Alycaeus regalis, 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 : 37-40

Alycaeus regalis sp. n. Figures 7T, 25, 31T

Alycaeus perakensis altispirus : Tarruella and Domènech 2011: figure 2E. [not Alycaeus altispirus ( Möllendorff, 1902)]

Type locality.

PHG 02 Gunung Senyum, Pahang (3°41'50"N, 102°26'04"E).

Type material.

Holotype. PHG 02 Gunung Senyum, Pahang: BOR/MOL 12990. Paratypes. PHG 02 Gunung Senyum, Pahang: BOR/MOL 12991/11. PHG 03 Gunung Jebak Puyuh, Pahang: BOR/MOL 6629/14.

Other examined materials.

PHG 02 Gunung Senyum, Pahang: BOR/MOL 6232/3, BOR/MOL 6240/4, BOR/MOL 6881/1, BOR/MOL 8393/5, ZRC 1975.2.22.581-600/20. PHG 03 Gunung Jebak Puyuh, Pahang: BOR/MOL 6883/1.

Etymology.

Latin, meaning royal. In reference to the species’ tall spire and colour reminiscent of the yellow royal parasol which is part of the regalia of Southeast Asian kingdoms.

Description.

Protoconch. Smooth.

Shell shape. Conical. Shell height: 6.57-7.18 mm. Shell width: 5.86-6.87 mm.

Spire. Spire height: 2.32-2.90 mm. Spire width: 2.88-3.21 mm. Number of whorls: up to 5 ½. Spire shape: oblong conical. Whorl periphery rounded. Umbilicus open.

Whorl constriction. At about 5 ¼ whorls posterior of protoconch.

Breathing tube. Length: 0.62-0.81 mm.

Aperture and peristome. Aperture circular, very expanded. Aperture height: 2.91-3.66 mm. Aperture width: 2.95-3.59 mm. Peristome double, sometimes thickened, slightly notched at suture. Peristome orientation 4-17° oblique with respect to the coiling axis.

Spiral lines. Regularly spaced. Approximately 20-36 lines per 1 mm.

Radial ribs running anterior of breathing tube. Radial ribs pronounced, evenly spaced. Approximately 7-15 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 6-15 ribs per 1 mm.

Radial ribs running posterior of breathing tube. Radial ribs pronounced and uneven immediately posterior of constriction, becoming pronounced and evenly spaced from the middle section until prior to aperture. Approximately 8-16 ribs per 1 mm.

Operculum. Flat. Exterior with proteinaceous coating and indistinct appressed multilamellae. Interior with proteinaceous coating, smooth, mamillated. Operculum interior sometimes with a hard, ligament-like proteinaceous extension embedded within the columellar muscle of the animal when alive.

Shell colour. Whorls yellow. Peristome white.

Living animal. Body cream-white. Head pinkish-brown. Tentacle tips brown.

Habitat and ecology.

This species lives on dry rock surfaces covered with powdery lichens. They never appear on wet and mossy sections of limestone rocks.

Distribution range.

Restricted to limestone karsts at central Pahang (Gunung Senyum and Gunung Jebak Puyuh) only.

Differential diagnosis.

Alycaeus regalis sp. n. is most similar to A. altispirus in shell size (shell height: 6.40-7.18 mm, shell width: 5.86-6.87 mm) and tall shell spire (spire height: 2.32-2.90 mm) but differs in the ultimate whorl periphery being rounder, upper palatal section lacking the posterior folding and peristome orientated parallel to the coiling axis.

Discussion.

Prior to this study, specimens of A. regalis sp. n. from Gunung Senyum were always labelled as Alycaeus perakensis altispirus ( Tarruella and Domènech 2011; ZRC collection lots) even though they clearly differ from each other, especially in the aperture shape. Alycaeus regalis sp. n. occur sympatrically with A. costacrassa sp. n. and A. senyumensis sp. n. although the two are separated by their habitat preferences. Alycaeus regalis sp. n. appear to prefer drier habitats whereas A. costacrassa sp. n. and A. senyumensis sp. n. are always found on wet rocks with mosses.