Theodoxus lutetianus Montfort, 1810 [unnecessary substitute name for Theodoxus fluviatilis (Linnaeus, 1758)]; by original designation.

Sample 1: c. 500 specimens (RGM 1310838) and 1 specimen (SNSB-BSPG 2023 XII 1); sample 2: 1 specimen tentatively attributed to the species (RGM 962606), 1 specimen (RGM 962607), 1 specimen (RGM 1310797), 123 specimens (RGM 1310839), 2 fragments and fragmented opercula (RGM 1310840), 1 specimen (SNSB-BSPG 2023 XII 2); sample 3: 53 specimens (RGM 1310841).

Oppenheim’s type material could not be found despite considerable efforts and is presumably lost (see Material and Methods section). To ensure nomenclatural stability and link the name to a type specimen, we herewith designate a neotype. The original type locality includes two localities, Giralan near Pamukkale and Bozalan near Buldan (“Abstieg nach Giralan.—Bosalan bei Bulladan.”) in the Denizli Basin (Fig. 1). No material from those localities is available to us, but considering the geographic vicinity of the newly collected material as well as the distinct morphological features, there can be no doubt that our material represents the same species as the one described by Oppenheim (1919). We select as neotype the specimen illustrated on Fig. 3I–L, which comes from sample 2 (RGM 962607).

Figure 3. 

Neritidae of the Kolankaya I fauna. A–D. Theodoxus percarinatus (Oppenheim, 1919), RGM 1310797, sample 2. E–H. T. percarinatus, SNSB-BSPG 2023 XII 2, sample 2. I–L. T. percarinatus, Neotype, RGM 962607, sample 2. M–P. T. percarinatus, SNSB-BSPG 2023 XII 1, sample 1. Q–T. T. cf. percarinatus, RGM 962606, sample 2. Scale bars: 1 mm.

Globular neritid with short, flattened spire and up to 3.3 whorls. Characteristic keel is observed in part of the material. In well preserved, keeled specimens narrow, distinct keel develops early in ontogeny. In first whorl it aligns with suture, but as shell growth becomes slightly more abapically oriented, keel emerges more clearly and separates whorl top and whorl flank. Expression and extent of keel varies, it may appear and disappear within 0.2 whorls or range until last whorl; however, no specimen is found with keel covering entire shell. Strength of keel very variable, ranging from robust and well delimited to almost obsolete. In much of the material the keel is worn. Aperture broadly semicircular with broad, smooth callus that is weakly thickened especially in its center (see lateral views). Coloration variable, including fully black, white with dark stripes, irregular mix of dark and white, white blotches arranged in spiral bands or entirely white.

6.64 × 7.76 mm (neotype, RGM 962607; Fig. 1I–L), 10.66 × 10.51 mm (RGM 1310797; Fig. 1A–D), 6.72 × 7.24 mm (SNSB-BSPG 2023 XII 1; Fig. 1M–P).

The species has not been treated in the literature since the original description. It was neither included in the Fossilium Catalogus by Wenz (1930), perhaps because he considered this form not to be a freshwater taxon, nor was it listed by Taner (1974a, 1975). The combination with the genus Theodoxus appears for the first time in Alçiçek (2010), but without discussion. Here, we formalize the classification and re-describe the species.

The diagnostic character of this species is its name-giving thin keel at the transition between whorl top and flank, which distinguishes the species from most others. A similarly keeled species is Theodoxus carinatus (Fuchs, 1877) from the Lower Pleistocene (Calabrian) of Livonates (mainland Greece). It differs in the flattened whorl flanks, the weakly raised spire, the broader keel and the color pattern consisting of wavy axial lines.

In addition to the majority of keeled specimens of Theodoxus percarinatus, shells occur that lack the keel entirely and have a slightly more elevated spire (Fig. 3Q–T). In terms of size, general shape, and color patterns these specimens fall well within the range of T. percarinatus. Many Theodoxus species are known to have highly variable shells (Sands et al. 2020), which complicates a taxonomic decision about the status of these specimens. Apparent intermediate specimens occur in our material, but the worn nature of much of the material, the small numbers of specimens, and the general variability of the genus preclude confirmation whether it concerns untypically unkeeled representatives of T. percarinatus or constitute a separate, rare, and potentially new species.

Only known from the Denizli Basin.

2 specimens (RGM 962608, RGM 1310796), 2 specimens and 1 fragment (RGM 1310842), 1 specimen (SNSB-BSPG 2023 XII 3); all from sample 2.

1.97 × 2.69 mm (RGM 962608; Fig. 4A–D, H), 3.66 × 3.88 mm (RGM 1310796; Fig. 4E–G).

Figure 4. 

Neritidae of the Kolankaya I fauna. A–D, H. Theodoxus aff. pilidei (Tournouër, 1879), RGM 962608, sample 2. E–G. T. aff. pilidei, RGM 1310796, sample 2. Scale bars: 1 mm.

Our material contains two moderately preserved specimens that exhibit a high variability in spire height and angulation. The low-spired morphotype (Fig. 4A–D, H) resembles Theodoxus pilidei (Tournouër, 1879), originally described from Pliocene or Lower Pleistocene strata of the Dacian Basin (Wenz 1942; Pană et al. 1981; Pană 2003; Papaianopol and Marinescu 2003), in terms of the general ovoid shell shape with depressed spire and the strong, papery lamellae. The illustrations of Pană et al. (1981) show quite some variability in the morphology of T. pilidei, including the expression of sculpture, which can be weak or nearly absent in some specimens. However, our material differs from that species particularly in the presence of a distinct angulation, which results in a nearly flat, apical plane. Specimens with elevated spire even show two angulations separated by a concave whorl flank (Fig. 4E–G). From the little material we have available it is difficult to judge the species’ range of variability as well as make a taxonomic assignment. The distinct angulation present in our material, however, makes an affiliation with T. pilidei unlikely.

