Clathrocaspia gmelinii

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 : 172-174

Clathrocaspia gmelinii (Clessin & W. Dybowski in W. Dybowski, 1887)

Fig. 11

Caspia Gmelinii nob.—Clessin & W. Dybowski in W. Dybowski 1887: 37–38.

[ Caspia ] Gmelini [sic] n. sp.—W. Dybowski 1888: 79, pl. 3, fig. 7a, b.

Clathrocaspia gmelini [sic] (Dyb.)— Kolesnikov 1947: 108, 111.

? Pyrgula [(Caspia)] gmelinii (Cless. et W. Dyb.) — Logvinenko & Starobogatov 1969: 378, fig. 367(7).

Pyrgula [(Caspia)] sowinskyi Logv. et Star. sp. n. — Logvinenko & Starobogatov 1969: 378, fig. 367(4) [partim].

C. [aspia] (Cl. [athrocaspia]) gmelinii Clessin et W. Dybowski, 1888 — Sitnikova & Starobogatov 1998: 1363, figs 1.12, 3.12, 5.4.

Caspia gmelinii Clessin et W. Dybowski in W. Dybowski, 1888— Kantor & Sysoev 2006: 87, pl. 41, fig. M.

Pyrgula sowinskyi Logvinenko et Starobogatov, 1969 — Kantor & Sysoev 2006: 104, pl. 45, fig. O. [partim]

Clathrocaspia gmelinii (Clessin & Dybowski in Dybowski, 1887)— Wesselingh et al. 2019: 69–70 [partim, without P. gaillardi and only parts of P. sowinskyi ].

Type material. Lectotype ( ZB-M W.Dyb. 77) and 82 paralectotypes ( ZB-M W.Dyb. 77 and 91) (designated by Anistratenko et al. 2019).

Type locality. “Kaspi-See” (Caspian Sea, without further details; Table 1 , locality 26).

Other material. Thirty specimens in Starobogatov’s collection ( ZIN) taken off Cheleken Peninsula ( Turkmenistan; locality 20) and nine specimens from the eastern part of the middle Caspian Sea, labelled in Starobogatov’s collection as “ Caspia valkanovi subbaeri ” (locality 3) and “ Caspia mediocaspica ” (localities 3, 4), two unavailable collection names, are referred to C. gmelinii herein. In addition, 29 specimens labelled as “ sowinskii ” [sic] were found in the Starobogatov collection ( ZIN). Although not unambiguously stated, it is likely to be the type series of Pyrgula sowinskyi Logvinenko & Starobogatov, 1969 . The material was collected from the western part of the South Caspian Sea close to the Kura river mouth and Salyan berth at a depth of 88 m (locality 24). No other identified material of that species has been found in ZIN ( Kantor & Sysoev 2006: 104). Several of the probable paratypes match C. gmelinii and are referred to here; the rest is referred to C. pallasii .

Description. Small, slender shell with tightly packed, low convex whorls. Protoconch low domical, comparably small (c. 320–345 µm), bearing faint, irregularly distributed wrinkles and spiral threads ( Fig. 11 t–v). Teleoconch covered by delicate reticulate sculpture that is usually restricted to last two whorls, sometimes even to last whorl. Aperture slender ovoid, typically tightly attached.

Remarks. Specimens labelled as “ Caspia valkanovi subbaeri ” and “ Caspia mediocaspica ” from the eastern part of the middle Caspian Sea may be considered varieties with slightly larger shells (“ subbaeri ”) or slightly rounder whorls (“ mediocaspica ”), but they match C. gmelinii in terms of the overall shape and the striated to weakly reticulated surface and the small protoconch ( Fig. 11i, j, o, p ).

