5 from Argentina (590.0-734.0 mm TL, 577.0-720.0 mm SL), FSFLEL 903; EM 202, 265, 321, 313.
Description:
D [-\ A ]W-]Z, 125-145; P1 15-17; P2U, 7; LLS 114-122; BR 9; GR 3+13-15=16-18.
HL 11.3-12.5% of SL; ED 1.9-2.3; BD 9.2-13.5; SN 3.4-3.8; IO 3.1-3.7; UJ 2.7-3.3; BD 9.2-13.5.
Body elongate and compressed with tapering tail. Head compressed with round snout. Eye moderate in size. Interorbital region fairly narrow and convex. Mouth small and inferior. Teeth in a row on upper jaw, in two rows on lower jaw. Two nostrils just in front of eye, closely situated each other but separated narrowly by smooth and scaleless skin. Palatine tooth patches meeting on midline, each with 2 to 4 irregular rows of slender inwardly curved teeth, medial ones longest. Opercular flap well developed, projecting backwark roundly. Right and left branchiostegal membranes united each other and free from isthmus. Dorsal fin composed of 8 or 9 spines only, its origin slightly posterior to pelvic fin origin. Head and body covered with fine cycloid scales. Lateral line single, running nearer to dorsal profile with gradual curve anteriorly.
Distribution:
Worldwide except tropical waters.
Remarks:
Our specimens show slight difference in several characters from N. chemnitzi reported by Yabe (1983). Besides two species described here, N. spinosus Garman, 1899 from the Pacific coast of northern South America, N. indicus Lloyd, 1909 from the Arabian Sea, N. abotti Fowler, 1934 from Philippines and southern Japan, and N. bonapartei Risso, 1840 from the Mediterranean and East Atlantic have been known so far (McDowell, 1973). Fully mature specimens differ from all other notacanths in large size, with a gnathoproctal length (the straight line distance from the tip of the lower jaw to the anal opening) in excess of 200 mm and reaching at least 443 mm (McDowell, 1973).
(Izumi NAKAMURA)
Distribution of Notacanthus chemnitzi in Patagonia.