Ulskia schorygini ( Logvinenko & Starobogatov, 1969 )

Anistratenko, Vitaliy V., Neubauer, Thomas A., Anistratenko, Olga Yu., Kijashko, Pavel V. & Wesselingh, Frank P., 2021, A revision of the Pontocaspian gastropods of the subfamily Caspiinae (Caenogastropoda: Hydrobiidae), Zootaxa 4933 (2), pp. 151-197 : 180-181

Ulskia schorygini ( Logvinenko & Starobogatov, 1969)

Fig. 15 a–d, f–i

Pyrgula (Ulskia) schorygini Logv. et Star. sp. n. — Logvinenko & Starobogatov 1969: 379, fig. 36711).

Pyrgula schorygini Logvinenko et Starobogatov, 1968 — Kantor & Sysoev 2006: 103, pl. 45, fig. E.

Type material. Holotype ( ZIN 4357 /1) and five paratypes ( ZIN #9 ). Further 88 probable paratypes are listed in ZIN systematic catalogue ( ZIN ##2–8, 10–18), collected by B.M. Logvinenko in various parts of the Middle ( ZIN ##2–8) and South ( ZIN ##10–18) Caspian Sea between 26/06/1956 and 06/08/1957.

Type locality. Caspian Sea off Apsheron Peninsula ( Table 1 , locality 15). The five paratypes studied herein come from the same locality; the other 88 probable paratypes derive from 16 different samples collected offshore Apsheron Peninsula, Kura delta and Cheleken Peninsula as well as in the northern part of the Middle Caspian Basin.

Other material. One specimen from the Caspian Sea off Apsheron Peninsula (locality 15), labelled as “ paratype ” of “ Caspia turrita ”, an unavailable collection name coined by Starobogatov ( ZIN, no number) .

Description. Small (up to 2.09 mm in height, 1.21 mm in width), slender shell with up to 4.5 low-convex, sometimes weakly stepped whorls. Protoconch unknown. Last whorl typically more bulgy than previous whorls. Aperture slender ovoid, poorly inclined, leaving wide umbilicus.

Remarks. The holotype of U. schorygini ( Fig. 15a, b ) shows a certain similarity to the lectotype of U. ulskii ( Fig. 16a ), but it has a more elongated shell, a relatively lower and slightly projecting last whorl, a wide umbilicus and weakly convex whorls. These features are found—with some variability—also in the paratypes and distinguish the species from U. ulskii . However, that species is known for its highly variable shell, and U. schorygini might just be another morphological variety. Until there is clear evidence (genetic or morphological) that the two species cannot be separated, U. schorygini is maintained as a valid species.

The ZIN collection of Starobogatov contains material from the Caspian Sea off Apsheron Peninsula (localities 14 and 15) labelled with the unavailable collection “ Caspia turrita ”, including a “ holotype ” and 18 “ paratypes ”. The “ holotype ” is not Caspiinae but a juvenile individual of a Pyrgulinae , perhaps a species of Caspiella ( Fig. 15e, j ), while some “ paratypes ” are real Ulskia . At least one “ paratype ” ( Fig. 15c, d ) resembles U. schorygini (which was collected from the same locality) concerning the conical shell and wide umbilicus and is tentatively referred to that species.

Distribution. Middle and South basins of the Caspian Sea, from depths of 45– 170 m.

Figures

FIGURE 15. (a, b, f–i) Ulskia schorygini (Logvinenko & Starobogatov, 1969): (a, b) Holotype (ZIN 4357/1); (f, g) Paratype (ZIN #9); (h, i) Paratype (ZIN #9). (c, d) U. cf. schorygini, specimen labelled as “Caspia turrita, paratype 2” (ZIN, no number). (e, j). Caspiella? sp., specimen labelled as “Caspia turrita, holotype” (ZIN, no number). All material from the South Caspian Basin off Apsheron Peninsula (locality 15). Scale bar = 1 mm.

FIGURE 16. Ulskia ulskii (Clessin & Dybowski in Dybowski, 1887) from the Caspian Sea Basin. (a) Lectotype, locality 26 (ZB-M W.Dyb. 76). (b) Paralectotype, locality 26 (ZB-M W.Dyb. 78). (c) Paralectotype, locality 26 (ZB-M W.Dyb. 78). (d) Paralectotype, locality 26 (ZB-M W.Dyb. 76). (e) Paralectotype, locality 26 (ZB-M W.Dyb. 76). (f, k) Specimen from locality 17 (ZIN, no number). (g, h) Holotype of Pyrgula nana, locality 15 (ZIN, no number). (i, j) Specimen labelled as “Caspia clessiniolaeformis, holotype”, locality 17 (ZIN, no number). (l) Holotype of Pyrgula behningi, locality 23 (ZIN #1). (m) Paratype of P. behningi, locality 14 (ZIN #2). (n, o) Paratype of P. behningi, locality 14 (ZIN #2). (p–s, u) Five specimens from the Holocene of the Kura delta (localities 25d and 25f, RGM 1310306–1310310). (t, v–z) Three specimens from Selitrennoye (locality 1, RGM 1309810, 1309809, 1309856). Scale bar = 1 mm.