Plagigeyeria zetatridyma ( Schütt, 1960 )

Grego, Jozef, 2020, Revision of the stygobiont gastropod genera Plagigeyeria Tomlin, 1930 and Travunijana Grego & Glöer, 2019 (Mollusca; Gastropoda; Moitessieriidae and Hydrobiidae) in Hercegovina and adjacent regions, European Journal of Taxonomy 691, pp. 1-56 : 24-25

Plagigeyeria zetatridyma ( Schütt, 1960)

Plagigeyeria zetaprotogona zetatridyma Schütt, 1960: 149 , fig. 4.

Plagigeyeria zetaprotogona zetatridyma – Schütt 1972: 121, pl. 7. figs 14–16.

Plagigeyeria zetatridyma – Bole & Velkovrh 1986: 202, fig. 37. — Bodon, Manganelli & Giusti 1996: 33, fig. 13.

Diagnosis

Large species (max 3.1 mm) with turreted spire and inflated body whorl, very faint and close-set axial striae at shell surface and corrugated varix, faint spiral ribs at early whorls and very expanded trumpetlike aperture with distinctly broadly folded adapical notch groove as well as smoothly impressed posterior channel. Columellar labral fold covering the umbilicus.

Distribution

Plagigeyeria zetatridyma has its main distribution range over Upper Nikšićko Polje (647 m a.s.l.), Krupac Polje (615 m a.s.l.), Slano Polje (613 m a.s.l.), Slivlje Polje (601 m a.s.l.) and in the main spring of Zeta River in Glava Zete (88 m a.s.l.) as well as in the left side springs of the Zeta River Valley (Viska Vrela, 47 m a.s.l.) in Montenegro. The empty shells of the species were detected by H. Schütt at Nikšićko Vrelo (342 m a.s.l.) at Miruše, in the basin of the Trebišnjica River, indicating the karstwater and its species divergence between basins of river Drin (Zeta) and Trebišnjica.

Remarks

Specimens of P. zetatridyma detected by Schütt (1963 and 1972) in one of the main springs of Trebišnjica (Nikšićko Vrelo, 342 m a.s.l.), show extraordinarily high shell morphology resemblance to the morphotype of the same taxon known from springs (spring Močila) and estavelles (Gornjepoljski Vir, 643 m a.s.l.) at the north-western edge of Upper Nikšićko Polje ( Montenegro). Its presence in a spring supplying the Trebišnjica River Basin represents additional proof of the transboundary groundwater communication with the Zeta River Basin at Nikšičko Polje. It is also possible, that the empty shells are washed from their Zeta Basin habitats into the neighbouring Trebišnjica aquifer only by the interim high water levels. Unfortunately the localities have been flooded by a hydropower dam so, we have lost the chance to get genetical proof of such groundwater divergence.