Bensonella Pilsbry & Vanatta 1900

GenusBensonellaPilsbry & Vanatta, 1900 Bifidaria (Bensonella) Pilsbry & Vanatta, 1900: 591. Boysidia (Bensonella) — Pilsbry 1917: 198. Boysidia (Paraboysidia) Pilsbry, 1917: 174, 201. Remarks. We have divided the genus Bensonella in two species groups: Group 1: Bensonella plicidens group which includes the majority of species. This group can be recognised by the combination of the following traits: i) a distinct palatal tubercle on the palatal lip (Fig. 9); ii) three barriers on the parietal side (angular, parietal, and infraparietal) (Fig. 9). Several species within the Bensonella plicidens group are not typical because they either lack a palatal tubercle or some of the three barriers on the parietal side (see remarks sections under those species). Group 2: Bensonella wangviangensis species group includes only four species (B. wangviangensis, B. cardiostoma sp. nov., B. fracta sp. nov., and B. mitochondria sp. nov.). This group is recognised by the combination of the following traits: i) triangular-conical shell shape; ii) angular lamella as strong as the parietal or stronger, fully reaching the peristome; iii) palatal tubercle not typical but clearly represents a slightly discontinued part of the upper palatal plica (thus, it is of more lamella-like than tubercle-like). This part of the upper palatal plica is most probably homologous to the palatal tubercle found in other Bensonella species; iv) angular lamella and palatal tubercle are situated close together leaving a relatively narrow canal to the sinulus. 1. Bensonella plicidens group Diagnosis. This species group is characterised by a distinct palatal tubercle on the peristome. as well as three barriers on the parietal side (angular, parietal, and infraparietal). Remarks. The group includes 32 species distributed from eastern India all the way to northern Vietnam but also present in Japan, China, Taiwan, and south to Indonesia.