Caucasogeyeria pseudocolchis 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

Caucasogeyeria pseudocolchis Grego & Mumladze sp. nov. Plates 15 (5-8); 17(4); 18(2)

Type locality.

Georgia • Samegrelo, Mukhuri, Shisha Spring (სოფელი მუხური, შიშა წყარო); 42°37'47"N, 42°11'26"E; 255 m a.s.l.

Material.

Holotype: Georgia • 1 adult, dry; type locality; 10 May 2018; J. Grego, L. Mumladze and M. Olšavský leg.; ISU FM-T006-H. Paratypes: Georgia • same as for holotype; coll. JG F1057/2 dry. • same as preceding; 10 October 2019; J. Grego, L. Mumladze and G. Bananashvili leg.; ISU FM-T006-P1/5 dry, SBMNH 635902/1 dry, coll. JG F1420/9 dry. • Samegrelo, Mukhuri, Shurubumu 1 Spring on left bank of Khobistskali River; 42°39'0"N, 42°12'21"E; 310 m a.s.l.; sediment at outlet; 10 May 2018; J. Grego, L. Mumladze and M. Olšavský leg.; coll. JG F1057/2 dry.

Diagnosis.

Caucasogeyeria pseudocolchis sp. nov. differs from all the members of the genus by its more deeply cut and broader sinuation at the posterior canal, at the junction of the labral margin with the body whorl. The larger sinulus-like deep grove and the characteristically unbent labral fold with a different aperture shape clearly distinguish the species from the closely related C. colchis sp. nov.

Description.

Shell: pyramidal with four inflated whorls, deeply cut suture and proportionally larger body whorl. Height 1.32-1.55 mm. The milky white shell with occasionally reddish brown inorganic encrustation. Umbilicus widely open. The expanded, rhomboidal aperture framed by a very deep and very broad cut at the posterior canal. The protruded labral fold straight, not curved inward. Labrum continues smoothly toward the lower extremity. Columellar margin is more or less straight. Protoconch surface with large regular deep pits.

Operculum: not known.

Animal body: not known.

Holotype measurements: H-1.45 mm; W-1.15 mm; BH-1.25 mm; BW-0.95 mm; AH-0.70 mm; AW-0.60 mm; CA: 28°.

Anatomy: not known.

Etymology.

Named after the very similar shell shape to the C. colchis sp. nov. known from the Pakhe Plateau near Pirveli Balda and Nakhriduri.

Habitat.

Stygobiotic species. Very worn and fragmented empty shells with only a few intact specimens were found in Shisha Spring, and a single live individual was found in a spring Shurubumu near Mukhuri. The condition of the material indicates a deep stygobiotic habitat far from the springhead with its accumulated recent thanatocoenoses.

Distribution.

Known only from the type locality at Shurubumu Spring and from Shisha Spring in the vicinity of Mukhuri.

Remarks.

The new species is sympatric with the C. cf. gloeri at Shurubumu Spring.

Conservation status.

The number of known locations (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.

Figures

Plate 15. 1 Caucasogeyeria ignidona sp. nov., Imereti, Kumistavi, Prometheus Cave, holotype 2 Caucasogeyeria colchis sp. nov., Samegrelo, Pirveli Balda, Motena Cave, holotype 3 Caucasogeyeria colchis sp. nov., Samegrelo, Pirveli Balda, spring in village, holotype 4 Caucasogeyeria colchis sp. nov., Imereti, Nakhriduri 2 left side spring in Turchu Gamosadivari Basin above small ford, paratype 5 - 8 Caucasogeyeria pseudocolchis sp. nov., Samegrelo, Mukhuri, Shisha Spring 5 holotype 6 - 8 paratypes. The numbers correspond to individuals, and the letters represent the different views of the same individual. Photograph J. Grego.