Another similar species is Theodoxus boteani (Porumbaru, 1881), which has a similar type of sculpture but more globular shells (Pană 2003). The extant, allegedly subterranean Theodoxus gloeri Odabaşi & Arslan, 2015 from Eskişehir region (Turkey), which also exhibits papery lamellae, differs in a slightly higher spire and the absence of an angulation (Odabași and Arslan 2015; Sands et al. 2020). Possibly our material signifies a new species.

Melanopsis esperi Férussac, 1823; by original designation.

Sample 1: 3 specimens (RGM 962691–962693), 10 specimens (SNSB-BSPG 2023 XII 4), ca. 300 specimens (RGM 1310843); sample 3: 13 specimens (RGM 1310844), 1 specimen (RGM 1365348).

16.25 × 7.78 mm (RGM 962691; Fig. 5A–C), 14.44 × 7.47 mm (RGM 962692; Fig. 5D, E).

Figure 5. 

Melanopsidae of the Kolankaya I fauna. A–C. Esperiana esperi (Férussac, 1823), RGM 962691, sample 1. D, E. E. esperi, RGM 962692, sample 1. F. E. esperi, RGM 962693, sample 1. Scale bars: 5 mm.

The present material matches well the extant Esperiana esperi concerning the elongate, smooth shell with adpressed whorls, lanceolate aperture with thickened inner lip and the slight concavity between base of the last whorl and base of the aperture (Welter-Schultes 2012; Glöer 2019). Even the color pattern, consisting of dissected zigzag lines to a chess-like arrangement of orange spots, and the corroded apex are typical of the modern species.

Shape, apertural characteristics and color pattern are also found in the Plio-Pleistocene species Melanopsis bergeroni Stefanescu, 1896 from the Dacian Basin (Romania) (Stefanescu 1896; Pană et al. 1981; Pană 2003). The same is true for Melanopsis esperioides Stefanescu, 1896 from the same region, which seems to be only slightly more slender and larger on average than M. bergeroni (Stefanescu 1896). It might well be that both species range within the morphological variability of E. esperi, but a final verdict on their status requires comparison with topotypic material from the Dacian Basin. In case of synonymy, the subgenus Melanopsis (Calodiona) Stefanescu, 1896, of which M. bergeroni is the type species, would become a synonym of Esperiana.

The specimens from the Denizli Basin studied by Taner (1974a) and identified as M. cf. bergeroni falls well into the range of E. esperi and considered conspecific herein.

Today in central to southeastern Europe (western Black Sea region to Hungary, Slovakia, Austria, and Slovenia) and northwestern Anatolia (Welter-Schultes 2012; Glöer 2019). Also found in Pleistocene strata of the North Caspian Basin (Neubauer et al. 2018).

Hydrobia vegorriticola Schütt, 1962; by original designation.

Named in honor of Hülya and M. Cihat Alçiçek, esteemed Turkish geologists with long research background in the Denizli Basin, for their continuing support and friendship.

RGM 962617 (Fig. 6A–E). Babadağ river valley along the Babadağ-Sarayköy road, c. 2.4 km NW of the town of Babadağ, Denizli, Turkey; sample 2 (37°50'44.5"N, 28°52'51.3"E). Kolankaya Formation, Lower Pleistocene, Gelasian.

Figure 6. 

Caspiinae (Hydrobiidae) of the Kolankaya I fauna. A–E. Graecoanatolica alcicekorum sp. nov., holotype, RGM 962617, sample 2. F–I. Graecoanatolica? sp., RGM 1365349, sample 1. Scale bars: 1 mm (1–D, F, G); 100 μm (E, H, I).

None (holotype only).

Slender, weakly ovoid shell with slightly tapered last whorl, adnate whorls with thin suture, faint subsutural concavity in late ontogeny, sinuate outer lip, and sigmoidal growth lines.

Slender, ovoid hydrobiid shell, with 4.75 whorls. Protoconch consisting of c. 1 whorl, low domed with broad nucleus, weakly, finely-meshed malleate surface; sculpture fades out toward P/T transition; transition indicated by growth stop and onset of growth lines. Whorls moderately convex in early ontogeny; penultimate whorl exhibits nearly straight-sided upper whorl half and regularly convex lower half; last whorl, portion below suture weakly concave, producing weak constriction and slightly irregularly convex whorl profile. Last whorl attains 60% of shell height. Base ~45°, straight-sided. Aperture drop-shaped, tightly coiled, leaving no umbilicus; peristome not thickened or notably expanded; outer lip distinctly sigmoidal in lateral view. Growth lines sigmoidal, with opisthocyrt upper half and slightly weaker, prosocyrt lower half.

2.21 × 0.97 mm (holotype, RGM 962617; Fig. 6A–E).

The species’ shell shape and size, the protoconch size, the subsutural concavity, the ovoid aperture with thin, sinuate peristome, and the sigmoidal growth lines are characteristics typical of extant members of the genus Graecoanatolica. The co-occurring species of Iraklimelania share many of these attributes, but they both have more slender shells with relatively smaller last whorls and larger protoconchs (1.2 whorls compared to 1 whorl).