Furthermore, several specimens of the (presumed) type series of Pyrgula (Caspia) sowinskyi Logvinenko & Starobogatov, 1969 fit well to the type series of C. gmelinii and are considered synonymous ( Fig. 11 k–n, s). A part of that material, however, matches shells of C. pallasii in terms of the elongate shape and bulbous protoconch. Since there is no proof of the material being the actual type material and which of the specimens is the holotype, the true identity of P. sowinskyi remains dubious. Logvinenko & Starobogatov’s (1969) concept of C. gmelinii , in turn, does not match well with the type series; the specimen they illustrate rather resembles C. gaillardi in the larger, broader, stepped shell.

Clathrocaspia gmelinii differs from C. pallasii in its more ovoid shell with shallower suture, the more delicate reticulate sculpture and especially the smaller protoconch (c. 320–345 µm for C. gmelinii versus c. 420–430 µm for C. pallasii ; Figs 11 t–v), 12r, s).

A morphologically even closer species is C. knipowitschii described from the Dniester river liman in the Black Sea Basin ( Makarov 1938). Clathrocaspia knipowitschii has typically a broader shell and more convex whorls, but there are specimens with low convex whorls as well ( Fig. 13g, h, j ) that strongly remind of C. gmelinii . The identities of the two species have not been assessed anatomically or genetically yet (also due to the lack of living material). Until further information becomes available, we consider them as distinct species, with C. knipowitschii being restricted to the Black Sea Basin and C. gmelinii being a Caspian element.

Live specimens of C. gmelinii in the Caspian Sea have only been studied by Sitnikova & Starobogatov (1998), who provided data on the female reproductive anatomy and the radula.

Distribution. Caspian Sea. The exact locality and depth range of the type series is not known, the other studied material was retrieved from the eastern part of the Middle Basin and the north-eastern and north-western parts of the South Basin from depths of 32– 88 m.

Figures

FIGURE 11. Clathrocaspia gmelinii (Clessin & W. Dybowski in W. Dybowski, 1887) from the Caspian Sea. (a) Lectotype, locality 26 (ZB-M W.Dyb. 77). (b) Paralectotype, locality 26 (ZB-M W.Dyb. 78). (c, d) Paralectotype, locality 26 (ZB-M W.Dyb. 81). (e, f, r, u) Paralectotype, locality 26 (ZB-M W.Dyb. 77). (g) Paralectotype, locality 26 (ZB-M W.Dyb. 81). (h, v) Paralectotype, locality 26 (ZB-M W.Dyb. 116). (i, j) Specimen labelled as “Caspia valkanovi subbaeri, holotype”, locality 3 (ZIN, no number). (k) Probable paratype of Pyrgula sowinskyi, locality 24 (ZIN, no number). (l, m) Probable paratype of P. sowinskyi, locality 24 (ZIN, no number). (n, s) Probable paratype of P. sowinskyi, locality 24 (ZIN, no number). (o, p) Specimen labelled as “Caspia mediocaspica, holotype”, locality 3 (ZIN, no number). (q, t) Paralectotype, locality 26 (ZB-M W.Dyb. 77). Scale bars = 1 mm (a–p), 100 μm (q–v).

FIGURE 13. Clathrocaspia knipowitschii (Makarov, 1938) from the Black Sea Basin. (a, b) Neotype, locality 30b (IZAN 522/1). (c, d) Specimen from locality 30b (IZAN 522/2). (e) C. knipowitschii aluschtensis (Golikov & Starobogatov, 1966), holotype, locality 29 (ZIN 4438/1). (f) Holotype of Pyrgula makarovi, locality 31 (ZIN 4492/1). (g, l, u) Specimen from Holocene deposits, locality 32 (IZAN, no number). (h, m) Specimen from same locality (IZAN, no number). (i, n) Paratype of C. brotzkajae from same locality (IZAN, no number). (j, k) Specimen from locality 30c (UGSB 25234). (o, s, t) Specimen identified as C. makarovi by Anistratenko (2013) from locality 30c (UGSB 25236). (p–r) Specimen from locality 30c (UGSB 25235). Scale bars = 1 mm (a–j, l–o), 500 μm (k), 100 μm (p–t), 50 μm (u).