Descriptive osteology of Corydoras aeneus
(Siluriformes: Callichthyidae)
by
Frank HUYSENTRUYT & Dominique ADRIAENS (1)
ABSTRACT. - Both the cranial and postcranial osteology of Corydoras aeneus (Gill, 1858) is described based on the
study of five adult specimens. The results were compared to the condition described for other loricarioid fishes. Most
results corresponded with the expected pattern based on studies dealing with parts of the callichthyid osteology, although
some differences were observed. One of these differences was the presence of a suprapreopercular bone, a bone that was
previously unmentioned in any callichthyid species. Further, several homologies were resolved and mainly confirmed
existing hypotheses. This way, for example, based on the presence of several branches of the lateral line system, the compound dorsolateral bone of the otic region was identified as the posttemporo-pterotico-supracleithrum. Further, the presence of several otoliths in the compound bone forming the neurocranial floor in the occipital region, confirmed the fact that
the bone comprised out of a fusion of both basi- and exoccipital bones. This study, however failed to resolve some other
questions regarding homologies (i.e., lacrymo-antorbital, suprapreopercle) pointing out the need for further ontogenetic
research. In this light, this study provides the basis for this further comparative and ontogenetic research on callichthyids
specifically and on loricarioids in general.
RÉSUMÉ. - Étude de l’ostéologie de Corydoras aeneus (Siluriformes : Callichthyidae).
L’ostéologie crâniale et postcrâniale de Corydoras aeneus (Gill, 1858) est décrite d’après cinq spécimens adultes. Les
résultats sont comparés avec ceux des autres poissons loricarioïdes. La plupart sont en accord avec les données de la littérature, qui s’intéressaient surtout à l’ostéologie des Callichthyidae. Néanmoins, quelques différences ont été observées
comme la présence d’un suprapréoperculaire, jamais observé chez aucune espèce de Callichthyidae. La majorité des homologies ont été résolues, confirmant principalement les hypothèses actuelles. L’os composé situé dorsolatéralement dans la
région otique du crâne a ainsi été identifié comme l’os post-temporo-ptérotico-supracleithrum sur la présence du plusieurs
branches du système de la ligne latérale. De plus, la présence du plusieurs otolithes dans l’os composé qui forme la base du
crâne occipital confirme que cet os est formé d’une fusion entre les os basi- et exoccipitaux. Quelques questions concernant
l’homologie restent cependant non résolues comme, par exemple, le lacrymo-antorbital ou le suprapréoperculaire), indiquant la nécessité d’une recherche ontogénétique. Cette étude est donc une base pour de futures études comparatives et
ontogénétiques sur les Callichthyidae, spécifiquement, et sur les Loricarioidea, en général.
Key words. - Callichthyidae - Corydoras aeneus - Osteology - Morphology.
The genus Corydoras, belonging to the Callichthyidae, is
widespread in South America (Gosline, 1940; Nijssen, 1970;
Kramer and Braun, 1983) and well known among aquarists
for its many ornamental species (Burgess and Quinn, 1992).
Corydoras aeneus (Gill, 1858) is particularly a popular
species in the trade of freshwater ornamental fish. It is annually bred and shipped in large quantities all over the world
(Tamaru et al., 1997). C. aeneus has already been studied
from both a morphological and physiological points of view
(Kramer and McClure, 1980, 1981; Kramer and Braun,
1983; Huysseune and Sire, 1997) as is also the case for its
reproductive biology (Kohda et al., 1995, 2002; Pruzsinszky
and Ladich, 1998). However, despite it being commercially
bred, almost nothing is known about its ontogeny. Some
attention has been paid to the early ontogeny of some
aspects of the head in other callichthyids (Hoedeman,
1960a), but still a lot of relevant information is lacking. The
same accounts for the adult morphology: a complete
overview of the cranial and postcranial morphology is
absent, despite of its relevance for ongoing phylogenetic
research on Loricarioidea, to which these callichthyids
belong (Reis, 1998; Britto and Castro, 2002). Even though
phylogenetic affinities between the families of these loricarioids is quite resolved (Schaefer, 1990; Reis, 1998; Aquino
and Schaefer, 2002), as well as the generic relationships
within the callichthyids (Reis, 1997, 1998), no information
exists on the phylogeny of the highly diverse genus Corydo ras. Even the monophyletic nature of this genus, comprising
approximately 140 species, is uncertain, possibly partially
overlapping the currently defined Brochis and Aspidoras
genera (Reis, 1998). Consequently, the aim of this study is to
provide a full description of the osteology of the species, as a
basis for further ontogenetic research on this species, as well
as to contribute to future phylogenetic studies.
(1) Ghent University, Evolutionary Morphology of Vertabrates, K.L. Ledeganckstraat 35, B-9000 Ghent, BELGIUM.
[frank.huysentruyt@ugent.be]
Cybium 2005, 29(3): 261-273.
HUYSENTRUYT & ADRIAENS
Descriptive osteology of Corydoras aeneus
MATERIALS AND METHODS
For this study we investigated five adult specimens of
Corydoras aeneus, obtained from an aquarium shop. The
specimens were sedated and killed, using an overdose of
MS-222 (3-aminobenzoic acid ethyl ester, Sigma) and afterwards cleared and stained using the technique described by
Hanken and Wassersug (1981). These specimens were then
investigated and drawn using a Wild M5 stereomicroscope.
For the nomenclature of the skeletal elements we followed
Schaefer (1990) and Reis (1998). The homology of the
autopalatine with the dorsal part of a premandibular arch follows Daget (1964) and Jarvik (1980).
RESULTS AND DISCUSSION
In Corydoras aeneus the neurocranium is pyriform, with
a small ethmoid and orbital region, broadening at the temporal region into a large occipital region.