The only fossil species of the genus was previously reported as G. denizliensis (Taner, 1974a) by Wesselingh et al. (2008) from the overlying “Didacna Beds” (= Kolankaya II fauna). The specimens, however, differ from true “Hydrobia” denizliensis in the much smaller, ovoid shell with strongly convex whorls. The original species described by Taner is a large hydrobiid (7 mm) with moderately convex whorls and elongated aperture. The species of Wesselingh et al. (2008), which is currently without a name but fits well in the genus Graecoanatolica, differs from the new species in the slightly broader shell, the more convex whorls, and the presence of a narrow umbilicus.

Graecoanatolica alcicekorum sp. nov. resembles several extant representatives of the genus. Shells of the North Macedonian Graecoanatolica macedonica Radoman & Stankovič, 1979 and the Greek G. vegorriticola (Schütt, 1962) are similarly slender, but whorls have a regularly convex profile. The Turkish G. dinarica Kebapçı, Koca & Yıldırım, 2012 has a shell with highly convex whorls, a slightly irregularly shaped last whorl and a smaller aperture (Kebapçı et al. 2012). Graecoanatolica lacustristurca Radoman, 1973b (the type species) and G. tenuis Radoman, 1973b, both also described from Turkey, have conical shells with broad, blunt apex and a narrow umbilicus (Kebapçı et al. 2012).

The genus was recently placed in Caspiinae by Delicado et al. (2023) based on a comprehensive phylogenetic analysis.

So far only known from the Early Pleistocene of the Denizli Basin.

1 specimen (RGM 1365349) from sample 1.

At first glance, this shell reminds of Iraklimelania minutissima sp. nov. (see below) in terms of the very small, slender shell with convex whorls. However, the protoconch of Graecoanatolica? sp. is higher, whorls are more regularly convex, the aperture is oblique in lateral view, and the umbilicus is clearly visible. In all these characteristics it closely resembles extant Graecoanatolica dinarica Kebapçı, Koca & Yıldırım, 2012, for which we have studied topotypical material from İncirlipınar in Afyonkarahisar region. That species differs from Graecoanatolica? sp. in the larger size, the comparatively larger apex, the faster whorl expansion rate, and the often irregular growth (Kebapçı et al. 2012). Yet, the growth lines of Graecoanatolica? sp. are nearly orthocline, which has not been observed in any Graecoanatolica species, which is why we only tentatively associate the species with this genus.

Iraklimelania levis Willmann, 1981; by original designation.

The revised attribution of Iraklimelania, originally tentatively placed in “Micromelaniidae” by Willmann (1981), to Caspiinae is based on two pillars. First, the protoconch sculpture, with the malleate surface bearing faint spiral striae and a thickened terminal portion, reminds of species of Caspiinae (Anistratenko et al. 2021). Extant Pontocaspian members are typically characterized by an increasing sculpture intensity toward the end and the upper whorl half of the protoconch, as well as sculpture-free triangle at the P/T boundary (Anistratenko et al. 2021), which is missing though in the Turkish material. Second, the close morphological similarity to species of Graecoanatolica, recently placed in Caspiinae as well, supports a classification in that subfamily.

Referring to the exceptionally small shell size.

RGM 962617 (Fig. 7A–E). Babadağ river valley along the Babadağ-Sarayköy road, c. 2.4 km NW of the town of Babadağ, Denizli, Turkey; sample 2 (37°50'44.5"N, 28°52'51.3"E). Kolankaya Formation, Lower Pleistocene, Gelasian.

Figure 7. 

Caspiinae (Hydrobiidae) of the Kolankaya I fauna. A–E. Iraklimelania minutissima sp. nov., holotype, RGM 962618, sample 2. F–J. Iraklimelania minutissima sp. nov., juvenile or subadult form, SNSB-BSPG 2023 XII 5, sample 2. K–P. Iraklimelania submediocarinata sp. nov., holotype, RGM 962689, sample 1. Scale bars: 1 mm (A–D, F–I, K–N); 100 μm (E, J, O, P).

One juvenile or subadult form (SNSB-BSPG 2023 XII 5; Fig. 7F–J) from sample 2.

Very small, slender hydrobiid with highly convex and slowly growing whorls that show weak subsutural concavity in late ontogeny, small aperture with weak bulge at columella, and sigmoidal growth lines.

Exceptionally small, slender hydrobiid shell, with slightly less than 5 whorls that slowly expand in width and height. Protoconch consisting of c. 1.2 whorls; low domed with broad nucleus, malleate surface, with initially tiny mesh-size, which becomes coarser toward P/T transition; P/T transition indicated by growth stop and onset of growth lines. Whorls highly convex throughout ontogeny; in last two whorls, faint concavity forms below suture. Last whorl attains c. 53% of total shell height. Base ~45°, straight-sided. Aperture small, elliptical; weak bulge occurs at columella. Inner lip covers sheet-like base of penultimate whorl, slightly expanded across columella, leaving very narrow umbilicus; outer lip not preserved. Growth lines distinct, sigmoidal, with opisthocyrt upper half and prosocyrt lower half.

1.93 × 0.83 mm (holotype, RGM 962618; Fig. 7A–E).

