Philalanka jambusanensis, 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

Philalanka jambusanensis sp. nov. Figures 34B , 35A-E

Material examined.

Holotype (SH 2.78 mm, SW 3.11 mm) (MZU.MOL.20.20), 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.VII.2011 . Paratypes: 1 ex. (ME0001879), same data as holotype .

Differential diagnosis.

It differs from Philalanka thienemanni Rensch, 1932, by having a shell with spiral striations only on the first 1½ whorls above the peripheral thread and a narrowly open umbilicus. This species is different from Philalanka micromphala Van Benthem-Jutting, 1952 in having a high conical white shell with no spiral sculpture above the periphery.

Description.

Shell very small, dextral, thin, translucent, white; spire conical-ovoid. Surface with a shiny lustre. Whorls flat or with slightly convex sides, rounded. Number of whorls 4¾. Protoconch whorls convex with moderately spaced spiral striations consisting of 4-6 rows of inconspicuous spiral threads towards the teleoconch. Teleoconch with no spiral sculpture above periphery, well-spaced below periphery, fine spiral threads present except in the umbilical region. Radial sculpture on the teleoconch consisting of densely spaced, fine, slightly oblique growth lines. Last whorl with a distinct peripheral thread coinciding with the suture of the penultimate whorl. Aperture: peristome simple; somewhat reflected and thickened on columellar side, not thickened nor reflected on basal or palatal side. Umbilicus open, narrow; umbilical region moderately concave. Dimensions: shell height 2.78 mm; shell width 3.11 mm; diameters of the first three whorls 0.61 mm, 1.22 mm, and 1.78 mm, respectively; shell aperture height 1.11 mm; shell aperture width 1.67 mm.

Geographic distribution and habitat.

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

Etymology.

The specific epithet Philalanka jambusanensis is from the name of Jambusan, where the specimens were found.

Figures

Figure 34. A Beilania philippinensis (C. Semper, 1874) ME 10290 Gunung Batu B Philalanka jambusanensis, sp. nov., ME 1879 Paratype Gunung Batu C Philalanka kusana (Aldrich, 1889) ME 5897 Gunung Batu D Philalanka moluensis (E. A. Smith, 1893) ME 0443 Gunung Doya [not in natural colour, shell surface coated with platinum for examination under scanning electron microscope].

Figure 35. Philalanka jambusanensis, sp. nov. A-F MZU. MOL. 20.20 Holotype. A Apical view B Basal view, C Enlargement of the apical side showing the apex D Enlargement of the teleoconch showing the shell sculpture E Enlargement of the basal side of the shell.