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The definition and scope of the genus Carcharhinus has undergone several changes over the years and recent molecular studies have questioned its monophyly by the inclusion of other carcharhinid genera. Although many descriptions of chondrocranium are available for Carcharhinus species, some inconsistences and divergences are found in the literature, mainly regarding the foramina of the orbital region. In this study, the chondrocranium of the silky shark, Carcharhinus falciformis, from specimens caught at the Brazilian coast and the terminology of its components is revised has been described. Chondrocrania of other Carcharhinus species and carcharhinid genera are also examined in order to investigate the phylogenetic significance of chondrocranial morphology. Three new anatomical terms and nine chondrocrania characters are proposed and described in detail. The chondrocranial morphology varies widely among Carcharhinus species mainly regarding the rostrum and nasal capsules. The chondrocrania of Prionace, Nasolamia, and Negaprion are similar to Carcharhinus species and reveal the need to further explore the relationships among these genera. Characters potentially informative for systematics are the shape of rostral node, the preorbital process, and the subethmoidal fossa, and the occurrence of an epiphyseal notch and foramen, and must be included in phylogenetic studies encompassing other carcharhiniforms.

The scapulocoracoid morphology in batoids has been investigated by previous authors but descriptions and illustrations of its ventral surface are lacking for Riorajini species. Here, we describe and illustrate the lateral and ventral views of the scapulocoracoid in females and males of Rioraja agassizi and Atlantoraja species, and six new measurements are proposed. In adult females, the distance between procondyles, distance between metacondyles, width of the coracoid bar, distance between mesocondyle and metacondyle, and the first posterior ventral foramen width are proportionally wider than in males. In juveniles of the four species, differences between sexes regarding proportional dimensions are less conspicuous. The wider and long scapulocoracoid of females may provide more space and protection for the development of embryos but further investigation is needed. Given the influence of sexual dimorphism in proportional dimensions and morphology of the scapulocoracoid, characters associated to this structure need to be cautiously analyzed in future phylogenetic studies.

Cirrhigaleus comprises a small genus of rare barbel-bearing dogfish sharks with distributions in limited regions of all oceans. Generic validity and taxonomic status of some species are upon controversies by morphological and molecular evidence that often suggest reallocation of Cirrhigaleus species into the genus Squalus. Particularly, the roughskin spurdog C. asper exhibits intermediary morphological characteristics within Squalidae that requires clarification. In the present study, a phylogenetic approach was undertaken to test the correct generic placement of C. asper using novel and revised morphological characters. We performed maximum parsimony analysis of 51 morphological characters of the internal (e.g., neurocranium, clasper cartilages, pectoral and pelvic girdles) and external anatomy applied to 13 terminal taxa. Cirrhigaleus represents a valid genus and it is supported by eight synapomorphies: high number of monospondylous vertebrae; medial nasal lobe supported by fleshy core and innervated by the buccopharyngeal branch of the facial nerve; neurocranium with greatest width across nasal capsules; one facet and one condyle in the puboischiadic bar for articulating with the basipterygium; two intermediate segments between the basipterygium of the pelvic fin and the axial cartilage of the claspers; five terminal clasper cartilages; and posterior medial process of the puboischiadic bar absent. Cirrhigaleus asper is sister-species to a small clade comprising C. barbifer and C. australis which is supported by one synapomorphy, presence of conspicuous cusplets in the dermal denticles. Cirrhigaleus barbifer, C. asper and C. australis are redescribed herein and the neotype of C. barbifer is designated. A key to Cirrhigaleus species is also given and the inner relationships within Squalus is tentatively discussed.

The definition and scope of the genus Carcharhinus has undergone several changes over the years and recent molecular studies have questioned its monophyly by the inclusion of other carcharhinid genera. Although many descriptions of chondrocranium are available for Carcharhinus species, some inconsistences and divergences are found in the literature, mainly regarding the foramina of the orbital region. In this study, the chondrocranium of the silky shark, Carcharhinus falciformis, from specimens caught at the Brazilian coast and the terminology of its components is revised has been described. Chondrocrania of other Carcharhinus species and carcharhinid genera are also examined in order to investigate the phylogenetic significance of chondrocranial morphology. Three new anatomical terms and nine chondrocrania characters are proposed and described in detail. The chondrocranial morphology varies widely among Carcharhinus species mainly regarding the rostrum and nasal capsules. The chondrocrania of Prionace, Nasolamia, and Negaprion are similar to Carcharhinus species and reveal the need to further explore the relationships among these genera. Characters potentially informative for systematics are the shape of rostral node, the preorbital process, and the subethmoidal fossa, and the occurrence of an epiphyseal notch and foramen, and must be included in phylogenetic studies encompassing other carcharhiniforms.

