Fig. 4.7. Osteology of Rasboroides nigromarginatus, 23.5 mm SL, WHT 0578. A, cranium
showing fontanel (fo) (so, supraocular); B, dorsal view of premaxillae (ap, acending
process; ke, kinethmoid); C, lateral view of left maxillae (pp, palatine process); D, lateral
view of right dentary and anguloarticular (co, coronoid process); E, lateral view of left
operculum; F, left suborbitals (only 1st, 2nd & 3rd; sc, sensory canals); G, dorsal fin; H,
ventral view of pelvic girdle (bp, basipterygium); I, anal fin; J, caudal fin; K, ventral
view of pectoral girdle (cl, cleithrum; cf, corocoid foramen); L, series of tubercles (arrow)
on the anterior edge of the pectoral fin of a male.
34
Present study discovered that Horadandia differs from Rasboroides by a consistent set of
autoapomorphies such as: (a) presence/ absence of bifurcation at posterior end of kinethmoid; (b)
anterior boarder of cleithrum in ventral view either concave or convex; (c) absence/ presence of
sensory canals in infraorbital bones; (d) presence/ absence of a concavity before the coronoid
process of dentary; (e) pharyngeal teeth surface ornamentation, either with cusps or grooves; (f)
absence/ presence of 6th hypural. In addition to that, (g) number of pre-ventral scales (9-12 vs.
13-16), and (h) number of caudal vertebrae (14-15 vs. 16-17) were the other important
distinguishing characters.
Congeners of Rasboroides are showing a remarkable sexual dimorphism by means of colouration,
morphology and morphometry, which is rare in Sri Lankan Rasborinii fishes, except Rasbora
armitagei.
4.1.1.3. Statistical analysis (Principal Component Analysis)
In addition, these two genera were recognized as discrete genera based on the statistical analysis
(Principal Component Analysis [PCA]).
Correlation matrix of continuous characters from
Horadandia and Rasboroides showed clear separation (Fig. 4.8). Total variance, 89.1% was
explained by the first principal component (PC1), which represented the body size axis (standard
length). Significant variance was explained by standard length, caudal peduncle length, and
internarial width (Appendix 2). Horadandia separates well from Rasboroides on the first
principal component axis (PC1) (Fig. 4.8).
35
Fig. 4.8. First principal component vs. second principal component of the principal component
analysis of Horadandia and Rasboroides.
Rasboroides lacks complete lateral line and have a smaller body organization, which is quite
different from Rasbora (sensu Brittan). This may be due to the description of a new subgenus
Rasboroides for Rasbora vaterifloris by Brittan (1954). Likewise, Horadandia also supports the
distant affinity to Rasbora; lack of lateral line, indistinct symphysial knob and two rows of
pharyngeal teeth. This unique combination of characters of genus Horadandia had confused
Deraniyagala (1943); who had a doubt about its (Horadandia’s) relationship to the extent
subfamilies of Cyprinidae. He described, “The shape of the mouth, lack of linea lateralis show
kinship to the Rasboriinae (= Danioninae), the lack of a symphysial knob, the protrusible mouth
and position of the ventrals resemble the Cypriniinae”.
36
Moreover, following characters identified by Liao et al. (2010), which had been used to diagnose
these two genera (Horadandia vs. Rasboroides) were also repeated and confirmed in this study:
(a) presence/ absence of a bowl-shaped depression on the supraethmoid; (b) attachment of
Baudelot’s ligament on the dorsal part of the cleithrum, to distal end/ not at the distal end; (c)
number of rows of pharyngeal teeth either two or three; and (d) lateral line absent or present
(when present, incomplete).
Kottelat & Vidthayanon (1993) suggested that Rasboroides could be a synonym of the
Horadandia. Liao et al. (2010) provided some evidence to separate two genera (see above), but
a few characters mentioned by them appear to be not reliable (i.e., character 12, 28 and 37). This
may be due to lack of all representative species from both genera (e.g. lack of H. atukorali from
Sri Lanka). However, Tang et. al. (2010) showed a possibility of merging the two genera (i.e.,
synonym Rasboroides).
According to Liao et. al. (2010), Horadandia and Rasboroides distinguished by six characters,
i.e., character 12 (supraorbital not reduced or greatly reduced; 26 (absence of a bowl-shaped
depression on the supraethmoid or presence); 28 (number of lateral process on each side of the
kinethmoid, either one or none); 36 (attachment of Baudelot’s ligament on the dorsal part of the
cleithrum, to distal end or not at the distal end, apart from the tip); 37 (Rasborin process on the
fourth epibranchial either absent or present); and 40 (number of rows of pharyngeal teeth either
three or two).
37
The characters, 26, 36 & 40 of Liao et. al. (2010) are repeated in this study, but character, 12, 28
& 37 were different. Supraorbitals of Horadandia atukorali were not reduced (supraorbital
length ~50 % of orbit diameter), but H. brittani with a greatly reduced supraorbitals (vs. ~44 %).
Rasboroides vaterifloris and Horadandia brittani lack lateral process in the kinethmoid (Table
4.1), whereas Rasboroides nigromarginatus and Rasboroides new species have one process, and
Rasboroides pallidus and Horadandia atukorali with two processes. Regarding the Rasborin
process (character 37), none of these samples of Rasboroides spp. possessed similar character.
Material of H. brittani for the present study also taken from the same area (Kottayam in the
Kerala State), in which the specimens (NRM 50137 & 56897) collected for the study of Liao et.
al. (2010). Thus, it (Rasborin process) may not be a good diagnostic character to distinguish
both genera. Likewise, the character 30 (Tripus, [0], the outermost anterior tip with a process,
the anterior outline oblique, dolabriform in dorsal view or [1], with a tiny apophysis, the anterior
outline rather straight) of Rasboroides vaterifloris exhibit state one [0] in contrast to second state
[1] in Liao et. al. (2010). It may be the lack of topotypical R. vaterifloris. Character 19 (outline
shape of tip of the ascending process of the premaxilla), is blunt in Horadandia in contrast to
straight in materials of Rasboroides referred in this study.
38
Table 4.1. Cranium, pectoral girdle and pelvic girdle character states of, Rasboroides vaterifloris (n= 3); R. nigromarginatus (n= 1); R.
pallidus (n= 5); Rasboroides new species (n= 2); Horadandi atukorali (n= 3); and H. brittani (n= 2).
Rasboroides
vaterifloris
R. nigromarginatus
R. pallidus
Rasboroides
new species
H. atukorali
H. brittani
Lateral processes on each side of
kinethmoid
-
1
2
1
2
-
Processes on anterior end of
kinethmoid
2
2
1
1
-
-
Convex
Convex
Straight
Convex
Concave
Concave
Absent
Moderately
notched
Present
Present
Moderately
notched
Absent
Deeply
notched
Absent
Deeply
notched
Absent
Deeply
notched
Character
Anterior boarder of cleithrum in
ventral view
Coracoid foramen
Basipterygium
Moderately notched
39
Liao et. al. (2010) stated that this process is blunt in Rasboroides as well. Regarding the
danionin notch, Rasboroides pallidus and Horadandia brittani exhibited this condition, but
according to Liao et. al. (2010) both genera lack the danionin notch.
Based on the eight characters discovered in present study and the four characters described in
a previous study (Liao et al., 2010), Horadandia and Rasboroides are two distinct genera in
the Tribe Rasborini.
4.1.2. Interspecific and intraspecific variations of Horadandia and Rasboroides
According a previous study (Rema Devi & Menon, 1992), Horadandia is having a subspecies.
This subspecies is currently in a doubtful taxonomic position (FishBase, 2011).
Deraniyagala’s (1958) subdivision of Rasboroides vaterifloris also has to be resolved.
4.1.2.1. Interspecific and intraspecific variations of Horadandia
The genus Horadandia was monotypic until the description of a subspecies Horadandia
atukorali brittani by Rema Devi & Menon in 1992.
Hence, hitherto, a species and a
subspecies described from the genus Horadandia (Deraniyagala, 1943; Rema Devi & Menon,
1992), of which only H. atukorali is considered as a valid species (FishBase, 2011).
4.1.2.1.1. Horadandia atukorali Deraniyagala, 1943
Horadandia atukorali was described by Deraniyagala (1943) after completion of his surveys
on freshwater fishes of Sri Lanka. Hence, he described this species as Horadandia atukorali:
40
‘Hora’ (hidden/ theif in Sinhala) and the local name for Cyprinid fish ‘Dandia’ (in Sinhala)
for genus epithet and for species epithet honouring the type collector, Vicky Atukorala.
4.1.2.1.1. 1. Description of H. atukorali (external morphology).
Based on this study, Horadandia atukorali and H. brittani are distinguished by following
external morphological and morphometric characters (Table 4.2): Horadandia atukorali is
having a more slender body depth (24.6-29.8 % SL, vs. 27.7-31.9 % in H. brittani); dorsal
profile of head slightly concave (vs. straight) behind the level of the eye; a greater eye
diameter (37-41 % of HL, vs. 27-37 % of HL); dorsal fin origin slightly posterior to (vs.
distinctly behind) origin of pelvic fin; pelvic fin reaching beyond anal fin origin (vs. just
reaching anal fin origin); dorsal fin origin located halfway between snout tip and hypural
notch (vs. closer to hypural notch).
41
Table 4.2. Morphometric data of Horadandia atukorali (n= 8) and H. brittani (n= 8).
Horadandia atukorali (n=8)
H. brittani (n=8)
range
mean
s.d.
range
16.1-19.3
17.9
1.1
15.7-20.4
17.4
1.7
Total length
123-134
130
3.7
125-135
130
3.4
Body depth
24.6-29.8
26.9
1.7
27.7-31.9
29.6
1.7
Head length
25.4-28.6
27.0
1.0
26.0-31.5
28.9
1.6
Pre-dorsal length
49.2-55.2
51.9
2.0
48.5-53.7
51.8
1.5
Dorsohypural distance
44.3-50.8
48.6
2.1
45.1-50.6
48.2
1.8
Dorsal fin base length
8.2-10.8
9.5
1.1
8.0-10.4
9.3
0.7
Dorsal fin height
24.1-28.9
26.0
1.7
24.7-30.2
27.7
1.6
6.4-8.8
8.0
0.9
5.1-9.4
7.0
1.6
Anal fin depth
15.7-19.3
17.9
1.3
14.2-20.2
17.7
2.0
Pelvic fin length
16.1-18.2
17.2
0.9
13.0-18.9
16.2
1.9
Pectoral fin length
13.6-19.3
15.9
1.8
12.7-18.9
16.0
2.3
Preanal length
57.5-67.7
62.3
3.4
57.1-63.5
60.5
2.6
Pre-pelvic length
47.0-51.4
48.7
1.4
44.1-52.0
47.3
3.0
Caudal peduncle length
22.4-28.1
24.8
1.9
20.6-25.4
23.1
1.4
Caudal peduncle depth
9.9-13.5
11.2
1.2
10.2-12.9
11.3
1.0
Length of upper caudal fin lobe
27.0-29.2
27.9
0.9
27.1-29.6
28.4
1.0
Length of lower caudal fin lobe
29.0-31.9
30.5
2.1
27.9-31.4
29.8
1.1
Length of median caudal fin rays
9.6-13.1
11.1
1.2
8.3-17.0
12.3
2.7
Snout length
18.0-27.1
21.7
3.5
14.6-26.8
20.3
3.9
Eye diameter
37.0-41.3
39.1
1.5
26.8-36.7
33.6
3.4
Inter-orbital width
16.7-26.1
21.5
3.0
14.3-25.0
19.1
3.1
Inter-narial width
6.5-15.1
11.9
2.7
6.3-17.0
13.1
3.9
Standard length (mm)
mean s.d.
As a % of standard length
Anal fin base length
As a % of head length
In Horadandia atukorali body is compressed, dorsal profile of head slightly concave behind
the level of the eye. Mouth small (rictus falling beneath anterior margin of eye), terminal,
42
oblique; posterior groove of lower lip interrupted medially. Barbels absent. Dorsal fin origin
located closer to hypural notch than to snout tip (Fig. 4.9), body translucent, abdomen, venter
and belly silvery, opercle and sclera silvery. Melanophores scattered on body scales and
region of snout. Dorsal, anal, pectoral and pelvic fins hyaline with scattered melanophores.
Females overall light whitish-orange, lighter ventrally and on fins, which are partly hyaline.
Colour of eye and opercle as in males. In preserved samples, overall colour olive brown;
upper one-third of body darker than lower part; all fins hyaline. Melanophores on body,
snout and on posterior one-third of head small and widely spaced. A dark-brown mid-lateral
streak on body.
Fig. 4.9. Horadandia atukorali, living specimen, from Hamilton canal, Sri Lanka (Courtesy
of Gerhard Ott).
Dorsal fin with 3 unbranched and 7½ branched rays; first unbranched ray minute, only
slightly visible, second less than half length of the third. Last unbranched dorsal fin ray
strong, relatively long, slightly recurved, its tip poorly ossified.
Anal fin with three
unbranched and 5½ branched rays. Caudal fin forked, with 17 branched rays, nine on upper
lobe, eight on lower one. Pectoral fin with one unbranched and 12½ branched rays. Pelvic
43
fin with one unbranched and 7½ branched rays. Lateral line absent; 18-21 (18[2], 19[2],
20[1], 21[2]) scales on body in lateral series. Body scales in transverse line ½7½[8], on
caudal peduncle ½2½[8]. Pre-dorsal scales 9-11 (9[1], 10[6], 11[1]); pre-ventral scales 9-12
(9[2], 10[4]), 11[1], 12[1] (Table 4.3).
