The Skate, Raja richardsoni Garrick 1961, Assigned to Bathyraja

Abstract

The deepwater skate, Raja richardsoni Garrick 1961, is assigned to the genus Bathyraja on the basis of studies of 18 specimens from the northwest Atlantic including 10 mature males. It is similar to other Bathyraja species and distinguished from Raja and Breviraja species especially by having in the clasper tip a ventral terminal cartilage completely enclosed within the skin of the ventral lobe and lacking a free sharp edge, and a sentinel (accessory terminal cartilage no. 1) in the form of a hatchet-shaped knife with a sharp distal edge. Its clasper also has a projection, whose support is the distal process of the ventral marginal cartilage, always found in Bathyraja but not in Raja of the northeast Atlantic. It differs also from Raja in having an uncalcifled or little calcified anterior part of the rostral cartilage, in the freedom of the appendices of the rostrum from the shaft and in the more anterior extension of the pectoral radiais toward the snout.