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The presence of claspers is one of the main characteristics of the cartilaginous fishes, but its variations across taxa have received limited use in shark systematics and have generally been neglected in descriptions of species. Clasper descriptions are available only for a few catshark species and most of these are focused only in external morphology. Besides that, divergences regarding the identification of some structures persist in the literature emphasizing the need of more encompassing morphological comparative analyses on claspers of scyliorhinids. In this study, claspers structures of almost all catshark genera were examined, described, and illustrated (except Akheilos and Pentanchus) and comments on their phylogenetic significance are provided. Some characters such as degree of development of rhipidions and terminal dermal cover, occurrence, position and size of accessory marginal and terminal cartilages proved to be useful for taxonomic purposes and their significance along carcharhiniforms systematics needs to be further investigated. RESEARCH HIGHLIGHTS: Clasper morphology of catsharks is described and compared and its systematic significance is discussed here. External morphology and skeleton components of claspers vary widely among scyliorhinids and may be useful in phylogenetic analyses.

Intersexual differences in morphometrics were investigated in five species of the catshark genus Scyliorhinus. ANCOVA was used to test 59 measurements, considering capture location and total length as covariates. In all examined species, pelvic-anal distances and pelvic-fin inner margin lengths were greater in males than in females, representing a clear pattern for the genus.

The catshark genus Scyliorhinus belongs to the family Scyliorhinidae, the most diverse family of sharks, and currently presents 16 valid species according to most modern accounts. The long history of taxonomic rearrangements and inaccurate descriptions of many species have contributed to misidentification of specimens and lack of information on the distributional range and diagnostic characters of its species. Species of Scyliorhinus are reviewed and redescribed here, with detailed descriptions on external morphology, neurocranium, claspers, dermal denticles, and tooth morphology provided for the first time for all species. Sixteen species are recognized as valid: Scyliorhinus boa (Goode & Bean, 1896), S. cabofriensis Soares, Gomes & de Carvalho, 2016, S. canicula (Linnaeus, 1758), S. capensis (Müller & Henle, 1838), S. cervigoni Maurin & Bonnet, 1970, S. comoroensis Compagno, 1988, S. duhamelii (Garman, 1913), S. garmani (Fowler, 1934), S. haeckelii (Miranda Ribeiro, 1907), S. hesperius Springer, 1966, S. meadi Springer, 1966, S. retifer (Garman, 1881), S. stellaris (Linnaeus, 1758), S. torazame (Tanaka, 1908), S. torrei Howell-Rivero, 1936, and S. ugoi Soares, Gomes & Gadig, 2015. The main taxonomic decisions herein taken include the resurrection of S. duhamelii (previously a junior synonym of S. canicula) and the synonimization of S. tokubee with S. torazame. Information on geographic distribution was updated for most species, especially for those with wide ranges (S. canicula, S. haeckelii, S. retifer, and S. stellaris).

The genus Scyliorhinus is part of the family Scyliorhinidae, the most diverse family of sharks and of the subfamily Scyliorhininae along with Cephaloscyllium and Poroderma. This study reviews the phylogenetic relationships of species of Scyliorhinus in the subfamily Scyliorhininae. Specimens of all Scyliorhinus species were examined as well as specimens of four of the 18 species of Cephaloscyllium, two species of Poroderma, representatives of almost all other catshark (scyliorhinid) genera and one proscylliid (Proscyllium habereri). A detailed morphological study, including external and internal morphology, morphometry and meristic data, was performed. From this study, a total of 84 morphological characters were compiled into a data matrix. Parsimony analysis was employed to generate hypotheses of phylogenetic relationships using the TNT 1.1. Proscyllium habereri was used to root the cladogram. The phylogenetic analysis, based on implied weighting (k = 3; 300 replications and 100 trees saved per replication), resulted in three equally most parsimonious cladograms with 233 steps, with a CI of 0.37 and an RI of 0.69. The monophyly of the subfamily Scyliorhininae is supported as well as of the genus Scyliorhinus, which is proposed to be the sister group of Cephaloscyllium. The phylogenetic relationships amongst Scyliorhinus species are presented for the frst time.

A new Southwestern Atlantic species of Parmaturus, P. angelae, new species, is described from two specimens captured off Brazil. It is distinguished from congeners by the following characters: origin of the first dorsal fin anterior to pelvic-fin origin, presence of well-developed upper and lower caudal crests of denticles, dorsal fins subequal, lateral denticles teardrop-shaped and lacking lateral cusplets, denticles evenly spaced, proportional dimensions, and vertebral counts. Parmaturus angelae, new species, is the second species of the genus reported from the Atlantic Ocean and only the third species outside of the Indo-West Pacific region. Parmaturus remains rather poorly defined as only two species have been studied anatomically in any detail.

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.

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.

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.