Morphological description of Dipturus mennii (Chondrichthyes: Elasmobranchii: Rajidae) and its differentiation from Dipturus trachyderma

Renan A Moreira,Ulisses L Gomes,Marcelo R De Carvalho

doi:10.1590/s1984-46702011000100014

Renan A Moreira, Ulisses L Gomes + Show 1 more

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https://doi.org/10.1590/s1984-46702011000100014

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Abstract

Squamation patterns and skeletal anatomy (neurocranium, visceral arches, synarcual cartilage, scapulocoracoid, puboischiadic bar, and mixopterigium) of Dipturus mennii Gomes & Paragó, 2001 are described as a contribution to our limited knowledge of the anatomy of species of Dipturus Rafinesque, 1810. The hyoid and branchial arches, as well as the synarcual cartilage, are described for the first time in this species. We provide morphological comparisons of this species with Dipturus trachyderma (Krefft & Stehmann, 1975), a species that may be confused with D. mennii; we further corroborate, through anatomical features, that these species warrant separate taxonomic recognition. The main differences between D. mennii and D. trachyderma were found in squamation of the nuchal and middisc region, neurocranium, pectoral girdle, and principally the clasper skeleton. The morphology of the pelvic girdle is similar in both species. Dipturus is characterized by having the ventral terminal cartilage J-shaped (as opposed to the Z-shaped ventral terminal cartilage in Zearaja, whose species were, until recently, placed in Dipturus). Additional characters that may be derived for Dipturus include the anterior rostral groove and elevated rostral proportions

Highlights

Skates (Rajidae) of the genus Dipturus Rafinesque, 1810 are distributed worldwide and have their greatest diversity in the continental slope but are present in deeper areas of the continental shelf (MCEACHRAN & MIYAKE 1990a, b, EBERT & COMPAGNO 2007, LAST et al 2008)
We provide morphological comparisons of this species with Dipturus trachyderma (Krefft & Stehmann, 1975), a species that may be confused with D. mennii; we further corroborate, through anatomical features, that these species warrant separate taxonomic recognition
The main differences between D. mennii and D. trachyderma were found in squamation of the nuchal and middisc region, neurocranium, pectoral girdle, and principally the clasper skeleton

Summary

Introduction

Skates (Rajidae) of the genus Dipturus Rafinesque, 1810 are distributed worldwide and have their greatest diversity in the continental slope but are present in deeper areas of the continental shelf (MCEACHRAN & MIYAKE 1990a, b, EBERT & COMPAGNO 2007, LAST et al 2008). Five species are presently recognized as valid from the southwestern Atlantic: Dipturus teevani (Bigelow & Schroeder, 1951), D. leptocauda (Krefft & Stehmann, 1975), D. trachyderma (Krefft & Stehmann, 1975), D. mennii Gomes & Paragó, 2001 (Dipturus diehli Soto & Mincarone, 2001 is a junior synonym), and D. argentinensis Astarloa, Mabragaña, Hanner & Figueroa, 2008. The aim of the present paper is to morphologically describe Dipturus mennii, its squamation patterns, neurocranium, branchial arches, synarcual cartilage, scapulocoracoid, pelvic girdle, and mixopterygial skeleton. We hope to improve our understanding of the taxonomy and morphology of southwestern Atlantic species of Dipturus, further corroborating the taxonomic separation between D. mennii and D. trachyderma

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