Ethmoid region (Figs 1-3)
The mesethmoid in Corydoras aeneus is narrow anteriorly and broadens posteriorly (also see Fink and Fink, 1996;
Arratia, 2003). It lacks cornua and broadens substantially
towards its posterior margin. Although a general trend
towards a reduction of the cornua is present in all catfishes
(Lundberg, 1982; Schaefer, 1987), a total lack of these cornua is only present within the Callichthyidae, with the
exception of the genus Brochis, in which extremely reduced
cornua are still present (Schaefer, 1990; Reis, 1998). Hoedeman (1960a) suggested an initial formation of these cornua
in Hoplosternum and Callichthys, but without further ossification, implying a reduction (presumably as a result of allometric growth). Further ontogenetic research will have to
reveal whether this also holds for C. aeneus. On its posterior
margin the mesethmoid contacts the frontals with a Vshaped suture dorsally and a W-shaped wedge with the prevomer ventrally. The posterior, V-shaped suture with the
frontals in C. aeneus is also found in other callichthyids, in
Nematogenys inermis and in the Scoloplacidae, but not in
Loricariidae, Astroblepidae and Trichomycteridae, which
reflects the plesiomorphic condition in the Loricarioidea
(Schaefer, 1990). Laterally, the mesethmoid contacts the lateral ethmoids and the autopalatine ventroposteriorly. In
addition, it is connected by a ligament to both the reduced
premaxilla and the maxilla (Fig. 4). The presence of such
ligaments is a condition which all Callichthyidae share with
the Scoloplacidae, Loricariidae and Astroblepidae (Schaefer,
1990). The well developed lateral ethmoids, together with
the mesethmoid, the frontal, the autopalatine and the lacrymo-antorbital, surround the nasal cavity, which is different
from the situation in the Callichthyinae, where a large
depression in the lateral ethmoid forms the total nasal capsule (Reis, 1998). In this cavity the free,
tube-like, nasal bone encloses the anterior
part of the supraorbital canal. This canal
directly enters the frontal bone at the posterior margin of the nasal (Fig. 5) in contrast to the situation in the Callichthyinae
where the supraorbital canal consequently
first enters the lateral ethmoid (Reis,
1998). The nasal bone has the typical catfish, tube-like shape, although it only bears
two pores, in contrast to the three pores
found in most diplomystids and primitive
loricarioids (Arratia and Huaquín, 1995).
The toothless prevomer is drop-shaped
and forms an elongated V-shaped suture
with the parasphenoid posteriorly. An
independent prevomer is, within the Loricarioidea, present in all families except the
Scoloplacidae (Schaefer, 1990; Arratia,
2003).
Figure 1. - Dorsal view of the skull in adult Corydoras aeneus. [Vue dorsale du crâne
d’un Corydoras aeneus adulte.]
262
Orbital region (Figs 1-3)
The first bone of the infraorbital series
of Corydoras aeneus, the lacrymo-antorbital, is a large, plate-like bone, which
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HUYSENTRUYT & ADRIAENS
Descriptive osteology of Corydoras aeneus
Figure 2. - Ventral view of the neurocranium in adult Corydoras aeneus.
[Vue ventrale du neurocrâne d’un
Corydoras aeneus adulte.]
Figure 3. - Lateral view of the skull in
adult Corydoras aeneus. [Vue latérale
du crâne d’un Corydoras aeneus
adulte.]
forms most of the ventral border of the orbita. This fusion of
the first infraorbital bone, the lacrymal, with the antorbital
Cybium 2005, 29(3)
bone is common among catfishes (Schaefer, 1990), but in C.
aeneus some questions regarding the true nature and origin
263
Descriptive osteology of Corydoras aeneus
HUYSENTRUYT & ADRIAENS
Figure 4. - Mesethmoid-palatine-maxillary mechanism in adult Corydoras aeneus. A: Dorsal view ; B: ventral view. [Mécanisme méseth moide-palatin-maxillaire chez un Corydoras aeneus adulte. A : Vue dorsale ; B : Vue ventrale.]
of the infraorbital bones remain. A first question is whether
this bone really is the lacrymo-antorbital, merely an expansion of the lacrymal bone or whether both lacrymal and/or
antorbital are totally absent (Schaefer, 1990; Reis, 1998;
Arratia, 2003). Subsequently, the homologies of the remaining infraorbital bones and of possible fusions within this
series remain unclear. Regardless, the first two infraorbitals
have become plate-like in all Callichthyidae, a condition
which they share with more primitive non-siluriform
teleosts, and some other Siluriformes (e.g., Clarias gariepi nus (Adriaens et al., 1997)). In general, in Siluriphysi, the
infraorbital series is reduced to tube-like bones bearing the
infraorbital canal. Plate-like infraorbitals are therefore
believed to be secondarily derived (Fink and Fink, 1996).
The lacrymo-antorbital bears the first part of the infraorbital
canal with two of its sensory pores. This canal further continues through the smaller second infraorbital bone (Fig. 5).
Furthermore, the anterior extension of this infraorbital canal
into the first bone of the series occurs in Corydoras, Aspido ras and Brochis but is not present in other callichthyid
species (Schaefer, 1990; Britto, 1998; Reis, 1998). On its
dorso-posterior margin the second infraorbital broadens and
connects both the sphenotic, of which the dermal part is in
fact the last infraorbital bone (Gosline, 1975), and the posttemporo-pterotico-supracleithrum. The orbital skull roof is
formed by the two large frontal bones, separated posteriorly
by the anterior cranial fontanel. This fontanel is divided into
two openings by the ossified epiphyseal bridge and is elongated posteriorly. As in the genera Hoplosternum,
Megalechis, Lepthoplosternum, Dianema and Brochis the
264
anterior fontanel enters the parieto-supraoccipital bone in C.
aeneus (Reis, 1998). The fontanel itself is minute, in contrast
to that in other callichthyids, where a larger fontanel is present (Schaefer, 1990; Reis, 1998). In astroblepids, scoloplacids and loricariids, however, no open cranial fontanels
are found. The frontals further contact the sphenotics laterally and the orbito- and pterosphenoid ventrally. The frontals,
as in other teleosts, bear the supraorbital canal, but in C.
aeneus an additional central pore is present (Fig. 5). According to Reis (1998) this pore represents the parietal branch of
that canal in other Siluriformes. Arratia and Huaquín (1995),
however, report the absence of a parietal branch as a loricarioid synapomorphy, but, they, on the other hand, do report the
presence of an epiphyseal branch in several loricarioids.
Therefore, and based on the position and orientation of this
pore we believe it to be homologous with this epiphyseal
branch. The wall of the orbital region is formed by the anterior orbito- and the posterior pterosphenoid, which both ventrally contact the orbital floor at the level of the parasphenoid. The orbito-, and pterosphenoid in C. aeneus all possess
the typical shape found in other Siluriformes (Schaefer,
1990; Reis, 1998; Arratia, 2003). The orbitosphenoid is
hour-glass-shaped in ventral view and holds a large foramen.
The parasphenoid is fairly narrow anteriorly and bears two
elongated, anterior processes (in between lies the prevomer).
Posteriorly, it broadens widely at the level of the prootics,
further ending in a narrow, sharp region. Anteriorly, the bone
shows a strong, midline ridge. The posterior “wings” of the
parasphenoid suture with both prootic bones and the posterior tip connects to the occipital bone complex. Further, the
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HUYSENTRUYT & ADRIAENS
Figure 5. - Cranial lateral line system in adult Corydoras aeneus.
