Caucasogeyeria chrysomallos 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 chrysomallos Grego & Mumladze sp. nov. Plates 16 (1-8); 17(3); 18(1); Fig. 14D

Type locality.

Georgia • Samegrelo, Kanti Village near Mukhuri, Mapeli Spring (სოფელი კანტი, მაპელის წყარო); 42°38'23"N, 42°10'08"E; 290 m a.s.l.

Material.

Holotype: Georgia • 1 adult, dry; type locality; 12 October 2019; J. Grego, L. Mumladze and G. Bananashvili leg.; ISU FM-T001-H. Paratypes: Georgia • same as for holotype; ISU FM-T001-P1/12 dry and 24 wet, SBMNH 633099/2 dry, NHMW 113365/1 dry, HNHM 104678/1 dry, NHMUK 20191334/2 dry, NHMB 563964/1 dry, SMF 358925/1 dry, NHMW 113365, ZMH 140630/1 dry, MNHN-IM-2016-7895, ZIN 1/507-2020/1 dry, coll. JG F1414/15 dry and 24 wet, coll. Glöer /1 dry. • same as for holotype; 10 May 2018; J. Grego, L. Mumladze and M. Olšavský leg.; coll. JG F1041/2 dry. Other material: Georgia • Samegrelo, Mapeli Cave, Mukhuri, water catchment (above cemetery); 42°38'22"N, 42°11'39"E; 325 m a.s.l.; 10 May 2018; J. Grego, L. Mumladze and M. Olšavský leg.; coll. JG/3 dry.

Diagnosis.

The new species differs from all congeners by its smaller more elongate-conical shell with more numerous whorls combined with a smaller umbilicus. The aperture sinuation shows similarity with C. gloeri sp. nov., however, the latter has a larger, more robust and less elevated shell shape with the columellar sinuation. Caucasogeyeria colchis sp. nov. differs from new species by its larger size and more deeply sinuated labral margin. Measurement comparison of Caucasogeyeria species is given in Table 8 .

Description.

Shell: elongate conical with five tumid whorls, a semi-deep suture, a blunt apex and a narrow umbilicus. Height 1.40-1.93 mm. Shell surface smooth, covered by a milky white periostracum, frequently overlaid by thick dark brown-black inorganic precipitate. The expanded aperture irregularly pear shaped. Labral margin with a weak but broad negative sinuation near the body whorl junction, followed by a characteristic inward curved but shallow labral fold. Columellar margin is straight, not sinuated. Protoconch surface regularly pitted, pitting fading out at the nucleus.

Operculum: light yellow, paucispiral with central nucleus.

Animal body: without eye spots, not pigmented, whitish translucent.

Holotype measurements: H-1.93 mm; W-1.21 mm; BH-1.21 mm; BW-1.07 mm; AH-0.84 mm; AW-0.65 mm; CA: 30°.

Anatomy: penis (Fig. 14D ) straight, simple, without any outgrowth.

Etymology.

Name derived from the Greek name Chrysomallos , meaning Golden Fleece (symbol of authority and monarchy), which, according to Greek mythology, was held in Colchis. Jason and his crew of Argonauts were sent out on a quest for the Golden Fleece by order of King Pelias.

Habitat.

Stygobiotic species. Live individuals as well as empty shells were washed out from its subterranean habitat through a small spring in Mapeli emerging near the road in village Kanti. The dense brown-black deposits on most of individuals indicates a subterranean habitat with chemolithotrophic bacteria. The second known population was found in the sediments of a subterranean cave stream inside Mapeli Cave, ca. 30 m from its entrance

Distribution.

Only known from the type locality and from Mapeli Cave.

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.

Remarks.

The population in Mapeli Cave is typical but has a lower spire and fewer whorls. Its taxonomic position will be clarified after the collection of live individuals.

Figures

Figure 14. A-C Caucasogeyeria ignidona sp. nov., Imereti, Kumistavi, Prometheus Cave D C. chrysomallos sp. nov., Kanti, Mapeli Spring, morphology of the penis. Photograph A. Falniowski and A. Rysiewska.

Plate 16. 1 - 6 Caucasogeyeria chrysomallos sp. nov., Samegrelo, Mukhuri, Kanti, Mapeli Spring 1 holotype 2 - 6 paratypes 7, 8 Caucasogeyeria chrysomallos sp. nov., Samegrelo, Mukhuri, Kanti, Mapeli Spring 9 Caucasogeyeria cf. gloeri, Samegrelo, Mukhuri, Mapeli Cave, paratype. The numbers correspond to individuals, and the letters represent the different views of the same individual. Photograph J. Grego.