イボオコゼ科の稀種ケラマオコゼの色彩と骨学を含む形態学的特徴

抄録

A single specimen of the rare velvetfish Cocotropus keramaensis, collected from the sandy bottom at 53–58 m depth off the Kerama Islands, Okinawa, Japan during dredge surveys in 2017, represents the second collection record for the species, and first with fresh coloration. Morphological characters, including squamation and osteology, are described in detail from radiographs, and scanning electron microscope (SEM) and computed tomography (CT) images. A published underwater photograph taken off Iriomote Island, Okinawa was also identified as C. keramaensis. Diagnostic characters of the species were revised as follows: XII, 9 or 10 dorsal fin rays; II, 7 anal fin rays; 12 or 13 pectoral fin rays; 25 or 26 vertebrae; 3 or 4 + 4–8 = 7–12 gill rakers; 5 distinct preopercular spines; upper jaw longer than lachrymal; 1 small papilla on posterior portion of maxilla; 4 distinct papillae on outer edge of lower jaw; 2nd sensory pore on lower jaw on both sides fused; anterior tip of isthmus attaining to position of 5th mandibular pore; 4 dorsal spines anterior to 3rd neural spine; a large light-colored region anteriorly on spinous dorsal fin; a dark region between maxilla, suborbital stay and lachrymal; many pupil-sized dark spots scattered on pectoral fin; a large blotch below bases of posterior dorsal fin spines; an eyesized blotch below bases of anterior dorsal fin soft rays; head and body reddish when fresh. CT scanning revealed a connection between the sensory pores on the lower jaw and the mandibular canal openings in this species.