Table 4.3. Meristics of Horadandi atukorali (n= 11) and H. brittani (n= 10).
Character
H. atukorali
H. brittani
Dorsal fin rays
3+7½
3+7½
Anal fin rays
3+6½
3+5½
9+8
9+8
Pectoral fin rays*
1+11½
1+11½
Pelvic fin rays*
1+6½
1+6½
Abdominal vertebrae*
10-11
10
Caudal vertebrae*
14-15
14
Total vertebrae*
24-26
24
Pharyngeal teeth*
4,3-3,4
4,3-3,4
Pre-dorsal scales
9-11
9-11
Pre-ventral scales
9-12
10-12
Scales in lateral series
18-21
20-23
Scales in transverse line on body
½6½
½6½
6
6
Caudal fin rays
Circumpeduncular scales
Counts taken from cleared and stained specimens are indicated with *.
44
4.1.2.1.1. 2. Description of H. atukorali (Osteology).
Palatine process on the maxilla with a distinct projection pointing dorsally (Fig. 4.10C);
supraorbitals not reduced, its length ~50% of orbital diameter (Fig. 4.10D); four infraorbitals,
Fig. 4.10. Horadandia atukorali: A, dorsal view of kineethmid; B, lateral view of left dentary
(co, coronoid process); C, lateral view of left maxillae (pp, palatine process); D, dorsal
view of cranium (so, supraocular; f, frontal).
greatly reduced (Fig. 4.1E); infraorbitals without sensory canals (Fig. 4.1E); 3rd infraorbital
enlarged, without a downward extension (Fig. 4.1E); 5th infraorbital absent; front margin of
lower part of maxilla concave (Fig. 4. 10C); outline shape of tip of ascending process of
premaxilla blunt (Fig. 4.1G); dorsal outline of lower jaw with a concavity next to symphyseal
knob; presence of a concavity before the coronoid process of dentary (Fig. 4.10B); danionin
notch absent (Fig. 4.11A); frontoparietal fontanel present (Fig. 4.1B); bowl-shaped
depression on supraethmoid; single lateral process on each side of kinethmoid; abdominal
45
Fig. 4.11. Ventral views of dentary showing presence (arrows) and absence of Danionin
notch: A, Horadandia atukorali; B, Horadandia brittani; C, Rasboroides vaterifloris; D,
Rasboroides nigromarginatus; E, Rasboroides pallidus; F, Rasboroides new species
(Scale bars 1.0 mm).
vertebrae10[2] or 11[1]; 14[1] or15[2] caudal vertebrae; 24-26 total vertebrae (Table 4.3);
shape of supracleithrum in ventral view, L-shaped; anterior outline of horizontal limb of
cleithrum straight in ventral view; absence of a foramen on anterior wall of horizontal limb of
cleithrum; lateral border of cleithrum straight in ventral view; coracoid foramen weakly
developed (Fig. 4.2D); lacking Rasborin process on the epibranchial; no hypohyal process on
46
the basihyal; apophysis of hypohyal process on the basihyal narrow; pharyngeal teeth in two
rows (4,3–3,4); pharyngeal teeth with 3-4 minute cusps terminally (Fig. 4.1K); a welldeveloped process on posterio-lateral border of 5th ceratobranchial (Fig. 4.1J); uroneural is
absent from pleurostyle; parahypural and first hypural fused posteriorly; 6th hypural absent
(4.2C).
4.1.2.1.1. 3. Distribution.
Horadandia atukorali is widespread in the western, north-western and southern provinces of
Sri Lanka, usually occurring among weeds in shallow ponds, rice paddies and wetlands of
Attidiya, Colombo, Gampaha, Dombagaskanda, Veyangoda (Western Province), Wakwella,
Baddegama, Madola (Southern Province), Mundel and Puttalam (Northwestern Province)
(Deraniyagala, 1943; Pethiyagoda, 1991; Ott, 2009) (Fig. 4.12).
Fig. 4.12. Records of Horadandia species from India and Sri Lanka; H. atukorali (closed
circles); H. brittani (open circles).
47
4.1.2.1.2. Horadandia brittani Rema Devi & Menon, 1992
Rema Devi & Menon (1992) described this species as a subspecies of Horadandia atukorali.
However, this subspecies was considered as a junior synonym of H. atukorali (FishBase,
2011).
4.1.2.1.2. 1. Description of H. brittani (external morphology).
Body compressed, dorsal profile more or less straight, ventral profile slightly convex. Dorsal profile
of head more or less straight behind the level of eye. Mouth small (rictus falling beneath anterior
margin of the eye), terminal, oblique; posterior groove of lower lip interrupted medially. Barbels
absent. Dorsal fin origin located closer to hypural notch than to snout tip (Fig. 4.13). Upper half of
body yellowish brown, lower half paler. A golden yellow lateral stripe present on either side of the
body. Upper half of opercle, posterior one third of the head and the abdomen golden yellow.
Infraorbital, preopercle regions and sclera silvery. Melanophores scattered on body scales, snout,
upper one third of opercle and posterior one third of the head. Dorsal, anal, pectoral and pelvic fins
hyaline. In preserved samples, overall colour dusky white with indistinct melanophores on body
scales, snout and posterior one-third of the head. A dark lateral streak present on the body; all the fins
hyaline.
Fig. 4.13. Horadandia brittani, Kerala, India (Courtesy of Frank Schäfer).
48
Dorsal fin with three unbranched and 7½ branched rays; first unbranched ray minute, only
just visible, second less than half the length of the third. Last unbranched dorsal fin ray
strong, relatively long, slightly recurved, its tip poorly ossified.
Anal fin with three
unbranched and 5½ branched rays. Caudal fin forked with 17 branched rays, nine on upper
lobe, eight on lower one. Pectoral fin with one unbranched and 12½ branched rays. Pelvic
fin with one unbranched and 7½ branched rays. Lateral line absent with 20-23 (20[3], 21[1],
22[0], 23[4]) scales on body in lateral series. Scales on body in transverse line ½6½[8], on
caudal peduncle ½2½[8]. Pre-dorsal scales 9-11 (9[4], 10[0], 11[4]); pre-ventral scales 10-12
(10[3]), 11[4], 12[1] (Table 4.3).
4.1.2.1.2. 2. Description of H. brittani (Osteology).
Supraorbitals greatly reduced, its length ~44% of orbital diameter (Fig. 4.14D); four
infraorbitals, greatly reduced; infraorbitals without sensory canals (Fig. 4.3E); 3rd infraorbital
enlarged, without a downward extension (Fig. 4.3E); 5th infraorbital absent; palatine process
on the maxilla with a less prominent projection pointing dorsally (Fig. 4.3D, 4.14C); front
margin of lower part of maxilla convex (Fig. 4.3D, 4.14C); outline shape of tip of ascending
process of premaxilla blunt (Fig. 4.4F); dorsal outline of lower jaw with a concavity next to
symphyseal knob; presence of a concavity before the coronoid process of dentary (Fig.
4.14B); danionin notch present (Fig. 4.11B); frontoparietal fontanel present (Fig. 4.3C,
4.14D); presence of bowl-shaped depression on supraethmoid; no lateral process on each side
of kinethmoid; 10 abdominal vertebrae; 14 caudal vertebrae; 24 total vertebrae; shape of
supracleithrum in ventral view, L-shaped; anterior outline of horizontal limb of cleithrum
straight in ventral view (Fig. 4.4D); absence of a foramen on anterior wall of horizontal limb
of cleithrum (Fig. 4.4D); lateral border of cleithrum straight in ventral view (Fig. 4.4D);
49
Fig. 4.14. Horadandia brittani: A, dorsal view of kineethmid; B, lateral view of left dentary
(co, coronoid process); C, lateral view of left maxillae (pp, palatine process); D, dorsal
view of cranium (so, supraocular; f, frontal).
coracoid foramen absent (Fig. 4.4D); lacking Rasborin process on the epibranchial; hypohyal
process on the basihyal is absent; apophysis of hypohyal process on the basihyal narrow; two
rows of pharyngeal teeth (4,3–3,4); pharyngeal teeth with minute cusps (Fig. 4.3J); a notch on
posterio-lateral border of 5th ceratobranchial (Fig. 4.3I); uroneural is absent from pleurostyle;
parahypural and first hypural fused posteriorly; 6th hypural absent (4.4C).
50
4.1.2.1.2. 3. Distribution.
Horadandia brittani is confined to the coastal floodplain of the southern Indian states of
Kerala, Tamil Nadu and perhaps also Karnataka.
This species was recorded from
Kumaragam in Kerala and from Pondicherry in Tamil Nadu by Rema Devi & Menon (1992)
and Rema Devi (1996) (Fig. 4.12).
In addition to that (Item external morphology), following osteological characters were used to
distinguish both species: palatine process on the maxilla of Horadandia atukorali with a
distinct projection pointing dorsally, whereas this projection is less prominent in H. brittani;
the front margin of the lower part of the maxilla of H. atukorali is concave (Fig. 4.1H) (vs.
convex in H. brittani; Fig. 4.3D); supraorbitals not reduced (Fig. 4.1B) (vs. greatly reduced,
Fig. 4.4C); superior border of anguloarticular is subtriangular shaped in H. atukorali (vs.
truncate in H. brittani); a process on posteriolateral border of 5th ceratobranchial is welldeveloped in H. atukorali (Fig. 4.1J) (vs. not well-developed in H. brittani; Fig. 4.4J); two
(vs. none) lateral process on each side of kinethmoid; anterior end of kinethmoid narrow (vs.
wide); and supraorbital length ~50 % of orbit diameter (vs. ~44 %).
4.1.2.1.3. Statistical analysis (Principal Component Analysis)
Two species of Horadandia were recognized as separate species based on the principal
components analysis (PCA). Correlation matrix of continuous characters from Horadandia
atukorali and H. brittani showed clear separation on the second component of PCA (Fig.
4.15). Total variance, 59.8% was explained by First Principal Component (PC1), which
51
represented the body size axis (standard length). Significant variance was explained by
orbital diameter, body depth and inter-narial width (Appendix 3).
Fig. 4.15. First Principal Component vs. Second Principal Component of the Principal
Component Analysis of Horadandia atukorali and H. brittani.
Thus, based on the above results, the identity of Horadandia atukorali brittani Rema Devi &
Menon, 1992 is confirmed and resurrected it to specific rank based on its characteristics.
Hence, Horadandia atukorali is endemic to Sri Lanka and H. brittani is confined to India.
4.1.2.2. Interspecific and intraspecific variations of Rasboroides
Deraniyagala (1958) described four subspecies of Rasboroides (then in Rasbora) from Sri
Lanka. He also included Meinken’s R. nigromarginatus as yet another subspecies of R.
vaterifloris. Hitherto, all these subspecies were considered as synonyms of Rasboroides
vaterifloris (Pethiyagoda, 1991).
52
4.1.2.2.1. Rasboroides vaterifloris (Deraniyagala, 1930)
Rasbora vaterifloris had been described first by Deraniyagala, (1930).
Subsequently
classified by Brittan (1954), which was the first recognition of the subgenus. It was the work
of Kottelat & Vidthayanon (1993), which led to the resurrection of the subgenus to the genus
rank.
4.1.2.2.1. 1. Description of R. vaterifloris (external morphology).
Males with upper body golden brown and becoming light on either side to silvery colour,
scattered with melanophores; belly silver. Dorsal, anal, pectoral and pelvic fins hyaline with
scattered melanophores. Caudal fin greenish yellow. Females, similar but lighter in colour:
yellowish-tan dorsally, whitish with scattered melanophores on sides; belly white (Fig. 4.16A,
B). In preserved samples (Fig. 4.16C), overall colour of both sexes light brown; upper onethird of body darker than lower two thirds; all fins hyaline. Dorsal profile of head slightly
convex above the eye in males. Mouth terminal, oblique; rictus beneath anterior margin of
the eye; posterior groove of lower lip interrupted medially. Dorsal fin origin a single scalewidth behind pelvic fin origin, which lies midway between pectoral fin base and anal fin
origin. Pectoral fin reaching beyond pelvic fin base; pelvic fin reaching beyond anal fin
origin.
53
Fig. 4.16. Rasboroides vaterifloris. A, B (females), living specimens, from Gilimale (in the
Induruwa Forest), Sri Lanka (Courtesy of WCSG); C, BMNH 1930.10.8.1, 25.7 mm SL,
syntypes, male (above) and female (below); Sri Lanka: Kalu River: Illukwatta (Courtesy:
Rohan Pethiyagoda).
General appearance (Fig. 4.16) indicate that body is compressed, its dorsal profile more or
less straight, ventral profile slightly convex and deep (body depth 31.1-32.8% SL in males,
31.0-31.7% SL in females) (Table 4.4).
54
Table 4.4. Morphometric data of Rasboroides vaterifloris (n= 10) and R. nigromarginatus (n= 12).
