Michel Chardon

Homologies among different adductor mandibulae sections of teleostean fishes, with special regard to catfishes (Teleostei: Siluriformes)

ABSTRACT

Biomechanics of feeding in vertebrates

Although feeding has not yet been thoroughly studied in many vertebrate taxa, and different conceptual and methodological approaches make a synthesis difficult, the aim of this volume is to provide a comprehensive overview of the feeding design in aquatic and terrestrial vertebrates with a detailed description of its functional properties. The book focuses on the constant interaction between function and form, behaviour and morphology in the course of evolution of the feeding apparatus and feeding mechanism in both a complementary and basic manner in relation to survival, interspecific competition, adaptation to environmental changes and adaptive radiation. Special emphasis is given to the quantification of the observational and experimental data on the morphology and biomechanics of the feeding design and its elements - jaws, teeth, hyoidean apparatus and tongue in order to allow the present and further comparisons in an evolutionary perspective.

The Structures Associated With Catfish (Teleostei: Siluriformes) Mandibular Barbels: Origin, Anatomy, Function, Taxonomic Distribution, Nomenclature and Synonymy

The morphological features of the ventral region of the head of 16 siluriform species were studied in detail and compared with those described in the literature as the foundation for a general survey of the origin, anatomy, function, taxonomic distribution, nomenclature and synonymy of the structures associated with catfish mandibular barbels. The restricted taxonomic distribution of some of these structures indicates that the study of these structures could reveal useful data to infer the phylogenetic relationships between different catfish groups.

Evolutionary Trends and Possible Origin of the Weberian Apparatus

A synthesis of anatomical, paleontological and ontogenetic knowledge of the Weberian apparatus is presented. The primitive state of the Weberian apparatus of the extant otophysan orders is deduced and evolutionary trends are discussed in a functional perspective. Main trends are shortening, reduction of weight, loss of intermediate structures, and ankylosis of anterior vertebral centra. Paleontological and developmental data help to develop a tentative reconstruction of a primitive Weberian apparatus, without a manubrium of the intercalarium. Sagemehls hypothesis on the origin of the Weberian apparatus, which considers the interossicular ligament as the first structure appearing, provides a basis for a more detailed scenario in which each step leads to a more efficient sound transmitter.

On the osteology and myology of the cephalic region and pectoral girdle of Franciscodoras marmoratus (Lütken 1874), comparison with other doradids, and comments on the synapomorphies and phylogenetic relationships of the Doradidae (Teleostei: Siluriformes)

The cephalic and pectoral girdle structures of Franciscodoras marmoratus are described and compared to those of representatives of the three main doradid groups, namely Anadoras weddellii (Astrodoradinae), Acanthodoras cataphractus (Platydoradinae) and Doras punctatus (Doradinae), as well as members of the other siluriform families, as the foundation for a discussion on the phylogenetic relationships of the Doradidae. Our observations and comparisons support the idea that the Doradidae is closely related to the Auchenipteridae. In addition, our observations and comparisons pointed out a potentially new doradid synapomorphy, namely, the presence of a well-developed, deep, oval fossa between the dorsomedian surface of the pterotic and the dorsolateral surface of the parietosupraoccipital.

Osteology and myology of the cephalic region and pectoral girdle of Batrochoglanis raninus, with a discussion on the synapomorphies and phylogenetic relationships of the Pseudopimelodinae and Pimelodidae (Teleostei: Siluriformes)

The cephalic and pectoral girdle structures of the pseudopimelodin Batrochoglanis raninus are described and compared to those of a representative of another pseudopimelodin genera, namely Microglanis cottoides, as well as to several other pimelodid and non-pimelodid catfishes, as the foundation for a discussion on the synapomorphies and phylogenetic relationships of the Pseudopimelodinae. Our observations and comparisons pointed out two new, additional features that could represent potential Pseudopimelodinae synapomorphies: 1) mesethmoid markedly bifurcated anteriorly; 2) spoon-shaped autopalatine with a somewhat roundish, markedly enlarged dorsoventrally, posterior tip. In addition, our observations and comparisons indicate that the subfamilies Pseudopimelodinae, Pimelodinae and Heptapterinae do constitute a monophyletic assemblage, and, thus, contradict the commonly accepted idea that the family Pimelodidae is a polyphyletic group.