We attribute the new species to the genus Iraklimelania based on the following characters matching the type species, I. levis Willmann, 1981, from the Lower Pleistocene Irakli Formation of Kos Island: the small size; the small, simple aperture, having a slight bulge at the columella; the highly convex whorls, characterized by a narrow, faint constriction below the suture (“weak, concave sulcus” of Willmann 1981); the sigmoidal growth lines; the faint spiral striae. Our species can be distinguished by the even smaller size, the exceptionally slender shape and the narrower subsutural constriction. The only other species known for that genus, ?Iraklimelania coa Willmann, 1981 from the Lower Pleistocene Tafi Formation of Kos, differs in the conical shell and the presence of a blunt keel near the lower suture.

In addition to the holotype, a juvenile or subadult specimen is considered to belong to the new species (Fig. 7F–J). In that shell, the sigmoidality of the growth lines is not yet fully expressed, but the other features fit well to the holotype.

So far only known from the Early Pleistocene of the Denizli Basin.

Named with respect to the keel below the whorl center.

RGM 962689 (Fig. 7K–P). Babadağ river valley along the Babadağ-Sarayköy road, c. 2.4 km NW of the town of Babadağ, Denizli, Turkey; sample 1 (37°50'40.3"N, 28°52'53.3"E). Kolankaya Formation, Lower Pleistocene, Gelasian.

None (holotype only).

Small, slender hydrobiid with distinct, blunt keel below whorl center, slowly growing whorls that show weak subsutural concavity in late ontogeny, small aperture, and sigmoidal growth lines.

Small, slender hydrobiid shell, with 6 whorls that slowly expand in width and height. Protoconch consisting of c. 1.2 whorls; low domed with broad nucleus, finely-meshed malleate surface with 6–7 widely, but more or less regularly, spaced, weak spiral striae; terminal phase thickened, devoid of surface sculpture; P/T transition indicated by growth stop and onset of growth lines. Distinct, blunt, relatively broad keel develops on about 2^nd teleoconch whorl; becomes quickly more pronounced toward 3^rd whorl; originally almost in whorl center, keel becomes successively shifted toward lower suture; on last whorl, it is placed between lower third and upper two thirds of whorl height. Keel leaves weak furrow inside shell, at least on last whorl (Fig. 7K). Disregarding keel, whorls are regularly convex in early whorls, but convexity decreases during ontogeny; whorl portion above keel in last whorl almost straight-sided, with faint concavity below upper suture. Last whorl attains c. 49% of total shell height. Base ~45°, grading from straight-sided upper part into concave neck. Aperture not preserved, but whorl cross-section suggests small, elliptical shape. Growth lines distinct, sigmoidal, with opisthocyrt upper half (above keel) and weakly prosocline lower half (below keel).

2.83 × 1.13 mm (holotype, RGM 962689; Fig. 7K–P).

As for the previous species, we consider this one to belong in Iraklimelania. It matches both I. minutissima sp. nov. and the type species in terms of the small, slender shell with convex whorls and narrow subsutural concavity, the small aperture with slight bulge and the sigmoidal growth lines. The main difference to both species is the blunt keel below the center of the whorls. This feature reminds of ?Iraklimelania coa, which differs however in the distinctly conical shell with nearly straight-sided whorls.

So far only known from the Early Pleistocene of the Denizli Basin.

Turbo minutus Totten, 1834 [= Ecrobia truncata (Vanatta, 1924)]; by original designation.

1 specimen (RGM 962612), 4 specimens (RGM 1310850), 1 specimen SNSB-BSPG 2023 XII 6); all from sample 2.

5.54 × 3.55 mm (RGM 962612; Fig. 8A–C, Q), 4.61 × 3.01 mm (SNSB-BSPG 2023 XII 6, Fig. 8D–F).

Figure 8. 

Hydrobiinae (Hydrobiidae) of the Kolankaya I fauna. A–C, Q. Ecrobia sp. RGM 962612, sample 2. D–F. Ecrobia sp. SNSB-BSPG 2023 XII 6, sample 2. G–I. P. Harzhauseria schizopleura gen. et sp. nov., holotype, RGM 962613, sample 2. J–L. Harzhauseria schizopleura gen. et sp. nov., paratype, RGM 962614, sample 2. M–O, R–T. Hydrobiinae sp. indet., RGM 1365350, sample 1. Scale bars: 1 mm (A–O); 100 μm (P–T).

The shape of the shell and the aperture and the type of growth lines are typical of the genus Ecrobia. The protoconch includes ~1.1 whorls and appears to be smooth (the preservation of the apex is, however, rather poor). The P/T boundary is marked by the onset of growth lines. Shape-wise our specimens fall well into the morphological range of extant E. grimmi (Clessin in Dybowski, 1887) from the Caspian Sea, but it also resembles stout forms of the widespread European E. ventrosa (Montagu, 1803) and the Black Sea/eastern Mediterranean species E. maritima (Milaschewitsch, 1916). Only, our material is exceptionally large for Ecrobia and has a slightly thickened aperture, which is untypical as well. It might well represent an undescribed species, but since Ecrobia species are known to be extremely variable (Kantor and Sysoev 2006; Neubauer et al. 2018; Vandendorpe et al. 2019) and we have only limited material available for comparison, we refrain from introducing a new species.

Harzhauseria schizopleura gen. et sp. nov.; designated herewith.

Named in honor of Mathias Harzhauser for his many contributions on fossil Mollusca, pan-Tethyan biogeography, and a long friendship.

As for the type species (so far only the type species is known).

As for the type species.

The shell shape, convex whorls, and round, large aperture remind of species of Ecrobia, such as the co-occurring Ecrobia sp. The presence of ribs, however, makes the species unique and clearly distinguishes it from any other known species or genus of Hydrobiinae (or other Hydrobiidae for that matter).

