Schapsugia kudepsta Chertoprud, Palatov & Vinarski, 2021

Chertoprud, Elizaveta M., Palatov, Dmitri M. & Vinarski, Maxim V., 2021, Revealing the stygobiont and crenobiont Mollusca biodiversity hotspot in the Caucasus: Part III. Revision of stygobiont microsnails (Mollusca: Gastropoda: Hydrobiidae) from the Russian part of Western Transcaucasia, with the description of new taxa, Zootaxa 5005 (3), pp. 257-275 : 267-268

Schapsugia kudepsta Chertoprud, Palatov & Vinarski , sp. nov.

( Fig. 7A–F ; Tables 2, 4)

Paladilhiopsis sp. Palatov & Sokolova, 2019: 3–4, fig. 2 B

.

Description. Shell small (SH <1.95 mm), elongate-ovoid, whitish. Whorl number up to 5.00. Body whorl high and rather slender (BWW up to 0.8 mm), its width almost does not exceed the width of the penultimate whorl. Aperture perfectly oval. Parietal and columellar margins thickened, first of them adjoins body whorl wall along its entire length. Umbilicus slit-like or even absent. Protoconch broad (up to 407 μm in diameter), low dome-shaped, consist- ing of 1.5–1.7 whorls. Width of the initial non-spiral part of embryonic shell (WE) between 183–216 μm. Sculpture pitted with wrinkles. Protoconch margin distinct. Operculum ovoid, thin, fragile, whitish, and transparent, without thickening.

Radula (see Fig. 7F ): Two basal cusps on each side of rachis and 4–5 cusps on each side of median cusp. On lateral tooth, there are 4–5 cusps on each side of the largest cusp. Inner marginal tooth with 20 cusps, outer marginal tooth with 18 cusps. Penis elongate, flattened, gradually tapering, with paddle-shaped lobe in medial part. Lobe distinct, extended (about 50 μm in length) towards base of penis, slightly expanded at tip. Distal-medial part of penis from lobe to tip has a harpoon-like shape with one blunt prong pointing backwards. Distal part bears a fin-like edging consisting of thin and relatively fragile cells. Tip triangular, narrowed, with papilla.

Holotype ( Fig. 7A , alcohol specimen): collected by E. Chertoprud, 11 th July 2020, No. 1/501–2021 ( ZIN). Shell dimensions of the holotype (mm): SH 1.86; SW 0.9; BWH 1.11; SpH 0.75; BWW 0.74; AH 0.6; AW 0.48.

Paratypes. 6 empty shells collected by E. Chertoprud, 11 th July 2020 (3 under No. 2/ 501–2021 in ZIN, 3 under No. Lc- 41085 in ZMMU) .

Type locality. Russia, Krasnodar Krai, Adlersky District, the hyporheic zone of the Kudepsta floodplain. 43°34′25.25″N 39°56′04.37″E 206 m a.s.l.

Etymology. The name is derived from the Kudepsta River (= “black river” in Adyghian).

Habitat and distribution. Endemic of Krasnodar Krai. Known only from the type locality. Inhabits groundwaters and the hyporheic zone of the Kudepsta floodplain ( Fig. 1B ). The mollusks were found in one of the weakly flowing springs near the riverbed. We were able to find only a few live individuals on the spring source’s stones. Most likely the population density is quite low, and most individuals are located deeper underground. Many empty shells were taken from spring sediments .

Differential diagnosis. This species is significantly smaller than Sch. pulcherrima comb. nov., its’ shell is lower and slenderer. Shell shape is closer to oval, aperture of perfect oval shape, without a tendency towards triangularity. Peristome margin is smooth, inner lip is evenly thickened. Protoconch comparably broader, with distinct margin. Operculum thin, without outgrowth on inner side. The penial lobe is more prominent and relatively larger than in Sch. pulcherrima comb. nov. The lateral lobe is adjacent to the surface of the penis and is directed towards the penial base ( Fig. 7G ).

Figures

FIGURE 1. Geographic position of the type localities of Schapsugia kudepsta sp. nov. (1), Sch. pulcherrima and Tachira valvataeformis (2), and Sch. occultata sp. nov. (3). A—map of the north-western Greater Caucasus showing the type localities of spe- cies discussed in this paper; B—a small spring in the floodplain of the Kudepsta River; C—Krasnoaleksandrovskaya (Takhira) Cave; D—Tigrovaya Cave; E—the source of the Natashinsky Spring.

FIGURE 7. Schapsugia kudepsta sp. nov. (A–I) and Schapsugia occultata sp. nov. (J–R). A, J—shell, holotype; B, C, K, L—shell; D, M—protoconch, lateral view; E, N, O—protoconch surface sculpture; F—radula; G, P—penis structure; H, I, Q, R—protoconch, apical view. White arrow points to the fin-like edging of the penis. Scale bars: A–C, J–L—500 μm; G, P—250 μm; D, H, I, M, Q, R—100 μm; E, N, O—20 μm; F—10 μm.