Morphology and phylogenetic significance of the pelvic articular region in elasmobranchs (Chondrichthyes).

The morphology of paired fins is commonly overlooked in morphological studies, particularly the pelvic girdle and fins. Consequently, previous phylogenetic studies incorporating morphological data used few skeletal characters from this complex. In this paper, the phylogenetic significance of pelvic articular characters for elasmobranchs is discussed in light of the morphological variation observed in 130 species, the most comprehensive study exploring the morphology of the pelvic girdle done so far.

Morphological study of the oral denticles of the porbeagle shark Lamna nasus.

Oral denticles of sharks are composed by a crown, dentine covered by a layer of enameloid and pulp cavity, the same structure of the dermal denticles found across the body surface of most elasmobranchs. In addition, oral papillae and taste buds are distributed among denticles within the oropharyngeal cavity, playing a fundamental role for tasting as part of the chemosensory system of fishes. Scanning electron microscopy (SEM) has been employed as an important tool for the study of dermal denticles and other structures, as well as histology and more recently computed tomography (CT) scan analysis.

Phylogenetic interrelationships of the eel families Derichthyidae and Colocongridae (Elopomorpha: Anguilliformes) based on the pectoral skeleton.

A cladistic analysis of the eel families Derichthyidae and Colocongridae is herein proposed for the first time on the basis of morphological data. We discovered dozens of new phylogenetic characters derived from a detailed analysis of the pectoral skeleton, an anatomical system neglected by most previous studies. Our maximum parsimony analysis indicates that Colocongridae sensu lato is paraphyletic, with its two constituent genera Coloconger and Congriscus appearing as successive sister groups of derichthyids.

Reconsidering pectoral girdle and fin morphology in Anguillidae (Elopomorpha: Anguilliformes).

The morphology of the pectoral girdle and fin of Anguillidae is reconsidered via the inclusion of skeletal components that have previously been unassessed. For example, the pectoral girdle and fin in Anguilla were erroneously reported to lack a scapular bone, a cartilaginous scapulocoracoid plate and a cartilaginous propterygium. The pectoral morphology of Anguilla is also compared with the closely related genus Nemichthys, including additional data on the anatomy of this eel family.

A new subfamily, Styracurinae, and new genus, Styracura, for Himantura schmardae (Werner, 1904) and Himantura pacifica (Beebe & Tee-Van, 1941) (Chondrichthyes: Myliobatiformes).

A new subfamily (Styracurinae, subfam. nov.) and genus (Styracura, gen.

Systematics and morphology of Potamotrygon orbignyi (Castelnau, 1855) and allied forms (Chondrichthyes: Myliobatiformes: Potamotrygonidae).

The Neotropical freshwater stingray Potamotrygom orbignyi (Castelnau, 1855), and other similar "reticulated" species occurring in northern South American basins, were submitted to a thorough taxonomic analysis based on an extensive external and internal morphological study. The identity of P. orbignyi and the taxonomic status of the related nominal species Potamotrygon dumerilii (Castelnau, 1855), Potamotrygon reticulata (Günther, 1880), and Potamotrygon humerosa Garman, 1913, are defined.

Potamotrygon limai, sp. nov., a new species of freshwater stingray from the upper Madeira River system, Amazon basin (Chondrichthyes: Potamotrygonidae).

Potamotrygon limai, sp. nov., is described from the Jamari River, upper Madeira River system (Amazon basin), state of Rondônia, Brazil.