Derived from the Ancient Greek syllables σχίζω (skhízō) and πλευρόν (pleurón), referring to the extraordinary sculpture, occasionally showing diverging ribs.

RGM 962613 (Fig. 8G–I, P). Babadağ river valley along the Babadağ-Sarayköy road, c. 2.4 km NW of the town of Babadağ, Denizli, Turkey; sample 2 (37°50'44.5"N, 28°52'51.3"E). Kolankaya Formation, Lower Pleistocene, Gelasian.

RGM 962614, SNSB-BSPG 2023 XII 7, SNSB-BSPG 2023 XII 8; all from the type locality and stratum.

Sample 1: 1 specimen with traces of intense growth lines rather than distinct ribs (SNSB-BSPG 2023 XII 9); sample 2: 6 nearly complete specimens, lacking aperture or last whorl, plus 13 fragments (RGM 1310851), 1 specimen with fragmented aperture and 2 fragments (SNSB-BSPG 2023 XII 10).

Small hydrobiine, conical, slender to slightly broader shell, with highly convex whorls that bear conspicuous irregular (straight to wavy, partly interfingering) ribs and large elliptical aperture.

Shell conical, slender to slightly broader, with 5 highly convex whorls. Protoconch smooth, consisting of c. 1.25 regularly coiled whorls; P/T transition marked by distinct growth stop. Numerous, weak, regularly shaped axial ribs develop on first teleoconch whorl. Ribs soon become irregular, variably spanning full whorl height or only parts, partly interfingering with each other (Fig. 8G–I) or they become sigmoidal (Fig. 8J–L). Distance and intensity of ribs also varies across specimens. Sometimes, rib tops are abraded, creating illusion of two ribs merging near upper and lower suture, leaving narrow concavity in between. Last whorl attains 60–64% (n = 2) of total shell height. Base ~45°, straight-sided. Aperture relatively large, well-rounded, elliptical; peristome weakly and equally thickened; umbilicus narrow. Growth lines faint.

3.50 × 2.23 mm (holotype, RGM 962613; Fig. 8G–I, P); 3.69 × 1.96 mm (paratype, RGM 962612; Fig. 8J–L).

There is considerable morphological variability in the little material available to us. This concerns both shell shape and the expression of the ribs. However, it is well known that species of Hydrobiinae, such as the (probably related) genus Ecrobia, are morphologically highly variable, which often complicates establishing species boundaries (e.g., Wesselingh et al. 2019; Andreeva et al. 2022).

So far only known from the Early Pleistocene of the Denizli Basin.

1 specimen (RGM 1365350) from sample 1.

2.52 × 1.37 mm.

A single specimen is available, characterized by a small, white, conical shell with convex whorls, simple aperture, and distinct, orthocline growth lines. The protoconch is low domed, forming a bulbous cap of ~1.2 whorls, and apparently smooth, but this might be a result of the moderate preservation. The available features suggest placement in Hydrobiinae, but at present an attribution to genus or species cannot be made.

Rissoa caspia Eichwald, 1838; by subsequent designation (Logvinenko and Starobogatov 1969).

1 specimen (RGM 962609) from sample 2.

8.21 × 4.10 mm.

The size and shape of the shell and the oblique, large, and slightly thickened aperture leaving a narrow umbilicus are characteristic of the Pontocaspian genus Laevicaspia. The species reminds of the Quaternary–extant species L. lincta (Milaschewitsch, 1908) from the Black Sea. That species is known for its high variability, which has led previous authors to introduce numerous species names (Wesselingh et al. 2019). The Denizli specimens differ from that species by a slightly broader shell with convex, spruce-like whorl profile. Laevicaspia lincta has mostly straight-sided whorls, sometimes convex ones; only some specimens approach this type of morphology [see lectotype illustrated by Kantor and Sysoev (2006: pl. 45, fig. D) as well as the holotype of Pyrgula iljinae Golikov & Starobogatov, 1966, now considered a synonym of L. lincta in Kantor and Sysoev (2006: pl. 49, fig. D)]. Also, the broad shell shape is approached by the holotype of the synonym Pyrgula (Laevicaspia) milachevitchi Golikov & Starobogatov, 1966 depicted in Kantor and Sysoev (2006: pl. 45, fig. C).

Another similar species is Prososthenia sublaevis Oppenheim, 1919, described from “Laodicäa”, an ancient city 6 km north of Denizli. It differs in the flattened whorls and the presence of a weak subsutural band. Prososthenia gregaria (Fuchs, 1877) from the Early Pleistocene of mainland Greece is more slender and has low-convex whorls (see also Esu and Girotti 2020, fig. 9A–F).

Figure 9. 

Pyrgulinae (Hydrobiidae) of the Kolankaya I fauna. A–C. Laevicaspia sp., RGM 962609, sample 2. Scale bar: 1 mm.

Potentially our specimen represents an undescribed species, but given the limited material availability and the high morphological variability of related taxa, we do not introduce a new name.

Prososthenia schwartzi Neumayr, 1869; by subsequent designation (Herbich and Neumayr 1875).

1 specimen (RGM 962615), 7 specimens, 2 apertural fragments, and 2 apical fragments (RGM 1310852), 1 specimen (SNSB-BSPG 2023 XII 11); all from sample 2.

Valley between Vokasia and Sefto valley, c. 3.5 km SW of Kos, Kos Island, Greece; lower Kos Formation, Lower Pleistocene.