Males of
Females of
Males of
Females of
Rasboroides vaterifloris
R. vaterifloris
R. nigromarginatus
R. nigromarginatus
(n= 5)
(n= 5)
(n= 6)
(n= 6)
range
mean
s.d.
range
mean
s.d.
range
23.9–28.4
25.4
1.8
22.1–25.5
23.8
1.3
26.2–30.2
Total length
130.7–133.5
132.4
1.1
131.8–136.4
134.0
1.8
Body depth
31.1–32.8
31.9
0.7
31.0–31.7
31.3
0.3
28.2–33.0
31.0
1.9
26.9–29.1
27.8
0.8
Head length
26.4–27.5
26.9
0.5
25.9–28.1
27.3
0.9
25.4–29.0
27.2
1.4
26.1–28.3
27.3
0.8
Pre-dorsal length
48.5–49.8
49.3
0.5
47.9–52.0
50.2
1.6
49.7–52.4
51.5
1.1
50.4–53.2
51.5
1.0
Dorsohypural distance
50.6–53.9
51.7
1.4
49.8–53.3
51.7
1.5
52.7–55.7
54.4
1.3
52.2–55.1
53.2
1.2
Dorsal fin base length
11.3–14.7
12.9
1.2
11.2–12.9
12.0
0.8
11.5–13.6
12.6
0.8
11.2–14.0
12.0
1.1
Dorsal fin height
29.5–32.7
30.5
1.4
30.2–32.5
31.2
1.2
19.5–35.9
31.4
6.9
25.4–32.1
27.9
2.9
Anal fin base length
12.6–14.1
13.2
0.7
13.0–14.0
13.6
0.4
13.2–16.5
14.1
1.3
11.9–14.3
13.1
1.0
Standard length (mm)
mean s.d.
28.5
1.7
range
mean
s.d.
26.5–27.3
26.9
0.3
129.9–135.2 132.6
2.3
As a % of standard length
130.8–139.3 134.6
3.4
55
Anal fin height
22.3–26.4
23.9
1.6
23.5–24.8
24.1
0.5
17.9–31.4
27.1
5.3
17.4–22.7
20.4
2.2
Pelvic fin length
20.3–21.5
21.0
0.4
17.8–21.7
20.2
1.6
21.0–26.8
24.4
2.8
17.9–21.9
19.4
1.7
Pectoral fin length
20.1–22.9
21.3
1.1
19.4–21.7
20.9
0.9
16.0–25.2
22.6
3.7
20.4–23.8
22.0
1.4
Pre-anal length
57.9–60.6
59.2
1.0
58.9–62.4
60.4
1.3
52.3–62.6
58.4
3.9
59.0–61.0
60.1
0.8
Pre-pelvic length
41.7–48.5
45.4
2.8
44.2–48.2
46.1
1.8
40.8–46.6
44.9
2.3
43.9–46.5
45.6
1.0
Caudal peduncle length
18.0–22.5
21.0
1.8
18.6–21.2
19.4
1.1
20.1–24.1
22.4
2.0
21.1–25.0
23.4
1.4
Caudal peduncle depth
11.6–14.1
12.6
0.9
12.4–13.4
12.9
0.4
11.1–13.6
12.0
1.0
10.4–12.3
11.5
0.7
Length of upper caudal fin lobe
32.0–34.0
33.1
0.9
31.8–33.9
32.6
1.1
26.5–33.2
24.5
2.9
30.1–35.5
33.4
2.4
Length of lower caudal fin lobe
34.5–37.2
35.6
1.0
34.7–37.2
36.0
1.0
32.1–35.9
34.0
1.8
32.0–34.8
33.8
1.3
Length of medial caudal rays
12.0–14.6
13.6
1.2
13.2–15.7
14.4
1.0
9.5–13.4
12.2
1.6
10.9–13.4
12.4
0.9
Snout length
23.5–25.4
24.4
0.7
22.4–26.2
24.3
1.3
21.7–30.5
26.0
3.8
21.9–27.1
24.5
2.3
Orbital diameter
37.3–41.3
38.8
1.5
37.9–43.9
40.6
2.2
36.2–40.8
38.4
2.0
40.5–42.7
41.4
0.8
Inter-orbital width
29.4–33.3
32.0
1.6
24.6––33.3
29.9
3.2
17.4–22.1
19.3
2.0
16.0–21.4
18.3
2.1
Inter-narial width
18.6–20.6
20.0
0.8
15.4–19.7
18.1
1.8
10.5–16.9
13.9
2.3
12.0–15.7
13.4
1.7
As a % of head length
56
Dorsal fin origin located halfway between snout-tip and hypural notch, with three unbranched
and 7½ branched rays, first unbranched ray minute, only just visible, second less than half the
length of the third. Last unbranched dorsal fin ray strong, slightly recurved, its tip poorly
ossified. Anal fin with three unbranched and 5½[2] or 6½[8] branched rays. Caudal fin
forked with 17 branched rays, nine on upper lobe, and eight on lower one. Pectoral fin with
one unbranched and 11½[4] or 12½ [6] branched rays. Pelvic fin with one unbranched and
6½ [3] or 7½ [7] branched rays. Lateral line incomplete, 21-25 (21[2], 22[1], 23[1], 24[5],
25[1]) scales in lateral series on body; 4-6 (4[3], 5[2], 6[5]) with perforated scales anteriorly.
Scales on body in transverse line ½8½, on caudal peduncle ½4½. Pre-dorsal scales, 10-12
(10[2], 11[6], 12[2]), pre-ventral scales 15[2]-16[8] (Table 4.5).
57
Table 4.5. Meristics of Rasboroides vaterifloris (n= 11); R. nigromarginatus (n= 13); R.
pallidus (n= 21); Rasboroides new species (n= 17).
Rasboroides
R. nigromarginatus
R. pallidus
vaterifloris
Dorsal fin rays
Rasboroides
new species
3+7½
3+7½
3+7½
3+7½
3+5-6½
3+6½
3+6½
3+6½
9+8
9+8
9+8
9+8
1+11½-12½
1+11½
1+11½
1+11½
1+6½-7½
1+6½
1+6½
1+6½
Abdominal vertebrae*
12-13
12
11-12
12-13
Caudal vertebrae*
16-17
16
16-17
17
29
28
28-29
29-30
Pharyngeal teeth*
5,4,3-3,4,5
5,4,3-3,4,5
5,4,3-3,4,5
5,4,2-2,4,5
Pre-dorsal scales
10-12
11-12
10-12
11-12
Pre-ventral scales
15-16
14-16
13-15
14-16
Scales in lateral series
21-25
23-27
20-24
25-28
Pored lateral-line scales
4-6
1-3
2-3
1-3
Scales in transverse line
½8½
½8½
½6½-½7½
½8½
10
10
8
10
Anal fin rays
Caudal fin rays
Pectoral fin rays*
Pelvic fin rays*
Total vertebrae*
on body
Circumpeduncular scales
*.Counts taken from cleared and stained specimens
4.1.2.2.1. 2. Description of R. vaterifloris (Osteology).
Supraorbitals not reduced; infraorbitals with sensory canals; 3rd infraorbital outer margin
with downward extension; four infraorbitals, not greatly reduced; 5th infraorbital absent;
anterior dorsal extension of the maxilla slightly overlaps the premaxilla dorsally; palatine
process of maxilla with a distinct projection pointing dorsally; front margin of lower part of
maxilla straight without an upward directed process; outline shape of the tip of the ascending
58
process of the premaxilla concave; dorsal outline of lower jaw with a shallow concavity next
to symphyseal knob (Fig. 4.17A); shallow concavity before the coronoid process of dentary
(Fig. 4.17A); superior border of anguloarticular elevated, convex (Fig. 4.17A); broad
coronoid process on dentary (Fig. 4.17A); dorsal boarder of operculum even (Fig. 4.17B);
Fig. 4.17. Rasboroides vaterifloris. A, Lateral views of dentary (co, coronoid process); B,
Right operculum.
danionin notch absent (Fig. 4.11C); frontoparietal fontanel present; a bowl-shaped depression
on supraethmoid; lack of lateral process on each side of the kinethmoid; anterior end of
kinethmoid with two processes; 12[1] or 13[1] abdominal vertebrae; 16[1] or 17[1] caudal
vertebrae; 29 total vertebrae (Table 4. 4); ventral view of the supracleithrum, L-shaped;
anterior outline of horizontal limb of cleithrum convex in ventral view; lateral border of
cleithrum rounded in ventral view; foramen on anterior wall of horizontal limb of cleithrum is
absent; coracoid foramen well-developed; basipterygium broad, not deeply notched; basihyal
with two lateral processes, apophysis narrow; Rasborin process on 4th epibranchial is abssent;
number of rows of pharyngeal teeth three (3,4,5–5,4,3); pharyngeal teeth with terminal
grooves; posterio-lateral border of 5th ceratobranchial with a deep notch; uroneural is absent
from pleurostyle; parahypural and first hypural fused posteriorly; six hypurals present.
4.1.2.2.1. 3. Distribution.
59
Deraniyagala (1952) gave the type locality as the Kalu River at Illukwatta ferry on the
Gilimale road. According to Pethiyagoda (1991), R. vaterifloris sensu stricto is restricted to
streams in tall, shaded forests in the mid-catchment regions of the Kalu to Nilwala basins, as
far as south of Akuressa.
Rasboroides vaterifloris sensu stricto was introduced to the
Ginigathhena area (Mahaweli River) by Senanayake & Moyle (1981). These populations
were observed by Sundarabarathy (2004) at Horakada, Ceypotha and Koladeniya in the Black
water stream. As presently understood, however, the species is restricted to the Kalu River
basin (Fig. 4.18).
.
Fig. 4.18. Distribution of Rasboroides vaterifloris (type locality, closed circle) in Sri Lanka.
4.1.2.2.2. Rasboroides nigromarginatus (Meinken, 1957)
60
Rasbora migromaginata had been described first by Meinken (1957).
However,
Deraniyagala (1958) considered it as a subspecies of R. vaterifloris. Subsequent authors
followed Deraniyagala’s (1958) classification and also considered a synonym of R.
vaterifloris (Pethiyagoda, 1991; Goonatilake, 2007) but Silva et al (2010) stated R.
nigromaginatus is a valid species without giving data.
4.1.2.2.2. 1. Description of R. nigromarginatus (external morphology).
Males dorsally golden orange, sides silvery, venter and belly silver. Dorsal fin orange-red,
longest unbranched dorsal fin ray distinctly black along its entire length. Pectoral, pelvic and
anal fins yellow and scattered with melanophores, unbranched rays of their leading edges
blackish; caudal fin orange. Upper third of sclera deep orange. Females similar but lighter in
colour, lacking black dorsal and anal fin margins: yellowish-tan dorsally, whitish with
scattered melanophores on sides; belly white.
In preserved specimens (Fig. 4.19B, D),
overall colour pale brown, fins dusky; last unbranched ray of dorsal fin blackish (Fig. 4.19);
body compressed, dorsal and ventral profiles moderately convex, deep. Dorsal profile of
head more or less straight, posterior to level of eye in males. Mouth small (rictus beneath
anterior margin of eye), terminal, oblique; posterior groove of lower lip interrupted medially.
Dorsal fin origin one scale-width behind pelvic fin origin. Pelvic fin origin closer to anal fin
base than pectoral fin base. Pectoral fin reaching beyond base of pelvic fin; pelvic fin
reaching beyond origin of anal fin; dorsal fin origin located halfway between snout-tip and
hypural notch (Fig. 4.19).
61
Fig. 4.19. Rasboroides nigromarginatus. A, living male specimen, from Atweltota, Sri Lanka
(Courtesy of WCSG; B, ZMH 1207, male holotype (Courtesy of Ralf Thiel); C, living
female specimen, from Atweltota, Sri Lanka (Courtesy of WCSG); D, ZMH 1208,
female paratype (Courtesy of Ralf Thiel).
62
Dorsal fin with three unbranched and 7½ branched rays, first unbranched ray minute, only
just visible, second less than half length of third. Last unbranched ray strong, slightly
recurved, its tip poorly ossified. Anal fin with three unbranched and 6½branched rays.
Caudal fin forked with 17 branched rays, nine on upper lobe, and eight on lower one.
Pectoral fin with one unbranched and 11½ branched rays. Pelvic fin with one unbranched
and 6½ branched rays; lateral line incomplete; 23-27 (23[1], 24[1], 25[7], 26[2], 27[1]) scales
in lateral series on body; 1-3 (1[1], 2[5], 3[7]) perforated scales anteriorly. Scales on body in
transverse line ½8½ and ½4½ on caudal peduncle; pre-dorsal scales 11[4]-12[6]; pre-ventral
scales 14-16 (14[2], 15[7], 16[3]) (Table 4.5).
Males differ from females by following characters: pelvic fins reaching beyond origin of anal
fin (reaching origin of anal fin in females); body depth 28.2–33.0 % of SL (vs. 26.9–29.0% of
SL); anal fin height 17.9–31.4% of SL (vs. 17.4–22.7% of SL); pelvic fin length 21.0–26.8%
of SL (vs. 17.9–21.9% of SL); caudal peduncle depth 1.5–2.1 times of its length (vs. 1.8–2.3);
caudal peduncle depth 11.1–13.6 % of SL (vs. 10.4–12.3% of SL) (Table 4.4).
4.1.2.2.2. 2. Description of R. nigromarginatus (Osteology).
