Leptochiton habei Saito, 1997

(Figs 13–15)

Leptосhitоn habei Sаito 1997: 44 –46, text figs 1D, 7; pl. 2, fig. 1; Sаito 2000: 7; Sirenko 2001: 41 –43, figs 1–15, 162–163; 2004: 114–115, tаb. 1; Sigwаrt & Sirenko 2012: 11.

Type material. Holotype (NMNS 70655) and paratypes (NMNS 70653, 70654, 70656, 70771).

Type locality. Suruga Bay, off Kogane-zaki, Izu Peninsula, Japan, 200–300 m.

Material examined. Taiwan, Bashi channel N/O Fishery Researcher 1,” TAIWAN 2000”, stn CP38, 21°32.1’N, 120°48.1’E, 1314–1317 m, 10 spms, BL 3.0–5.0 mm, 01.08.2000; stn CP58, 24°35.1’N, 122°05.8’E, 221 m, 2 spms, BL 4.5–5.0 mm, 04.08.2000; NE coast of Taiwan, off Tashi, Fishing Boat Chung Tung Long N26, stn CP76, 24°56.5’N, 122°01.5’E, 115–170 m, 1 spm, BL 4.5–5.0 mm, 07.05.2001; stn CP95, 24°55.8’N, 122°05.7’E, 269–360 m, 2 spms, BL 5.0– 7.5 mm, 18.05.2001.

Distribution. Known from Japan (200–300 m: Saito 1997), Vanuatu (765–780 m: Sirenko 2001), Solomon Islands (200–350 m: Sigwart & Sirenko 2012) and now near Taiwan (170–1314 m). Found living and feeding on sunken terrestrial plant remains. The present report from off Taiwan extends the distribution and depth of this species considerably.

Remarks. The Taiwan specimens are very similar to Vanuatu specimens (Sirenko 2001) and differ from the holotype of L. habei from Suruga Bay by (1) distinct granules on the tegmentum of the head valve, the lateral area of intermediate valves and the postmucronal area of the tail valve, and (2) the presence of smooth sensitive needles at the suture and at the margin. The disarticulated specimen from Taiwan (stn CP76, BL 7.0 mm) has five almost equal gills on each side; its radula is 2.4 mm long with 32 transverse rows of mature teeth. Each suture has up to seven smooth delicate needles. There are seven (rarely eight or nine) aesthetes pores in each granule on the tegmentum.