Shell elongate, ovoid, with 5 whorls that decrease in convexity. Early whorls regularly convex; penultimate to last whorl weakly convex to flattened in whorl center; last whorl occasionally has faint concavity below faintly expressed subsutural bulge; suture moderately incised. Base weakly convex to straight-sided. Aperture typically drop-shaped, relatively broad, only weakly inclined; slightly offset in fully grown specimen; peristome weakly and equally thickened, faintly expanded; umbilicus very narrow. Growth lines rather weak, weakly prosocline in upper half to nearly orthocline in lower half, crossed by faint spiral furrows. Protoconch consisting of ~0.9 whorls, with broad nucleus, covered by fine-meshed malleate sculpture.

2.86 × 1.33 mm (RGM 962615; Fig. 10A–E), 2.77 × 1.20 mm (SNSB-BSPG 2023 XII 11; Fig. 10F–J).

Figure 10. 

Pyrgulinae (Hydrobiidae) of the Kolankaya I fauna. A–E. Prososthenia cf. sturanyi communis Willmann, 1981, RGM 962615, sample 2. F–J. P. cf. sturanyi communis, SNSB-BSPG 2023 XII 11, sample 2. K–Q. Xestopyrguloides ? sagitta sp. nov., holotype, RGM 962616, sample 2. R. Xestopyrguloides ? heldreichii (Fuchs, 1870), lectotype (designated by Willmann 1981), NHMW 1878 XX 28, Megara, Pliocene. S–U. Xestopyrguloides? sp., RGM 1365347, sample 2. Scale bars: 1 mm (A–D, F–I, K–N, R–T); 100 μm (E, J, O–Q).

Prososthenia sturanyi encompasses shells with highly variable shapes and sizes (Willmann 1981). Slender specimens of P. s. communis from Kos Island match the Denizli material in terms of general shape, the flattened whorl flanks, the presence of a weak subsutural band, and faint spiral furrows, as well as the shape of the aperture (compare Willmann 1981, pl. 6, fig. 11). Yet, the Kos specimens are slightly larger and the apex appears to be smaller. Considering the otherwise close similarity, the generally great variability of the species, and the similar age and geographic vicinity, we tentatively refer the Denizli material to Prososthenia sturanyi communis.

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).

Prososthenia sturanyi sturanyi (Bukowski, 1896) from Plio–Pleistocene formations of Rhodes has a stouter shell with a shorter spire (Willmann 1981). Prososthenia gregaria (Fuchs, 1877) from the Early Pleistocene of mainland Greece is much larger and has a slender, elongate shell with regularly, low-convex whorls. A particularly similar species is Prososthenia eburnea Brusina, 1897 from Middle Miocene (Langhian) strata of Miočić, Croatia, regarding the decreasing degree of whorl convexity through ontogeny. The species is, however, much larger and more regularly ovoid. The malleate protoconch (Fig. 10E), prosocline-orthocline growth lines, and the presence of spiral furrows also agree with a placement in the genus Prososthenia (compare Neubauer et al. 2020).

The taxon is also surprisingly similar to “Caspia” laevigata Jekelius, 1944 (p. 123–124, pl. 45, figs 9, 10) from the Early Pannonian (Early Tortonian) of Soceni in Romania. That species has a similarly slender, ovoid shell with straight-sided whorls, an angulation on the last whorl toward the straight base, and a slender ovoid aperture. It differs in the early whorls being also nearly straight-sided, where the Denizli species has convex whorls. Furthermore, there seems to be no umbilicus in the Romanian species. On a side note, despite the superficial similarity, it is questionable whether that species is a member of the genus Caspia and the Caspiinae. Shells of that group are characterized by a broad and rounded, dome-like protoconch. The Romanian species rather suggests a placement in Pyrgulinae, perhaps even Prososthenia. If, however, the species was transferred to Prososthenia, the species name Prososthenia laevigata Volkova, 1953 would be become a secondary homonym.

Late Pliocene to Early Pleistocene (Phoka, Sefto, and Kos formations) of Kos Island (Willmann 1981) and, tentatively, Early Pleistocene of the Denizli Basin (this study).

Xestopyrguloides neumayri Willmann, 1981; by original designation.

After the Latin sagitta meaning “arrow”, referring to the slender, pointy shape reminding of an arrowhead (noun in apposition).

RGM 962616 (Fig. 10K–Q). Babadağ river valley along the Babadağ-Sarayköy road, c. 2.4 km NW of the town of Babadağ, Denizli, Turkey; sample 2 (37°50'44.5"N, 28°52'51.3"E). Kolankaya Formation, Lower Pleistocene, Gelasian.

SNSB-BSPG 2023 XII 12, specimen lacking aperture and apex; from type locality and stratum.

1 almost complete specimens and 5 fragments (RGM 1310853), 1 apertural fragment and 1 apical fragment (SNSB-BSPG 2023 XII 13); all from sample 2.

Very slender, weakly ovoid pyrguline shell characterized by small last whorl, small aperture, narrow but distinct basal keel, and whorl convexity decreasing through ontogeny.