Supraorbitals not reduced (Fig. 4.7A); four infraorbitals, greatly reduced; 5th infraorbital
absent; infraorbitals with sensory canals (Fig. 4.7F); three infraorbital, outer margin with
downward extension (Fig. 4.7F); anterior dorsal extension of the maxilla slightly overlaps the
premaxilla dorsally; palatine process of maxilla with a distinct projection pointing dorsally
(Fig. 4.7C); front margin of lower part of maxilla concave with a upward directed process;
outline shape of tip of the ascending process of the premaxilla straight (Fig. 4.7B); dorsal
63
boarder of operculum with a deep indentation (Fig. 4.7E, 4.20B); dorsal outline of lower jaw
with a concavity next to symphyseal knob (Fig. 4.20A); concavity before the coronoid
Fig. 4.20. Rasboroides nigromarginatus. A, Lateral views of dentary (co, coronoid process);
B, Right operculum (arrow- showing indentation).
process of dentary is absent (Fig. 4.20B); superior boarder of anguloarticular not elevated but
truncate (Fig. 4.20A); danionin notch absent (Fig. 4.11D); narrow coronoid process of
dentary (Fig. 4.7D); frontoparietal fontanel present (Fig. 4.7A); absence of bowl-shaped
depression on supraethmoid; one lateral process on each side of kinethmoid; anterior end of
kinethmoid with two process; 12 abdominal vertebrae; 16 caudal vertebrae; 28 total vertebrae
(Table 4.4); basipterygium broad, not deeply notched (Fig. 4.7H); basihyal with two lateral
processes, apophysis wide; absence of Rasborin process on 4th epibranchial; ventral view of
supracleithrum L-shaped; anterior outline of horizontal limb of cleithrum in ventral view
convex (Fig. 4.7K); lateral border of cleithrum in ventral view rounded (Fig. 4.7K); absence
of a foramen on anterior wall of horizontal limb of cleithrum; coracoid foramen welldeveloped (Fig. 4.7K); three rows of pharyngeal teeth (3,4,5–5,4,3); pharyngeal teeth with
64
terminal grooves; absence of a notch on posterio-lateral border of 5th ceratobranchial;
uroneural is absent from pleurostyle; parahypural and first hypural fused posteriorly; six
hypurals present.
4.1.2.2.2. 3. Distribution.
Rasboroides nigromarginatus appears to be restricted to the Atweltota region of the Kalu
River (Fig. 4.21).
Fig. 4.21. Distribution of Rasboroides nigromarginatus in Sri Lanka.
65
4.1.2.2.3. Rasboroides pallidus Deraniyagala, 1958
Rasbora vaterifloris pallida is described by Deraniyagala (1958) as a subspecies of R.
vaterifloris.
This subspecies is long been considered as a synonym of R. vaterifloris
(Pethiyagoda, 1991; Goonatilake, 2007). Along with Rasboroides pallidus, Deraniyagala
(1958) described yet another two subspecies, Rasbora vaterifloris ruber and Rasbora
vaterifloris rubioculis. These two subspecies are conspecific with R. pallidus. Hence, R.
pallidus is precedent over R. rubioculis and R. ruber, both which are considered to be junior
synonyms of R. pallidus.
4.1.2.2.3. 1. Description of R. pallidus (external morphology).
Males ranging from pinkish-grey to dark golden-yellow dorsally, lighter laterally, silvery on
venter and belly. Opercle suffused with dark red. Dense melanophores on sclera above and
below iris, giving effect of a black bar on the eye. Dorsal, anal, pectoral and pelvic fins
golden yellow; caudal fin lighter, its upper lobe hyaline (Fig. 4.22A, B). Females overall
light whitish-orange, lighter ventrally and on fins, which are partly hyaline. Colour of eye
and opercle as in males. In preserved specimens (Fig. 4.22C), overall colour olive brown;
upper one-third of body darker than lower two-thirds; fins hyaline; body compressed, its
dorsal and ventral profiles convex. Dorsal profile of head slightly concave behind level of
the eye, arched thereafter. Mouth small (rictus falling under anterior margin of the eye),
terminal, oblique; posterior groove of lower lip interrupted medially. Barbels absent. Dorsal
fin origin is three scale-width behind the pelvic fin origin, which falls midway between
pectoral fin base and anal fin origin. Pectoral fin reach the base of pelvic fin; pelvic fin reach
66
the origin of anal fin. Dorsal fin origin located halfway between snout-tip and hypural notch
(Fig. 4.22).
Fig. 4.22. Rasboroides pallidus; A, not preserved, male, in life; Gin River: Kottawa-Kombala
forest reserve; B, not preserved, male, in life; Bentara River, Pituwala; C, WHT 9703,
24.3 mm SL, male; Sri Lanka: Kottawa forest reserve (All photographs, Courtesy of
WCSG).
67
Table 4.6. Morphometric data of Rasboroides pallidus (n= 15) and Rasboroides new species (n= 18).
Males of
Females of
Males of
Female of
Rasboroides pallidus
R. pallidus
Rasboroides new species
Rasboroides new
(n=12)
(n=3)
(n=10)
species
(n=8)
range
mean s.d. range
mean s.d. range
mean s.d. range
mean s.d.
21.5-24.6
22.9
1.0
20.2-20.7
20.4
0.3
25.3-35.5
31.4
3.0
23.0-30.8
27.5
2.7
Total length
126-137
132
3
131-133
132
1
125-135
131
3
126-134
131
3
Body depth
34.3-37.5
35.5
1.2
33.0-36.7
35.5
2.1
35.6-40.0
37.8
1.6
33.3-36.8
34.5
1.2
Head length
25.6-31.3
28.4
1.6
27.6-30.4
28.7
1.5
26.5-29.4
28.1
0.9
25.6-29.4
27.3
1.2
48.4-52.7
50.7
1.3
44.6-51.7
49.2
4.0
45.7.1-51.0
49.0
1.9
45.7-48.9
47.1
1.1
distance
50.2-55.3
51.7
1.0
49.8-55.2
52.6
2.7
53.1-59.1
55.6
1.9
52.9-57.8
54.5
1.6
Dorsal fin
9.8-14.2
11.9
1.5
11.8-12.9
12.3
0.5
Standard
length (mm)
As a % of
standard
length
Pre-dorsal
length
Dorsohypural
68
base length
12.5-17.4
14.2
1.5
12.8-14.9
13.7
0.6
Dorsal fin
height
31.6-34.4
33.2
0.9
29.7-37.2
33.0
3.8
28.1-40.9
35.5
3.8
28.4-33.2
30.6
1.8
12.0-17.2
14.9
1.9
13.8-15.8
15.0
1.1
14.5-17.6
16.0
1.0
13.4-18.2
15.7
1.5
21.7-37.2
32.1
4.8
21.0-28.6
24.5
2.7
Anal fin base
length
Anal fin
depth
26.5-31.3
27.7
1.3
24.1-27.5
26.1
1.8
19.5-26.7
22.1
1.9
20.3-22.2
21.6
1.1
20.9-27.8
25.4
2.4
20.0-23.5
21.6
1.1
23.3-26.9
25.4
1.2
22.7-26.6
24.2
2.1
23.7-31.7
27.9
2.6
21.3-27.2
24.3
1.7
60.3-64.3
61.8
1.2
53.7-63.4
59.3
5.0
56.5-64.9
60.6
2.3
45.2-62.1
57.6
5.2
43.8-48.0
44.6
0.8
44.3-49.0
47.1
2.4
41.9-48.4
46.5
1.8
42.9-48.2
45.5
2.0
17.7-22.7
19.5
1.6
17.8-19.3
18.8
0.8
17.8-23.3
20.5
2.1
17.3-22.7
20.0
1.9
12.2-13.9
12.8
0.6
10.1-11.8
11.1
0.9
10.3-13.0
12.2
0.8
11.0-12.7
11.8
0.6
Pelvic fin
length
Pectoral fin
length
Pre-anal
length
Pre-pelvic
length
Caudalpeduncle
length
Caudalpeduncle
depth
69
Length of
upper caudal
fin lobe
29.8-34.6
31.4
1.1
30.7-33.8
32.2
1.6
28.4-33.1
31.0
1.7
27.2-33.7
30.3
2.3
30.7-37.3
34.4
2.4
33.0-34.2
33.7
0.6
31.5-37.3
34.1
2.0
28.0-35.4
33.0
2.8
11.2-15.1
13.5
1.6
12.8-13.5
13.2
0.4
11.4-15.0
13.4
1.2
10.9-15.9
13.5
1.8
Snout length
20.5-31.3
23.7
2.3
20.6-22.8
21.6
1.1
23.7-34.4
27.1
3.1
17.5-26.9
23.1
3.0
Eye diameter
36.6-42.2
39.1
2.4
38.6-39.7
39.2
0.5
32.6-39.8
37.0
2.1
28.8-33.7
31.5
2.0
26.0-38.1
30.4
2.2
33.3-35.7
34.7
1.2
27.4-35.0
31.1
2.1
25.0-28.3
26.5
1.1
12.9-23.8
14.9
1.4
14.3-17.5
15.9
1.6
15.9-20.8
18.4
1.8
9.8-17.5
13.4
2.5
Length of
lower caudal
fin lobe
Length of
median
caudal rays
As a % of
head length
Inter-orbital
width
Inter-narial
width
70
Dorsal fin with three unbranched and 7½ branched rays; first unbranched ray minute, only
slightly visible, second less than half the length of the third. Last unbranched ray strong,
relatively long, and slightly curved backwards, its tip poorly ossified. Anal fin with three
unbranched and 6½ branched rays. Caudal fin forked with 17 branched rays, nine on upper
lobe, and eight on lower one. Pectoral fin with one unbranched and 11½ branched rays.
Pelvic fin with one unbranched and 6½ branched rays. Lateral line incomplete, with 20-24
(20[1], 21[1], 22[7], 23[0], 24[6]) scales on body in lateral series; 1[11]-2[4] perforated
scales anteriorly. Scales on body in transverse line ½6[3]-7½[12], on caudal peduncle ½3½.
Pre-dorsal scales 10-12 (10[7], 11[5], 12[3]); pre-ventral scales 13-15 (13[7], 14[4], 15[2])
(Table 4.4).
4.1.2.2.3. 2. Description of R. pallidus (Osteology).
Dorsal boarder of the operculum slightly convex (Fig. 4.5G); three rows of pharyngeal teeth
(3,4,5–5,4,3); front margin of lower part of maxilla concave without an upward projecting
process (Fig. 4.5I) lacking a notch on posterio-lateral border of 5th ceratobranchial (Fig.
4.5L); pharyngeal teeth with terminal grooves (Fig. 4.5M); supraorbitals not reduced (Fig.
4.5B); frontoparietal fontanel present; lack the bowl-shaped depression on supraethmoid;
ventral view of supracleithrum L-shaped; anterior outline of horizontal limb of cleithrum
straight in ventral view (Fig. 4.6D); lateral border of cleithrum angled in ventral view (Fig.
4.6D); lack a foramen on anterior wall of horizontal limb of cleithrum; coracoid foramen
well-developed (Fig. 4.6D); basipterygium narrow, deeply notched (Fig. 4.6F); dorsal outline
of lower jaw with a concavity next to symphyseal knob; shallow depression before the
coronoid process of dentary (Fig. 4.5J, 4.23A); four infraorbitals, greatly reduced (Fig. 4.5K);
71
infraorbitals with sensory canals (Fig. 4.5K); first infraorbital, greatly enlarged (Fig. 4.5K);
3rd infraorbitals greatly enlarged, outer margin with downward extension (Fig. 4.5K); 5th
infraorbital absent; anterior dorsal extension of the maxilla slightly overlaps the premaxilla
dorsally; palatine process of maxilla has a distinct projection pointing dorsally (Fig. 4.5I);
outline shape of tip of the ascending process of the premaxilla straight (Fig. 4.5H); broad
coronoid process of dentary (Fig. 4.5J, 4.23A); superior border of anguloarticular convex,
elevated (Fig. 4.5J, 4.23A); two lateral processes on the kinethmoid;
Fig. 4.23. Rasboroides pallidus. A, Lateral views of dentary (co, coronoid process); B,
Kinethmoid (arrows-lateral process).
11-12 (11[4], 12[1], 13[1]) abdominal vertebrae; 16[2]-17[4] caudal vertebrae; 28-29 total
vertebrae (Table 4.4); hypohyal process on the basihyal is absent, apophysis wide; lacking
Rasborin process on the 4th epibranchial; danionin notch present (Fig. 11E); two lateral
processes on each side of kinethmoid (Fig. 4.23B); uroneural is absent from pleurostyle;
parahypural and first hypural fused posteriorly; six hypurals present.
72
4.1.2.2.3. 3. Distribution.
Rasboroides pallidus was recorded from shallow, slow-flowing, densely shaded lowland rainforested streams with a sandy-silt substrate in the following river basins: Kalu River
(Mahakalupahana, Yagirala), Bentara River (Bambarawana), Gin River (Kottawa-Kombala
forest reserve), Polathu-Modera River (Kombala- Kottawa forest reserve) and Nilwala River
(Dediyagala forest reserve, Beraliya forest reserve) (Fig. 4.24).
Fig. 4.24. Distribution of Rasboroides pallidus (type locality, closed circle) in Sri Lanka.
73
4.1.2.2.4. Rasboroides new species
This species of Rasboroides was collected from Walawe River in which the genus has not
been reported. The specimens referred to this species were compared with all the existing
species in the genus and observed that it is the largest on all known Rasboroides species, with
several morphological and morphometric characters, which were used to diagnose the new
species from previously described species.
4.1.2.2.4. 1. Description of Rasboroides new species (external morphology).
Sexes alike: greyish-yellow dorsally, golden-yellow on sides, ventrally silvery-white. Dorsal,
pectoral and pelvic fins golden yellow; anal and lower lobe of caudal fin yellow-orange;
upper lobe of caudal fin hyaline. In preserved samples, overall colour light brown, fins
darker. Body compressed, its dorsal and ventral profiles moderately convex. Dorsal profile
of head approximately straight posterior to level of the eye (Fig. 4.25). Mouth small (rictus
falling beneath anterior margin of the eye), terminal, oblique; posterior groove of lower lip
interrupted medially. Barbels absent. Dorsal fin origin three scale-widths behind pelvic fin
origin, which is closer to anal fin origin than to pectoral fin base. Pectoral fin reaching base
of pelvic fin; pelvic fin reaching origin of the anal fin. Dorsal fin origin located halfway
between snout-tip and hypural notch (Fig. 4.25).
