Clathrocaspia isseli ( Logvinenko & Starobogatov, 1969 )

Anistratenko, Vitaliy V., Sitnikova, Tatiana Ya. & Anistratenko, Olga Yu., 2021, Holotypes for three Caspian gastropods of the family Hydrobiidae tracked down description and taxonomic interpretations, Zootaxa 5027 (3), pp. 408-416 : 412

Clathrocaspia isseli ( Logvinenko & Starobogatov, 1969)

Fig. 2a–d

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 .

Clathrocaspia isseli ( Logvinenko & Starobogatov, 1969) — Anistratenko et al. 2021: 174 , fig. 12i–l, q.

Type material. Holotype ( ZIN 1 /532-2021) and 32 paratypes ( ZIN 2 /532-2021) derive from the same lot, labeled “50/1957” ( Tab. 1, locality 16), collected by B.M. Logvinenko off Cheleken Peninsula on 4 August 1957.

Further 128 paratypes ( ZIN 3 /532-2021–8/532-2021, 11/532-2021 and 12/532-2021) are stored in eight separate tubes, labels only marked with the number of station and year, collected in various parts of the Middle ( Tab. 1, locality 2) and South (localities 14, 15, 16, 17, 21, 42) Caspian Sea between 26 June 1956 and 2 August 1957 ( Fig. 1 ) .

Type locality. Originally given as “Southern Caspian Sea between 40–75 m water depth” without further details ( Logvinenko & Starobogatov 1969). The holotype was collected in the Caspian Sea off the Cheleken Peninsula, Turkmenistan ( Table 1, locality 16) from 71 m depth .

Remarks. Recently rediscovered material determined by Starobogatov as the paratypes of C. isseli contain a variety of morphologies. Some match the typical C. isseli as described by Logvinenko & Starobogatov (1969) and the morphology of the holotype ( Fig. 2a, b ). However, some paratypes ( Fig. 2i, j, o–r ) resemble C. pallasii (Clessin & W. Dybowski in W. Dybowski, 1887) closely and study of these and additional material confirms that some of the paratypes were classified under that species correctly ( Anistratenko et al. 2021).

Despite their overall similarity in shell shape, C. pallasii can be distinguished from C. isseli by the consistently lower whorl base, the less convex whorl profile, the slightly detached aperture and the larger and more bulbous protoconch. Clathrocaspia isseli differs from C. gmelinii (Clessin & W. Dybowski in W. Dybowski, 1887) in its more slender shape (see Anistratenko et al. 2021 for further details).

Distribution. Endemic to the Caspian Sea, only known from 8 localities (see above) in the Middle and South Basins from water depths of 40 and 107 m. Also found in the Holocene deposits of the Kura delta ( Anistratenko et al. 2021).

Figures

FIGURE 1. Geographic overview of the study area, with the indication of sampling points and places mentioned in the text (modified from Wesselingh et al. 2019). See Table 1 for details.

FIGURE 2. (a, b) Clathrocaspia isseli (Logvinenko & Starobogatov, 1969), holotype, locality 16 (ZIN 1/532-2021). (c, d) C. isseli, paratype, locality 21 (ZIN 12/532-2021). (e, f) C. pallasii (Clessin & Dybowski in Dybowski, 1887), lectotype, locality 26 (ZB-M W.Dyb. 104). (g, h) C. pallasii, paralectotype, locality 26 (ZB-M W.Dyb. 104). (i, j) C. pallasii, paratype of C. isseli, locality 14 (ZIN 11/532-2021). (k, l) C. pallasii, holotype of Pyrgula sowinskyi Logvinenko & Starobogatov, 1969, locality 17 (ZIN 1/533-2021). (m, n) C. pallasii, paratype of P. sowinskyi, locality 24 (ZIN 12/533-2021). (o–r) C. pallasii, two paratypes of C. isseli, locality 15 (ZIN 4/532-2021). Images c–j, m, n reproduced after Anistratenko et al. 2021. Scale bar = 1 mm.