Shell slender, elongate, faintly ovoid, almost conical, consists of about 7 whorls. Protoconch low domed, no sculpture discernible (perhaps because of poor preservation; Fig. 10O–Q); P/T boundary not visible. Initial teleoconch whorls are convex, but convexity decreases rapidly around 3^rd to 4^th whorl. Following whorls are straight-sided or nearly so, with only faint convexity remaining in center of whorls. Whorls bear thin keel directly at lower suture. Keel produces slight swelling at upper suture of following whorl where it overgrows keel. Onset of keel in ontogeny uncertain due to near full overlap; keel visible in parts on at least last four whorls, matching approximately change in convexity. Last whorl relatively small, attaining 43% of shell height. Keel there produces sharp angle toward straight-sided shallow base (~55° to shell axis). Aperture not full preserved, but appears to be narrow ovoid. Inner lip covers umbilicus. Growth lines opisthocyrt, but more distinctly in upper half of whorls.

3.65 × 1.37 mm (holotype, RGM 962616; Fig. 10K–Q).

Only two other Xestopyrguloides have been described so far: the type species X. neumayri (Willmann, 1981) from the Early Pleistocene of Kos Island and X. ? heldreichii (Fuchs, 1877) from the Pliocene of Megara, whereas the second species is only tentatively referred to the genus (Willmann 1981, p. 202–203, textfig. 67). Both species have elongated shells with straight whorl flanks and distinct keel close to lower suture (or sometimes directly above it). Below the keel occurs a marked constriction toward the suture, which results in a weakly spruce-like appearance. Xestopyrguloides ? heldreichii has in addition a slightly thickened peristome, especially at the inner lip. The lectotype designated by Willmann (1981, p. 203; NHMW 1878 XX 28) is illustrated on Fig. 10R.

The straight-sided whorls and keel at the lower suture are also present in Xestopyrguloides sagitta sp. nov. The aperture is, however, much smaller and the base is more shallow than in the other species of that genus, which is why we only tentatively allocate the Turkish species there.

A Xestopyrguloides sp. was mentioned by Schütt and Kavusan (1984) from supposedly Miocene deposits of the area around Harmancık but not illustrated. Judging from the brief description, referring to a rather stout form with lower height and a sharp keel right above the suture, it is a different species than the one we describe herein.

The new species also reminds of representatives of the genus Falsipyrgula Radoman, 1973a, many of which have a keel near the lower suture as well (Schütt and Yildirim 1999). The type species, Falsipyrgula pfeiferi (Weber, 1927), also shares the slender shape and the straight whorl flanks (Radoman 1973a). On average, however, Falsipyrgula species are broader and have larger and broadly ovoid apertures.

The placement in Pyrgulinae is preliminary and based on the comparison with Pontocaspian Turricaspia and Laevicaspia, with which Xestopyrguloides ? sagitta sp. nov. shares the elongate, multi-whorled shell and the flattened, often smooth or faintly ornamented protoconch (Neubauer et al. 2018; T.A.N., pers. obs.).

So far only known from the Early Pleistocene of the Denizli Basin.

1 fragment (RGM 1365347) from sample 2.

A second species is tentatively referred to the genus Xestopyrguloides. A single incomplete shell is available, containing the last 2.5 whorls and the upper part of the aperture. The shell is similarly elongate as Xestopyrguloides ? sagitta sp. nov. and also bears a narrow basal keel, as well as the same type of growth lines. However, the shell is larger, the whorls are moderately convex, and the aperture is larger and drop-shaped. The basal keel and shape of the aperture, as well as the size, would also fit to the Greek X. neumayri and Xestopyrguloides ? heldreichii (Fig. 10R), but both species have straight-sided whorls.

The Staja–Falsipyrgula species complex

Remarks. The enormous morphological variability of the Denizli specimens, as well as other material from Turkey and Greece assigned to the genus Staja (e.g., Willmann 1982), makes a systematic classification incredibly difficult. This concerns variation in shell shape, size, and presence and expression of sculpture, which – if our assessment is correct – varies even within single species. The keeled representatives remind of and are considered to belong in the Pyrgulinae genus Falsipyrgula, while the smooth morphotypes are classically assigned to Staja, a genus that is originally described from the Late Miocene of the Pannonian Basin.

A full revision of the Greek–Turkish Staja–Falsipyrgula species complex is beyond the scope of this study. We follow the literature for the genus classifications of the known species, yet being aware of the unresolved genus concepts. A new species is placed in Falsipyrgula due to the close similarities to extant congeners.

Staja adiaphora Brusina, 1897; by subsequent designation (Cossmann 1898).

Sample 1: 21 specimens and 5 fragments (RGM 1310854), 1 specimen (RGM 1365351), 2 specimens (SNSB-BSPG 2023 XII 14); sample 2: 1 specimen (RGM 962619), 1 specimen (SNSB-BSPG 2023 XII 15).

Tlos (an ancient city in Muğla Province near Seydikemer), Turkey; probably Eşen Formation (Kocaçay Member), Zanclean, Lower Pliocene.

Ovoid, slender to slightly broader shell with up to 5 moderately convex whorls. Protoconch low-domed, consisting of c. 1.2 apparently smooth whorls; P/T boundary marked by growth rim and onset of growth lines. Last whorl attains 79–82% (n = 3) of total height. Aperture oblique, ovoid to almost elliptical, weakly inclined in lateral view. Inner lip touches base of penultimate whorl but weakly detaches in some specimens near adapical tip and base, leaving very narrow umbilicus; latter occasionally opens into narrow canal that runs along inner lip toward base and is demarcated by weak fasciole. Shell surface smooth except for numerous faint spiral furrows detected in well-preserved specimens.

