Valvata sp. 2

Neubauer, Thomas A. & Wesselingh, Frank P., 2023, The Early Pleistocene freshwater mollusks of the Denizli Basin (Turkey): a new long-lived lake fauna at the crossroads of Pontocaspian and Aegean-Anatolian realms, Zitteliana 97, pp. 53-88 : 53

Valvata sp. 2

Fig. 15A-D, H

Material.

1 specimen (RGM 962690) from sample 1.

Dimensions.

4.60 × 4.97 mm.

Remarks.

Only a single specimen for that species is available. It closely resembles V. monachorum Bukowski, 1896 from the Pliocene Istrios Formation of Rhodes, which Willmann (1981) considered (together with V. aberrans Bukowski, 1896) as a synonym of V. skhiadica (Fig. 15I-P ). Our specimen matches this species regarding the conical, high-spired but apically flattened shell with the typical, adapically flattened whorls and the moderately wide umbilicus. However, the Turkish specimen bears distinct riblets, has a more pronounced convexity at the transition between whorl flank and base, and the base is straight-sided. In addition, our material is stratigraphically younger by several million years.

Another similar species is Valvata hellenica Tournouër in Fischer, 1877 from Rhodes ( Fischer 1877, p. 55), probably from the Lower Pleistocene Kritika Formation ( Willmann 1981, p. 133, pl. 3, figs 8-17). Willmann (1981) included a great variety of morphologies under that name and it is unlikely that all belong to the same species. The morphotype from the Lower Pleistocene Tafi Formation of Kos illustrated by Willmann (1981, pl. 3, fig. 9) resembles our specimen regarding the general shape, but like V. skhiadica above Tournouër’s species has a more depressed spire (see also Bandel 2010, pl. 4, figs 49-51).

Valvata orientalis Fischer, 1866, which was also found in the Denizli Basin ( Fischer 1866), has a similarly bulbous apex but a higher spire and a relatively smaller aperture. We illustrate for comparison the syntype of that species from Quaternary strata at Lake Buldur stored at Muséum national d’Histoire naturelle (MNHN.F.B41478; Fig. 15E-G ). The syntype from Denizli could not be located at MNHN and might be lost (J.-M. Pacaud, pers. comm. 12/2022). To settle the taxonomic status of Valvata orientalis we hereby designate the illustrated specimen as lectotype.

Figures

Figure 15. Valvatidae of the Kolankaya I fauna. A-D, H. Valvata sp. 2, RGM 962690, sample 1. E-G. Valvata orientalis Fischer, 1866, lectotype (designated herein), MNHN. F. B 41478, Lake Buldur, Quaternary. I-L. Valvata skhiadica Bukowski, 1896, lectotype of V. monachorum Bukowski, 1896 (designated by Willmann 1981), IGUW 1895 XII / 30, Skiadhi Monastery, Rhodes, Greece, Istrios Formation (Pliocene). M-P. V. skhiadica, lectotype (designated by Willmann 1981), IGUW 1895 XII / 27, same locality and stratum. Q-T. Valvata sp. 3, RGM 962697, sample 2. Scale bars: 1 mm (A-S); 100 μm (T).