A: Dorsal view ; B: ventral view. [Système de la ligne latérale chez
un Corydoras aeneus adulte. A : Vue dorsale ; B : Vue ventrale.]
bone is much broader than what is described for all Corydoradinae in Reis (1998). In between the orbitosphenoid,
pterosphenoid, parasphenoid and prootics, as in most Siluriformes, the combined foramen for the fasciculus opticus and
the trigemino-facial nerve is situated. A connection between
the parasphenoid and pterosphenoid, thereby splitting the
foramen in an orbital and trigemino-facial fenestra, is
absent.
Otic region (Figs 1-3)
The floor of this region is formed by the posterior tip of
the parasphenoid, flanked by the prootic bones. These
square-shaped prootics further connect to the sphenotics and
Cybium 2005, 29(3)
Descriptive osteology of Corydoras aeneus
posttemporo-pterotico-supracleithrum laterodorsally and to
the occipital complex posteriorly. The prootics enclose the
utricle with the lapillus and furthermore bear a large foramen. These foramina are not homologous to the auditory
foramen (Schaefer, 1987), although their true purpose
remains unknown. The lateral margins of the otic region are
made up by the sphenotics that are also square and make
additional contact with the parieto-supraoccipital dorsally
and the posttemporo-pterotico-supracleithrum posteriorly. In
the sphenotics, both supraorbital and infraorbital canal come
together into the otic canal, which exits the sphenotic at its
posterior margin and continues into the posttemporo-pterotico-supracleithrum. The latter bone has often been described
as the fusion of both supracleithrum and pterotic with the
absence of the posttemporal (Regan, 1911; Lundberg, 1975),
while other authors described it as the fusion between a
compound supracleithrum (supracleithrum, posttemporal
and an ossified Baudelot’s ligament) and pterotic (Schaefer
and Lauder, 1986; Schaefer, 1987, 1990; de Pinna, 1993;
Reis, 1998). A compound nature of this bone is also supported by the presence of several segments and branches of the
lateral line system (Schaefer and Aquino, 2000). At about
one-third of the bone length, the preopercular canal branches
off and from that point on the otic canal continues in the postotic canal, from which, at about two-thirds of the bone
length, a first postotic branch, the pterotic branch, branches
off. The canal then continues through the remaining onethird of the bone into the posttemporal branch and leaves the
bone at its posterior margin (Fig. 5). The presence of both
the preopercular and pterotic branch indeed confirm the fact
that the pterotic bone is included in this bony complex since
both branches are generally inherent to the pterotic (Schaefer and Aquino, 2000). This situation, in which only one postotic branch (the pterotic branch) is present, occurs in all
Corydoradinae. In other callichthyid species two postotic
branches are present (Schaefer and Aquino, 2000). Furthermore, the presence of a posttemporal branch confirms the
presence of the posttemporal bone in the complex. Further,
in Corydoras aeneus, the posttemporo-pterotico-supracleithrum also bears a large articular cavity for the articulation
of the pectoral girdle with the skull. Finally, it remains
unclear whether the epiotic bones have disappeared during
the development of C. aeneus or whether they have become
incorporated within other bone complexes (Arratia, 2003).
Occipital region (Figs 1-3)
The skull roof in this region is formed by one, large,
compound bone, the parieto-supraoccipital. The fusion of
the dermal parietal bones and perichondral supraoccipital
bones during ontogeny is typical for Siluriphysi (Bamford,
1948; Lundberg, 1975; Fink and Fink, 1996). Here, the bone
neither bears a posterior fontanel nor latero-sensory canals
265
Descriptive osteology of Corydoras aeneus
and has a large posterior process which contacts the nuchal
plate and the first pair of laterodorsal bony scutes. The neurocranium floor in this region is formed by the compound
occipital bone, a fusion between the basi- and exoccipitals.
Within the Loricarioidea, a similar fusion only occurs in
Scoloplacidae and Callichthyidae (Reis, 1998). Evidence for
the presence of the basioccipital bone within the complex is
found in the position of the bone contacting the parasphenoid anteriorly and articulating with the centre of the first
vertebrae posteriorly, where it forms the posterior rim of the
neurocranium (Rojo, 1991). Another indication is the fact
that the bone encapsulates the asteriscus. Similar, the encapsulation of the sagitta confirms the presence of the exoccipitals within the bone complex. Further, this bone contacts the
complex vertebral centrum and its outgrowths on its posterior side and the posttemporo-pterotico-supracleithrum
through the ossified Baudelot’s or trans-scapular ligament on
its dorsolateral side [for a nomenclature on this structure, see
Lundberg (1975), Fink and Fink (1981), Schaefer (1987)
and Reis (1998)].
Maxillary bones (Figs 1-4)
The highly reduced premaxillary bone is toothless in
adult specimens of Corydoras aeneus and bears a small dorsal process. The absence of teeth on the premaxilla is common to all callichthyids, although teeth are present in the
early stages of C. aeneus (Machado-Allison and Garcia,
1986; Huysseune and Sire, 1997). The maxillary bone is also
reduced to a small bone lacking dentition and supporting the
maxillary barbel. In C. aeneus the bone is comma-shaped
and bears a small process on its postero-lateral face. The
bone articulates with the autopalatine through two articular
Figure 6. - Lateral view of the right suspensorium, opercular and
lower jaw in adult Corydoras aeneus (dotted lines represent
removed eye, preopercular and suprapreopercular). [Vue latérale
du suspensorium droit, de l’opercule et de la mâchoire inférieure
chez un Corydoras aeneus adulte (les lignes pointillées représen tent l’œil, le préopercule et le suprapréopercule enlevés).]
266
HUYSENTRUYT & ADRIAENS
facets which creates a hinge-joint. Both premaxillary and
maxillary bones are ligamentously connected to the mesethmoid and next to that another ligament connects the maxillary bone to the palatine. A similar highly mobile and
reduced premaxilla is present in all Callichthyidae. The fact
that this increased mobility is caused by a ligamentous junction with the mesethmoid is a character shared with Astroblepidae and Loricariidae, but not with Scoloplacidae (Schaefer and Lauder, 1986). The shape and function of the maxillary bone (small, toothless and supporting the maxillary barbel) is the same as in all Siluriformes, with the exception of
the Diplomystidae and †Hypsidoridae (Grande, 1987; Fink
and Fink, 1996; Grande and de Pinna, 1998; Arratia, 2003).
