First Japanese record for a species of Chaunax (Acanthopterygii: Chaunacidae)

Abstract

A single large specimen [197.8 mm standard length (SL)] of the genus Chaunax Lowe, 1846 (Lophiiformes: Chaunacidae), captured during a commercial bottom trawl at a depth of 150–250 m off Cape Daio-zaki, Shima, Mie Prefecture, Japan on November 2016. Lacked markings on the body surface, thereby differing clearly from the three Japanese congeners (Chaunax fimbriatus Hilgendorf, 1879, Chaunax penicillatus McCulloch, 1915 and Chaunax abei Le Danois, 1978) known to date. Subsequently identified as Chaunax apus Lloyd, 1909, the specimen was characterized as follows: body without marking, reddish dorsally and paler ventrally (fresh condition), becoming uniformly whitish (preserved) ; tips of cirri on esca partially dark; dorsal surface of head lacking cirri; head length 39.3% SL; and 3 neuromasts in upper preopercular series, 3 in lower preopercular series, and 15 in pectoral series. The specimen represents both the northernmost and easternmost records of the species in the Pacific Ocean, in addition to being the first from Japanese waters. Intraspecific variation was noted in the count of spinules bridging the lateral-line complex (4–5 pairs in the present specimen vs. usually 3 pairs in previous reports of the species). The need for reconsideration of two of the three species groups recognized in the genus Chaunax [C. abei (including C. apus) and C. fimbriatus species groups] was discussed from the viewpoint of new morphological data obtained from the above specimen. The new standard Japanese name “Akafusen” is proposed for C. apus, in referring to its characteristic body shape and color.