74
Fig. 4.25. Rasboroides new species; A , WHT 9711, 31.3 mm SL, male; B, WHT 9720, 34.1
mm SL, female, in life; Sri Lanka: Walawe River basin: Suriyakanda (Photographs,
Courtesy of WCSG).
Dorsal fin with three unbranched and 7½ branched rays, first unbranched ray minute, only
just visible, second less than half length of third; last unbranched ray strong, slightly recurved,
its tip poorly ossified. Anal fin with three unbranched and 6½ branched rays. Caudal fin
forked with 17 branched rays, nine on upper lobe, and eight on lower one. Pectoral fin with
one unbranched and 11½ rays. Pelvic fin with one unbranched and 6½ branched rays.
Lateral line incomplete, with 25-28 (25[3], 26[8], 27[1], 28[3]) scales in lateral series, 1-3
75
(1[6], 2[3], 3[5]) perforated scales anteriorly. Scales on body in transverse line ½8½, on
caudal peduncle ½4½. Pre-dorsal scales, 11-13 (11[5], 12[6], 13[4]) and pre-ventral scales
14-16 (14[3], 15[9], 16[3]) (Table 4.4).
4.1.2.2.4. 2. Description of Rasboroides new species (Osteology).
Supraorbitals not reduced; front margin of lower part of the maxilla straight with a upward
directed process; outline shape of the tip of the ascending process of the premaxilla concave;
anterior dorsal extension of the maxilla slightly overlaps the premaxilla dorsally; palatine
process of maxilla with a distinct projection pointing dorsally; infraorbitals with sensory
canals; 3rd infraorbital outer margin without a downward extension; four infraorbitals,
greatly reduced; dorsal boarder of operculum without a deep indentation; 5th infraorbital
absent; dorsal outline of lower jaw with a shallow concavity next to symphyseal knob (Fig.
4.26A); shallow concavity before the coronoid process of dentary (Fig. 4.26A); superior
border of anguloarticular straight (Fig. 4.26A); broad, blunt coronoid process of dentary (Fig.
4.26A); frontoparietal fontanel present; bowl-shaped depression on supraethmoid is absent;
single lateral process on each side of kinethmoid (Fig. 4.26B); anterior end of kinethmoid
with a single process; 12 abdominal vertebrae; 17 caudal vertebrae; 29 total vertebrae (Table
4.5); ventral view of supracleithrum L-shaped; anterior outline of horizontal limb of
cleithrum convex in ventral view; also lateral border of cleithrum convex in ventral view;
lacking a foramen on anterior wall of the horizontal limb of cleithrum; coracoid foramen
absent; basipterygium narrow, deeply notched; basihyal with two lateral processes, apophysis
wide; Rasborin process on 4th epibranchial is absent; three rows of pharyngeal teeth (2,4,5–
5,4,2); pharyngeal teeth with terminal grooves; a notch on the posterio-lateral border of 5th
76
ceratobranchial is absent; danionin notch absent (Fig. 4.11F); uroneural is absent from
pleurostyle; parahypural and first hypural fused posteriorly; six hypurals present.
Fig. 4.26. Rasboroides new species. A, Lateral views of dentary (co, coronoid process); B,
Kinethmoid (arrow-lateral process).
4.1.2.2.4. 3. Distribution.
Rasboroides new species has up to now been recorded only from Suriyakanda, in the Walawe
River (Fig. 4.27). The species was found in shallow, slow-flowing, shady streams with a
substrate of sandy-silt and dense leaf litter in submontane forest. Rasboroides new species is
sympatric with Belontia signata, Pethia nigrofasciata, Puntius titteya and Rasbora
microcephala.
77
Fig. 4.27. Distribution of Rasboroides new species in Sri Lanka.
For this study, all putative topotypical material representing Rasboroides were collected and
examined (all subspecies mentioned by Deraniyagala [1958] including R. nigromarginatus)
also a new locality for Rasboroides (i.e., Suriyakanda [Walawe River]). Samples were taken
from Kalu River (Gilimale, Atweltota), Bentota River (Valallawita, Mahakalupahana), Gin
River (Kanneliya, Kottawa), Polathu Modara River (Kottawa, Imaduwa), Nilwala River
(Dediyagala, Beraliya) and Walawe River (Suriyakanda). Based on this study, some of these
disjunctive populations of Rasboroides were recognized as different species: including
Deraniyagala’s (1958) forma typica (R. vaterifloris), two subspecies (R. nigromarginatus and
R. pallidus) and a new species as well (Item 3.1).
78
Morphological approach (including morphometry) was used to distinguish all the four species
recognized here, R. vaterifloris, R. nigromarginatus, R. pallidus and the new species (from
Suriyakanda).
The new species tentatively named as Rasboroides new species.
It is
distinguished from the other three species previously described by means of colouration,
morphometry and morphology (external and osteology). Deraniyagala (1958) identified all
these populations except Suriyakanda population, from where the new species was collected.
4.1.2.2.2. Statistical analysis (Principal Component Analysis)
Based on the Principal Components Analysis (PCA), four species of Rasboroides were
identified. Correlation matrix of continuous characters of the four species explained 82.4%
of total variance by first principal component (PC1), which represented the body size axis
(standard length). Significant variance is explained by inter-orbital width, pre-dorsal length,
caudal peduncle length and inter-narial width (Appendix 4).
Out of the four species,
Rasboroides nigromarginatus and Rasboroides the new species was separated well from R.
vaterifloris and R. pallidus (Fig. 4. 28). Rasboroides nigromarginatus was further separated
from the other three species on the second component (PC2) of PCA (Fig. 4.28). On the
second axis (PC2) of PCA, R. vaterifloris, R. pallidus and Rasboroides new species are
almost indistinguishable. Rasboroides vaterifloris overlapped with R. pallidus (Fig. 4.28).
79
Fig. 4.28. First principal component vs. second principal component of the Principal
Components Analysis of four species of Rasboroides identified by the present study.
Males of Rasboroides nigromarginatus is immediately distinguished from its females by the
presence of strongly serrated first simple ray of pectoral fin (Fig. 4.7L) (vs. smooth first
simple ray of pectoral fin). However, this character was not mentioned by Meinken (1957)
and was not observed in the type material (ZMH 1207) of R. nigromarginatus. Hence, it
appears to be a secondary sexual character, which becomes prominent during the breeding
season. This condition is confirmed by the cleared and stained specimens (did not observe
the serration in cleared and stained specimens of Rasboroides).
According to Deraniyagala (1958), R. nigromarginatus is a yet another subspecies of R.
vaterifloris. In the same publication, he described four subspecies of Rasboroides vaterifloris
80
from three Provinces of Sri Lanka, Sabaragamuwa (Gilimale & Parakaduwa), the forma
typica; Western Province (Meegahatenna to Vallallavita), ruber; Southern Province, two
subspecies, one from Akuressa, rubrioculis and the other pallida from Kottawa (Galle). All
these locations are distant from Atweltota where R. nigromarginatus was present Atweltota
(06°33’N, 80°17’E) lies in between the Gilimale-Parakaduwa (in the Kalu River) and
Meegahatenna-Vallallavita (in the Bentota River) locations in the Kalu Ganga (= River) basin
and flows via the Pelany Ganga and the Kuda Ganga.
Rasboroides pallidus is the smallest congener (~24.6 mm Standard length) of Rasboroides.
In the PCA (Fig. 4.28) R. pallidus and R. vaterifloris overlapped on the first principal
component (PC1, the size axis). However, these two species are morphologically different.
Even though specimens from Kalu River (e.g. Gilimale, Parakaduwa and Atweltota)
represent slender bodied Rasboroides spp. (i.e., R. vaterifloris and R. nigromarginatus),
specimens from Valallawita exhibit somewhat deeper bodied individuals. Hence, along with
other diagnosable characters, this population merged to Rasboroides pallidus. Remarkably,
Rasboroides pallidus population from Bentara River (i.e., Elpitiya) had ½7½ transverse
scales in males, whereas ½6½ in females, which represented consistently in all examined
materials (from Elpitiya).
Whereas the populations in the Gin River (i. e., Kottawa,
Kanneliya), Polatu Modera River (Walpola) and Nilwala River (Dediyagala) had ½6½-½7½
transverse scales in both males and females. The specimens from Beraliya (Nilwala River)
had ½7½ transverse scales in all the materials.
The new species described here from Suriyakanda is distinguished from its members by
morphological and morphometric characters (Fig. 4.28).
Rasboroides collected from the Walawe River.
This was the first record of
81
Since the description of Rasboroides nigromarginatus (Meinken, 1957), it was considered as
a subspecies or a junior synonym of Rasboroides vaterifloris (Deraniyagala, 1958;
Pethiyagoda, 1991). However, Silva et. al. (2010) stated that R. nigromarginatus as a valid
species without examining relavent materials.
Rasboroides vaterifloris and R.
nigromarginatus are easily distinguished by each other based on many characters (Item
4.1.2.2.2.).
Thus, a beautiful fish species, which has long been lain the synonymy is
resurrected by the present study. Rasboroides pallidus was also considered as a synonym of
R. vaterifloris (Pethiyagoda, 1991) up to the present study.
This study uncovered four species of Rasboroides identified as distinct, discrete species
based on their morphology and morphometry.
Rasboroides vaterifloris is restricted to
Gilimale and Parakaduwa (Kalu River), R. nigromarginatus to Atweltota (Kalu River), R.
pallidus to Elpitiya, Kottawa, Valallawita, Kanneliya, Dediyagala (Gin, Bentara and Nilwala
Rivers), and the new species to Suriyakanda (Walawe River).
82
4.1.3. Taxonomic key to the species of the genera Horadandia and Rasboroides
1.
Maximum SL, 20.4 mm SL; lateral line absent; 9–10 pre-ventral scales; two rows of
pharyngeal teeth; pharyngeal teeth with minute cusps (Fig. 4.1K, 4.3J). .........................
................................................................................................................. (Horadandia) 2
–
Maximum SL, 30.2 mm; lateral line present, incomplete; 13–16 pre-ventral scales;
three rows of pharyngeal teeth; pharyngeal teeth with terminal grooves (Fig. 4.5M)
................................................................................................................ (Rasboroides) 3
2.
Presence of distinctly convex dorsal profile (Fig. 4.9); body depth 24.6–29.8% of SL;
dorsal profile of head slightly concave behind level of eye (Fig. 4.9); orbital diameter
37.0–41.3% of head length; dorsal fin origin slightly behind origin of pelvic fins (Fig.
4.9); distance between pelvic fins and pectoral fin base origin about 2 times length
between pelvic fin & anal fin; pelvic fins reaching origin of anal fin; dorsohypural
distance, when carried forward, reaching anterior margin of eye. ............... H. atukorali
–
Dorsal profile more or less straight (Fig. 4.13); body depth 27.7–31.9% of SL; dorsal
profile of head straight behind level of eye (Fig. 4.13); orbital diameter 26.8–36.7% of
head length; dorsal fin origin distinctly behind origin of pelvic fins (Fig. 4.13);
distance between pelvic fins and pectoral fin base origin about 1.5 times length
between pelvic fin and anal fin; pelvic fins reaching beyond the origin of anal fin;
dorsohypural distance, when carried forward, reaching middle of eye ........... H. brittani
83
3.
Dorsal profile more or less straight (Fig. 4.16, 4.19); body depth % of SL, 28.2–33.0
(males), 26.9–31.7 (females); dorsal fin origin slightly behind (single row of scales)
origin of pelvic fins; dorsohypural distance, when carried forward, reaching middle
eye ................................................................................................................................... 4
–
Dorsal profile distinctly convex (Fig. 4.22, 4.25); body depth % of SL, 34.3–40.0
(males), 33.3–36.8 (females); dorsal fin origin markedly behind (3 rows of scales)
origin of pelvic fins; dorsohypural distance, when carried forward, reaching tip of
snout ................................................................................................................................ 5
4.
Males with 16.7–22.1 inter-orbital length % of head length, 10.5–16.9 inter-narial
length % of head length; females with anal fin height, 17.4–22.7 % of head length;
caudal peduncle depth, 10.4–12.3% of head length; pelvic fins are located towards
anal fin origin than pectoral fin base origin ...................................... R. nigromarginatus
–
Males with 29.4–33.3 inter-orbital length % of Head length, 18.6–20.6 inter-narial
length % of head length; females with anal fin height, 23.5–24.8 % of head length,
caudal peduncle depth, 12.4–13.4% of head length; pelvic fins are located midway
between pectoral fin base and anal fin origin ............................................ R. vaterifloris
5.
Maximum SL, 24.6 (males), 20.7 (females) mm SL; ½6½-½7½ lateral transverse
scales; 20-24 scales along lateral line series; 13–15 pre-ventral scales ........... R. pallidus
–
Maximum SL, 35.5 (males), 29.8 (females) mm SL; ½8½ lateral transverse scales; 2528 scales along lateral line series; 15–17 pre-ventral scales ..... Rasboroides new species
84
4.2.
Experiment 2 :Evaluation of the present distribution pattern of Rasboroides
pallidus in Gin River.
Among the selected five sites (i.e., Madola, Kottawa, Homadola, Kanneliya and Kosmulla),
Rasboroides pallidus was recorded only from Kottawa and Kanneliya. Based on the presence
of putative natural habitat of Rasboroides (forested sites), all the above indicated sites were
selected. However, this species was observed in two sites only, inferring that the other three
sites lacked the specific habitat requirements of R. pallidus (Fig. 4.29).
Fig. 4.29. Distribution of Rasboroides pallidus in the study sites of Gin River:
Kottawa (below) and Kanneliya (above) in red colour (Rasboroides pallidus
present). Madola (below), Homadola (middle), and Kosmulla (above) in black
colour (Rasboroides pallidus absent).
