Pterocyclos subalatus Sykes, 1903

Sutcharit, Chirasak, Tongkerd, Piyoros & Panha, Somsak, 2014, The land snail genus Pterocyclos Benson, 1832 (Caenogastropoda: Cyclophoridae) from Thailand and Peninsular Malaysia, with descriptions of two new species, Raffles Bulletin of Zoology 62, pp. 330-338 : 333

Pterocyclos subalatus Sykes, 1903

( Figs. 1 , 3G )

Pterocyclos subalatus Sykes, 1903: 195 , 196, pl. 20, figs 21, 22. Type locality: Gunong Inas, at 5000 feet.

Pterocyclus subalatus — Laidlaw, 1928: 30. Maassen, 2001: 27.

Type specimens. Holotype UMZC 1032 (height 8.8 × diameter 17.2 mm, Fig. 3G ) (no other material was available).

Remark. Pterocyclos subalatus has been described in detail, based on two shells ( Sykes, 1903). Because of its relatively small size (diameter about 15 mm), and its thick and brownish periostracum, this species superficially resembles the genus Cyclotus . However, the holotype clearly shows the typical characters of Pterocyclos , i.e., the expanded apertural lip, with thin channel and shortly expanded of apertural lip at suture area, operculum low cup shape, and multilamellae outside.

This species clearly differs from P. spaleotes and P. umbraticus because its last whorl is not disconnected from the penultimate whorl, while its accessory respiratory structure has a shallow channel. It further differs from P. umbraticus by having a smooth shell surface and much smaller shell size.

Figures

Fig. 1. Distribution map of Pterocyclos species examined in this study. The numbered locality names are detailed in Table 1. The approximate type locality of Pterocyclos subalatus, and Pterocyclos umbraticus, are indicated by locality numbers 3 and 5, respectively.

Fig. 3. A–D, Shell and operculum of Pterocyclos rupestris: A, lectotype UMZC 2359.1; B, paralectotype UMZC 2359.2; C, syntype of var. 3 UMZC 2359.3; D, operculum from same lot of the paralectotype (showing top, side and bottom views). E, F, Specimens of P. blandi from Langkawi Island, Perlis, Malaysia CUMZ 4582. G, Holotype UMZC 1032 of P. subalatus. H–J, Pterocyclos spaleotes: H, lectotype NMW 1955.158.01107, I, paralectotype NMW 1981.118.02705; J, topotype specimen CUMZ 4585. K, Holotype ZMA Moll. 135622 of P. umbraticus. L–P, Pterocyclos diluvium Sutcharit & Panha, new species: L, holotype CUMZ 4595, M, paratype CUMZ 4588, N, specimen from Gua Cenderawasih, Perlis, Malaysia CUMZ 4592; and O, P, specimens from Tam Tone-din, Kuan-Don, Satun, Thailand CUMZ 4590 showing a: O, uniform whitish shell; and P, dark brown colour patterns. Q–S, Pterocyclos frednaggsi Sutcharit & Panha, new species: Q, holotype CUMZ 4594; R, paratype CUMZ 4581; S, specimen from Gua Pulai, Gua Musang, Kelantan, Malaysia CUMZ 4597.