Also the presence of a pair of palatine condyles on the bone
is common to all Siluriformes, except Astroblepidae and
Helogenes-species (de Pinna, 1993). The bone’s postero-lateral process serves as an insertion site for the musculus
retractor tentaculi.
Premandibular arch (Figs 1-4)
The autopalatine is rod-shaped and straight, with a flat
lateral surface. It bears a small posterior process, which contacts the lateral ethmoid, a shape which is different from that
in less advanced catfish families like Diplomystidae and
†Hypsidoridae (Grande, 1987; Schaefer, 1990; Arratia,
1992). Anteriorly the bone bears a large cartilaginous
condyle for articulation with the maxillary bone, to which it
is also ligamentously connected. The posterior process, on
the other hand, bears no cartilaginous tip and is small compared to primitive catfishes (Arratia, 1992; Reis, 1998), but
not as small as in Callichthys (Reis, 1998). The absence of
this cartilaginous tip is variably present among catfishes, but
common to all non-nematogenyid loricarioids (de Pinna,
1993). The process serves as the insertion site of the musculus extensor tentaculi (Fink and Fink, 1981; Reis, 1998).
Mandibular arch (Figs 3, 6-7)
The metapterygoid bone is nearly triangular and has a
narrow, elongated, anterior process that ends near the
autopalatine. This process is single in Corydoras, as it is in
Aspidoras and Brochis, whereas, in Callichthys, it is bifurcated (Reis, 1998). The metapterygoid itself was first
described as a fusion of ecto-, ento- and metapterygoid by
Howes and Teugels (1989), although other authors reported
the ecto- and entopterygoid to be absent (Regan, 1911; Arratia, 1990; Reis, 1998). In addition, the hypothesis by Howes
and Teugels (1989) was, due to the lack of ontogenetic evidence, contradicted by Arratia (1992), who thus defined the
bone as being the metapterygoid only. The bone further contacts the hyomandibula on its posterior margin through a serrated suture, as in all Corydoradinae (Reis, 1998). The
metapterygoid is also joint synchondrally to the quadrate
Cybium 2005, 29(3)
HUYSENTRUYT & ADRIAENS
Figure 7. - Medial view of the right lower jaw in adult Corydoras
aeneus. [Vue médiale de la mâchoire inférieure droite chez un
Corydoras aeneus adulte.]
bone and ligamentously attached to the lateral ethmoid. The
quadrate bone is a simple, small, triangular bone, the typical
condition found in Diplomystidae, as well as in most Siluriformes (Arratia, 1992; Reis, 1998). The bone connects synchondrally to both the metapterygoid and the hyomandibula.
On its postero-ventral margin it articulates with the angular
bone complex. This complex is considered to consist of the
fused angular, the articular and the retro-articular bone
(Arratia, 2003). This compound bone is small, not canalbearing, and connected to the dentary bone complex. It articulates with the quadrate dorsally and is ligamentously connected with both the interopercule and posterior ceratohyal
bone. The angular bone complex further bears a laminar
coronoid process, which serves as an insertion site for parts
of the musculus adductor mandibulae complex (Reis, 1998).
The last bone of the mandibular arch is another compound
bone called the dentary complex. The bone is a fusion of the
mento-meckelium and the dental bone. It forms the main
Descriptive osteology of Corydoras aeneus
part of the lower jaw and is toothless in adult specimens of
Corydoras aeneus, a condition that is different from that in
the early ontogenetic stages (Huysseune and Sire, 1997). It
bears a small process antero-medially for insertion of the
intermandibular muscle. Further it medially encloses the
Meckel’s cartilage. The fact that the Meckel’s cartilage is
small and that no coronomeckelian bone is present are conditions the Callichthyidae share with Astroblepidae, Loricariidae, Trichomycteridae and several other non-loricarioid
catfishes (de Pinna, 1993). As in the angulo-retroarticular,
the dentary complex does not bear a part of the preoperculomandibular branch of the lateral line system, a condition
shared by all Loricarioidea, except Nematogenys inermis
(Schaefer, 1990).
Hyoid arch (Figs 6, 8-9)
The hyomandibula articulates with the neurocranium
through the sphenotic and posttemporo-pterotico-supracleithrum. It also bears a large process on its dorso-posterior
margin for the articulation with the opercule. The perichondral part of the hyomandibula is long and bears a bony plate
on its ventro-anterior side, which contacts the metapterygoid
and quadrate. On its medial side the bone articulates with the
rest of the hyoid arch through the small interhyal bone. This
interhyal articulates with the posterior ceratohyal, which, in
turn, synchondrally contacts the anterior ceratohyal. The
anterior ceratohyal has a twisted surface with a medial, bony
outgrowth and articulates with three branchiostegal rays on
its medial posterior margin and with the larger, fourth ray on
its lateral posterior margin. The anterior part of the hyoid
Figure 8 - Dorsal view of the hyoid arch
and branchial basket in adult Corydoras
aeneus. [Vue dorsale de l’arc hyoïde et
des arcs branchiaux chez un Corydoras
aeneus adulte.]
Cybium 2005, 29(3)
267
Descriptive osteology of Corydoras aeneus
arch consist of both a ventral and a dorsal hypohyal, both
square-shaped and articulating with the ventral, plate-like
parurohyal. The presence of both dorsal and ventral hypohyals in Corydoras aeneus and in most other Corydoradinae
(Reis, 1998) is in contrast to other Loricarioidea. According
to Arratia and Schultze (1990) most catfishes have two pairs
of hypohyals, except for Trichomycteridae, Loricariidae and
Callichthyidae, which is contradicted by our findings. The
former study, however, was solely based on observations on
Callichthys, where indeed only the ventral hypohyals are
present (Arratia and Schultze, 1990; Reis, 1998). Schaefer
(1987) confirms this and mentions a loss of the dorsal hypohyal only in Trichomycteridae and Loricariidae, but contrary
to Arratia and Schultze (1990), he also mentions a similar
loss in Astroblepidae.