Morphology of the buccal apparatus and related structures in four Carapidae

The aims of this study were (1) to compare the morphology of the buccal apparatus, the suspensorium and the opercle in four species of Carapidae (Carapus acus, Encheliophis boraborensis, Encheliophis homei and Encheliophis gracilis) and (2) to investigate the relationships between their cranial anatomy, their carnivorous diet, and their well known ability to enter holothurians. The complex and strong dentition and the wide hyomandibular with thickenings that seem to suit the constraints of the adductor mandibulae muscles partly inserted on the neurocranium are signs of a carnivorous diet. C. acus, E. boraborensis and E. homei have extremely strong buccal pieces and can protrude their upper jaws. However, in E. gracilis, the jaws are more slender, and the insertions of the A1 along the entire length of the maxillary associated with the lack of mobility between the maxillary and the premaxillary prevent buccal protrusion. These differences could be related to the diet: C. acus, E. boraborensis and E. homei can feed on fishes and crustaceans, whereas E. gracilis feeds only on holothurian tissue. The cephalic morphology of the four species is not incompatible with entering the host. However, the neutralisation of the suboperculum spine by ecartilaginousi tissue could be considered to be a particular adaptation to this behaviour.

On the osteology and myology of the cephalic region and pectoral girdle of Heteropneustes fossilis (Siluriformes: Heteropneustidae), with comments on the phylogenetic relationships between Heteropneustes and the clariid catfishes

The osteological and myological structures of the cephalic region and pectoral girdle of the Asiatic catfish Heteropneustes fossilis are described and compared with those of several other catfishes, as the foundation for an analysis on the phylogenetic relationships of the genus Heteropneustes . Our observation and comparisons support a close relationship between Heteropneustes and the clariid catfishes. More specifically, the present study supports De Pinnas 1993 study, according to which Horaglanis and Uegitglanis , two genera commonly included in the family Clariidae, are the successive sister-groups of a monophyletic clade composed by the genus Heteropneustes and the remaining clariid genera.

Osteology and myology of the cephalic region and pectoral girdle of Schilbe mystus and comparison with other schilbids, with comments on the monophyly and phylogenetic relationships of the Schilbidae (Teleostei: Siluriformes)

The cephalic and pectoral girdle structures of Schilbe mystus are described and compared with those of other schilbids, as well as several other non-schilbid catfishes, as the foundation for a discussion on the monophyly and the phylogenetic relationships of the Schilbidae. Our observations and comparisons suggest that the family Schilbidae is a monophyletic group, defined, at least, by three autapomorphies, namely: 1) the adductor mandibulae A2 is lateral to the A1-Ost; 2) the posterior margin of the horizontal portion of Meckels cartilage is situated further beyond the coronoid process; 3) the adductor mandibulae Aω is visible in a lateral view of the cephalic region. With respect to the phylogenetic relationships of the Schilbidae, our observations and comparisons support a close relationship between this family and the Pangasiidae.

On the osteology and myology of the cephalic region and pectoral girdle of Chaca bankanensis Bleeker 1852, with comments on the autapomorphies and phylogenetic relationships of the Chacidae (Teleostei: Siluriformes)

The cephalic and pectoral girdle structures of Chaca bankanensis are described and compared to those of other catfishes, as the foundation for a discussion on the autapomorphies and phylogenetic relationships of the Chacidae. Our observations and comparisons pointed out six new chacid autapomorphies, namely: (1) absence of abductor superficialis; (2) ethmoid cartilage with long, thin, anterolateral projections situated ventrally to the anterolateral arms of mesethmoid; (3) interopercular with well-developed, deep concavity to articulate with posterior surface of preopercular; (4) dorsal process 2 of the cleithrum highly developed and markedly extended posteriorly. In addition, our observations and comparisons support a close relationship between the chacids, the plotosids and the clariids.