Hypselostoma dilatatum van Benthem Jutting 1962

Hypselostoma dilatatum van Benthem Jutting, 1962 Figs 111 P, 132, 182 Hypselostoma dilatatum van Benthem Jutting, 1962: 5–6, fig. 2. Hypselostoma dilatatum — Schileyko 2011: 3; Vermeulen et al. 2019: 39. Type material examined. Vietnam • 2 paratypes; Nui Xo Ngach, 16 km SE of Haiten; 1960; E. Saurin leg.; RMNH.Moll.137167. Additional material examined. Vietnam • 4 shells; Kien Giang Province, Kien Luong district, Binh An commune, Ba Nui village, cave Mo So, limestone rocks; 10°13.659'N, 104°36.975'E; 18 Sept. 2018; I. Dedov, N. Simov, R. Bekchiev, P. Beron leg., coll. PGB. Type locality. “ Xa Ngach, à 16 km. au S. - E. de Hatien, Sud Vietnam ”. Differential diagnosis. This species is similar to H. cambodjense from which it differs by its hooked apertural barriers and a narrower umbilicus. See also under H. rupestre. Distribution. This species is known from the Vietnam part of the Mekong Delta limestone. Remarks. One paratype is figured, the second paratype was corroded and with broken hooked barriers in the aperture. It was also slightly larger than the figured specimen.