Travunijana tribunicae ( Schütt, 1963 ) Grego, 2020

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 : 40

Travunijana tribunicae ( Schütt, 1963) comb. nov.

Figs 13C , 14 C–D

Plagigeyeria tribunicae Schütt, 1963: 208–209 , figs 4–7.

Plagigeyeria tribunicae – Schütt 1972: 116, 123, pl. 8. figs 21–22. — Willmann & Pieper 1978: 126 — Bole & Velkovrh 1986: 202 — Bodon, Manganelli & Giusti 1996: 33, fig. 13. — Bank 2013. Fauna Europaea v. 2.6 — Bank & Neubert 2017: 25

Diagnosis

Flat discoid shell 1.9–2.5 mm high with prominent body whorl having angled basal keel at its lower part and an ear-shaped aperture. Spire height variable, from entirely flat to elevated broad conical shape. Shell shape unique within the genera Travunijana and Plagigeyeria . Lateral labral profile straight and columellar labrum possesses a weak sinuation. Protoconch surface regularly and deeply pitted.

Distribution

Only known from the springs of Trebišnjica River (342 m a.s.l.) in Bileća (Schütt 1972), currently flooded under the lake behind the Grančarevo Dam (Bilećko Jezero). The Trebišnjica River springs represent a rather complicated hydrological drainage pattern. Most of the springs receive their water supplies from Gatačko Polje (936 m a.s.l.), Cerničko Polje (816 m a.s.l.) and partly through Fatničko Polje (452 m a.s.l.), but at least two of the springs, Vrelo “Oko” and Nikšićko Vrelo, collecting also the interim divergent groundwaters from Northern Nikšićko Polje (643 m a.s.l.).

Remarks

The distinct shells of T. tribunicae ( Schütt, 1963) detected in the subsidiary spring of the Trebišnjica (Nikšićko Vrelo, 342 m a.s.l.), show a remarkable variability in spire height from flat to pyramidal form (Schütt 1972). Unfortunately the type locality is currently flooded by the Grančarevo Dam, and it is questionable whether the lake had altered the subterranean aquifer water streams in a negative way leading to the species’ extinction, or if the species might still have survived in some other part of the aquifer. The shell morphology with dominant body whorl and keeled umbilicus significantly resembles the Plagigeyeria sp. morphotypes found at the north-western edge of Nikšićko Polje ( Montenegro, 643 m a.s.l.), confirming the transboundary communication of aquifers at least during high groundwater periods. However, the pitted protoconch structure is more similar to that of the genus Travunijana . The slightly reflexed margin is unique in the genus Travunijana and its position within this genus is only provisional. Based on the conditions of empty shells, the habitat is most likely upstream inside the undiscovered cave system, far from the actual spring water outlet (recently under the Bilećko Jezero) where the empty shells were collected.

Figures

Fig. 13. Historical type specimens of species of Plagigeyeria from Hercegovina and adjacent regions, currently transferred to the genus Travunijana Grego & Glöer, 2019. A. Plagigeyeria robusta Schütt, 1959, Hercegovina, spring Čepelica near Bileća, holotype (SMF 162833). B. P. klemmi Schütt, 1961, Croatia, spring Stenjevac south of Vrgorac, holotype (SMF 164344). C. P. tribunicae Schütt, 1963, Hercegovina, spring Trebišnjica near Bileća, holotype (SMF 168968). D. P. edlaueri Schütt, 1961, Hercegovina, spring Sopot Mlin in Svitavsko Blato, holotype (SMF 164342). E. P. angelovi Schütt, 1972, Croatia, spring Ombla (Rijeka Dubrovačka) in Komolac, holotype (SMF 221242). F. P. nitida Schütt, 1963, Hercegovina, spring Sopot Mlin in Svitavsko Blato, holotype (SMF 168970).

Fig. 14. A. Travunijana vruljakensis Grego & Glöer, 2019, Hercegovina, Vrelo Studenac, Gorica near Trebinje, SBMNH 625961 (SEM SBMNH Vanessa Delnavaz). B. T. angelovi (Schütt, 1972), Spring Ombla, Komolac near Dubrovnik, paratype (SMF 318892). C–D. T. tribunicae (Schütt, 1963), Hercegovina, Bileća, main spring of Trebijšnica. C. SMF 191518. D. SMF 318909. Scale bars = 1 mm (B–D SEM SMF Sigrid Hof).