本種の詳しい生態については,Hart(1946)が述べている。Stromateus属魚類には多くの種類がこれまで記載されて来たが,ここにとりあげた2種(S. brasiliensis, S. stellatus)とS. fiatola Linnaeus,1758の合計3種が正しい種として認められている(Haedrich, 1967)。
(中村 泉)
Material examined:
10 from Argentina (187.8-305.8 mm SL), FAKU 42794, 42991, 43062; AP 187, 188, 481-485.
Description:
D 48-54; A 40-47; P1 19-21; GR 4-8+12-15=18-20; BR 6:; X 16-17+27-29=43-46.
HL 20.0-23.5% of SL; ED 2.5-2.7; BD 36.8-40.9; SN 6.3-7.4; IO 7.7-8.7; UJ 4.7-5.9; CP 5.5-7.3; P1L 17.0-20.5; DH ;11.1-15.3; AH 7.0-8.4.
Body deep and extremely compressed, body depth 2.5-2.8 times in SL. Head small, 4.5-5.0 times in SL. Snout blunt, its lenght about 2.8 times in head. Eye small, its diameter 6-7 times in head. Nostrils situated nearer to tip of snout than to anterior margin of eye, anterior nostril elliptical and posterior nostril slit-like. Gill -raker short. Pseudobranchiae present. Mouth small, posterior end of upper jaw extending to middle between tip of snout and anterior margin of eye. Extremely minute (almost microscopic) uniserial teeth on both upper and lower jaws. Interorbital region prominently convex, its length about equal to head length. No pelvic fin. Dorsal fin low with fairly high anterior lobe, its base long. Anal fin base slightly shorter than dorsal fin base. Caudal fin small, deeply forked. Lateral line obscure, gently curved, running parallel to dorsal profile from posttemporal region to caudal fin base. Small deciduous cycloid scales on body. Head naked except gill-cover. Body blue green above, silvery white below. Many round dark blue spots on upper half of body. Distal parts of fins darker.
Distribution:
The Atlantic coast of South America, Tierra del Fuego north to southern Brazil.
Remarks:
Hart (1946) reported the seasonal distribution, biology and potential fishery for this species (=his Stromateus maculatus). Though numerous species have been described, there seem to be no more than two, or possibly three, valid ones: S. brasiliensis, S. stellatus and S. fiatola Linnaeus, 1708 (Haedrich, 1967).
(Izumi NAKAMURA)
Distribution of Stromateus brasiliensis in Patagonia.
Scale below lateral line (right) and leteral line scale (left).