Acmella ovoidea Vermeulen, Liew & Schilthuizen

Vermeulen, Jaap J., Liew, Thor-Seng & Schilthuizen, Menno, 2015, Additions to the knowledge of the land snails of Sabah (Malaysia, Borneo), including 48 new species, ZooKeys 531, pp. 1-139 : 5-6

Taxon classification Animalia Littorinimorpha Assimineidae

Acmella ovoidea Vermeulen, Liew & Schilthuizen sp. n. Figure 4

Acmella ovoidea nomen nudum: Clements et al. 2008: 2761-2762.

Acmella sp. "bor-01 [V 7980]": Schilthuizen and Vermeulen 2003: 95.

Acmella minutissima auct.: Schilthuizen et al. 2013: online supplementary data.

Holotype.

Malaysia, Sabah, Interior Province , Pinangah valley , Batu Urun (= Bukit Sinobang ) (leg. J.J. Vermeulen, RMNH.5003949 ).

Examined material from Sabah.

Interior Province. Pinangah valley, Batu Urun (= Bukit Sinobang) (leg. J.J. Vermeulen, V 7980, BOR/MOL 526; leg. M. Schilthuizen, BOR/MOL 528). Pun Batu c. 30 km West of Sepulut (leg. J.J. Vermeulen, V 1269). Sepulut valley, Batu Punggul (leg. J.J. Vermeulen, V 1913; leg. M. Schilthuizen, BOR/MOL 600); Batu Temurung (leg. J.J. Vermeulen, V 8019, BOR/MOL 525); Gua Pungiton (leg. J.J. Vermeulen & M. Schilthuizen, V 7528); Gua Sanaron (leg. J.J. Vermeulen & M. Schilthuizen, V 7645; leg. J.J. Vermeulen & M. Schilthuizen, V 7664); Batu Tinagas (leg. M. Schilthuizen, BOR/MOL 527). Sandakan Province. Kinabatangan valley, Batu Keruak near Sukau (leg. J.J. Vermeulen & M. Schilthuizen, V 9785; leg. T.S. Liew & B. Elahan, BOR/MOL 1872, BOR/MOL 1835); Batu Batangan (leg. M. Schilthuizen, BOR/MOL 1737); Batu Mawas (leg. M. Schilthuizen, BOR/MOL 1732; leg. T.S. Liew & M. Schilthuizen, BOR/MOL 1946, BOR/MOL 1981, BOR/MOL 1945, BOR/MOL 3588); Batu Pangi (leg. J.J. Vermeulen & M. Schilthuizen, V 9639, BOR/MOL 1730); Batu Tai (not Bod Tai) near Gomantong (leg. J.J. Vermeulen & M. Schilthuizen, V 9577, BOR/MOL 1736; leg. T.S. Liew & B. Elahan, BOR/MOL 3590, BOR/MOL 3589, BOR/MOL 1901); Batu Tai (leg. M. Schilthuizen, BOR/MOL 1733); Batu Tomanggong Besar (leg. M. Schilthuizen, BOR/MOL 607, BOR/MOL 1738; leg. T.S. Liew & B. Elahan, BOR/MOL 2270, BOR/MOL 2243); Batu Tomanggong Kecil (leg. J.J. Vermeulen & M. Schilthuizen, V 9708, BOR/MOL 1734; leg. T.S. Liew & B. Elahan, BOR/MOL 2048, BOR/MOL 2016; leg. M. Salverda & H. van Oosten, BOR/MOL 1740); Batu Tulug (Batu Putih) along road Lahad Datu-Sandakan, North of bridge over Kinabatangan River (leg. J.J. Vermeulen & H. Duistermaat, V 1504); Gomantong Hill 30 km South of Sandakan (leg. J.J. Vermeulen & H. Duistermaat, V 1621; leg. T.S. Liew & J.P. King, BOR/MOL 3625; leg. A. van Til, BOR/MOL 3275, BOR/MOL 3336, BOR/MOL 3272; leg. M. Schilthuizen, BOR/MOL 603); Tandu Batu (leg. J.J. Vermeulen & M. Schilthuizen, V 9622, BOR/MOL 1731); Batu Materis (leg. M. Schilthuizen, BOR/MOL 1735; leg. T.S. Liew & B. Elahan, BOR/MOL 2104, BOR/MOL 2074); Unnamed hill near Sukau Police Station (leg. T.S. Liew & B. Elahan, BOR/MOL 2207, BOR/MOL 2175; leg. T.S. Liew, BOR/MOL 2141, BOR/MOL 3591; leg. M. Schilthuizen, BOR/MOL 1757, BOR/MOL 1741). Pinangah valley, Batu Melikop (leg. R. Kiew, V 7717). Segama valley, North end of limestone ridge on East bank Tabin River (leg. J.J. Vermeulen & M. Schilthuizen, V 7761). Tawau Province. Batu Baturong c. 50 km W.S.W. of Lahad Datu (leg. J.J. Vermeulen & H. Duistermaat, V 1846); North slope (leg. J.J. Vermeulen, V 7573). Gua Madai c. 40 km S.S.W. of Lahad Datu (leg. J.J. Vermeulen & H. Duistermaat, V 1733). Semporna area, Segarong Hills, Batu Tengar, 25 km E.S.E. Of Kunak (leg. J.J. Vermeulen & H. Duistermaat, V 1809); Bukit Pababola, 25 km E.S.E. Of Kunak (leg. J.J. Vermeulen & H. Duistermaat, V 1785).

Description.

Shell minute, rather thin, translucent, white. Surface shiny. Spire conical with slightly convex sides to ovoid, apex (broadly) obtuse, whorls slightly to moderately convex, sometimes slightly shouldered. Sculpture. Spiral sculpture predominant. Radial sculpture: scattered, inconspicuous growth lines only, in some shells locally grading into slight, densely placed and regularly spaced riblets on the crests of the spiral threads. Spiral sculpture: densely placed and regularly spaced, very fine, low and wide threads with only very narrow grooves in between. Aperture obliquely ovate in outline, with a concave to slightly convex parietal side, transition from parietal to basal side rounded. Umbilicus open, narrow. Dimensions. Height 0.85-1.35 mm; width 0.80-1.00 mm; h/w 1.00-1.35; number of whorls 3 1/2-5; height aperture 0.40-0.55 mm; width aperture 0.40-0.50 mm.

Habitat in Sabah and distribution.

Primary and secondary forest on limestone bedrock, at 0-700 m alt. Sabah: Interior Province, South part; along the East coast from the Kinabatangan River valley Southwards. Also in Sarawak; Kalimantan Timur. Endemic to Borneo.

Cross diagnosis.

Characterized among the Sabah species by the more or less ovoid outline of the shell.

Differs from Acmella minutissima (Maassen, 2000) (= Anaglyphula minutissima Maassen), from Sumatra, by the same character. In addition, the sculpture on the teleoconch is different: the spiral threads are much wider, leaving only very narrow grooves in between. The radial sculpture cuts into the crests of the spiral grooves.

Remarks.

The index h/w is highly variable, and the umbilicus may be wider than in the illustrated shell.

Etymology.

The name refers to the shell outline [ovoideus (L.) = egg-shaped].