Notoptychia polydona

Notoptychia polydona (Mabille, 1887) (Fig. 1B) Clausilia polydona Mabille, 1887a: 45 Type locality: “ Tonkin ”. Locality data: Tam Dao N. P., rain forest, 800–900 m, leg. A. Napolov 1998; Tam Dao N. P., forest – 1 km NE of the centre of the resort (21.4607°N 105.6488°E), 1060 m, leg. R. Bekchiev, I. Dedov, M. Langurov & N. Simov 2023 (Fig. 2A, B); Tam Dao N. P., forest 2.1 km north of the centre of the resort (21.4733°N 105.6394°E), 980 m, leg. R. Bekchiev, I. Dedov, M. Langurov & N. Simov 2023 (Fig. 2C); Tam Dao N. P., forest 1.4 km north of the centre of the resort (21.4672°N 105.6440°E), 1010 m, leg. R. Bekchiev, I. Dedov, M. Langurov & N. Simov 2023. Distribution: The species occurs sporadically in Bac Kan, Lang Son, Thai Nguyen, Son La and Hoa Binh Provinces. Habitat: Undisturbed forests, under and inside decaying tree trunks. Remark: This species was described from a gastropod material collected by Benedict Balansa in Tonkin and provided without more precise locality data (Mabille 1887a, 1887b). However, the species diversity of Balansa’s material suggests that all of the samples originate from the central part of Lang Son Province. So far, N. polydona is known only from Vietnam but occurrence data near the borders suggest its possible presence in Guangxi Province (China) and Houaphanh Province (Laos).