Everettia minuta, 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 minuta sp. nov. Figures 41C , 42A-C

Material examined.

Holotype (SH 5.72 mm, SW 10.00 mm) (MZU.MOL.20.23), Malaysia, Sarawak, Kuching Division , 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 . Paratypes: 7 ex. (ME0008965), same data as the holotype ; 1 ex. (MZU.MOL.20.24), the same locality as the holotype, coll. M. E. Marzuki, 23.VI.2010 ; 5 ex. (ME0001512), the same locality, coll. M. E. Marzuki, 11.III.2011 ; 1 ex. (ME0001513), 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, 11.III.2011 ; 4 ex. (ME0009139), 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, 15.IV.2017 ; 1 ex. (ME0009222), 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 ; 1 ex. (ME0009466), Serian Division; Gunung Storib, small northern peak of Gunung Silabor, 15 miles S Serian, 0°57'30.75"N, 110°30'3.00"E, 22.IX.2017 .

Differential diagnosis.

The new species is similar to Everettia jucunda (Pfeiffer, 1863), E. bangueyensis (Smith, 1895) and E. jucundior Liew, Vermeulen & Schilthuizen, 2009 from Sabah. Everettia jucunda differs by having a larger shell (<17.3 mm wide), with one and half more whorls. Everettia jucundior differs by having a larger shell (<19.5 mm wide) with slightly shouldered whorls. Everettia bangueyensis differs by having a smaller shell (<9.0 mm wide), and a flat spire with slightly shouldered whorls.

Description.

Shell small, rather thin, translucent, pale brown, spire moderately elevated. Surface with a glossy lustre. Whorls convex. Number of whorls < 5¼. Protoconch almost smooth, spiral striation absent with inconspicuous radial threads near the suture. Teleoconch: spiral sculpture with inconspicuous, densely placed spiral grooves on both apical side and apertural sides. Radial sculpture almost smooth, with inconspicuous radial threads near suture and below periphery. Periphery round; suture slightly depressed. Aperture lunulate. Peristome simple; continuous, somewhat sinuous, thickened, and reflected on columellar side, not thickened nor reflected on basal and palatal sides. Umbilicus narrow, partly covered by the reflected peristome; umbilical region moderately concave. Dimensions: shell height <7.62 mm; shell width <13.17 mm; diameters of the first three whorls 1.45 mm, 2.40 mm, and 4.34 mm, respectively; aperture height <4.65 mm; aperture width <6.58 mm.

Geographic distribution and habitat.

Known from the Bau and Serian-Padawan limestone hills. Only dry shells were not found during the surveys.

Etymology.

From the Latin Everettia minuta , meaning small, in reference to the smaller shell compare to other species of Everettia from Sarawak.

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.