Everettia microrhytida, 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

Everettia microrhytida sp. nov. Figures 41B , 42D-F

Material examined.

Holotype (SH 12.14 mm, SW 22.00 mm) (MZU.MOL.20.25), Malaysia, Sarawak, Kuching Division , Gunung Batu , limestone outcrop along Skio road, Jambusan, 2.4 miles E Bau, 1°23'50.65"N, 110°11'19.99"E, coll. M. E. Marzuki, 10.II.2017 . Paratypes: 1 ex. (MZU.MOL.20.26), the same locality as holotype, coll. M. E. Marzuki, 10.VII.2011 ; 1 ex. (ME0006829), 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. (ME0003498), 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 ; 6 ex. (ME0009145), 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 ; 1 ex. (ME0009845), the same locality, coll. M. E. Marzuki, 12.V.2018 .

Differential diagnosis.

This species is similar to Everettia consul (Pfeiffer, 1854) in terms of general shape and size. However, it differs from E. consul by lacking spiral sculpture and having only very fine (sometimes inconspicuous), somewhat wrinkled, puncture-like sculpture on both the apical and apertural sides. Everettia consul , on the other hand, has a shell with a more elevated spire and its shell surface has densely placed radial threads and somewhat cut by irregularly spaced spiral grooves.

Description.

Shell moderately large, rather thin, translucent, pale to dark brown, spire slightly elevated. Surface with a glossy lustre. Whorls convex. Number of whorls < 6¼. Protoconch: almost smooth, spiral striation absent with inconspicuous radial threads near the suture. Teleoconch with no: spiral sculpture but with very fine, inconspicuous, somewhat wrinkled, puncture-like shell sculptures on both apical and apertural sides. Radial sculpture of teleoconch very fine as well as inconspicuous growth lines, most conspicuous radial threads near the suture and below periphery. Periphery round; suture shallow. Aperture lunulate. Peristome simple; somewhat thickened and reflected on columellar side, not thickened nor reflected on basal and palatal sides. Umbilicus open, narrow; sometimes partly covered by reflected peristome; umbilical region moderately concave. Dimensions: shell height <12.58 mm; shell width <22.13 mm; diameters of the first three whorls 1.60 mm, 2.55 mm, and 4.90 mm, respectively; aperture height <8.94 mm; aperture width <11.66 mm.

Geographic distribution and habitat.

It is known from the Bau and Serian-Padawan limestone hill clusters. Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

Etymology.

From the Greek mikro rytídes, meaning extremely small wrinkles, in reference to the shell sculpture.

Figures

Figure 41. A Everettia cutteri (H. Adams, 1870) ME 8968 Gunung Doya Kapor B Everettia microrhytida, sp. nov., MZU. MOL. 20.25 Holotype Gunung Batu C Everettia minuta, sp. nov., MZU. MOL. 20.23 Holotype Gunung.

Figure 42. Everettia spp. A-C Everettia minuta, sp. nov., MZU. MOL. 20.24 Paratype A Enlargement of the apical side showing the apex B Enlargement of the teleoconch showing the shell sculpture C Enlargement of the basal side of the shell D-F Everettia microrhytida, sp. nov., MZU. MOL. 20.26 Paratype D Enlargement of the apical side showing the apex E Enlargement of the teleoconch showing the shell sculpture F Enlargement of the basal side of the shell.