Clathrocaspia isseli ( 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 : 174

Clathrocaspia isseli ( Logvinenko & Starobogatov, 1969)

Fig. 12 i–l, q

Pyrgula (Caspia) isseli Logv. et Star. sp. n. — Logvinenko & Starobogatov 1969: 378, fig. 367(6).

Pyrgula isseli Logvinenko et Starobogatov, 1968 — Kantor & Sysoev 2006: 100, pl. 45, fig. P.

Clathrocaspia isseli ( Logvinenko & Starobogatov, 1969) — Wesselingh et al. 2019: 70 .

Type material. Holotype not traced, should be in ZIN. In contrast to Kantor & Sysoev (2006: 100), who stated that no identified material of this species is found in ZIN, we could locate two lots with 23 specimens in the collection of Starobogatov, which he labelled as “ Caspia isseli ”. Likely, these are paratypes of C. isseli . However, the collection includes a variety of morphologies, some of which match the typical C. isseli as described by Logvinenko & Starobogatov (1969) (e.g. Fig. 12i, j ), while some resemble C. pallasii closely and should be classified under that species (e.g. Fig. 12g, h ). Given the lack of the holotype, the identity of C. isseli is doubtful. For the time being, we use all of the presumed paratypes that are not misidentified C. pallasii to characterise C. isseli .

Type locality. Originally given as “Southern Caspian Sea between 40–75 m water depth” without details on the locality. The presumed paratype material derives from the Caspian Sea off Apsheron Peninsula, Azerbaijan ( Table 1 , locality 14), and off Cheleken Peninsula, Turkmenistan (locality 21) .

Other material. A single shell from Holocene deposits of the Kura delta (locality 25f, RGM 1310305).

Description. Slender, elongate, conical shell with up to 5 low convex, tightly coiled whorls. Protoconch bulbous, bears small wrinkles and thin spiral threads throughout ( Fig. 12q ). Strong reticulate sculpture covers teleoconch, whereas spiral keels are more prominent than axial ribs ( Fig. 12 i–l). Small subsutural ramp occurs above first keel, sometimes resulting in slightly stepped outline ( Fig. 12l ). First 1–2 keels are always more prominent and separated by wider interspaces than the ones following abapically. Aperture adjoined, base steep.

Remarks. The material Starobogatov distinguished as C. isseli and C. pallasii contains a mix of both. In addition to the mix up in the type material of C. isseli (see above), Starobogatov’s material of C. pallasii also contains specimens of C. isseli (e.g. Fig. 12k ). Despite their overall similarity in shell shape, C. pallasii can be distinguished from C. isseli by the consistently lower base, the less convex whorls, the slightly detached aperture and the larger and more bulbous protoconch. Clathrocaspia isseli differs from C. gmelinii in its more slender shape.

Distribution. Endemic to the Caspian Sea, only known from two localities in the South Basin (from depths of 40 and 107 m). Also found in Holocene deposits of the Kura delta.

Figures

FIGURE 12. (a, b) Clathrocaspia pallasii (Clessin & Dybowski in Dybowski, 1887), paralectotype, locality 26 (ZB-M W.Dyb. 104). (c, d) C. pallasii, lectotype, locality 26 (ZB-M W.Dyb. 104). (e) C. pallasii, paralectotype, locality 26 (ZB-M W.Dyb. 105). (f) C. pallasii, specimen labelled as “Caspia microcingulifera, paratype”, locality 9 (ZIN, no number). (g, h) C. pallasii, paratype of C. isseli (Logvinenko & Starobogatov, 1969), locality 14 (ZIN, no number). (i, j). C. isseli, paratype, locality 21 (ZIN, no number). (k) C. isseli, specimen misidentified as C. pallasii, locality 16 (ZIN, no number). (l, q) C. isseli, from Holocene deposits of the Kura delta (locality 25f, RGM 1310305). (m, n) C. pallasii, paratype of Pyrgula sowinskyi, locality 24 (ZIN, no number). (o, r) C. pallasii, paralectotype, locality 26 (ZB-M W.Dyb. 105). (p, s) C. pallasii, paralectotype, locality 26 (ZB-M W.Dyb. 74). Scale bars = 1 mm (a–n), 100 μm (o–s).