Electrolux addisoni   , a new genus and species of electric ray from the east coast of South Africa (Rajiformes: Torpedinoidei: Narkidae), with a review of torpedinoid taxonomy

Abstract

A new genus and species of sleeper ray, Electrolux addisoni (Family Narkidae), with two dorsal fins is described from two adult males (total lengths 50 and 52 cm) caught on a shallow reef off the east coast of South Africa. Electrolux is distinguished from other genera of Narkidae by its prominent spiracular papillae, the morphology of its nostrils, nasal curtain, mouth, jaws, chondrocranium, basibranchial skeleton, pectoral and pelvic girdles, and unique and complex colour pattern. It has higher vertebral, pectoral radial, tooth and intestinal valve counts than other narkids and reaches a greater size than all species with the possibly exception of Typhlonarke aysoni . Taxonomic definitions are provided for the electric rays, for the family Narkidae, and for Electrolux, as well as keys to families of electric rays and to the genera of Narkidae. The systematics of the narkid genus Heteronarce is reviewed and the genus validated. Members of the Narkidae may include the smallest, or at least the shortest, living chondrichthyans (Temera hardwickii and an undescribed species of Narke). Electrolux addisoni is a reef-dweller that eats polychaete worms and small crustaceans, and has been photographed and videotaped by divers while actively feeding in the daytime. The conspicuous dorsal colour pattern may be aposematic, as the ray was seen to make a possible threat display when closely approached. Electrolux addisoni is recorded from four localities along an approximately 310 km. strip of coastline from Coffee Bay, Eastern Cape Province, to just north of Durban, kwaZulu-Natal inside the 50 m isobath. This conspicuous, active ray is known only from a few diver records from reefs reported over approximately two decades, and its conservation status needs to be critically assessed