Branchial arches (Figs 8-9)
In Corydoras aeneus, the branchial basket bears the typical siluriform configuration in which five branchial arches
are present. Only basibranchials II and III are present as distinct, ossified elements. The posterior copula remains cartilaginous. Ossified hypobranchials I and II are present,
whereas separate hypobranchials III and IV show no ossification. The fifth hypobranchial is absent. The ceratobranchials of all five arches are well ossified, bearing cartilaginous tips (with exception of the posterior tip of the fifth
one). All ceratobranchials support hemibranchs. The fifth
ceratobranchial bears the lower pharyngeal tooth plate and is
the only ossified bone in this arch. The first four epibranchials are very variable in shape, with the second and
HUYSENTRUYT & ADRIAENS
fourth bearing an uncinate process. All four are fully ossified
and bear hemibranchia. Furthermore, the two first epibranchials are synchondrally connected to each other distally. They contact the ossified third infra-pharyngobranchial
bone through a fused cartilaginous first and second infrapharyngobranchial. The latter is synchondrally connected to
the third epibranchial and to the fourth infrapharyngobranchial. This fourth infrapharyngobranchial is connected to
the fourth epibranchial bone and supports the upper pharyngeal tooth plate.
Opercular series (Figs 3, 5)
The opercular series consist of the opercular, interopercular, preopercular and suprapreopercular bones. This condition differs within different groups of catfishes and even loricarioids. In Loricariidae, for example, the interopercular
bones have been lost entirely. The opercule itself is large,
more or less triangular, and is connected to the interopercule
on its ventro-anterior margin. It also bears a process for the
articulation with the hyomandibula on its dorso-anterior
margin. In Astroblepidae and Loricariidae this articulation
shifts towards the dorsal side of the opercular bone (Schaefer, 1987, 1988). The interopercule is a small, triangular
bone, which is ligamentously connected to the lower jaw at
the level of the angulo-retroarticular bone. Dorso-anteriorly
from the interopercule and anterior to the ventral part of the
opercule, lies the preopercule. This bone, present in all loricarioid families, bears part of the preopercular canal with
two of its pores, one centrally and one anteriorly, which are
homologue to pores 4 and 5 in Diplomystes (Schaefer,
Figure 9. - Ventral view of the mandibular arch, hyoid arch and branchial
basket in adult Corydoras aeneus. [Vue
ventrale de l’arc mandibulaire, de l’arc
hyoïde et des arcs branchiaux chez un
Corydoras aeneus adulte.]
268
Cybium 2005, 29(3)
HUYSENTRUYT & ADRIAENS
1988). The part of the preopercular canal running through
the preopercle and suprapreopercle in Corydoras aeneus, as
in all Callichthyidae, does no longer connect to the part of
the preopercular canal that is present in the posttemporopterotico-supracleithrum. In Nematogenys inermis and in
several non-loricarioid catfishes, this canal continues into
the mandible and is consequently referred to as the preoperculo-mandibular branch. In trichomycterids, on the other
hand, the preopercular canal is extremely reduced and does
not even enter the preopercule, but remains limited to an
opening in the pterotic bone (Baskin, 1972; Schaefer, 1988).
Finally, the presence of a suprapreopercular bone in C.
aeneus, is a condition that has never been mentioned within
the Callichthyidae but which was present in all specimens
examined. Therefore, further ontogenetic research will focus
on the development of this bone, attempting to reveal
whether this bone is truly homologous to the suprapreopercular bone found in other fish groups.
Descriptive osteology of Corydoras aeneus
dae (Schaefer, 1990; Reis, 1998). However, since Coburn
and Grubach (1998) mention the loss of the first two vertebrae, their derivatives (claustrum, scaphium and intercalarium) are also missing and their results show the tripus to be a
myoseptal tripus (formed in the paravertebral sac and the
dorsal myoseptum of vertebra-III).
Vertebral column (Figs 2, 10-11)
In the specimens examined, the total number of vertebrae, including the first five incorporated in the Weberian
apparatus, was 28. This number equals that found in several
other Corydoras and callichthyid species, and is one more
than the number found in Scoloplacidae and some Loricariidae (e.g. Otocinclus, Hypoptopoma) (Schaefer, 1990). Britto (2000) mentions the presence of 28-31 vertebrae in several Aspidoras-species, which corresponds to the 27-32 vertebrae described by Regan (1911) for the family of the Callichthyidae. The first articulating vertebra, the sixth vertebra,
has two large parapophyses that articulate with the complex
centrum of the Weberian apparatus. These parapophyses further support a large, hollow rib, which contacts the first ventrolateral bony scutes behind the pectoral girdle. Vertebrae
7-12 each carry a small, thin rib. The presence of such a
large, hollow rib on the parapophysis of the sixth vertebral
centre, followed by several small ribs is typical for all Callichthyidae (Regan, 1911; Hoedeman, 1960b; Reis, 1998;
Britto, 2000). In contrast to Hoedeman (1960b) mentioning
only four to five of these small ribs in Corydoras-species, six
were found here. The number of caudal vertebrae is 14, of
which, in the first three to four, the haemal spines are
Weberian apparatus (Fig. 2)
In Corydoras aeneus the Weberian apparatus is part of a
complex structure, comprising a fusion between several vertebrae. Normally, the complex vertebral centre of the Weberian apparatus is a fusion of the second to the fifth vertebral
centres in all Siluriformes, except Diplomystes, where the
fifth centre is excluded from the complex (Arratia, 1987;
Fink and Fink, 1996). Additionally, in Loricarioidea the first
vertebral centre is also fused to the complex (Schaefer, 1990;
Reis, 1998). Coburn and Grubach (1998), however, discovered, after ontogenetic research, that in C. paleatus only three
vertebrae are fused within the complex and that
the first two vertebrae are missing. The gas bladder is divided into two chambers which are encapsulated in the expansions of the transversal processes of this complex centrum. Laterally to the
compound centre, two foramina are situated
through which passes the duct that connects these
two chambers. Gas bladder contact with the external medium occurs through an aperture in the
posttemporo-pterotico-supracleithrum, covered
by a hollow expansion bearing the latero-sensory
canal. This condition is possibly homologous to
the condition found in Astroblepidae and Loricariidae, where the aperture is completely covered
by the posttemporo-pterotico-supracleithral bone
(Reis, 1998). The connection between the gas
bladder and inner ear is made up of one compound bone referred to as the compound tripus
(Schaefer, 1990). The compound tripus found in
C. aeneus was suggested to be a fusion between
the tripus, intercalarium, scaphium and interossicFigure 10. - Lateral view of the dorsal fin skeleton in adult Corydoras aeneus.
ular ligament, typically found in all Siluriformes, [Vue latérale du squelette de la nageoire dorsale chez un Corydoras aeneus
but with the loss of the claustrum in Callichthyi- adulte.]
