The land snail genus Pterocyclos Benson, 1832 (Caenogastropoda: Cyclophoridae) from Thailand and Peninsular Malaysia, with descriptions of two new species Author Sutcharit, Chirasak Author Tongkerd, Piyoros Author Panha, Somsak text Raffles Bulletin of Zoology 2014 2014-05-30 62 330 338 journal article 10.5281/zenodo.5458831 2345-7600 5458831 CAABF079-BFA8-48C9-986C-2BD100B3CB7E Pterocyclos spaleotes ( Tomlin, 1932 ) ( Figs. 1 , 2D , 3H – J ; Table 1 ) Rhiostoma spaleotes Tomlin, 1932: 227 , pl. 26 text figure. Type locality: In a hole in the rock just outside the Batu Caves, near Kula Lumpur, Selangor . Laidlaw, 1932: 36 . Maassen, 2001: 28 . Type specimens. The specimen herein designated as the lectotype NMW 1955.158 .01107 (height 11.4 × diameter 22.8 mm ; Fig. 3H , no operculum), to stabilise the name, is the shell figured in the original description ( Tomlin, 1932 , pl. 26 text figure). The other specimen from the same lot of the lectotype becomes the paralectotype NMW 1981.118 .02705 (1 shell, Fig. 3I , no operculum) . Other material examined. Topotypes from Batu Cave , Kuala Lumpur , Malaysia ( 03°14.276' N , 101°41.079' E ): CUMZ 4585 ( 35 specimens in ethanol, Fig. 3J ), 4747 (52 shells) . Remark. Pterocyclos spaleotes is only known from its type locality, despite several surveys in nearby areas. Originally, it was described from two shells without an operculum, which leads Tomlin (1932) to assign it to the genus Rhiostoma Benson, 1860 . However, after examining the types ( Fig. 3G, H ) and topotypic specimens ( Fig. 3I ), this generic placement seems untenable. The unique characters of P. spaleotes are: the small and thin shell, the corneous and transparent periostracum, and the surface with a variegated brown zigzag colour pattern and a dark brown peripheral band. The last whorl is usually partially disconnected from the penultimate whorl.Aperture rounded, with a white lip and a little expansion of the upper part. The accessory respiratory structure has a short, tubular shape. The operculum is calcareous, slightly concave inside and multilamellae outside. 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. Table 1. Shell size variation in Pterocyclos spp. Specimen collections and catalogue numbers are indicated in parentheses.

Species and Locality (CUMZ nos.)	No. of Specimens	Ranges, Mean ± S.D. (mm) of the Shell Height (H) Diameter (D) H/D Ratio			Number of Whorls
Pterocyclos blandi
1. Pulau Langkawi, Malaysia	180	8.9–13.2	19.3–25.4	0.42–0.57	4¾–5½
(3880, 4582, 4583, 4584)	11.0 ± 0.84	22.2 ± 1.28	0.50 ± 0.03
2. Gua Cerita, Pulau Langkawi,	9	8.9–10.6	18.9–25.6	0.40–0.47	4¾–5
Malaysia (3879)	9.7 ± 0.67	22.4 ± 1.85	0.44 ± 0.02
Pterocyclos spaleotes
4. Batu Cave, Kuala Lumpur,	71	8.3–12.1	15.6–20.7	0.48–0.68	4¾–5½
Malaysia (4585, 4747)	9.7 ± 0.92	17.8 ± 1.16	0.55 ± 0.04
Pterocyclos diluvium Sutcharit & Panha , new species
6. Tam Sumano, Patthalung,	13	11.8–14.4	21.8–25.2	0.52–0.61	4¾–5½
Thailand (4588)	13.3 ± 0.74	23.8 ± 1.06	0.56 ± 0.02
7. Tam Puttha Kodome, Patthalung,	9	12.0–15.6	20.1–25.0	0.57–0.62	4¾–5½
Thailand (3812)	13.2 ± 1.18	22.5 ± 1.65	0.59 ± 0.02
8. Tam Phaya Hong, Kong Ra,	11	11.3–15.0	22.9–27.1	0.47–0.57	4¾–5½
Patthalung, Thailand (4870)	13.1 ± 1.16	25.2 ± 1.54	0.52 ± 0.03
9. Tarutao National Park, Satun,	54	9.8–14.4	18.6–27.2	0.49–0.61	4¾–5½
Thailand (4589, 4593, 4749, 4750)	11.9 ± 0.95	21.7 ± 1.50	0.55 ± 0.03
10. Tam Tone-din, Kuan-Don, Satun,	41	13.0–16.6	26.1–31.5	0.43–0.55	4½–5¾
Thailand (4590, 4591, 4866)	14.5 ± 0.88	28.0 ± 1.42	0.50 ± 0.04
11. Gua Kelam, Perlis,	17	10.7–13.3	20.0–26.7	0.45–0.59	4–5½
Malaysia (3877, 4587)	11.7 ± 0.70	22.6 ± 1.96	0.52 ± 0.04
12. Perlis State Park, Malaysia (4586)	7	12.6–15.0	24.4–28.3	0.49–0.61	4½–5½
13.8 ± 0.97	26.0 ± 1.30	0.53 ± 0.04
13. Sungi Jenia, Perlis, Malaysia (3878)	26	9.9–14.2	18.7–24.0	0.47–0.62	4¾–5½
11.9 ± 0.99	21.9 ± 1.49	0.54 ± 0.03
14. Gua Cenderawasih, Perlis,	29	11.5–15.6	21.0–27.5	0.49–0.61	4¾–5½
Malaysia (3881, 4592)	13.3 ± 1.25	24.3 ± 1.51	0.55 ± 0.03
Pterocyclos frednaggsi Sutcharit & Panha , new species
15. Bukit Chintamanis, Pahang,	47	10.8–14.8	21.8–32.0	0.43–0.60	4½–5¼
Malaysia (4581, 4571)	13.1 ± 0.78	25.6 ± 1.64	0.51 ± 0.03
16. Gua Pulai, Gua Musang, Kelanta,	9	13.4–16.8	26.6–31.3	0.49–0.56	4½–5¼
Malaysia (4597)	14.8 ± 1.17	28.6 ± 1.80	0.52 ± 0.02

Pterocyclos spaleotes clearly differs from any Rhiostoma species by the shape of its accessory respiratory structure located on the sutural area, and by its calcareous, low cupshaped and multilamellae operculum. Moreover, P. spaleotes has been recorded ( type locality) much further south than Rhiostoma , which does not occur south of the limestone karst in Perlis , Malaysia . Finally, preliminary analysis of the DNA sequence of a fragment of the cytochrome oxidase subunit I gene supports the transfer of Rhiostoma spaleotes to Pterocyclos (Tongkerd, unpublished data).