A new species of the Genus Harpadon (Aulopiformes, Synodontidae) from the north-eastern Arabian Sea, India

Abstract

A new species of Harpadon Lesueur, 1825 captured from the continental slope area 19° 53’ N - 69° 23’E (north-eastern Arabian Sea) is described. The species Harpadon nudus sp. nov. was identified possessing a prominent trilobed caudal fin and a wide mouth with strong fang like barbed teeth and has been distinguished from its congeners by the following combination of characters: slender, completely scaleless body with very short pectoral (8.6 - 13.8% SL) and pelvic (16.4 - 21.6% SL) fins, large eyes (9.1 - 15.1% HL) with narrow inter-orbital width (15% of HL) and single pair of nares, situated close to the tip of the narrow snout. Morphologically it differs from the partially scaled species such as Harpadon nehereus in having very short pectoral fins not reaching up to its dorsal fin, single pair of nares and a pointed snout in dorsal view. It can be distinguished from Harpadon microchir by its greater head length of 22 - 26% SL; absence of scales at the base of the adipose fin and on the lateral line as well as the dorsal fin count of 12 rays. It is differentiated from Harpadon mortenseni by its lower lateral line pores count (40 - 43), higher number of branchiostegals (17 to 20), absence of scales on the lateral line or caudal peduncle and absence of vomerine teeth. It is distinct from Harpadon translucens which has a translucent body, partially covered with scales in the caudal region and protruding bristle like teeth on the jaw symphysis. It is distinguished from Harpadon squamosus which has scales on its head, trunk and caudal region with a relatively deeper body (5.8 in SL), by its slender and elongate body (8 - 10 in SL), short pelvic fins (16.4 - 21.6% SL) not extending to the anal vent and a narrow snout. It is also distinguished from Harpadon erythraeus which has a dark body entirely covered with scales and black fins, short head and rounded snout. H. nudus sp. nov. stand apart from H. nehereus (Kimura 2 Parameter distance 20%), the only species reported from the Arabian Sea and H. microchir (K2P 19%) by forming a distinct clade with 100% bootstrap support.