Specimens of the operculated land snail genus Pterocyclos Benson, 1832, from Thailand and Peninsular Malaysia were investigated based on their shell characteristics. Type specimens and topotypic material were studied and compared with newly collected specimens. Two new species are described, viz. Pterocyclos diluvium Sutcharit & Panha, new species, from Tam Sumano, Patthalung, Thailand, adjacent areas in Thailand, and Malaysia, and Pterocyclos frednaggsi Sutcharit & Panha, new species, collected from Bukit Chintamani, Pahang, Malaysia, and adjacent areas in Peninsular Malaysia. Two species that hitherto were included in Pterocyclos, viz. P. blandi Benson, 1851 and P. subulatus Sykes, 1903, were retained in this genus, while two other former Pterocyclos species were re-assigned to other genera, viz. Pearsonia regelspergeri (Morgan, 1885) and Ptychopoma perrieri (Morlet, 1889). Conversely, two previously described species in other genera (Rhiostoma spaleotes Tomlin, 1932, and Cyclotus umbraticus Benthem Jutting, 1949) are here transferred to Pterocyclos, viz. P. spaleotes (Tomlin, 1932) and P. umbraticus (Benthem Jutting, 1949). To stabilise the nomenclatural status, the lectotype of Pterocyclos rupestris
Benson, 1832, and Pterocyclos spaleotes are designated herein.
Key words: Taxonomy, systematics, limestone, biodiversity, Gastropoda
Chirasak Sutcharit, Piyoros Tongkerd & Somsak Panha. 2014. The Land Snail Genus Pterocyclos Benson, 1832 (Caenogastropoda: Cyclophoridae) from Thailand and Peninsular Malaysia, with Descriptions of Two New Species. Raffles. Bull. Zool. 62: 330–338.