Rhinobatos nudidorsalis, a new species of shovelnose ray (Batoidea: Rhinobatidae) from the Mascarene Ridge, central Indian Ocean

Abstract

A new shovelnose ray, Rhinobatos nudidorsalis, is described from the Mascarene Ridge, an inadequately surveyed chain of seamounts in the central Indian Ocean. Of the three subgroups of Rhinobatos occurring in the Indian Ocean, it most closely conforms with the subgenus Rhinobatos (Linnaeus). A small species, known only from the holotype, it is unique within the family in having an almost completely naked dorsal surface. In addition, it is further distinguished from other Indo-Pacific members of the genus by the combination of a pale, plain-colored disc, large eyes, the inner edge of the anterior nasal flap penetrating slightly into the internarial space, low dorsal fins, a long pelvic-fin inner margin, a narrow interdorsal space, two spiracular folds, an elongate to oval-shaped denticle patch on the caudal peduncle, and a small, weakly asymmetrical caudal fin.