Microcystina kilat, 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 kilat sp. nov. Figures 23C , 26A-F

Material examined.

Holotype (SH 1.33 mm, SW 2.42 mm) (MZU.MOL.20.18), Malaysia, Sarawak, Kuching Division , 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 . Paratypes: 1 ex. (ME0009430), same data as Holotype ; 5 ex. (ME0009898), Bukit Sokwang ( Site 2), northern site of Gunung Doya, limestone hill along Skio road, 2.05 miles E Bau, 1°23'45.69"N, 110°10'35.04"E, coll. M. E. Marzuki, 22.IV.2017 ; 1 ex. (ME0001764), Lobang Angin ( Site 1), limestone outcrop near Sungai Sarawak Kanan, 1.75 miles W of Bau, 1°24'48.14"N, 110°8'12.21"E, coll. M. E. Marzuki, 11.III.2011 ; 1 ex. (ME0009273), Lobang Angin ( Site 3), limestone outcrop near Sungai Sarawak Kanan, 1.75 miles W of Bau, 1°24'54.96"N, 110°8'13.62"E, coll. M. E. Marzuki, 23.IV.2017 ; 5 ex. (ME0001829), 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, 11.III.2011 ; 2 ex. (ME0009895), the same locality, coll. M. E. Marzuki, 23.VI.2010 ; 6 ex. (ME0008088), the same locality, coll. M. E. Marzuki, 17.IX.2016 ; 1 ex. (ME0010477), the same locality, coll. M. E. Marzuki, 7.VIII.2008 ; 1 ex. (ME0009902), the same locality, coll. M. E. Marzuki, 8.IV.2017 ;> 10 ex. (ME0009899), 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 ; 9 ex. (ME0009646), the same locality, coll. M. E. Marzuki, 7.I.2018 ; 24 ex. (ME0009001), 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 ; 2 ex. (ME0009897), Bukit Sokwang ( Site 1), northern site of Gunung Doya, limestone hill along Skio road, 2.05 miles E Bau, 1°23'52.11"N, 110°10'27.93"E, coll. M. E. Marzuki, 22.IV.2017 ; 4 ex. (ME0008943), 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 ; 2 ex. (MZU.MOL.20.19),> 10 ex. (ME0009904), Gunung Batu , limestone hill along Skio road, Jambusan, 2.4 miles E Bau, 1°23'50.65"N, 110°11'19.99"E, coll. M. E. Marzuki, 10.VII.2011 ; 1 ex. (ME0001767), the same locality, coll. M. E. Marzuki, 23.VI.2010 ; 10 ex. (ME0001699), Limestone escarpment near Kampung Benuk, 8.2 miles SW Kota Padawan, 1°18'41.43"N, 110°17'32.03"E, coll. M. E. Marzuki, 20.VIII.2008 ; 8 ex. (ME0001770), small limestone outcrop at Kampung Beratok , Serian-Kuching road, 14.3 miles NW Serian, 1°18'41.05"N, 110°24'37.13"E, coll. M. E. Marzuki, 21.VI.2010 ; 7 ex. (ME0006997), Gua Raya , along Kampung Skuduk-Chupak, 8.8 miles SE Siburan, 1°14'23.29"N, 110°25'49.05"E, coll. M. E. Marzuki, 1.I.2016 ; 3 ex. (ME0009455), Serian Division, Gunung Storib, small northern peak of Gunung Silabor, 15 miles S Serian, 0°57'30.75"N, 110°30'3.00"E, coll. M. E. Marzuki, 22.IX.2017 ; 6 ex. (ME0001773), Gunung Suka , Limestone outcrop near Kampung Picsing, Tebakang-Tebedu road, 8.45 miles SW Serian, 1°8'5.08"N, 110°26'53.30"E, coll. M. E. Marzuki, 20.VI.2010 .

Differential diagnosis.

It differs from Microcystina callifera Vermeulen, Liew & Schilthuizen, 2015, in having a shell without spiral sculpture. The shell with an umbilicus that is entirely covered by a callus separates this new species from Microcystina microrhynchus Vermeulen, Liew & Schilthuizen, 2015 from Sabah.

Description.

Shell very small, thin, translucent, white, lenticular, spire almost flat or slightly elevated. Surface with shiny or a slightly silky lustre. Whorls slightly convex. Number of whorls <4. Protoconch smooth, sometimes with a few inconspicuous, scattered radial grooves only. Teleoconch: spiral sculpture absent. Radial sculpture teleoconch growth lines inconspicuous, next to these inconspicuous to distinct, densely placed shallow grooves, often at irregular intervals. Aperture lunulate. Peristome simple; somewhat reflected on the columellar side, not thickened nor reflected on the basal and palatal side. Umbilicus entirely covered by callus; columellar wall thickened; umbilical region is moderately concave. Dimensions: shell height 1.33-1.85 mm; shell width 2.42-3.70 mm; diameters of the first three whorls 0.42 mm, 0.79 mm, and 1.50 mm, respectively; aperture height <1.08 mm; aperture width <1.25 mm.

Geographic distribution and habitat.

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

Etymology.

From the Malay Microcystina kilat , meaning shiny, in reference to the shell surface of the new species.

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 26. Microcystina kilat, sp. nov. A-F MZU. MOL. 20.18 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.