Alycaeus alticola, Foon, Junn Kitt & Liew, Thor-Seng, 2017

Foon, Junn Kitt & Liew, Thor-Seng, 2017, A review of the land snail genus Alycaeus (Gastropoda, Alycaeidae) in Peninsular Malaysia, ZooKeys 692, pp. 1-81 : 8-9

Alycaeus alticola sp. n. Figures 7J, 8, 31G

Type locality.

PHG 77 Bukit Mengapur, Pahang (3°44'42"N, 102°50'16"E).

Type material.

Holotype. PHG 77 Bukit Mengapur, Pahang: BOR/MOL 12977. Paratypes. PHG 77 Bukit Mengapur, Pahang: BOR/MOL 6888/1, BOR/MOL 8398/26.

Other examined materials.

PHG 77 Bukit Mengapur, Pahang: BOR/MOL 8397(11).

Etymology.

Latin for "dweller at heights". Named after the species’ apparent ecological preference for habitats at higher and drier parts of limestone hills.

Description.

Protoconch. Smooth.

Shell shape. Conical. Shell height: 5.08-6.04 mm. Shell width: 5.04-5.87 mm.

Spire. Spire height: 1.64-2.23 mm. Spire width: 2.32-2.71 mm. Number of whorls: up to 5. Spire shape: oblong conical. Whorl periphery rounded. Umbilicus open.

Whorl constriction. At about 4 ¾ whorls posterior of protoconch.

Breathing tube. Length: 0.42-0.58 mm.

Aperture and peristome. Aperture circular, moderately expanded. Aperture height: 2.40-2.70 mm. Aperture width: 2.32-2.72 mm. Peristome double, not thickened, slightly notched at suture. Peristome orientation 35-38° oblique with respect to the coiling axis.

Spiral lines. Indistinct, regularly spaced. Approximately 22-44 lines per 1 mm.

Radial ribs running anterior of breathing tube. Radial ribs pronounced, evenly spaced. Approximately 10-14 ribs per 1 mm.

Radial ribs running perpendicular to breathing tube. Radial ribs pronounced, white and thicker than those anterior of breathing tube, evenly spaced. Approximately 9-15 ribs per 1 mm.

Radial ribs running posterior of breathing tube. Radial ribs absent immediately posterior of constriction, becoming pronounced and regularly spaced at the middle until prior to aperture. Approximately 7-15 ribs per 1 mm.

Operculum. Concave, rounded. Exterior covered with very thin calcareous layer, with indistinct appressed multilamellae. Interior covered with proteinaceous coating, smooth, with indistinct appressed multilamellae and indistinct mamilla.

Shell colour. Whorls yellow, fading to white posterior of constriction. Peristome white.

Living animal. Body cream-white with fine brown blotches. Head brown. Tentacles brown.

Habitat and ecology.

Lives on rock surfaces covered with powdery lichen at higher and drier areas of the limestone hills, often at open places exposed to ambient sunlight. They never appear on wet and mossy sections of limestone rocks and are rarely seen in lower parts of limestone hills that are shaded by forest cover.

Distribution range.

Restricted to Bukit Mengapur, Pahang.

Differential diagnosis.

Alycaeus alticola sp. n. varies in the degree of ultimate whorl expansion within population but has a consistently more expanded and globose whorl compared to A. costacrassa sp. n., A. selangoriensis sp. n. and A. kapayanensis . Alycaeus alticola sp. n. shares similar shell shape with Alycaeus charasensis sp. n. but differs in the presence of pronounced radial ribs and spiral lines, as well as less expanded ultimate whorl.

Discussion.

A. alticola sp. n. is among the larger yellow, conical shelled Alycaeus in Peninsular Malaysia.