Dermal denticles and morphometrics of the sailfin roughshark Oxynotus paradoxus...

• Author(s): Azevedo, José M. N. ; Sousa, Fernando L. ; Brum, João M. M.
• Date: 2003
• Persistent ID: http://hdl.handle.net/10400.3/336
• Origin: Repositório da Universidade dos Açores
• Subject(s): Oxynotidae; Oxynotus paradoxus; ANE; Dermal Denticles; Distribution; Depth Range; Shark
• Document Type: Article
• Language: English

Description

The dermal denticles of the sailfin roughshark Oxynotus paradoxus are described and illustrated with SEM pictures, based on two specimens captured at the Azores. The flank denticles are similar to those of O. centrina, with a central cusp flanked by two smaller lateral cusps, rising from the lateral ridges, and a secondary median cusp posterior to the main one. Differences in squamation between both species are described. Body proportions of the Azorean specimens are given and found to be consistent with those reported by previous authors. The published information shows depth of capture to have a mode at 570 m. A bathybenthic habitat has been suggested, with spring reproductive migrations to the continental shelf. The presence of this species in the Azores and Mid-Atlantic Ridge represents a significant westward extension of its previously known geographic distribution, the continental shelf and upper slope of the north and eastern Atlantic. It is possible that O. paradoxus is continuously distributed along the north-eastern Atlantic floor, deeper than presently known. Alternatively, separate slope and ridge populations may exist.