Alycaeus balingensis Tomlin, 1948

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 : 12

Alycaeus balingensis Tomlin, 1948 Figures 7 A–B, 10, 31A

Alycaeus balingensis Tomlin, 1948: 224-226, plate 11, figure, 3; Maassen 2001: 21; Clements et al. 2008: 2760; Tarruella and Domènech 2011: 72.

Type locality.

KDH 01 Bukit Baling, Kedah (5°40'50"N, 100°54'25"E).

Type material.

Syntype. Bukit Baling, Kedah: NHMUK 1948.10.2.4/1 (1 specimen seen).

Other examined materials.

KDH 01 Bukit Baling, Kedah: BOR/MOL 6524/1, BOR/MOL 6853/1, BOR/MOL 8356/13, BOR/MOL 8357/27, ZRC 1997/4, ZRC 1975.2.21.1-85/85. KDH 02 Gunung Pulai, Kedah: BOR/MOL 6856/1, BOR/MOL 8360/18, BOR/MOL 8361/26. Mykarst-171 'Tasik Temenggor Hill S2', Perak: BOR/MOL 6245/1.

Description.

Protoconch. Smooth.

Shell shape and size.

Globose. Shell height: 4.75-5.87 mm. Shell width: 5.11-6.00 mm.

Spire. Spire height: 1.23-2.16 mm. Spire width: 2.09-2.54 mm. Number of whorls: up to 4 ⅛. Spire shape: oblong conical. Whorl periphery rounded. Umbilicus open.

Whorl constriction. At about 3 ¾ whorls posterior of protoconch.

Breathing tube. Length: 0.70-0.82 mm.

Aperture and peristome. Aperture circular, moderately expanded. Aperture height: 2.60-3.13 mm. Aperture width: 2.69-3.22 mm. Peristome double, not thickened, slightly notched at suture. No interspace. Peristome orientation 4-8° oblique with respect to the coiling axis.

Spiral lines. Absent.

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

Radial ribs running perpendicular to breathing tube. Radial ribs pronounced, evenly spaced. Approximately 7-10 ribs per 1 mm.

Radial ribs running posterior of breathing tube. Radial ribs initially indistinct and dense, but increasingly becomes pronounced and evenly-spaced towards the aperture. Approximately 2-4 ribs per 1 mm.

Operculum. Concave, rounded. Exterior covered by calcareous layer, with short calcareous spikes. Interior covered by proteinaceous layer, smooth.

Shell colour. Red, yellow or white at apical whorls. All colours fade to white towards ultimate whorl.

Living animal. Body greenish-black. Head greenish-black. Tentacle green with brown tips.

Habitat and ecology.

Lives in crevices on wet limestone boulders and shrubs close to the ground. In forested areas of limestone hills.

Distribution. Restricted to northern Perak (mykarst-171) and northeastern Kedah (Bukit Baling and Gunung Pulai).

Differential diagnosis.

Alycaeus balingensis shares similar shell shape (globose whorls) with Alycaeus liratulus and Alycaeus thieroti but differs in having whorls with denser and more pronounced radial ribs, absence of spiral lines, operculum exterior with short spikes and greenish-black body.

Discussion.

Alycaeus balingensis is listed as Critically Endangered in the IUCN Red List as it was known only from the actively quarried Bukit Baling at the time of assessment ( Clements 2009). Given that new populations have now been discovered in two other localities in Kedah and Perak, the conservation status of A. balingensis should be revised.