Imeretiopsis gorgoleti Grego & Mumladze, 2020

Grego, Jozef, Mumladze, Levan, Falniowski, Andrzej, Osikowski, Artur, Rysiewska, Aleksandra, Palatov, Dimitry M. & Hofman, Sebastian, 2020, Revealing the stygobiotic and crenobiotic molluscan biodiversity hotspot in Caucasus: Part I. The phylogeny of stygobiotic Sadlerianinae Szarowska, 2006 (Mollusca, Gastropoda, Hydrobiidae) from Georgia with descriptions of five new genera and twenty-one new species, ZooKeys 955, pp. 1-77 : 1

Imeretiopsis gorgoleti Grego & Mumladze sp. nov. Plates 7 (3); 8(1-4, 9-14); Fig. 11C

Type locality.

Georgia • Racha, Gorgoleti; 42°31'03"N, 42°54'59"E; 620 m a.s.l.; small cave spring on the right bank of the Shareula River between Gorgoleti and Tsakhi villages.

Material.

Holotype: Georgia • 1 adult, dry; type locality; 13 October 2019; J. Grego, L. Mumladze and G. Bananashvili; ISU FM-T013-H. Paratypes: same as for holotype; ISU FM-T013-P1/49 dry and 83 wet, SBMNH 635910/7 dry, NHMW 113279/2 dry, HNHM 104681/2 dry, NHMUK 20191337/2 dry, NHMB 563968/2 dry, SMF 358928/2 dry, ZMH 140633/2 dry, MNHN-IM-2016-7897, ZIN 1/509-2020/2 dry, coll. JG F1430/49 dry and 84 wet.

Diagnosis.

The new species differs from all the related species of the region by its more robust shape, more open umbilicus and more expanded rounded aperture. The most similar shell morphology can be seen in I. iazoni sp. nov., however, I. gorgoleti sp. nov. has a much larger and robust shell with a more open umbilicus and more expanded aperture. From the members of the genus Caucasopsis gen. nov. as the C. tsurtsume sp. nov. it differs by its less sinuated labral margin and by a more regular apertural form.

Description.

Shell: height ranges from 1.52 to 2.18 mm, conical to ovate-conical shell, with 4½ whorls, blunt protoconch, rather inflated whorls and deep suture. Umbilicus widely open. Shell surface glossy, milky-translucent with very faint almost invisible axial growth lines. Aperture subcircular and expanded. Lateral labral profile weakly sinuated adapically toward the body whorl; columellar labrum has a weak sinuation near columella. Protoconch surface densely covered by large regular weak pits.

Operculum: translucent, milky whitish, paucispiral with excentric nucleus.

Animal body: animal white, eyeless with light brown pellets and randomly spread dark grey diffused fibre-like streaked blotches on mantle visible through the translucent shell from body whorl up to the early whorls.

Holotype measurements: H-2.18 mm; W-1.44 mm; BH-1.35 mm; BW-1.15 mm; AH-0.94 mm; AW-0.82 mm; CA: 38°.

Anatomy: the penis (Fig. 11C ) bent, cylindrical, distally with no filament but broadly conical, in its median part a characteristically shaped double outgrowth, proximally broad and distally blunt.

Etymology.

Name derived from Gorgoleti village (Racha region) (სოფელი გორგოლეთ), which is the closest village to the type locality.

Habitat.

Stygobiotic species. Many live specimens were found on tree roots submerged in small cave ponds. The phreatic rhizosphere habitat provides enough food either directly through root exudation ( Canarini et al. 2019), by direct feeding on root tissue or feeding on microbial slime covering the submerged roots, as well as on the decaying roots.

Distribution.

Only known from the type locality.

Conservation status.

The number of known localities (2) is no more than 5 and EOO is smaller than 20 km2. There is no reason to suppose that AOO, EOO, number of locations, number of subpopulations or the number or mature individuals are declining however due to its extremely small EOO we assessed as Vulnerable (VU) D2.

Remarks.

The phreatic rhizosphere habitat for gastropods was known to us from Central and South-eastern Europe. There it hosts mostly valvatiform shelled stygobiotic gastropods; however, the rich food source it provides can attract various gastropod species. We suppose the slightly sinuated aperture (labral and columellar margin) of Imeretiopsis could help the animals in attaching to cylindrical shape of the fine roots.

Figures

Plate 7. 1 Imeretiopsis prometheus sp. nov., Imereti, Kumistavi, Prometheus Cave, paratype SBMNH 633098 2 I. nakeralaensis sp. nov., Imereti, Tikbuli, spring below Nakerala Pass, paratype SBMNH 633110 3 I. gorgoleti sp. nov., Racha, Gorgoleti, above road to Tsakhi, paratype SBMNH 635910 4 Caucasopsis egrisi sp. nov., Pirveli Blada, spring in village, paratype SBMNH 639559. Scale bars: 1 mm. SEM SBMNH Vanessa Delnavaz.

Figure 11. Morphology of the penis A, B Caucasopsis letsurtsume sp. nov., Samegrelo: A ventrally B dorsally C Imeretiopsis gorgoleti sp. nov. Photograph A. Falniowski and A. Rysiewska.