Abstract
Young specimens of Icosteus aenigmaticus Lockington have been reported from several places in Japan.All of these specimens were less than 326 mm in total length and were described as deep-bodied, having blotches on body, pelvic fins, and rounded posterior margin of the caudal fin.The specimen reported here is a mature male collected from Suruga Bay, : Shizuoka Prefecture, on March 15, 1970.The total length is 950 mm.The body color before fixation was dark brown and the pelvic fin is absent.The posterior margin of the caudal fin is lunate.The characters of this specimen match well with those of the specimen described as Acrotus willoughbyi Bean, which has been considered to be a junior synonym of Icosteus aenigmaticus.The appearance of the specimen in Suruga Bay is probably related to the appearance of unusually cold water masses off the coast of southern Japan on the Pacific side.
