Caecum japonicum ( Habe, 1978 )

Walter, Angelo Vannozzi & Renda, Walter, 2024, Sampling the depth: New data on the Caecidae (Mollusca, Gastropoda) from northeastern Papua New Guinea, Zoosystema 46 (14), pp. 327-347 : 330-332

Caecum japonicum ( Habe, 1978)

( Fig. 2 I-L)

Pictocaecum japonicum Habe, 1978: 3 , pl. 1, figs 14-17.

Caecum japonicum – Vannozzi 2019b: 87 and synonymy therein.

TYPE MATERIAL. — Holotype. Japan • sh; Kyushu, Matsugaura, Chiran-cho on the coast of Kagoshima Bay ; NSMT Mo 55371 ( NMNS). Paratype. Japan • 1 sh; same data as for holotype; NSMT Mo 55372 ( NMNS) .

TYPE LOCALITY. — Pacific Ocean, Japan, Kyushu, Matsugaura, Chiran-cho on the coast of Kagoshima Bay.

MATERIAL EXAMINED. — Papua New Guinea • 2 sh (1 juv); New Ireland; 2°44’S, 150°35’E; 240-305 m depth; 3.IX.2014; KAVIENG 2014 Stn DW4463; MNHN • 2 sh; New Ireland; 2°43’S, 150°36’E; 140-214 m depth; 3.IX.2014; KAVIENG 2014 Stn DW4464; MNHN • 2 sh; New Ireland; 2°43’S, 150°36’E; 90-228 m depth; 3.IX.2014; KAVIENG 2014 Stn DW4465; MNHN .

DISTRIBUTION.— Maldives, Andaman, Thailand, Philippines, Japan, northern Australia, northeastern PNG, New Caledonia, Vanuatu, Fiji, Tonga ( Habe 1963; Hasegawa 2000; Pizzini et al. 2013; Vannozzi 2017, 2019b, unpublished data).

DIAGNOSIS. — Shell of average size for the genus, whitish or colourless, usually showing brown and/or white bands arranged in collabral or zigzag pattern. Protoconch planorbid, multispiral of c. 2 whorls. Teleoconch tubular, arched, almost smooth. Early teleoconch conical, slightly twisted with very fine rings disappearing during the growth. Adult shell subcylindrical, smooth, tapering toward the apex, bent toward the aperture. Aperture simple, contracted, inclined. Septum low dome-shaped, slightly protruding without mucro, recessed below the cutting plane. Periostracum light brown, sometimes hairy. Operculum thin and flat. Animal described by Vannozzi (2019b). Adult shell length c. 2.5 mm, protoconch size c. 360 µm.

REMARKS

Caecum japonicum is a widespread and common species, showing a variety of colour patterns that allow easy identification, although colourless specimens occur. Worn specimens appear white.

Figures

FIG. 2. — Caecum Fleming, 1813 species from deep-water stations from northeastern PNG: A, B, C. sepimentum de Folin, 1868 from Stn DW4463 (B: juvenile); C, D, C. sepimentum from Mactan, Philippines, beached (coll. WR); E-H, C. vertebrale Hedley, 1899 from Stn DW3754; I, J, C. japonicum (Habe, 1978) from Stn. DW4464; K, L, C. japonicum from Stn DW4463 (L, juvenile); M, C. inflatulum Vannozzi, 2017 from Stn DW4463; N, C. inflatulum from Kotok, Indonesia, beached (coll. WR). Scale bar: 1 mm, details not to scale.