Parin and Bekker(1972)によるとタチモドキ属Benthodesmusは世界中に7種(うち1種は3亜種に分かれる)ある。その後も本属には続々新種が加えられ,その分類はまだ確立していない。
(中村 泉)
Material examined:
1 from Argentina (1015.5 mm SL), FSFL EM 895.
Description:
D 156; A 104; P1 15; P2T; GR 6+7=13; BR 7.
HL 11.5% of SL; ED 2.2; BD 3.2; BW 1.7; SN 5.1; IO 1.8; UJ 4.4; CP 0.3; P1L 2.5; P2L 0.05; PreD 9.4; PreP1 11.4; PreP2 11.5; PreA 39.2 ; PreAn 37.8.
Body without scales, covered by delicate, deciduous, silvery pigments. Body extremely elongate and compressed. Head elongate with a gradual slope on frontal part and a small concave on dorsal part. Nostril single and crescent-shaped. Mouth large and not protrusible. Lower jaw projected anterior to upper jaw. A conical dermal process on tip of each jaw, that on upper jaw smaller. Posterior margin of upper jaw scarecely reaching anterior margin of eye. Three pairs of fangs on anterior part of upper jaw and a pair of small fangs on anterior part of lower jaw. Lateral teeth on both jaws large, caniniform teeth on upper slightly larger and more densely arranged than teeth on lower jaw. Tongue wide, elongate. Vomer toothless. A row of acute small canine teeth on palatines. Gill-rakers small, spinescent. Dorsal fin base extremely long, first dorsal fin base shorter than 1/2 of second dorsal fin base. Anal fin base shorter than second dorsal fin base. First spine of anal fin scale-like. Caudal fin very small. Lateral line tubular, running obliquely anteriorly and straight posteriorly.
Distribution:
Argentine Patagonia, also known from the northwestern Atlantic, the northwestern Pacific, South Africa and the Tasman Sea (Parin and Bekker, 1972).
Remarks:
Three species were recognized by Tucker (1953, 1956) and then 4 species (one of them separated into 3 subspecies) were added by Parin and Bekker (1972). Recently several more species were newly described. So, the taxonomy of Benthodesmus is not fully understood.
(Izumi NAKAMURA)
Distribution of Benthodesmus elongatus in Patagonia.