Ulskia ulskii (Clessin & W. Dybowski in W. Dybowski, 1887)

Neubauer, Thomas A., Velde, Sabrina van de, Yanina, Tamara & Wesselingh, Frank P., 2018, A late Pleistocene gastropod fauna from the northern Caspian Sea with implications for Pontocaspian gastropod taxonomy, ZooKeys 770, pp. 43-103 : 43

Ulskia ulskii (Clessin & W. Dybowski in W. Dybowski, 1887) Fig. 5A-K

Ulskia ulskii *1887 Caspia Ulskii nob.; W. Dybowski: 38-39.

Ulskia ulskii 1888 [ Caspia ] Ulskii n. sp. - W. Dybowski: 79, pl. 3, fig. 8.

Ulskia ulskii 1952 Caspia ulskii W. Dyb., 1888. - Zhadin: 205, fig. 205.

Ulskia ulskii 1969 Pyrgula [( Ulskia )] Pyrgula nana Logvinenko & Starobogatov: 379, fig. 367 (12).

Ulskia ulskii 1969 Pyrgula [( Ulskia )] Pyrgula schorygini Logv. et Star. sp. n.; Logvinenko & Starobogatov: 379, fig. 367 (11).

Ulskia ulskii 1969 Pyrgula [( Ulskia )] Pyrgula ulskii (Cless. et W. Dyb.). - Logvinenko & Starobogatov: 379, figs 367 (10).

Ulskia ulskii 2006 Pyrgula nana Logvinenko et Starobogatov, 1968. - Kantor & Sysoev: 101, pl. 47, fig. D.

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

Ulskia ulskii 2006 Pyrgula ulskii (Clessin et W. Dybowski in W. Dybowski, 1888). - Kantor & Sysoev: 104, pl. 45, fig. F.

Ulskia ulskii 2016 Pyrgula nana Logvinenko et Starobogatov, 1968. - Vinarski & Kantor: 240-241.

Ulskia ulskii 2016 Pyrgula schorygini Logvinenko et Starobogatov, 1968. - Vinarski & Kantor: 242.

Ulskia ulskii 2016 Pyrgula ulskii (Clessin et W. Dybowski in W. Dybowski, 1888). - Vinarski & Kantor: 244.

Material.

19 specimens ( RGM 1309790 , RGM 1309810 , RGM 1309856 , RGM 1310208 , LV 201506 ) .

Type material.

" Probable syntype ": ZIN 4608 /1. Holotype of P. schorygini : ZIN 4357 /1. Holotype of P. nana not traced.

Type locality.

“Kaspi-See” (Caspian Sea, no further details mentioned). Type locality of P. schorygini : Caspian Sea; off Apsheron Peninsula, 40°07.5'N, 50°57.5'E, WGS 84, 88 m (after Vinarski and Kantor 2016). Type locality of P. nana : western part of the Caspian Sea, 70- 120 m.

Dimensions.

2.05 × 1.13 mm ( RGM 1309810, Fig. 5A, F, H, I ); 2.16 × 1.16 mm ( LV 201506, Fig. 5B, C, G ); 2.12 × 1.10 mm ( RGM 1309856, Fig. 5D, E ); 2.12 × 1.23 mm ( RGM 1309790, Fig. 5J, K ).

Description.

Slender ovoid shell with up to 4.7 whorls. Protoconch broad, low dome-shaped, comprising 1.25 whorls that measure 365 µm; nucleus is ca. 105 µm wide; protoconch surface finely but strongly malleate; pattern irregular on initial part and only partly present on nucleus; P/T transition marked by thin axial line and slight step in the upper suture. Teleoconch whorls slightly ton-shaped, weakly convex in abapical half and straight-sided or almost so in adapical half, followed by pronounced convexity at upper suture, producing slightly stepped spire. Last whorl attains ca. 61-66%, descends into steep, straight base. Aperture slender ovoid, slightly inclined, with faint adapical notch at contact to penultimate whorl. Peristome slightly thickened and expanded. In lateral view, outer lip exposes marked adapical indentation and very weak abapical indentation; columellar lip straight. Umbilicus narrow but always open. Growth lines weak but distinctly sigmoidal, with opisthocyrt upper half and prosocline lower half. In addition, faint spiral threads are visible on some shells.

Discussion.

Pyrgula schorygini Logvinenko & Starobogatov, 1969 and P. nana Logvinenko & Starobogatov, 1969, both of which were also originally included in the subgenus Pyrgula Ulskia , closely resemble this species. Logvinenko and Starobogatov (1969) did not discuss similarities or differences among the species involved, but their descriptions suggest they considered minor differences in whorl profile and suture depth sufficient to discriminate species. A similar range of variability is present in our sample as well and might rather reflect intraspecific variation. We thus consider the three species synonymous.

Two more species were attributed to the subgenus Pyrgula Ulskia by Logvinenko and Starobogatov (1969). The shell of Caspia derzhavini (Logvinenko & Starobogatov, 1969) is more slender and has more whorls. Caspia behningi (Logvinenko & Starobogatov, 1969) differs in its broader and distinctly conical shape.

Distribution.

Endemic to the Caspian Sea, reported from water depths between 45 and 120 m ( Logvinenko and Starobogatov 1969).

Figures

Figure 5. Caspiinae. A, F, H, I Ulskia ulskii (Clessin & W. Dybowski in W. Dybowski, 1887), RGM 1309810 B, C, G U. ulskii, LV 201506 D, E U. ulskii, RGM 1309856 J, K U. ulskii, RGM 1309790.