Belgrandiella pussila Angelov, 1959

Distribution in Bulgaria: Species known only from the type locality – the source of Petreska River, near Lakatnik town, Stara Planina Mts. (Angelov 1959, 2000).

Material examined: 6 shells (1 fresh, 5 old), 07.03.2010, Temnata Dupka cave, Lakatnik town, UTM FN96, D. Georgiev leg.

Diagnosis: The distinctive characters of this species discerning it from the rest of the Bulgarian Belgrandiella are the cylindrical shell with obtuse apex and the oval small aperture (Angelov 1959). Its shell is smaller and its morphology is very different from these ones of the two other freshwater snails found in this cave (Wagner 1927): Belgrandiella hessei Wagner, 1927 and Bythiospeum bureschi (Wagner, 1927) (= Paladilhiopsis bureschi Wagner, 1927). From the first species it differs by the smaller aperture having a simple lip, cylindrical shell, obtuse apex, and flatter whorls, and from the second – by the smaller number of whorls, having not so deep suture, its cylindrical shell, and simple aperture lip (Fig. 1).

Other associated molluscs: In the deposits of the river in Temnata Dupka cave studied we also collected and one juvenile shell of a freshwater mussel from the genus Pisidium Pfeiffer, 1821 .