Alycaeus clementsi, 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 : 17-19

Alycaeus clementsi sp. n. Figures 7L, 13, 31J

Alycaeus perakensis : Benthem Jutting 1960a: 13. [not Alycaeus perakensis Crosse, 1879]

Type locality.

Gua Kelam, PRS 64 Wang Ulu, Perlis (6°38'41"N, 100°12'09"E).

Type material.

Holotype. Gua Kelam, PRS 64 Wang Ulu, Perlis: BOR/MOL 12970. Paratypes. Gua Kelam, PRS 64 Wang Ulu, Perlis: BOR/MOL 276/3, BOR/MOL 6865/1, BOR/MOL 8371/2. Bukit Ayer, PRS 64 Wang Ulu, Perlis: BOR/MOL 8365/2. Hill 9 km along the road from Kangar to Kaki Bukit, Perlis: BOR/MOL 270/1. KDH 10 Bukit Kodiang, Kedah: BOR/MOL 12969/1, BOR/MOL 8377/62. KDH 04 Gunung Keriang, Kedah: BOR/MOL 8407/7, BOR/MOL 12968/1. Limestone hill north of Sungai Ewa, Pulau Langkawi, Kedah: BOR/MOL 265/3.

Other examined materials.

Gua Kelam, PRS 64 Wang Ulu, Perlis: BOR/MOL 6194/4, BOR/MOL 6867/1, BOR/MOL 8370/11, BOR/MOL 8373/3, ZRC 1997.21/2. Bukit Ayer, PRS 64 Wang Ulu, Perlis: BOR/MOL 6251/6, BOR/MOL 6861/1, BOR/MOL 8364/10. PRS 40 Bukit Merbok, Perlis: BOR/MOL 7071/1. KDH 04 Gunung Keriang, Kedah: BOR/MOL 6246/8, BOR/MOL 6252/20, BOR/MOL 6864/1, BOR/MOL 8369/40, BOR/MOL 8378/1, BOR/MOL 12971/1, BOR/MOL 6191/10, ZRC 1997.19/2. ZRC 1997.20/2, ZRC 1975.2.22.67-98/32. KDH 10 Bukit Kodiang, Kedah: BOR/MOL 6872/1.

Etymology.

Named after Gopalasamy Reuben Clements, in recognition of his contribution to the study of land snail biogeography on Peninsular Malaysian karsts.

Description.

Protoconch. Smooth.

Shell shape. Conical. Shell height: 5.65-6.98 mm. Shell width: 5.71-7.32 mm.

Spire. Spire height: 1.87-2.62 mm. Spire width: 2.39-3.32 mm. Number of whorls: up to 5 ⅛. Spire shape: oblong conical. Whorl periphery rounded. Umbilicus open.

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

Breathing tube. Length: 0.59-0.90 mm.

Aperture and peristome. Aperture circular, moderately expanded. Aperture height: 2.95-3.88 mm. Aperture width: 2.83-3.49 mm. Peristome double, thickened, notched at suture. Peristome orientation 25-45° oblique with respect to the coiling axis.

Spiral lines. Distinct. Regularly spaced. Approximately 11-34 lines per 1 mm.

Radial ribs running anterior of breathing tube. Radial ribs pronounced, evenly spaced. Approximately 9-16 lines 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 11-16 radial ribs per 1 mm

Radial ribs running posterior of breathing tube. Radial ribs pronounced, unevenly spaced immediately posterior of constriction, becoming pronounced and evenly spaced from the middle section until prior to aperture. Approximately 11-16 ribs per 1 mm.

Operculum. Concave, rounded. Exterior covered with thin calcareous layer, surface finely granulated with a scattered arrangement of calcareous blunt spikes. Interior covered with proteinaceous coating, smooth, mamillated.

Shell colour. Yellow at the first 4 whorls. Fades to white towards aperture.

Living animal. Body cream-white. Head pink. Tentacles cream-white, tips pink.

Habitat and ecology.

Lives on wet limestone rock walls and crevices. In shady forests on limestone hills.

Distribution range.

In Perlis, retricted to limestone hills of the Nakawan Range. In Kedah, restricted to limestone hills of the Langkawi archipelago, Kodiang and Gunung Keriang.

Differential diagnosis.

Alycaeus clementsi sp. n. is similar to A. kelantanensis in its shell colouration. Despite shell size of A. clementsi sp. n. being variable within populations across its range, A. clementsi sp. n. is distinguished from A. kelantanensis by its consistently large shell (larger by about 2.13 mm in shell height, 2.32 mm in shell width), thick expanded peristome, spiky operculum exterior as well as the animal colouration.

Discussion.

Historically, Alycaeus clementsi sp. n. shells from Kaki Bukit, Perlis were misidentified as A. perakensis in Benthem Jutting (1960a). Shells of A. clementsi sp. n. in Perlis usually have thicker peristome compared to shells from Kedah albeit all other diagnostic characters remain identical. Shell size of A. clementsi sp. n. is variable within populations across its range and does not appear to have any geographical pattern. This species may occur in Thailand at areas adjacent to Perlis and northern Kedah.