Hypselostoma frequens Gojšina & Hunyadi & Sutcharit & Tongkerd & Auffenberg & Grego & Vermeulen & Reischütz & Páll-Gergely 2025, comb. nov.

Hypselostoma frequens (van Benthem Jutting, 1950) comb. nov. Figs 224 C, 227, 241 Paraboysidia frequens van Benthem Jutting, 1950: 17, fig. 7. Paraboysidia frequens — van Benthem Jutting 1950: 38; van Benthem Jutting 1960: 14; van Benthem Jutting 1961: 35; Berry 1963: pl. 5, fig. 40; Zilch 1984: 165; Maassen 2001: 73–74; Foon and Marzuki 2023: 142, fig. 1 AQ. Paraboysidia oreia van Benthem Jutting, 1961: 37, pl. 9, fig. 3. syn. nov. Gyliotrachela frequens — Schilthuizen et al. 1999: 284, fig. 2. Paraboysidia oreia — Maassen 2001: 75; Foon et al. 2017: 79–80, fig. 30 D. Type localities. “ Kota Tongkat, Pahang ”, Malaysia (H. frequens); “ Gunong Batu Kurau, Perak ”, Malaysia (P. oreia). Type material examined. Malaysia • 48 paratypes of Paraboysidia frequens; from the type locality; 1947; Raffles Museum, Singapore ex. coll.; RMNH.Moll.137114 • 23 paratypes of Paraboysidia oreia; from the type locality; RMNH.Moll.137132. Additional material examined. Malaysia • 1 shell; Perak, Ipoh, Perak Tong Temple; Oct. 1998; Hemmen leg.; coll. PGB • 5 shells; Selangor, Batu Caves (N of Kuala Lumpur); Nov. 1998; Hemmen leg.; coll. PGB • 1 shell; Selangor, Templer Park, Bukit Takun (NNW of Kuala Lumpur); Nov. 1998; Hemmen leg.; coll. PGB • 4 shells; Kedah, Gunung Keriang (N of Alor Setar); Sept. 1999; Hemmen leg.; coll. PGB. Differential diagnosis. See under H. kelantanense, H. modestum, H. muaklekense and H. serpa. This species also similar to the distant Bensonella perfecta sp. nov. from which it differs by less numerous barriers on the palatal side, the absence of the palatal tubercle on the peristome edge, non-spiniferous apertural barrier surface, less conical shell, and very slightly narrower umbilicus. Distribution. This species is known from Pahang, Kedah, Perak, and Selangor provinces of Peninsular Malaysia. Possibly more widely spread. Remarks. In the original description of Paraboysidia oreia, van Benthem-Jutting (1961) mentioned that it differs from H. frequens by the less numerous barriers, less inflated and more rounded last whorl. During our examination of the type material, we found no differences between the two species: the last whorl was not more inflated nor more rounded. The apertural barriers were sometimes more numerous in H. frequens but this is only true for smaller and more variable barriers which are of none or very limited taxonomic importance. Therefore, we treat P. oreia as a junior synonym of H. frequens.