85
4.2.1. Fish sampling and distribution
Total sampling yielded about seven to eight species from each location, whereas a lower
number of species were recorded from Homadola (four species). This could be due to rapid
water flow and low habitat complexity. In contrast, Kosmulla, Kanneliya and Kottawa
showed a diverse fish fauna. Moreover, Kanneliya had the greatest abundance during the
study period and one of the sites where R. pallidus observed had the highest abundance when
compared with the other sites (Fig. 4.30).
Abundance
1200
Abundance
1000
800
Ma Dola
600
Kottawa
400
Homadola
200
Kanneliya
Kosmulla
0
Ma Dola
Kottawa Homadola Kanneliya Kosmulla
Site
Fig. 4.30. Cumulative number of individuals observed during the study period at each site.
The total number of species in the Kanneliya was very high, mainly because it was relatively
undisturbed and larger forest cover than the Kottawa forest. The site Kosmulla though
86
situated in Sinharaja forest reserve, it did not possess such diversity because Kosmulla
streams were torrents and the substrate was having rocks and large boulders.
Six species including R. pallidus had an abundance of only ~40 individuals at Kanneliya:
Devario sp., Dawkinsia singhala, Pethia nigrofasiata, Rasbora dandia and Systomus
pleurataenia. All these species are either omnivorous or herbivorous; none of them is a
potential predator of R. pallidus. Sampling of fish were performed during the daytime.
Hence, predators of R. pallidus were not observed. However, presence of Channa ara and
Clarias brachysoma, which are potential predators of R. pallidus had been recorded in those
sites (Pethiyagoda, 1991; De Silva, 1997; De Silva et al., 2015; D. S. Kandamby, pers.
comm.).
The abundance distribution of the species across sites sampled showed a typical right skew
(Fig. 4.31) that is similar to studies of birds, butterflies and other communities (Williams,
1964; Magurran, 2004). This means that most of the fish species are relatively rare, while a
few species dominate an area in terms of their abundance. Fortunately, exotic invasive
species like Oreochromis spp. were not collected from all these sites, but there is a single
record of O. mossambicus in Hiyare reservoir (De Silva, 1997) near Madola.
87
Fig. 4.31. Distribution of species richness and abundance in all the sites.
The mean abundance of Rasboroides pallidus was very high in Kanneliya forest (Fig. 4.32),
which may be due to higher extent of forest cover, availability of natural habitats, feeds and
minimal pollution. In the Kottawa forest reserve, human encroachment was very high with
only a few natural streams (often polluted). In addition, this species was restricted to a few
locations within the Kottawa forest though R. pallidus was observed since late 90s in the
Kottawa forest (pers. obs.). Neighboring people diverted the stream to the pool, which
resulted in not having sufficient water to the down stream where R. pallidus were dwelling.
As a result, and within ~10 years, all the fish in this down stream disappeared (pers. obs.).
Selected site from Kottawa forest was situated close to the boarder of the forest and adjacent
to the Tea Research Institute, Kottawa (TRI).
.
88
Mean Abundance
160
Mean Abundance
140
120
100
80
60
40
20
0
Kottawa
Kanneliya
Site
Kottawa
Kanneliya
Fig. 4.32. Mean abundance of R pallidus in the two sites during the study period.
Rasboroides pallidus can be considered as a seasonal spawner (Fig. 4.33), because there was
a peak in the number of individuals between July to November. Between these months
juveniles were very high. From March to July all the sites received heavy rains. The rainy
season is the breeding season of Rasboroides pallidus (Fig. 4.33).
89
Fig. 4.33: Number of individuals (including juveniles) of Rasboroides pallidus observed in
the Kottawa and Kanneliya.
Rasboroides pallidus is not easy to collect or observe during the rainy season. Deraniyagala
(1958) also reported that the forma typica (i.e., Rasboroides vaterifloris) had extirpated at the
type locality. However, as Pethiyagoda (1991) noted and based on the present data, this
species persists in small, shaded streams and rivulets in and around Gilimale. Moreover,
Pethiyagoda (1991) noted that the survey referred to by Deraniyagala (1958) had conducted
during the rainy season, when streams were often turbid and swollen. R. vaterifloris is not
easy to collect under such conditions. During the course of this study, several individuals of
R. pallidus were observed in Kanneliya forest where fishes swam up the smaller rivulets to
spawn in shallow waters during periods of heavy rain.
90
4.2.2. Physico-chemical characteristics
To determine the habitat characteristics preferred by Rasboroides pallidus in Gin River,
following physico-chemical parameters were determined:
(A).
Water temperature
(B).
Stream pH
(C).
Stream depth (maximum depth)
(D).
Stream flow rate
(E).
Percentage of canopy cover
(F).
Substrate and
(G).
Turbidity
4.2.2.1. Water temperature
Monthly water temperature pattern of the sampling sites indicated bi-modal variation with
two peaks in February and October (Fig. 4.34). There was a gradual decrease in water
temperature from May to August because south-western wet zone receives monsoon rains
during this period. Except the disturbed sites (i.e., Madola and Homadola), the other sites
showed relatively lower water temperature (Fig. 4.34).
91
Fig. 4.34. Variation of water temperature of the sampling sites throughout the study period
(January-December).
4.2.2.2. Stream pH
Lower pH was observed during rainy seasons, whereas during dry season, pH values were
markedly higher (Fig. 4.35). Electrical conductivity values of stream water in the forest sites
(Kanneliya, Kosmulla) were consistent throughout the year, while the other three sites
indicated fluctuations. These deviations may be due to the intensive agricultural practices in
Homadola, Madola and Kottawa sites. Although Koattawa site was located close to a rain
forest, it was also very close to Tea Research Institute, Kottawa. It may be due to certain
92
agrochemical discharges entering the stream.
Discharges of intensive land use systems
dissolve chemical compounds in water and thus have a bigger impact on stream water quality
(Kato et al., 2009). pH gradually decreased with the onset of monsoonal rains (Fig. 4.35).
Fig. 4.35. Fluctuation of pH in the selected sites (from January to December).
4.2.2.3. Depth of the water column
Depth of the water column in all the sites gradually increased with the rainfall. Two physical
characteristics of the sites, velocity (flow rate) and water depth simultaneously increased with
the onset of the rains from April to July (Fig. 4.36). Rasboroides pallidus was abundant in
0.4-0.7 m depths at Kanneliya and Kottawa. Wikramanayake & Moyle (1989) had given ~0.6
m as the optimum depth for R. vaterifloris.
93
Fig. 4.36. Fluctuations of water depth in the selected sites (January-December).
4.2.2.4. Stream flow rate (Velocity)
Stream flow rate of the sampling points fluctuated with the onset of monsoon. Flow rate
significantly increased in Homadola area indicating the highest disturbance to the stream due
to encroachments (Fig. 4.37). All the other sites did not show such a sudden increase in flow
rate. Rasboroides pallidus prefers to live in slow flowing waters at Kanneliya and Kottawa.
This is in confirmity with the data provided for R. vaterifloris by Wikramanayake & Moyle
(1989). The rainfall interception by dense canopy cover and high infiltration due to thick
94
litter in the forest have reduced surface runoff and peak flow rate indicating least fluctuation
of stream flow as described by Mathur & Sajwan (1978).
Fig. 4.37. Variations [n the flow rate in different sampling sites throughout the study period
(January-December).
4.2.2.5. Percentage of canopy cover
A high percentage of canopy cover was observed in all but Madola. However, according to
the results, canopy cover alone did not contribute to the existence of Rasboroides pallidus in
the Gin River. Homadola and Kosmulla also possessed a high canopy cover, but the flow
rate and substrate compositions were lower in those two sites. This may be the reason for the
95
absence of Rasboroides in both sites. Mathur & Sajwan (1978) emphasized that dense
canopy and undergrowth in small watersheds contribute to reduce the total runoff by 28 %
and peak rate by 73 %. In addition to that, Madola and Homadola were somewhat disturbed
and polluted streams in secondary forests (Table 4.7).
Table 4.7. Percentage of canopy cover and substrate categories in the selected sites
Site
Madola
Kottawa
Canopy cover (%)
50%
75%
Substrate type
Pebbles and sand
Sand with submerged macrophytes
Homadola
70%
Rocks and boulders
Kanneliya
60%
Sand, leaf litter and submerged logs
Kosmulla
60%
Rocks and boulders
4.2.2.6. Substrate
Rasboroides spp. were always in sandy substrates with extremely low silt and leaf debris and
sometimes were among submerged vegetations. The slightly fast flow rate might have
washed the silt particles in their microhabitats. Most of the time, these fish preferred to live
somewhat close to a water fall or a torrent but far way from the high flow areas (i.e., close to
river or stream banks). Among the selected sites, preferable substrates were observed in
Kanneliya and Kottawa forests. Wikramanayake & Moyle (1989) mentioned sand as the
most preferred substrate for R. vaterifloris.
96
Kosmulla though situated in the Sinharaja Forest Reserve, but did not possess the substrate
that is preferred by Rasboroides. Similarly, at Madola Rasboroides pallidus was not found.
At Madola, high flow rate during rainy seasons would have disturbed the fish and the spill
might have facilitated predatory fish to enter this site. Homadola did not have the necessary
substrates for Rasboroides and the stream was extremely swift. The only observed common
species were torrent-preferred fish such as, a Devario sp., Schistura notostigma and several
species of Sicydiinae goby.
4.2.2.7. Turbidity
Turbidity rapidly changed due to rains. When heavy rains occurred, visibility changed to
either average or a poor condition. During the dry months, turbidity was low (Fig. 4.38).
Fig. 4.38. Variation of turbidity throughout the study period (January-December)
97
CHAPTER V
5.0 CONCLUSIONS
Comparison of all congeners of Horadandia (two spp.) and Rasboroides (four spp.)
confirmed the identity of two distinct genera in the tribe Rasborini by means of external
morphology and osteology.
Horadandia (i.e., brittani + atukorali) differs from
Rasboroides (vaterifloris+nigromarginatus+pallidus+a new species) by a consistent set of
autoapomorphies: (a) absence/ presence of bifurcation at posterior end of kinethmoid; (b)
anterior boarder of cleithrum in ventral view either concave or convex; (c) absence/ presence
of sensory canals in infraorbital bones; (d) absence/ presence of a concavity before the
coronoid process of dentary; (e) pharyngeal teeth surface ornamentation, either with grooves
or cusps; (f) absence/ presence of 6th hypural. In addition to those, following characters
reported by Liao et al., (2010), used to diagnose these two genera were also repeated and
confirmed in this study: (a) absence/ presence of a bowl-shaped depression on the
supraethmoid; (b) attachment of Baudelot’s ligament on the dorsal part of the cleithrum, to
distal end or not at the distal end; (c) number of rows of pharyngeal teeth either two or three;
and (d) lateral line absent or present.
Prior to the study of Liao et al. (2010), both genera were in an uncertain taxonomic position
(Kottelat & Vidthayanon, 1993; Tang et al., 2010).
Liao et al.
(2010) has given six
characters to distinguish Horadandia from Rasboroides. However, according to this study,
three characters mentioned by Liao et al. (2010) are in doubt. Hence, this study is confirmed
the identity of two distinct genera by giving ~12 characters, of which eight characters were
revealed by the present study with the other four characters described in Liao et al. (2010).
98
Thus far, both genera were considered as monotypic genera (Pethiyagoda, 1991, Goonatilake,
2007; Liao et al., 2010). The interspecific and intraspecific variations of Horadandia and
Rasboroides uncovered two distinct species represented in Horadandia, whereas four species
in Rasboroides. Based on this study, Rasboroides vaterifloris and Horadandia atukorali
were redescribed and also resurrected R. nigromarginatus, which has long been considered as
a synonym of R. vaterifloris. In addition, two subspecies, Rasboroides vaterifloris pallidus
and Horadandia atukorali brittani were resurrected to species level.
Moreover, a new
species of Rasboroides from Walawe River was also described. Discovery of Rasboroides
new species was the first record of the genus from Walawe River. These findings add three
new freshwater fishes to the island’s ichthyofaunal list while also adding a new Indian fish as
well.
South East Asian cyprinid genus Trigonostigma appears to be the sister genus to Horadandia
and Rasboroides (Rüber et al., 2007; Liao et al., 2010; Tang et al., 2010). Trigonostigma
congeners are superficially resemble congeners of Horadandia and Rasboroides. Currently,
these three genera (i.e., Horadandia+Rasboroides +Trigonostigma) show a disjunctive
distribution in South East Asia and in South Asia. However, recent studies showed that sister
species of Sri Lankan taxa occur in Southeast Asia as well (Cylindrophis Gower et al., 2005;
Eutropis Das et al., 2008; Hypnale Pyron et al., 2013; agamids Grismer et al., 2016).
Considering the distribution pattern of Rasboroides pallidus in the Gin River, it was observed
only in two sites and within least disturbed rain forests, Kanneliya and Kottawa. Physicochemical parameters of both sites (Kottawa and Kanneliya) showed similar characteristics.
Thus, Rasboroides pallidus may be a habitat specialist.
99
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APPENDIX 1. Materials referred to this study
Horadandia atukorali Deraniyagala, 1943. WHT 2023, 8, 16.1-19.3 mm SL; WHT 2023,
15.4 mm SL (c&s); Sri Lanka: Kalu River basin: Dombagaskanda, Ingiriya, 6°44' N 80°09' E;
K. Manamendra-Arachchi & D. Gabadage, 28 Dec 1991. WHT 11017, 15.4 mm SL; WHT
11104, 17.8 mm SL (c&s); Sri Lanka: Mundel, 7°49' N 79°49' E; D. Gabadage, 13 Sep 1995.
