Alycaeus virgogravida, 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 : 47-49

Alycaeus virgogravida sp. n. Figures 30, 31S

Type locality.

Limestone hill at east side of Pulau Dayang Bunting, off Langkawi Island, Kedah (6°12'26"N, 99°47'04"E).

Type material.

Holotype. Limestone hill at east side of Pulau Dayang Bunting, off Langkawi Island, Kedah: BOR/MOL 12978. Paratypes. Limestone hill at east side of Pulau Dayang Bunting, off Langkawi Island, Kedah: BOR/MOL 12979/1, BOR/MOL 6248/6.

Etymology.

Latin, meaning pregnant maiden. Named after the type locality, Pulau Dayang Bunting, meaning island of the pregnant maiden.

Description.

Protoconch. Smooth.

Shell shape. Conical. Shell height: 4.71-5.14 mm. Shell width: 4.44-4.97 mm.

Spire. Spire height: 1.68-1.77 mm. Spire width: 2.19-2.50 mm. Number of whorls: up to 4 ½. Spire shape: oblong conical. Whorl periphery rounded. Umbilicus open.

Whorl constriction. At about 4 ¼ whorls posterior of protoconch.

Breathing tube. Length: 0.49-0.51 mm.

Aperture and peristome. Aperture circular, expanded. Aperture height: 2.10-2.36 mm. Aperture width: 2.10-2.29 mm. Peristome double, not thickened, notched at suture. Peristome orientation 29-33° oblique with respect to the coiling axis.

Spiral lines. Distinct. Regularly spaced. Approximately 18-34 lines per 1 mm.

Radial ribs running anterior of breathing tube. Radial ribs pronounced, evenly spaced. Approximately 11-15 ribs per 1 mm.

Radial ribs running perpendicular to breathing tube. Radial ribs pronounced and thicker than those anterior of breathing tube, evenly spaced. Approximately 14-17 ribs per 1 mm.

Radial ribs running posterior of breathing tube. Radial ribs pronounced, unevenly spaced throughout.

Operculum. Concave, rounded. Exterior calcareous layer thick, smooth and polished. Exterior nucleus punctured through, with a cup-like projection. Four concentric ridges were distributed in the tunnel within the thick, cup-like projection. Interior calcareous, with dense concentric circles of multimellae, nucleus punctured through. Operculum edge teethed, etched with regularly spaced grooves.

Shell colour. Whorls yellow. Peristome white.

Living animal. Unknown.

Habitat and ecology.

Unknown.

Distribution range.

Known only from the type locality Pulau Dayang Bunting, Langkawi archipelago.

Differential diagnsosis.

Alycaeus virgogravida sp. n. is similar to A. kapayanensis in having a conical shell but is distinguished by its more expanded whorls, spacing of radial and spiral ribs, and notably, the thick, calcareous operculum with cup-shaped nucleus. Alycaeus virgogravida sp. n. is distinguished from the globose-shelled Alycaeus liratulus , the only other species in Peninsular Malaysia with cup-shaped operculum nucleus, by its conical shell.

Discussion.

Alycaeus virgogravida sp. n. is the only small, conical and yellow Alycaeus species in Peninsular Malaysia with cup-shaped operculum.