Ecrobia cf. grimmi (Clessin 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

Ecrobia cf. grimmi (Clessin in W. Dybowski, 1887) Fig. 6A-E, L

Ecrobia grimmi cf. * 1887 Hydrobia Grimmi Cless.; W. Dybowski: 55-56.

Ecrobia grimmi cf. 1888 [ Hydrobia ] Grimmi Clessin. - W. Dybowski: 79, pl. 3, fig. 2.

Ecrobia grimmi cf. 1952 Hydrobia grimmi (Clessin) W. Dyb., 1888. - Zhadin: 225, fig. 147.

Ecrobia grimmi cf. 1969 Pyrgohydrobia grimmi (Cless. et W. Dyb.) - Logvinenko & Starobogatov: 249, fig. 358 (11).

Ecrobia grimmi cf. 2006 Caspiohydrobia grimmi (Clessin in W. Dybowski, 1888). - Kantor & Sysoev, 91-92, pl. 43, fig. E.

Ecrobia grimmi cf. 2009 Caspiohydrobia grimmi (Clessin et Dybowski, 1888). - Filippov & Riedel: 70-72, 74-76, figs 4a-d.

Ecrobia grimmi cf. 2016 Caspiohydrobia grimmi (Clessin et W. Dybowski in W. Dybowski, 1888). - Vinarski & Kantor: 229.

Material.

345 specimens ( RGM 1309845 , RGM 1309847 , RGM 1310207 , LV 201508 ) .

Type material.

Not traced.

Type locality.

“Kaspi-See” (Caspian Sea, no further details mentioned).

Dimensions.

2.56 × 1.45 mm ( LV 201508, Fig. 6A, B, L ); 2.83 × 1.54 mm ( RGM 1309845, Fig. 6C, D ); 2.19 × 1.30 mm ( RGM 1309847, Fig. 6E ); 3.88 × 2.26 mm; 3.48 × 1.97 mm; 3.77 × 1.99 m; 3.50 × 1.89 mm; 3.26 × 1.79 mm; 3.33 × 1.66 mm.

Description.

Shell shape highly variable, ranging from broad ovoid to slender conical, comprising up to 6.5 whorls. Protoconch consisting of about one whorl, with nucleus immersed; initial part slightly raised, producing acute apex; surface weakly granular to malleate; P/T transition clear. Protoconch and teleoconch whorls highly convex, sometimes slightly flattened centrally in later whorls; suture deep. Size of last whorl varies between 55-62%, descends into straight-sided base. Aperture regularly ovoid, slightly inclined, touching base of penultimate whorl, leaving wide umbilicus. Peristome simple, sometimes weakly expanded. Surface smooth expect for very fine prosocline growth lines.

Discussion.

The shells of Ecrobia can only be reliably identified on the species-level using molecular data ( Haase et al. 2010). Therefore, we tentatively assign the detected specimens to Ecrobia grimmi , which is the only Ecrobia species occurring in the Caspian Sea today ( Haase et al. 2010).

Most of the species presently assigned to Caspiohydrobia Starobogatov, 1970, including its type species, Pyrgohydrobia eichwaldiana Golikov & Starobogatov, 1966, range within the morphological variability of this species. Previous examination of both reproductive systems ( Sitnikova et al. 1992) and juvenile shells ( Filippov and Riedel 2009) did not yield criteria supporting interspecific differentiation. Very likely all of the thirty Caspiohydrobia species listed by Kantor and Sysoev (2006) are morphotypes of a single species, probably E. grimmi . Given the problems of using shell morphology to identify Ecrobia , taxonomic conclusions on the synonymy of the Caspiohydrobia species require molecular data.

Note on species authority.

W. Dybowski (1887: 7) noted that all diagnoses were drafted by Clessin and himself and most new species were therefore marked with “nob.” (Lat. nobis, “us”). However, W. Dybowski obviously made exceptions. In case of the new genus Clessinia , he marked the authority with “m.” (Lat. meus, “mine”). For Hydrobia grimmi , the authority is clearly indicated with “Cless.”, making Clessin the sole author of the species (unlike indicated by several authors).

Distribution.

Caspian Sea; Lake Sawa, Iraq ( Haase et al. 2010); salt lakes near Chelyabinsk, Russia ( Shishkoedova 2010). Subfossil records derive from Holocene deposits of the Aral Sea ( Filippov and Riedel 2009).

Figures

Figure 6. Hydrobiinae and Horatiinae. A, B, L Ecrobia cf. grimmi (Clessin in W. Dybowski, 1887), LV 201508 C, D E. cf. grimmi, RGM 1309845 E E. cf. grimmi, RGM 1309847 F, G Andrusovia brusinai Starobogatov, 2000, RGM 1309840 H, K, N A. brusinai, LV 201509 I, J, M A. brusinai, RGM 1309839.