Acmella umbilicata 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 : 3-4

Taxon classification Animalia Littorinimorpha Assimineidae

Acmella umbilicata Vermeulen, Liew & Schilthuizen sp. n. Figure 2

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

Holotype. Malaysia, Sabah, Interior Province , Pinangah valley , Batu Urun (= Bukit Sinobang ) (leg. J.J. Vermeulen, RMNH.5003946 ).

Examined material from Sabah.

Interior Province. Pinangah valley, Batu Urun (= Bukit Sinobang) (leg. J.J. Vermeulen, V 8016, MOL/BOR 610; leg. M. Schilthuizen, V 13508, MOL/BOR 611). Sepulut valley, Gua Sanaron, inside cave (leg. M. Schilthuizen, V 13559).

Description.

Shell minute, thin, somewhat translucent, white. Surface shiny. Spire conical with flat or slightly concave sides, apex obtuse, whorls convex, sometimes slightly shouldered. Sculpture. Radial sculpture predominant: densely placed and regularly spaced, almost orthocline riblets which are about straight with a few slightly sinuous around the periphery in between, and which below the periphery are about as strong as above, rarely bifurcating. Spiral threads inconspicuous or almost absent. Aperture approx. obliquely elliptic in outline, with a straight parietal side, transition from parietal to basal side rounded to obtusely angular. Umbilicus open, very wide. Dimensions. Height 1.15-1.50 mm; width 0.95-1.15 mm; h/w 1.00-1.37; number of whorls 4 1/8-5; height aperture 0.45-0.55 mm; width aperture 0.45-0.50 mm.

Habitat in Sabah and distribution.

(Disturbed) primary forest on limestone bedrock, at c. 400 m alt. Sabah: Interior Province, South part only. Endemic to Sabah.

Cross diagnosis.

Differs from Acmella cyrtoglyphe by the almost orthocline radial ribs.

Remarks.

Just as in Acmella cyrtoglyphe , we observe variability in the ratio height/width of the shell, and with it in the width of the umbilicus.

Etymology.

The name refers to the wide umbilicus.