Microcystina lirata, 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

Microcystina lirata sp. nov. Figures 23D , 27A-F

Material examined.

Holotype (SH 0.77 mm, SW 1.35 mm) (MZU.MOL.20.14), Malaysia, Sarawak, Kuching Division , Buddha Caves (Site 3), north part of Gunung Kapor, 3 miles SW Bau, 1°23'26.51"N, 110°7'10.02"E, coll. M. E. Marzuki, 9.IV.2017 . Paratypes: 2 ex. (MZU.MOL.20.15),> 10 ex. (ME0009214), same data as the holotype ; 1 ex. (ME0006721), small limestone escarpment near Kampung Padang Pan , 15 miles SW Bau, 1°19'24.07"N, 110°3'46.34"E, coll. M. E. Marzuki, 27.IX.2015 ; 2 ex. (ME0008774), Bukit Sokwang ( Site 3), northern site of Gunung Doya, limestone hill along Skio road, 2.05 miles E Bau, 1°23'49.87"N, 110°10'32.14"E, coll. M. E. Marzuki, 22.IV.2017 ; 4 ex. (ME0009166), Lobang Angin ( Site 2), limestone outcrop near Sungai Sarawak Kanan, 1.75 miles W of Bau, 1°24'51.01"N, 110°8'13.48"E, coll. M. E. Marzuki, 16.IV.2017 ; 3 ex. (ME0008979), Fairy Caves (Site 1), south part of Gunung Kapor, 4 miles SW Bau, 1°22'53.76"N, 110°7'4.34"E, coll. M. E. Marzuki, 8.IV.2017 ;> 10 ex. (ME0009235), Fairy Caves (Site 2), south part of Gunung Kapor, 4 miles SW Bau, 1°22'56.09"N, 110°6'58.82"E, coll. M. E. Marzuki, 8.IV.2017 .

Differential diagnosis.

It differs from Microcystina circumlineata ( Möllendorff, 1897) by having a smaller white shell with somewhat punctured-like secondary spiral grooves in between moderately spaced spiral threads.

Description.

Shell very small, rather thin, translucent, white, lenticular, spire moderately elevated. Surface with a silky lustre. Whorls slightly convex. Number of whorls < 4¼. Protoconch with a fine, moderately spaced spiral striation consisting of rows of minute, rather sharply outlined pits which are arranged in a cancellated pattern towards the teleoconch. Teleoconch: spiral sculpture present with very distinct, moderately spaced, continuous elevated spiral threads. In between these very fine, two rows of low, somewhat punctured-like secondary spiral grooves. Radial sculpture of teleoconch very fine as well as irregularly spaced growth lines. Periphery rounded; suture shallow. Aperture lunulate. Peristome simple; somewhat thickened and reflected on the columellar side, not thickened nor reflected on the basal and palatal side. Umbilicus open, narrow, partly covered by reflected peristome; umbilical region is moderately concave. Dimensions: shell height <1.17 mm; shell width <1.92 mm; diameters of the first three whorls 0.60 mm, 0.90 mm, and 1.37 mm, respectively; aperture height <0.83 mm; aperture width <0.83 mm.

Geographic distribution and habitat.

It is known from the Bau limestone hill clusters only. Only dry shells were found during the surveys.

Etymology.

From the Latin Microcystina lirata , in reference to the prominent spiral sculpture of the shell.

Figures

Figure 23. A Microcystina arabii, sp. nov., MZU. MOL. 20.06 Holotype Gunung Batu B Microcystina atoni, sp. nov., MZU. MOL. 20.11 Paratype Gunung Batu C Microcystina kilat, sp. nov., MZU. MOL. 20.19 Paratype Gunung Batu D Microcystina lirata, sp. nov., MZU. MOL. 20.15 paratype Gunung Kapor.

Figure 27. Microcystina lirata, sp. nov. A-F MZU. MOL. 20.14 Holotype A apertural view B apical view C basal view D enlargement of the apical side showing the apex E enlargement of the body whorl showing the shell sculpture F enlargement of the basal side of the shell.