Cryptopecten Dall, Bartsch & Rehder 1938

Cryptopecten sp. A (Fig. 5A)

MATERIAL EXAMINED. — Récif Neilson. BENTHAUS, stn DW 1925, 27°00’S, 146°05’W, 560-790 m, 1 rv.

DISTRIBUTION. — Austral Islands, only a single valve at 560 m depth.

REMARKS

The present specimen somewhat resembles Cryptopecten phrygium (Dall, 1886), from the tropical western Atlantic, in having an identical sculpture of longitudinal hollow sections on both sides of the primary radial ribs and intercostal commarginal lamellae. A similar sculpture also exists in Cryptopecten vesiculosus (Dunker, 1877), from southern Japan, and in C. bullatus and C. nux (Hayami 1984). A delicate shell layer covers these hollow sections (Hayami 1984: pl. 13, fig. 1c), but in eroded specimens this shell layer is often lacking and a longitudinal groove appears on each side of the main ribs. The present specimen is considerably larger in size than the other Cryptopecten species (Cryptopecten sp. A 57 mm, C. phrygium 43 mm, C. vesiculosus 34 mm, C. bullatus 25 mm, and C. nux 20 mm in height) (Hayami 1984), and strongly posteriorly oblique (other Cryptopecten species are more circular). Because a single valve is available, this new species is not named here.