A new species of the grenadier genus Coryphaenoides (Actinopterygii: Gadiformes: Macrouridae) from Japan and a range extension of Coryphaenoides rudis Günther 1878 in the northwestern Pacific

Abstract

A new species of grenadier, Coryphaenoides soyoae, is described from two specimens collected from the Shichito-Iojima Ridge (type locality) and off Fukushima, Honshu, Japan, at depths of 2740–2991 m. The new species belongs to the subgenus Coryphaenoides and is most similar to Coryphaenoides castaneus Shcherbachev and Iwamoto 1995 and Coryphaenoides longicirrhus (Gilbert 1905). It differs from all other congeners in having the following combination of features: pelvic-fin rays 11; snout short, scarcely protruding beyond upper jaw; terminal snout scute absent; scales on lateral angles of snout and head ridges only slightly enlarged and thickened; dorsal contour of head prominently humped over nape; posterior end of upper jaw extending to below hind 1/3 of orbit or beyond; posterior end of rictus not restricted by lip folds; outer gill slit greatly restricted, length 7–8 % of head length (HL); barbel length 11–15 % HL; head bones and body flesh firm; teeth in posteriorly tapering bands on both jaws, with outer premaxillary series enlarged; body scales not deciduous, covered with narrowly divergent rows of needle-like spinules, and the last spinule in each row greatly overlapping posterior scale margin; snout fully scaled dorsally, broadly naked ventrally; interdorsal space slightly less than first dorsal-fin base length; origins of second dorsal and anal fins on about same vertical; height of first dorsal fin 87 % HL; second spinous ray of first dorsal fin serrated along its leading edge; outer pelvic-fin ray greatly prolonged, its tip extending well beyond anal-fin origin; head and body uniformly blackish. In addition, Coryphaenoides rudis Gunther 1878 is recorded for the first time from Japan, based on six specimens collected from Hyuga-nada, Suruga Bay, and the west of Minami-torishima Island (=Marcus Island), at depths of 1100–1481 m. A previous record of this species from Japanese waters was based on a misidentified specimen of a different genus.