Staja? cibyratica (Spratt & Forbes, 1847)

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

Staja? cibyratica (Spratt & Forbes, 1847)

Fig. 11J-R, T

*1847 Paludina Cibyratica - Spratt and Forbes: 177, textfig. b.

1928 Viviparus cibyraticus (Forbes) - Wenz: 2304.

? 1982 Pseudamnicola ( Staja ?) Staja cibyratica (Forbes 1847) - Willmann: 315-318, textfigs 6, 7, 9g-h.

Material.

Sample 2: 1 specimen (RGM 962620), 1 specimen (RGM 962621), 23 mostly poorly preserved specimens (RGM 1310855), 35 mostly poorly preserved specimens and a few fragments (RGM 1310856), 1 specimen (SNSB-BSPG 2023 XII 16); sample 3: 10 mostly poorly preserved specimens (RGM 1310857), 4 mostly poorly preserved specimens and 1 fragment (SNSB-BSPG 2023 XII 17).

Type locality.

Between Altınyayla (former Dirmil) and the ancient city Kibyra ("between Tremeely and Cibyra"), Çameli Basin, Burdur, Turkey; Çameli Formation ( Değne Member), Upper Pliocene; and Minare, Eşen Basin, Muğla; Eşen Formation ( Kocaçay Member), Lower Pliocene.

Description.

Large, bulky shell with up to 5.5 whorls. Apex raised, but top of protoconch depressed; protoconch consists of c. 1.2 whorls without discernible sculpture; P/T boundary marked by growth rim and onset of growth lines. Teleoconch whorls moderately convex to almost straight-sided; latter type creates nearly perfectly conical profile. Teleoconch bears keel close to or directly at lower suture. Expression of keel highly variable, ranging from distinct, blunt crest, typically with irregular surface (such as fused nodules), to almost absent, only with faint trace. Additionally, numerous fine spiral furrows cover well-preserved specimens. Last whorl attains 75-80% (n = 3) of total shell height; final portion occasionally grows stronger in adapical direction, creating slightly irregular shape and “raises” keel above whorl base (Fig. 11J-L ). Base steep and straight-sided or weakly convex and passing into concavity toward neck. Aperture ovoid, pointed adapically, weakly inclined in lateral view. Peristome thin or occasionally thickened, with adnate inner lip. Umbilicus narrow, opens into narrow canal that runs along inner lip toward base, bordered by distinct, sharp fasciole.

Dimensions.

7.79 × 5.57 mm (RGM 962621; Fig. 11J-L, U ), 11.02 × 7.28 mm (RGM 962620; Fig. 11M-O ), 5.20 × 3.96 mm (SNSB-BSPG 2023 XII 16; Fig. 11P-R ).

Remarks.

This species covers a great variety of shell shapes and sizes, which complicates establishing species boundaries. The morphological variability is even larger when including Willmann’s (1982) material from the Çameli Basin, which shows much thicker, bulkier shells with a thickened peristome and a keel that is blunt or entirely absent. Our specimens correspond more to the original, but rather poor illustrations by Spratt and Forbes (1847) showing shells bearing a slender keel and a thin peristome. Regarding size, the nearly conical spire, and the laterally oblique aperture, as well as the presence of a fasciole, our specimens correspond well to Willmann’s.

The systematic placement of this species has proven difficult in the past. Because of its relatively large size and bulky morphology it was originally attributed to viviparids ( Neumayr 1880b; Wenz 1923). Neumayr (1880b, footnote on p. 266) stated that he could not distinguish the species from juveniles of Viviparus vukotinovicii (Frauenfeld, 1862) ["die ich von jungen Exemplaren von Viv. Vukotinovici [sic] Frfld. aus Slavonien nicht unterscheiden kann"].

The species is classified in Staja following the opinion of Willmann (1982), but shell shape and keel remind of the genus Falsipyrgula , also in comparison with the co-occurring F. cf. sieversi and F.? coronata sp. nov. (see below). As stated above, the species complex and genus classifications therein may need reconsideration after a thorough revision.

Distribution.

Known from several localities with Pliocene strata in the Çameli and Eşen basins ( Spratt and Forbes 1847; Willmann 1982) and the Early Pleistocene of the Denizli Basin (this study).

Figures

Figure 11. The Staja - Falsipyrgula species complex of the Kolankaya I fauna. A-C. S. Staja lycica (Oppenheim, 1919), RGM 962619, sample 2. D, T. S. lycica, SNSB-BSPG 2023 XII 15, sample 2. E. Staja orientalis (Bukowski, 1896), lectotype (designated herein), IGUW 1895 XII / 45, between Profilia and Istrios, Rhodes, Greece, Istrios Formation (Pliocene). F. S. orientalis, paralectotype, IGUW 1895 XII / 46, same locality and stratum. G-I. S. lycica, RGM 1365351, sample 1. J-L, U. Staja? cibyratica (Spratt & Forbes, 1847), RGM 962621, sample 2. M-O. S.? cibyratica, RGM 962620, sample 2. P-R. S.? cibyratica, SNSB-BSPG 2023 XII 16, sample 2. Scale bars: 1 mm (A-R); 100 μm (S-U).