Cybium 2005, 29(3)
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Descriptive osteology of Corydoras aeneus
HUYSENTRUYT & ADRIAENS
the number of remaining true fin rays fits
our findings. Seven fin rays, with the last
ray branched up to the base, corresponds
with the original description of C. aeneus
by Gill (1858) and of other Corydorasspecies (Isbrücker and Nijssen , 1973,
1992; Nijssen, 1970). The number of dorsal
fin rays is a character of great taxonomic
value within the Corydoradinae and a number of 7-9 is determinative for Corydorasspecies, whereas a number of 10 or more is
determinative for species belonging to
Brochis (and different from the plesiomorphic siluriform condition). The distinction
between Aspidoras, on the one hand, and
Corydoras and Brochis, on the other hand
can also be done based on dorsal fin morphology. Here, a lack of contact between
the nuchal plate and the posterior process of
Figure 11. - Lateral view of the caudal fin skeleton in adult Corydoras aeneus. [Vue
the parieto-supraoccipital is held as being
latérale du squelette de la nageoire caudale chez un Corydoras aeneus adulte.]
typical for Aspidoras-species (Reis, 1996).
expanded and plate-like. These haemal spines are ventropos- Within the Loricarioidea, all families have the plesiomorteriorly oriented, thus forming a protective, posterior wall phic siluriform number of branched dorsal fin rays, except
for the abdominal cavity. Furthermore, the last preural verte- for the Scoloplacidae, where a reduction of the number has
bra is incorporated within the ural complex together with the occurred and only four are present (Reis, 1998).
last vertebra, the first ural vertebra (Lundberg and Baskin,
1969).
Anal fin
The anal fin consists of a single unbranched and seven
Dorsal fin (Fig. 10)
branched fin rays. The bases of the first four rays articulate
In Corydoras aeneus the dorsal fin bears a first small fin with the haemal spines of vertebrae 20 to 22. The number of
ray, modified to serve a spine-locking mechanism, followed fin rays (n = 7) found in Corydoras aeneus corresponds with
by a second, large one (Alexander, 1965). After this, seven the number given in the original description by Gill (1858),
branched dorsal fin rays are present, of which the last is split although the presence of a possible eighth branched ray is
up to its base. The pterygiophores of these
spines plus the first five fin rays are connected to the 10th to 13th vertebral neural
spine. The first pterygiophore bears a large
transverse process, which connects to the
lateral body scutes. In Callichthyids, this
process is further ligamentously connected to the sixth rib, whereas in scoloplacids, astroblepids and loricariids, this
ligament ossifies into a lateral bone
(Schaefer, 1990). Preceding the first dorsal fin spine, a nuchal plate is present,
which is connected to the ninth vertebra
and contacts the parieto-supraoccipital at
its anterior side. The condition where two
fin spines with seven fin rays are present,
as is the case here, fits the plesiomorphic
nine fin rays found in Diplomystes
Figure 12. - Dorsal view of the pectoral girdle in adult Corydoras aeneus with the clei(Alexander, 1965). Although most authors thrum removed on the left side. [Vue dorsale de la ceinture pectorale chez un Corydodo not count the first modified fin spine, ras aeneus adulte, cleithrum gauche enlevé.]
270
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HUYSENTRUYT & ADRIAENS
Descriptive osteology of Corydoras aeneus
mentioned. The presence of a single, unbranched, anal fin
ray is a derived condition within the Callichthyidae, which
only occurs in some Corydoras-species and all Leptho plosternum-species. Among the Loricarioidea, this condition
is also found in Scoloplacidae, Astroblepidae and Loricariidae, in contrast to trichomycterids and Nematogenys iner mis, where two unbranched rays are present (Reis, 1998).
Adipose fin
The adipose fin consists of a single spine, derived from a
small dorsal bony plate.
The homology of this spine initially was unclear. The
spine could be considered as a transformed bony scute or a
true fin ray that is covered by these dermal plates. Hoedeman
(1960b), however, mentions the presence of “two strong
muscle bundles” used for erection of the spine in Callichthyinae, which would mean that the spine in Corydoras,
although not movable in the Corydoradinae, is homologous
to a fin ray.
Caudal skeleton (Fig. 11)
As mentioned before, in many Siluriformes and Cypriniformes, the first preural vertebra is fused to the complex centre of the caudal skeleton (Lundberg and Baskin, 1969). The
caudal skeleton in Corydoras aeneus is of the pleurostyl
type and consists of two bony plates. The dorsal plate is
formed by a fusion of the urostyl and the dorsal hypurals III,
IV and V, a fusion which, as well as the development of a
plate-like lamina on the epural (the neural spine of the first
preural centre), could be revealed by preliminary ontogenetic data. The ventral plate comprises the parhypural and
hypurals I and II. Hypurals II and III are variably fused on
their left and/or right side or on neither side. The fact that the
dorsal hypurals are also fused to the compound centre is
common to all loricarioids, except for Nematogenys inermis
(Schaefer, 1990). The number of principal rays is 7/7, which
is common among Corydoras species (Isbrücker and
Nijssen, 1973, 1992). Surprisingly, the number found here
differs from that given in the original C. aeneus description
by Gill (1858) (n = 6/6). Further, both the neural and haemal
spine of the preural vertebral centre II are heavily ossified
and branched. This state is, to a lesser extent, also present in
the preural vertebral centre III.
Pectoral girdle (Fig. 12)
The pectoral girdle consists of the cleithrum, which articulates with the supracleithrum, part of the posttemporopterotico-supracleithrum and embedded in the skull. The
Figure 13. - Pelvic girdle in adult Corydoras aeneus. A: Dorsal
view ; B: Ventral view ; C: Lateral view. [Ceinture pelvienne chez
un Corydoras aeneus adulte. A : Vue dorsale ; B : Vue ventrale ;
C : Vue latérale.]
Cybium 2005, 29(3)
271
Descriptive osteology of Corydoras aeneus
cleithral bones are medially connected by a simple suture.
The ventral part of the pectoral girdle consists of the scapulocoracoid. As in all Siluriformes the scapulocoracoid bone
is a compound bone, comprising the scapula, the coracoid
and the mesocoracoid. In Callichthyidae, the posterior process of this scapulocoracoid and of the cleithrum are sutured
behind the articulation of the fin with the girdle, this way
forming a bony shield around the entire base of that fin
(Reis, 1998). The scapulocoracoid bones also connect ventrally, but in contrast to the cleithral bones, here a heavily
interdigitating suture is present. Cleithrum and scapulocoracoid are connect medially by means of a coracoid bridge
(see also Diogo et al., 2001). The pectoral spine is pungent
as in all Corydoradinae (this in contrast to the Callichthyinae), bears serrations on both its anterior and posterior face
and a large articulation head, which also suits a spine locking mechanism (Hoedeman, 1960b; Alexander, 1965). Ten
branched rays together with two proximal radials are present.
