Taxon classification Animalia Littorinimorpha Assimineidae

Acmella subcancellata Vermeulen, Liew & Schilthuizen sp. n. Figure 6

Holotype. Malaysia, Sabah, Tawau Province, Batu Baturong c. 50 km W.S.W. of Lahad Datu (leg. J.J. Vermeulen & H. Duistermaat, RMNH.5003945).

Examined material from Sabah.

Malaysia, Sabah, Tawau Province. Batu Baturong c. 50 km W.S.W. of Lahad Datu, North slope (leg. J.J. Vermeulen, V 7572).

Description.

Shell minute, rather thin, somewhat translucent, white. Surface shiny. Spire conical with flat to slightly convex sides, apex somewhat narrowly obtuse, whorls (moderately) convex, sometimes slightly shouldered. Sculpture. Spiral sculpture predominant. Radial sculpture: scattered, inconspicuous growth lines, grading into inconspicuous, rather 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 a very narrow groove in between. Aperture obliquely ovate in outline, with a slightly concave to approx. straight parietal side, transition from parietal to basal side rounded. Umbilicus open, narrow. Dimensions. Height 1.19-1.30 mm; width 0.95-1.10 mm; h/w 1.11-1.26; number of whorls 4 1/8-4 1/2; height aperture 0.58-0.69 mm; width aperture 0.49-0.59 mm.

Habitat in Sabah and distribution.

(Disturbed) primary forest on limestone bedrock, at c. 100 m alt. Sabah: East coast, Baturong Hill only. Endemic to Sabah.

Cross diagnosis.

Most similar in size and shell sculpture to Acmella ovoidea; differs by its conical shell. The sculpture is somewhat more prominent than in Acmella ovoidea .

The general shell shape is virtually identical to Acmella minutissima (Maassen, 2000), from Sumatra. Acmella subcancellata differs by its teleochonch sculpture, consisting of much wider spiral threads, leaving only narrow grooves in between, as well as by the radial sculpture cutting into the crest of the spural threads.

Etymology.

The name refers to the shell surface [sub-cancellata (L.) = with an inconspicuous, trellis-like structure].