Horadandia brittani Rema Devi & Menon, 1992. WHT 466, 7, 15.7-20.4 mm SL; India:
Kerala: Kumaragam, 13 km west of Kottayam, 9°35' N 76°30' E; K. Manamendra-Arachchi,
7 Jun 1995. WHT 7468, 16.2 mm SL; India: same locality; R. Pethiyagoda, 20 Mar 1996.
WHT 466, 1, 14.8 mm SL (c&s); India: Kerala: Kumaragam, 13 km west of Kottayam, 9°35'
N 76°30' E; K. Manamendra-Arachchi, 7 Jun 1995. WHT 11100, 1, 14.4 mm SL (c&s); India:
Kerala: Kumaragam, 13 km west of Kottayam, 9°35' N 76°30' E; R. Pethiyagoda, 7 Jun 1995.
Rasboroides vaterifloris (Deraniyagala, 1930). WHT 9700, 10, 22.1-28.4 mm SL; WHT
9701, 1, 25.5 mm SL (c&s); Sri Lanka: Ratnapura District: Kalu River basin, Induru Stream:
Induruwa Forest Reserve, near Gilimale: 6°45' N 80°26' E; M. de Silva & S. Batuwita, 2 May
2012. WHT 9702, 10, 22.2- 27.5 mm SL; WHT 9702, 1, 25.6 mm SL (c&s); Sri Lanka:
Ratnapura District: Kalu River basin, Adona Stream: Parakaduwa; 6°49' N, 80°18' E; R.
Krishantha, 4 May 2012.
Rasboroides nigromarginatus (Meinken, 1957). WHT 578, 12, 26.2-30.2 mm SL; WHT
578, 1, 29.0 mm SL (c&s); Sri Lanka: Kalutara District: Kalu River basin: Atweltota, 6°33' N
80°17' E; R. Pethiyagoda & K. Manamendra-Arachchi, 24 April 1994.
116
Rasboroides pallidus Deraniyagala, 1958. All from Sri Lanka: WHT 9703, 1, 24.3 mm SL;
WHT 9704, 4, 20.2-24.6 mm SL; Galle District: Gin River basin: Kombala-Kottawa forest
reserve, 6°06' N 80°20' E; S. Batuwita et al., 3 Mar 2012. WHT 9705, 10, 20.3-24.0 mm SL;
same locality; M. de Silva et al., 6 Feb 2012. WHT 9706, 2, 20.9-24.9 mm SL; Matara
District: Nilwala River basin: Dediyagala forest reserve, 6°10' N 80°26' E; M. de Silva & P.
Krishantha, 24 Mar 2012. WHT 9708, 2, 20.5-24.1 mm SL; Galle District: Gin River basin:
Kanneliya forest reserve, 6°15' N 80°20' E; S. Udugampala & S. Akmeemana, 9 Apr 2012.
WHT 9709, 2, 23.1-26.6 mm SL; Galle District: Benatara River basin: Porawagama
(Elpitiya), 6°16' N 80°11' E; S. Udugampala et al., 17 Mar 2012. WHT 11055, 1, 23.5 mm
SL (c&s); Kalutara District: Kalu River basin: Yagirala, 6°22' N 80°10' E; S. Batuwita, 22
Jan 2003. WHT 11101, 1, 17.7 mm; WHT 11113, 1, 20.0 mm SL (c&s); Galle District: Gin
River basin: Kombala-Kottawa forest reserve, 6°06' N 80°20' E; S. Batuwita, 14 Jun 2001.
WHT 11051, 1, 22.7 mm SL (c&s); Galle District: Bentara River basin: Bambarawana (near
Elpitiya), 6°18.5' N 80°15' E; S. Batuwita, 25 Apr 2000. WHT 9713, 10, 23.1-32.4 mm SL;
WHT 9715, 1,30.5 mm SL (c&s); Matara District: Nilwala River basin: Beraliya, near
Akuressa, 6°06' N 80°28' E; R. Krishantha & S. Akmeemana, 7 May 2012. WHT 11098, 1,
24.3 mm SL (c&s); Matara District: Nilwala River basin: Opatha (Akuressa), 6°14' N 80°24'
E; S. Batuwita, 10 Jun 2002.
Rasboroides new species. WHT 9710, 34.0 mm SL; Sri Lanka: Ratnapura District: Walawe
River basin, Rakwana Ganga tributary: Suriyakanda, 6°26'59" N 80°37'10" E, 980 m above
sea level; S. Udugampala & R. Krishantha, 3 June 2013. WHT 9711, 2, 30.8-31.3 mm SL;
same data as WHT 9710. WHT 9712, 11, 28.2-32.0 mm SL; same locality as WHT 9710; R.
Krishantha, 9 Feb 2012. WHT 9720, 4, 25.3-35.5 mm SL; same locality as WHT 9710; R.
Krishantha, 3 May 2012.WHT 9714, 2, 25.6-29.5 mm SL (c&s): same locality as above; R.
Krishantha, 9 Feb 2012.
117
APPENDIX 2. Principal component analysis of cintinous variables of genera
Horadandia and Rasboroides
Eigenanalysis of the Correlation Matrix
Eigenvalue
15.152
0.585
0.316
0.193
0.181
0.132
0.097
0.079
0.057
Proportion
0.891
0.034
0.019
0.011
0.011
0.008
0.006
0.005
0.003
Cumulative
0.891
0.926
0.944
0.956
0.966
0.974
0.980
0.984
0.988
Eigenvalue
0.047
0.039
0.036
0.025
0.023
0.021
0.012
0.007
Proportion
0.003
0.002
0.002
0.001
0.001
0.001
0.001
0.000
Cumulative
0.990
0.993
0.995
0.996
0.998
0.999
1.000
1.000
Variable
PC1
PC2
PC3
Standard length (mm)
0.253
-0.145
-0.084
Body depth
0.249
0.182
0.131
Head length
0.251
-0.058
-0.075
Pre-dorsal length
0.249
-0.166
-0.101
Dorsohypural distance
0.253
-0.120
-0.013
Dorsal fin base length
0.245
0.019
-0.006
Dorsal fin height
0.248
0.116
0.269
Anal fin height
0.242
0.161
0.474
Pelvic fin length
0.247
0.095
0.331
Pectoral fin length
0.247
0.161
0.296
Preanal length
0.252
-0.051
-0.107
Pre-pelvic length
0.250
-0.115
-0.129
Caudal peduncle length
0.198
-0.787
0.048
Caudal peduncle depth
0.243
0.094
-0.053
Snout length
0.236
0.077
-0.126
Orbital diameter
0.235
0.023
-0.423
Internarial width
0.220
0.419
-0.487
118
APPENDIX 3: Principal component analysis of cintinous variables of Horadandia
atukorali and H. brittani
Eigenanalysis of the Correlation Matrix
Eigenvalue
11.357
1.760
1.487
1.222
0.775
0.524
0.493
0.378
0.305
Proportion
0.598
0.093
0.078
0.064
0.041
0.028
0.026
0.020
0.016
Cumulative
0.598
0.690
0.769
0.833
0.874
0.901
0.927
0.947
0.963
Eigenvalue
0.284
0.183
0.094
0.060
0.050
0.023
0.004
0.000
0.000
Proportion
0.015
0.010
0.005
0.003
0.003
0.001
0.000
0.000
0.000
Cumulative
0.978
0.988
0.993
0.996
0.999
1.000
1.000
1.000
1.000
Eigenvalue
-0.000
Proportion
-0.000
Cumulative
1.000
Variable
PC1
PC2
PC3
PC4
PC5
Standard length (mm)
0.282
-0.010
0.091
-0.078
0.087
Body depth
0.240
-0.332
0.012
-0.202
0.020
Head length
0.252
-0.263
0.062
-0.095
0.070
Pre-dorsal length
0.271
-0.017
0.163
-0.191
0.195
Dorsohypural distance
0.286
-0.012
-0.076
-0.079
-0.043
Dorsal fin base length
0.256
0.223
-0.215
-0.037
-0.131
Dorsal fin height
0.224
-0.252
0.052
0.123
-0.464
Anal fin base length
0.128
0.282
0.284
0.534
0.307
Anal fin height
0.180
-0.103
-0.254
0.564
-0.292
Pelvic fin length
0.232
0.051
-0.247
0.262
-0.167
Pectoral fin length
0.174
0.030
0.517
0.074
-0.192
Preanal length
0.276
0.001
0.207
-0.096
0.181
Pre-pelvic length
0.278
0.043
0.129
-0.075
0.003
Caudal peduncle length
0.220
0.243
-0.058
-0.364
-0.296
Caudal peduncle depth
0.222
0.277
-0.007
-0.063
-0.237
Snout length
0.216
-0.286
0.058
0.194
0.325
Orbital diameter
0.171
0.523
0.034
0.066
0.169
Interorbital width
0.160
0.181
-0.537
-0.102
0.308
Internarial width
0.209
-0.295
-0.278
0.057
0.256
119
APPENDIX 4: Principal component analysis of cintinous variables of Rasboroides
vaterifloris, R. nigromaginatus, R. pallidus and Rasboroides new species
Eigenanalysis of the Correlation Matrix
Eigenvalue
15.654
1.460
0.485
0.300
0.210
0.199
0.145
0.125
0.084
Proportion
0.824
0.077
0.026
0.016
0.011
0.010
0.008
0.007
0.004
Cumulative
0.824
0.901
0.926
0.942
0.953
0.964
0.971
0.978
0.982
Eigenvalue
0.075
0.068
0.048
0.042
0.026
0.025
0.022
0.015
0.011
Proportion
0.004
0.004
0.003
0.002
0.001
0.001
0.001
0.001
0.001
Cumulative
0.986
0.990
0.992
0.995
0.996
0.997
0.998
0.999
1.000
Eigenvalue
0.006
Proportion
0.000
Cumulative
1.000
Variable
PC1
PC2
PC3
PC4
PC5
Standard length (mm)
0.244
0.174
-0.071
0.069
0.105
Body depth
0.238
-0.221
0.168
-0.052
0.067
Head length
0.245
0.100
0.038
-0.089
-0.015
Pre-dorsal length
0.230
0.271
0.079
0.282
0.079
Dorsohypural distance
0.246
0.145
-0.033
-0.008
-0.020
Dorsal fin base length
0.235
-0.009
-0.220
-0.271
-0.187
Dorsal fin height
0.240
-0.106
0.158
0.018
-0.018
Anal fin base length
0.233
-0.112
-0.011
-0.454
-0.321
Anal fin height
0.233
-0.138
0.390
0.069
-0.277
Pelvic fin length
0.235
-0.025
0.387
0.114
-0.241
Pectoral fin length
0.238
-0.101
0.357
0.027
0.165
Preanal length
0.245
0.088
-0.005
0.177
0.240
Pre-pelvic length
0.243
0.101
-0.069
0.057
0.298
Caudal peduncle length
0.190
0.453
-0.275
0.125
-0.326
Caudal peduncle depth
0.236
-0.033
-0.097
0.268
-0.198
Snout length
0.230
-0.015
-0.268
-0.488
-0.048
Orbital diameter
0.226
0.221
-0.067
-0.194
0.536
Interorbital width
0.162
-0.589
-0.147
-0.023
0.282
Internarial width
0.189
-0.378
-0.517
0.457
-0.131
120
APPENDIX 5: NEW CHARACTER STATES USED IN THIS STUDY
Orbit
1. Sensory canals in infraorbitals.—States: absent (Fig. 2E, 4E); present (Fig. 8K).
2. Infraorbital 3.—States: outer boarder without a downward extension (Fig. 2E, 4E);
outer margin with an extension (Fig. 8K).
Jaw bones
3. Palatine process on the maxilla.—States: with a less prominent projection pointing
dorsally (Fig. 4D); with a distinct projection pointing dorsally (Fig. 2H, 8I).
4. Front margin of the lower part of the maxilla.—States: almost straight; convex;
concave.
5. Concavity before the coronoid process of dentary.—States: a distinct concavity; less
prominent concavity; no concavity.
6. Superior border of anguloarticular.—States: truncate or convex; subtriangular-shaped.
Pectoral girdle
7. Lateral border of cleithrum in ventral view.—States: straight; angled or convex.
8. Coracoid foramen.—States: absent; weakly developed; well-developed.
Gill arch
9. Apophysis of hypohyal process on the basihyal.—States: broad; narrow.
10. Phyrangeal teeth.—States: with terminal grooves; with minute cusps.
11. Lateral border of 5th ceratobranchial.—States: with an apophysis; with a less
prominent process; well-developed process.
121
APPENDIX 6: SELECTED CHARACTER STATES OF LIAO ET. AL. (2010) USED
IN THIS STUDY
Squamation and fins
1. Number of circumpeduncular scales (Liao et al., 2010: character 6).—States: [0], 14–18;
[1], 10–12.
2. Relative position of dorsal and pelvic fin insertions (slightly changed character 11 of Liao
et al., 2010).—States: [0], dorsal fin insertion greatly posterior to pelvic fin insertion, with
more than five scales in between; [1], dorsal fin insertion one scale behind pelvic fin insertion;
[2], 3 scales behind pelvic fin insertion; [3], dorsal fin insertion 1 scale anterior to pelvic fin
insertion.
Orbital series
3. Supraorbital (Liao et al., 2010: character 12).—States: [0], not reduced or slightly reduced;
[1], greatly reduced.
4. Infraorbital 2 (Fang 2003: character 17; Liao et al., 2010: character 13).—States: [0],
greatly reduced; [1], not reduced or slightly reduced.
5. Infraorbital 4 (Liao et al., 2010: character 14).—States: [0], not reduced or slightly reduced;
[1], greatly reduced.