Pelvic girdle (Fig. 13)
The pelvic girdle consists of two basipterygia, which
bear both an internal and an external anterior process. The
homology of both these processes was questioned by
Shelden (1937), and both were referred to as “projections”.
Since no obvious motivation was given to support this idea,
we do not follow his views on this matter and consider them
to be the internal and external process. The internal process
is well developed and bears a small dorsal lamina. The presence of a dorsal lamina on the internal process is a typic callichthyid feature (Reis, 1998). Second, the external process
also bears a lamina, which, in Corydoras aeneus is connected to a scute of the lower, lateral series of bony scutes, by
means of connective tissue (Reis, 1998). A third laminar process is present on the ischiac process, where it connects to
the ventral tip of a scute of the lower, lateral series (Reis,
1998). This ischiac process is further divided into a dorsal
and a ventral process, of which the dorsal part is bent laterally. These callichthyid features in the pelvic girdle are possibly related to reproductive strategies (Reis, 1998). Furthermore, the pelvic fin bears six branched rays.
REFERENCES
ADRIAENS D., VERRAES W. & L. TAVERNE, 1997. - The cranial lateral-line system in Clarias gariepinus (Burchell, 1822)
(Siluroidei: Clariidae): Morphology and development of canal
related bones. Eur. J. Morphol., 35: 181-208.
ALEXANDER R.M., 1965. - Structure and function in the catfish.
J. Zool., 148: 88-152.
AQUINO A.E. & S.A. SCHAEFER, 2002. - Revision of Oxyropsis
Eigenmann and Eigenmann, 1889 (Siluriformes, Loricariidae).
Copeia, 2002: 374-390.
272
HUYSENTRUYT & ADRIAENS
ARRATIA G., 1987. - Description of the primitive family
Diplomystidae (Siluriformes, Teleostei, Pisces): Morphology,
taxonomy and phylogenetic implications. Bonn. Zool. Mono gr., 24: 11-20.
ARRATIA G., 1990. - Development and diversity of the suspensorium of trichomycterids and comparison with loricarioids
(Teleostei: Siluriformes). J. Morphol., 205: 193-218.
ARRATIA G., 1992. - Development and variation of the suspensorium of the primitive catfishes (Teleostei: Ostariophysi) and
their phylogenetic relationships. Bonn. Zool. Monogr., 32: 1148.
ARRATIA G., 2003. - Catfish head skeleton: An overview. In: Catfishes (Kapoor A.S., Arratia G., Chardon M. & R. Diogo, eds),
pp. 3-46. Enfield, NH, USA: Science Publishers, Inc.
ARRATIA G. & L. HUAQUÍN, 1995. - Morphology of the lateral
line system and of the skin of diplomystid and certain primitive
loricarioid catfishes and systematic and ecological considerations. Bonn. Zool. Monogr., 36: 5-110.
ARRATIA G. & H.-P. SCHULTZE, 1990. - The urohyal: Development and homology within osteichthyans. J. Morphol., 203:
247-282.
BAMFORD T.W., 1948. - Cranial development of Galeichthys
felis. Proc. Zool. Soc. Lond., 118: 364-391.
BASKIN J.N., 1972. - Structure and relationships of the Trichomycteridae. Unpublished PhD thesis. 389 p. New York.
BRITTO M.R., 1998. - Two new species of the genus Aspidoras
(Siluriformes: Callichthyidae) from Central Brazil. Ichthyol.
Explor. Freshw., 8: 359-368.
BRITTO M.R., 2000. - Aspidoras depinnai (Siluriformes: Callichthyidae): A new species from northeastern Brazil. Copeia,
2000: 1048-1055.
BRITTO M.R. & R.M.C. CASTRO, 2002. - New corydoradine catfish (Siluriformes: Callichthyidae) from the Upper Paraná and
São Francisco: The sister group of Brochis and most of Cory doras species. Copeia, 2002: 1006-1015.
BURGESS W.E. & J. QUINN, 1992. - Colored Atlas of Miniature
Catfish. 215 p. New Yersey: T.F.H. Publications.
COBURN M.M. & P.G. GRUBACH, 1998. - Ontogeny of the
Weberian apparatus in the armored catfish (Siluriformes: Callichthyidae). Copeia, 1998: 301-311.
DAGET J., 1964. - Le crâne des Téléostéens. Mém. Mus. Natl.
Hist. Nat., sér. A, 31: 163-341.
DE PINNA M.C.C., 1993. - Higher-level phylogeny of Siluriformes, with a new classification of the Order (Teleostei, Ostariophysi). Unpublished PhD thesis. 482 p. New York.
DIOGO R., OLIVEIRA C. & M. CHARDON, 2001. - On the osteology and myology of catfish pectoral girdle, with a reflection
on catfish (Teleostei: Siluriformes) plesiomorphies. J.
Morphol., 249: 100-125.
FINK S.V. & W.L. FINK, 1981. - Interrelationships of the ostariophysan fishes (Teleostei). Zool. J. Linn. Soc., 72: 297-353.
FINK S.V. & W.L. FINK, 1996. - Interrelationships of ostariophysan fishes (Teleostei). In: Interrelationships of Fishes (Stiassny M.L.J., Parenti L.R. & G.D. Johnson, eds), pp. 209-249.
London: Academic Press.
GILL T.N., 1858. - Synopsis of the fresh water fishes of the western
portion of the island of Trinidad, W. I. Ann. Lyc. Nat. Hist. N.Y.,
363-430.
GOSLINE W.A., 1940. - A revision of the neotropical catfishes of
the family Callichthyidae. Stanf. Ichthyol. Bull., 2: 1-29.
GOSLINE W.A., 1975. - The cyprinid dermosphenotic and the subfamily Rasborinae. Occas. Pap. Mus. Zool., Univ. Michig.,
673: 1-13.
Cybium 2005, 29(3)
HUYSENTRUYT & ADRIAENS
GRANDE L., 1987. - Redescription of †Hypsidoris farsonensis
(Teleostei: Siluriformes), with a reassessment of its phylogenetic relationships. J. Vert. Paleontol., 7: 24-54.
GRANDE L. & M.C.C. DE PINNA, 1998. - Description of a second species of the catfish †Hypsidoris and a reevaluation of the
genus and the family †Hypsidoridae. J. Vert. Paleontol., 18:
451-474.
HANKEN J. & R. WASSERSUG, 1981. - The visible skeleton. A
new double-stain technique reveals the native of the “hard” tissues. Funct. Photogr., 16: 22-26.
