Squalus is a genus of reportedly cosmopolitan shark species that have a high taxonomic complexity due to difficulties in their morphological differentiation; many of its species need revision. Currently, there are 26 valid species of Squalus, which have been divided into three species-groups according to overall morphological similarity, the S. acanthias, S. megalops, and S. mitsukurii groups. Loss of type specimens, propagation of erroneous identifications in the literature, and difficulties in obtaining representative series for comparison are secondary challenges that have impeded a global taxonomic revision of the genus. This problem applies clearly to species from the Southwestern Atlantic Ocean, including species that occur off Brazil. Following a current global tendency, a regional taxonomic revision of Squalus was conducted in order to investigate which species are valid in the Southwestern Atlantic Ocean and provide diagnostic morphological characters that can be efficiently used for identifying species. Comparative detailed analysis of external (e.g. morphometrics, dentition, and color pattern) and skeletal morphology (primarily meristic data, neurocrania and claspers) of specimens of Squalus from the region revealed four new species that are herein described (S. albicaudus sp. nov., S. bahiensis sp. nov., S. lobularis sp. nov., and S. quasimodo sp. nov.), as well as S. acanthias, which is redescribed from the region based on new material. Comparisons are offered based on examinations of congeneric species; this work is part of a global systematic revision of Squalus.

ABSTRACT. The Caribbean skate Diplul'us leevani (Bigelow & Schroeder, 1951 (Bigelow & Schroeder, 1951). They are typical inhabitants of deep waters between the outer shelf edge (195-200m) and the slope (more than 500m). Although morphologically conservative, the species of Diplurus can be distinguished from each other by the number of dorsal and nuchal thorns, the number of caudal thorns, dorsal and ventral spinulation and specific total length. An identification key for the species of Diplurus recorded Irom Brazil is presented.

Sharks of the genus Scyliorhinus from the southwestern Atlantic are reviewed; identification problems and taxonomic misinformation given in the literature are rectified. After extensive examination of the external and internal morphology of specimens collected mostly off southeastern and southern Brazil, Scyliorhinus besnardi Springer & Sadowsky, 1970 is placed in the synonymy of S. haeckelii (Miranda Ribeiro, 1907), which is thoroughly redescribed. Additionally, a new species, Scyliorhinus cabofriensis, sp. nov., is described from the state of Rio de Janeiro, distinguished from all southwestern Atlantic congeners by its color pattern, clasper and neurocranial morphology, and proportional measurements. A key to Scyliorhinus species occurring in the southwestern Atlantic is also provided.

No abstract

A new species of catshark (Carcharhiniformes, Scyliorhinidae), Scyliorhinus ugoi sp. nov., is described from off Northeastern and Southeastern Brazil. The new species is closest to the Scyliorhinus haeckelii/besnardi group and S. hesperius but differs in background coloration, head width, sexual maturity, and in cranial and body proportions.