6. Infraorbital 5 (Fang 2003: character 18; Liao et al., 2010: character 15).—States: [0], not
reduced or slightly reduced; [1], absent or fused with infraorbital 4; [2] greatly reduced.
122
Jaw bones
7. Dorsal extensions of the maxilla (Conway, 2005: character 2; Liao et al., 2010: character
16).—States: [0], anterior extension covers part of the premaxilla or slightly overlaps the
premaxilla dorsally (Conway, 2005: fig. 1a & c); [1], anterior extension covers the major part
of the premaxilla except for the ascending process (Conway, 2005: fig. 1b).
8. Outline shape of tip of the ascending process of the premaxilla (Fang 2003: character 20;
Liao et al., 2010: character 19).—States: [0], blunt (Fang 2003: fig. 5B); [1], straight or
slightly concave (Fang 2003: fig. 5A).
9. Dorsal outline of the lower jaw (Conway, 2005: character 25; Liao et al., 2010: character
20).—States: [0], one concavity next to a well developed symphyseal knob; [1], the dorsal
outline next to the symphyseal knob is straight, and the symphyseal knob is rather weak or
absent.
10. Danionin notch (Fang 2003: character 9; Liao et al., 2010: character 21).—States: [0],
present (Fang 2003: fig. 2D & E); [1], absent.
Suspensorium
11. Metapterygoid (Fang 2003: character 25; Liao et al., 2010: character 22).—States: [0],
dorsal outline with a deep indentation (Fang 2003: fig. 6B); [1], dorsal outline relatively
straight (Fang 2003: fig. 6A).
123
12. Opercular canal (Cavender & Coburn 1992: character 37; Conway, 2005: character 8;
Liao et al., 2010: character 23).—States: [0], absent (Liao et al., 2010: fig. 4A & C); [1],
present (Liao et al., 2010: fig. 4B).
13. Shape of the opercle (Liao et al., 2010: character 24).—States: [0], roughly D-shaped
(Liao et al., 2010: fig. 4A & B); [1], triangular, with a dorsal process (Liao et al., 2010: fig.
4C).
Neurocranium
14. Frontoparietal fontanel (Liao et al., 2010: character 25).—States: [0], absent; [1], present.
15. A bowl-shaped depression on the supraethmoid (Liao et al., 2010: character 26).—States:
[0], absent; [1], present.
16. Kinethmoid (Liao et al., 2010: character 27).—States: [0], anterior end wide (Liao et al.,
2010: fig. 12A–C); [1], anterior end narrow and round, like a bead (Liao et al., 2010: fig.
12D).
17. Number of lateral process on each side of the kinethmoid (Liao et al., 2010: character
28).—States: [0], 1 (Liao et al., 2010: fig. 10A); [1], 0; [2], 2 (Liao et al., 2010: fig. 10B).
Weberian apparatus and vertebrae
18. Dorsal view of the lateral process of the second vertebra (Liao et al., 2010: character
29).—States: [0], arched with the distal end pointing posteriorly (Liao et al., 2010: fig. 5A);
124
[1], more or less straight, with the distal end slightly pointing posteriorly (Liao et al., 2010:
fig. 5B).
19. Tripus (Liao et al., 2010: character 30).—States: [0], the outermost anterior tip with a
process, the anterior outline oblique, dolabriform in dorsal view (Liao et al., 2010: fig. 5A);
[1], the outermost anterior tip with a tiny apophysis, the anterior outline rather straight (Liao
et al., 2010: fig. 5B).
Pectoral girdle
20. Ventral-view shape of the supracleithrum (Liao et al., 2010: character 32).—States: [0],
L-shaped; [1], flat or slightly arched.
21. Anterior outline of the horizontal limb of the pectoral girdle in the ventral view (Liao et
al., 2010: character 33).—States: [0], the anterior edge of the horizontal limb of the cleithrum
straight, the anterior outline of the pectoral girdle straight (Liao et al., 2010: fig. 9C); [1], the
anterior edge of the horizontal limb of the cleithrum rounded, the anterior outline of the
pectoral girdle concave (Liao et al., 2010: fig. 9A); [2], the anterolateral corner of the
horizontal limb of the cleithrum with a process, the anterior outline of the pectoral girdle
convex with a rudimentary apophysis in the middle; [3], the anterolateral corner of the
horizontal limb of the cleithrum with a rudimentary process, the anterior outline of the
pectoral girdle acute (Liao et al., 2010: fig. 9B).
22. Foramen on the anterior wall of horizontal limb of the cleithrum (Liao et al., 2010:
character 34).—States: [0], present (Liao et al., 2010: fig. 6A); [1], absent (Liao et al., 2010:
fig. 6B).
125
23. Attachment of Baudelot’s ligament on the neurocranium (Liao et al., 2010: character
35).—States: [0], exoccipital; [1], basioccipital.
24. Attachment of Baudelot’s ligament on the dorsal part of the cleithrum (Liao et al., 2010:
character 36).—States: [0], distal end; [1], not at the distal end, apart from the tip.
Gill arch
25. Rasborin process on the epibranchial 4 (Liao et al., 2010: character 37).—States: [0],
absent (Fig. 7A); [1], present (Liao et al., 2010: fig. 7B).
26. Hypohyal process on the basihyal (Liao et al., 2010: character 38).—States:[0], without
process; [1], two bulges on the ventrolateral side; [2], two caudal processes on the
ventrolateral side of the basihyal (Liao et al., 2010: fig. 13).
27. Third branchiostegal ray connects to (Liao et al., 2010: character 39).—States: [0],
epihyal; [1], ceratohyal.
28. Number of row of pharyngeal teeth (Conway, 2005: character 10; Liao et al., 2010:
character 40).—States: [0], 3; [1], 2.
126
APPENDIX 7: SUMMARY OF PHYSICO-CHEMICAL PARAMETERS MEASURED DURING THE STUDY
Canopy
Site
R. pallidus
Substrate
cover
percentage
Ma Dola
Absent
Sandy,
Pebbles
Rainy
months
Water
Temperature
0
Mean (SD) in C
Maximum
Water
Water
water depth
velocity
pH level
Mean (SD) in Mean (SD)
Mean
metres
in m/s
(SD)
Median
Turbidity
of water
50%
Mar-Aug
29.0 (1.6)
0.63 (0.39)
0.21 (0.12)
5.7 (0.6)
Average
75%
Mar-Jul
25.7 (1.2)
0.62 (0.14)
0.07 (0.04)
6.0 (0.6)
Good
70%
Mar-Jul
26.3 (0.5)
0.70 (0.23)
0.38 (0.19)
5.3 (0.1)
Average
60%
Mar-Jul
24.2 (0.4)
0.79 (0.29)
0.07 (0.03)
5.3 (0.3)
Good
22.4 (0.4)
0.64 (0.04)
0.08 (0.02)
5.1 (0.2)
Good
Sandy,
Kottawa
Present
Aponogeton
sp.
Homadola
Absent
Rocky, Pools
Sandy, Leaf
Kanneliya
Present
litter,
Submerged
logs
Kosmulla
Absent
Gravel, Rocky
60%
Jan-Jul,
Dec
127
APPENDIX 8: PUBLICATIONS BASED ON THE THESIS
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ISSN 0936-9902
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Ichthyological Exploration
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Ichthyological Exploration of Freshwaters
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Volume 24 • Number 2 • November 2013
pages 97-192, 48 figs., 15 tabs.
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121
Ichthyol. Explor. Freshwaters, Vol. 24, No. 2, pp. 121-140, 8 figs., 4 tabs., November 2013
© 2013 by Verlag Dr. Friedrich Pfeil, München, Germany – ISSN 0936-9902
A review of the danionine genera Rasboroides and Horadandia
(Pisces: Cyprinidae),
with description of a new species from Sri Lanka
Sudesh Batuwita*, **, ***, Madura de Silva** and Udeni Edirisinghe*
The taxonomy of Rasboroides and Horadandia, two genera of small danionine cyprinids that occur in southern
India and Sri Lanka, is reviewed. Rasboroides comprises four species, distinguished as follows: R. vaterifloris and
R. nigromarginatus differ from their congeners by a lesser body depth (26.9-33.0 % SL); and from each other by a
greater interorbital width in males (29-33 % HL vs. 17-22) and greater anal-fin depth in females (23.5-24.8 % SL
vs. 17.4-22.7) of R. vaterifloris. Rasboroides pallidus differs from R. rohani, new species, by its smaller size (up to
24.6 mm vs. 35.5 mm SL), by possessing fewer scales in transverse line on body (1/2 6 1/2-1/2 7 1/2 vs. 1/2 8 1/2) and in
lateral series (20-24 vs. 25-28). Rasboroides differs from Horadandia, its sister group, by the presence in males of a
series of tubercles on the leading edge of the pectoral fin (absent in Horadandia) and by possessing 3 (vs. 2) rows
of pharyngeal teeth, while the pharyngeal teeth of Horadandia are ornamented distally by a series of cusps, a
character absent in Rasboroides. Horadandia brittani is recognized as a valid species, distinguished from H. atukorali by possessing a smaller eye (eye diameter 27-37 % HL, vs. 37-41) and having the dorsal-fin origin closer to
the hypural notch (vs. midway between snout-tip and hypural notch). The genus Rasboroides is restricted to
shaded rainforest streams in the south-western ‘wet zone’ (Kalu to Walawe Rivers) of Sri Lanka, whereas Horadandia occurs in the coastal floodplains of western Sri Lanka and southern India.
Introduction
Brittan (1954) created the monotypic subgenus
Rasbora (Rasboroides) for Rasbora vaterifloris Deraniyagala, 1930, which he distinguished from
other Rasborinae mainly by its having an incomplete lateral line, a deep body, eye diameter
greater than interorbital width and scales chaotically arranged. The subgenus, however, was
ignored by subsequent authors (e. g., Pethiya-
goda, 1991) until Kottelat & Vidthayanon (1993)
validated it and elevated it to generic rank.
Kottelat & Vidthayanon (1993) also suggested
that Rasboroides could be a synonym of Horadandia, a genus established by Deraniyagala (1943)
for a diminutive species of cyprinid fish, H. atukorali. Deraniyagala distinguished Horadandia
from other cyprinid genera mainly by the absence
of barbels and a lateral line, 6 branched anal-fin
rays, and the pharyngeal-teeth in two rows with
* Postgraduate Institute of Agriculture, University of Peradeniya, Sri Lanka. E-mail: udeni@pdn.ac.lk
** Wildlife Conservation Society Galle, Biodiversity Education and Research Center, Hiyare Reservoir, Hiyare,
Galle, Sri Lanka. E-mail: dsmanusha@gmail.com
*** Corresponding author: E-mail: sudesh.batuwita@gmail.com
Ichthyol. Explor. Freshwaters, Vol. 24, No. 2
Ichthyological Exploration of Freshwaters
An international journal for field-orientated ichthyology
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Ichthyological Exploration of Freshwaters
An international journal for field-orientated ichthyology
Volume 24 • Number 2 • November 2013
CONTENTS
Nebeshwar, Kongbrailatpam and Waikhom Vishwanath: Three new species of Garra
(Pisces: Cyprinidae) from north-eastern India and redescription of G. gotyla ..................
97
Batuwita, Sudesh, Madura de Silva and Udeni Edirisinghe: A review of the danionine
genera Rasboroides and Horadandia (Pisces: Cyprinidae), with description of a new
species from Sri Lanka ...............................................................................................................
121
Costa, Wilson J. E. M.: Hypsolebias caeruleus, a new seasonal killifish of the Hypsolebias adornatus complex from the Caatinga of north-eastern Brazil, São Francisco River basin
(Cyprinodontiformes: Rivulidae) .............................................................................................
141
Mattos, José L. O., Felipe P. Ottoni and Maria A. Barbosa: Microglanis pleriqueater, a new
species of catfish from the São João river basin, eastern Brazil (Teleostei: Pseudopimelodidae).........................................................................................................................................
147
Caires, Rodrigo A.: Microphilypnus tapajosensis, a new species of eleotridid from the Tapajós basin, Brazil (Gobioidei: Eleotrididae) ..............................................................................
155
Ng, Heok Hee and Rohan Pethiyagoda: Mystus zeylanicus, a new species of bagrid catfish
from Sri Lanka (Teleostei: Bagridae) .......................................................................................
161
Plongsesthee, Rungthip, Maurice Kottelat and F. William H. Beamish: Schistura crocotula,
a new loach from Peninsular Thailand (Teleostei: Nemacheilidae) ...................................
171
Ng, Heok Hee and Kevin W. Conway: Pseudolaguvia assula, a new species of crypto-benthic
sisorid catfish from central Nepal (Teleostei: Sisoridae) ......................................................
179
Decru, Eva, Jos Snoeks and Emmanuel Vreven: The true identity of the holotype of Hepsetus odoe and the names of the two West African species of Hepsetus (Teleostei: Hepsetidae)..........................................................................................................................................
187
Cover photograph
Horadandia atukorali (photograph by G. Ott)
Sudesh Batuwita, Madura de Silva and Udeni Edirisinghe
(this volume pp. 121-140)
Articles appearing in this journal are indexed in:
AQUATIC SCIENCES and FISHERIES ABSTRACTS
BIOLIS - BIOLOGISCHE LITERATUR INFORMATION SENCKENBERG
CAMBRIDGE SCIENTIFIC ABSTRACTS
CURRENT CONTENTS/AGRICULTURE, BIOLOGY & ENVIRONMENTAL SCIENCES and SCIE
FISHLIT
ZOOLOGICAL RECORD
Sudesh Batuwita