HOEDEMAN J.J., 1960a. - Studies on callichthyid fishes: (5)
Development of the skull of Callichthys and Hoplosternum (2)
(Pisces - Siluriformes). Bull. Aquat. Biol., 2: 21-36.
HOEDEMAN J.J., 1960b. - Studies on callichthyid fishes (6): The
axial skeleton of Callichthys and Hoplosternum (Pisces: Siluriformes). Bull. Aquat. Biol., 2: 37-44.
HOWES G.J. & G.G. TEUGELS, 1989. - Observations on the
ontogeny and homology of the pterygoid bones in Corydoras
paleatus and some other catfishes. J. Zool., 219: 441-456.
HUYSSEUNE A. & J.-Y. SIRE, 1997. - Structure and development
of teeth in three armoured catfish, Corydoras aeneus, C. arcua tus and Hoplosternum littorale (Siluriformes, Callichthyidae).
Acta Zool., 78: 69-84.
ISBRÜCKER I.J.H. & H. NIJSSEN, 1973. - Two new species of
the callichthyid catfish genus Corydoras from Brazil (Pisces,
Siluriformes, Callichthyidae). Beaufortia, 21: 1-7.
ISBRÜCKER I.J.H. & H. NIJSSEN, 1992. - Corydoras breei, a
new species of callichthyid catfish from the Corantijn River
basin in Surinam (Pisces, Siluriformes, Callichthyidae). Beau fortia, 43: 9-14.
JARVIK E., 1980. - Basic Structure and Evolution of Vertebrates.
Vol. I. 575 p. London: Academic Press.
KOHDA M., TANIMURA M., KIKUE-NAKAMURA M. & S.
YAMAGISHI, 1995. - Sperm drinking by female catfishes: A
novel mode of insemination. Environ. Biol. Fish., 42: 1-6.
KOHDA M., YONEBAYASHI K., NAKAMURA M., OHNISHI
N., SEKI S., TAKAHASHI D. & T. TAKEYAMA, 2002. Male reproductive success in a promiscuous armoured catfish
Corydoras aeneus (Callichthyidae). Environ. Biol. Fish., 63:
281-287.
KRAMER D.L. & E.A. BRAUN, 1983. - Short-term effects of
food availability on air-breathing frequency in the fish Corydo ras aeneus (Callichthyidae). Can. J. Zool., 61: 1964-1967.
KRAMER D.L. & M. MCCLURE, 1980. - Aerial respiration in the
catfish, Corydoras aeneus (Callichthyidae). Can. J. Zool., 58:
1984-1991.
KRAMER D.L. & M. MCCLURE, 1981. - The transit cost of aerial
respiration in the catfish Corydoras aeneus (Callichthyidae).
Physiol. Zool., 54:189-194.
LUNDBERG J.G., 1975. - Homologies of the upper shoulder girdle and temporal region bones in catfishes (Order Siluriformes), with comments on the skull of the Helogeneidae.
Copeia, 1: 66-74.
Descriptive osteology of Corydoras aeneus
LUNDBERG J.G., 1982. - The comparative anatomy of the toothless blindcat, Trogloglanis pattersoni Eigenmann, with a phylogenetic analysis of the ictalurid catfishes. Misc. Publ. Mus.
Zool., Univ. Michig., 163: 1-85.
LUNDBERG J.G. & J.N. BASKIN, 1969. - The caudal skeleton of
the catfishes, order Siluriformes. Am. Mus. Nov., 2398: 1-19.
MACHADO-ALLISON A. & C. GARCIA, 1986. - Food habits
and morphological changes during ontogeny in three serrasalmin fish species of the Venezuelan floodplains. Copeia, 1:
193-196.
NIJSSEN H., 1970. - Revision of the Surinam catfishes of the
genus Corydoras Lacepède, 1803 (Pisces, Siluriformes, Callichthyidae). Beaufortia, 18: 1-75.
PRUZSINSZKY I. & F. LADICH, 1998. - Sound production and
reproductive behaviour of the armoured catfish Corydoras
paleatus (Callichthyidae). Environ. Biol. Fish., 53: 183-191.
REGAN C.T., 1911. - The classification of the teleostean fishes of
the order Ostariophysi: 2. Siluroidea. Ann. Mag. Nat. Hist., (8),
8: 553-577.
REIS R.E., 1996. - Callichthyidae. The tree of life web project,
http://tolweb.org/tree?group=Callichthyidae&contgroup=Siluriformes.
REIS R.E., 1997. - Revision of the neotropical catfish genus
Hoplosternum (Ostariophysi: Siluriformes: Callichthyidae),
with the description of two new genera and three new species.
Ichthyol. Explor. Freshw., 7: 299-326.
REIS R.E., 1998. - Anatomy and phylogenetic analysis of the
neotropical callichthyid catfishes (Ostariophysi, Siluriformes).
Zool. J. Linn. Soc., 124: 105-168.
ROJO A.L., 1991. - Dictionary of Evolutionary Fish Osteology.
273 p. Florida: CRC Press.
SCHAEFER S.A., 1987. - Osteology of Hypostomus plecostomus
(Linnaeus) with a phylogenetic analysis of the loricariid subfamilies (Pisces: Siluroidei). Contrib. Sci., 394: 1-31.
SCHAEFER S.A., 1988. - Homology and evolution of the opercular series in the loricarioid catfishes (Pisces: Siluroidei). J.
Zool., 214: 81-93.
SCHAEFER S.A., 1990. - Anatomy and relationships of the scoloplacid catfishes. Proc. Acad. Nat. Sci. Philad., 142: 167-210.
SCHAEFER S.A & A.E. AQUINO, 2000. - Postotic laterosensory
canal and pterotic branch homology in catfishes. J. Morphol.,
246: 212-227.
SCHAEFER S.A. & G.V. LAUDER, 1986. - Historical transformation of functional design: Evolutionary morphology of feeding
mechanisms in loricarioid catfishes. Syst. Zool., 35: 489-508.
SHELDEN F.F., 1937. - Osteology, myology, and probable evolution of the nematognath pevic girdle. Ann. NY Acad. Sci., 37: 196.
TAMARU C.S., COLE B., BAILEY R. & C. BROWN, 1997. - A
Manual for commercial Production of the Tiger Barb, Capoeta
tertrazona, a temporary paired Tank Spawner. 50 p. Hawaï:
Center for Tropical and Subtropical Aquaculture.
Reçu le 29 mars 2004.
Accepté pour publication le 12 novembre 2004.
Cybium 2005, 29(3)
273