Belgrandiella pussila Angelov, 1959

Georgiev, Dilian, 2011, New localities of four Bulgarian endemic Hydrobiidae species (Mollusca: Gastropoda: Risooidea), ZooNotes 2011 (16), pp. 1-4 : 1-2

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 .

Figures

Fig. 1. Shells of the stygobite snails of the Temnata Dupka cave (Lakatnik): 1 – the newly recorded Belgrandiella pussila, 2 – Belgrandiella hessei, 3 – Bythiospeum bureschi. The shells are displayed in respective proportions.