Acmella bauensis, Marzuki & Liew & Mohd-Azlan, 2021

Marzuki, Mohammad Effendi bin, Liew, Thor-Seng & Mohd-Azlan, Jayasilan, 2021, Land snails and slugs of Bau limestone hills, Sarawak (Malaysia, Borneo), with the descriptions of 13 new species, ZooKeys 1035, pp. 1-113 : 1

Acmella bauensis sp. nov. Figures 15A , 16A-E , 17A-C

Material examined.

Holotype (SH 1.24 mm, SW 0.96 mm) (MZU.MOL.20.01), Malaysia, Sarawak, Kuching Division , Fairy Caves, south part of Gunung Kapor, 4 miles Southwest Bau, 1°22'53.97"N, 110°7'2.29"E, coll. M. E. Marzuki, 10.VII.2011 . Paratypes: 1 ex. (ME0002340), same data as Holotype .

Differential diagnosis.

This species differs from other Bornean Acmella species by having dull shell surface with inconspicuous, closely spaced spiral striae crossed by inconspicuous growth lines. Acmella conica Vermeulen & Junau, 2007 and Acmella obtusa Vermeulen & Junau, 2007, both from Central Sarawak, have a smaller shell with an elliptic aperture with a flattened parietal side. Acmella minuttisima (Maassen, 2000), from Sumatra, and Acmella subcancellata Vermeulen, Liew & Schilthuizen, 2015, from Sabah have more prominent spiral striae on the shell surface.

Description.

Shell minute, rather thin, translucent, and white. Surface not glossy. Spire conical with slightly convex side, apex rounded, whorls moderately convex, and slightly shouldered. Suture impressed. Protoconch sculpture microscopically cancellated. Teleoconch spiral sculpture with very fine, closely spaced, continuous spiral striae crossed by inconspicuous growth lines just visible at 80 times magnification. Aperture obliquely ovate in outline, with a concave to slightly convex parietal side, transition from parietal to basal side rounded. Peristome simple, expanded but not reflected on the columellar side. Umbilicus open, narrow, 0.08 mm in diameter. Dimensions: height <1.24 mm; width <0.96 mm; the number of whorls <4; aperture height <0.52 mm; aperture width <0.44 mm.

Geographic distribution and habitat.

It is known only from the type locality. Only dry shells were found during the surveys.

Etymology.

The specific epithet Acmella bauensis is from the name of Bau District, where the shells were found.

Figures

Figure 15. A Acmella bauensis, sp. nov., MZU. MOL. 20.01 holotype Gunung Kapor B Acmella cyrtoglyphe Vermeulen, Liew & Schilthuizen, 2015 ME 8960 Gunung Doya [not in natural colour, shell surface coated with platinum for examination under scanning electron microscope] C Acmella nana Vermeulen, Liew & Schilthuizen, 2015 ME 8497 Gunung Kapor D Acmella ovoidea Vermeulen, Liew & Schilthuizen, 2015 ME 2215 Gunung Batu E Anaglyphula sauroderma Vermeulen, Liew & Schilthuizen, 2015 ME 6910 Gunung Doya F Solenomphala scalaris (Heude, 1882) ME 8810 Gunung Batu.

Figure 16. Acmella bauensis sp. nov. A-F MZU. MOL. 20.01 holotype A apertural view B basal view C enlargement of the apical side showing the apex D enlargement of the body whorl showing the shell sculpture E enlargement of the basal side of the shell.

Figure 17. Acmella bauensis sp. nov. A-C ME 0002340 paratype A enlargement of the apical side showing the apex B enlargement of the body whorl (abapertural side) showing the shell sculpture C enlargement of the body whorl (apertural side) showing the shell sculpture. Acmella nana Vermeulen, Liew, & Schilthuizen, 2015 D-E ME 0009091 SPECIMEN D apertural view E enlargement of the body whorl (apertural side) showing the shell sculpture.