6.08 × 4.24 mm (Fig. 11A–C, S; RGM 962619), 3.90 × 2.76 mm (SNSB-BSPG 2023 XII 15; Fig. 11D, T), 4.41 × 2.83 (Fig. 11G–I; RGM 1365351).

Here, we combine a variety of morphologies under the name Staja lycica. This includes a comparatively large, broad morphotype with highly convex whorls (Fig. 11A–C, S; RGM 962619), which matches the features illustrated by Oppenheim (1919). Also the overall size, the faint spiral furrows indicated by Oppenheim, as well as the slightly inclined aperture fit well. The very weak detachment of the aperture from the base of the last whorl and the “layered peristome” referred to by Oppenheim and shown in his illustrations match a morphotype that is more slender and smaller but otherwise fits the original description and illustration and cannot be reasonably distinguished (Fig. 11G–I). Since Oppenheim’s type material seems to be lost, topotypic material from the Eşen Basin is needed to clarify the identity and variability of this species.

Staja orientalis (Bukowski, 1896) from the Pliocene Istrios Formation of Rhodes differs from S. lycica in the even broader shape, larger size, and presence of an umbilicus (Fig. 11E, F). However, some specimens of S. orientalis from Attica (mainland Greece) illustrated by Willmann (1982, fig. 3i–l) closely resemble S. lycica. Willmann (1982) even hypothesized that both species might be synonymous. A thorough revision of the Staja lycica–orientalis species group is required to settle these uncertainties. To fix the identity of S. orientalis, we hereby designate the specimen illustrated by Bukowski (1896, pl. 10, fig. 1) as the lectotype (IGUW 1895 XII/45; Fig. 11F).

The specimen from the Kolankaya II fauna of the upper Kolankaya Formation attributed to S. orientalis by Wesselingh et al. (2008) rather range within S. lycica; they even show the slightly detached aperture as mentioned by Oppenheim.

So far only known from the type locality in the Eşen Basin (Oppenheim 1919), which is of Late Pliocene age according to (Alçiçek et al. 2019), and the Early Pleistocene of the Denizli Basin (this study).

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).

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.

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.

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).

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.

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).

The species epithet means “crowned” in Latin and refers to the beaded keel.

RGM 1310837 (Fig. 12A–C). Babadağ river valley along the Babadağ-Sarayköy road, c. 2.4 km NW of the town of Babadağ, Denizli, Turkey; sample 2 (37°50'44.5"N, 28°52'51.3"E). Kolankaya Formation, Lower Pleistocene, Gelasian.

RGM 962611 (Fig. 12J–L) from sample 2; SNSB-BSPG 2023 XII 18 (Fig. 12D–F, T) from sample 2; SNSB-BSPG 2023 XII 19 (Fig. 12I) from sample 3.

Figure 12. 

The Staja–Falsipyrgula species complex of the Kolankaya I fauna. A–C. Falsipyrgula ? coronata sp. nov., holotype, RGM 1310837, sample 2. D–F, T. F. ? coronata sp. nov., SNSB-BSPG 2023 XII 18, sample 2. G, H. Falsipyrgula cf. sieversi (Boettger, 1881), RGM 1310376, sample 2. I. F. ? coronata sp. nov., SNSB-BSPG 2023 XII 19, sample 3. J–L. F. ? coronata sp. nov., RGM 962611, sample 2. M–O, U. F. cf. sieversi, RGM 962610, sample 2. P–R. F. cf. sieversi, SNSB-BSPG 2023 XII 20, sample 2. S. F. ? coronata sp. nov., RGM 1310377, sample 2. Scale bars: 1 mm (A–R); 100 μm (S–U).

Sample 2: 1 specimen (RGM 1310377), 27 partly incomplete specimens and 10 fragments (RGM 1310858); sample 3: 4 specimens and 2 fragments (RGM 1310859).

Conical pyrguline shell characterized by central to subcentral, typically beaded keel, topped by shallow, straight-sided subsutural whorl profile, convex portion below keel, grading into straight-sided base, thin peristome, and narrow umbilicus.

Moderately sized conical shell with up to 6 whorls. Protoconch poorly preserved in all studied specimens; surface and P/T boundary unknown. Already on approximately first to second teleoconch whorl a central to subcentral keel appears, which increases continuously in strength through ontogeny. Also in cases with early keel placed at whorl center, keel becomes distinctly subcentral in later ontogeny. Keel typically bears nodules (Fig. 12D–F), which are sometimes not visible, probably due to abrasion (Fig. 12A–C, I–L). Whorl portions above and below keel straight-sided. Last whorl attains ~68–71% (n = 3) of total shell height; passes over weak convexity into moderately steep (~45°), straight-sided base. Aperture broadly ovoid, with rather thin peristome and adnate inner lip; umbilicus narrow.

7.82 × 5.26 mm (holotype, RGM 1310837; Fig. 12A–C), 10.02 × 6.35 mm (paratype, RGM 962611; Fig. 12J–L), 6.73 × 3.78 mm (paratype, SNSB-BSPG 2023 XII 19; Fig. 12I), 4.05 × 2.84 mm (paratype, juvenile, SNSB-BSPG 2023 XII 18; Fig. 12D–F, T).

As for other members in the Staja–Falsipyrgula species complex, the shell of this species exhibits a certain degree of variability. Occasionally, species with a more slender shell (Fig. 12I) or a narrower, non-beaded keel (Fig. 12J–L) are observed. The latter feature may, however, be the result of poor preservation, in many cases shell surfaces and sculptural elements are abraded. Common to all specimens is the conical shell, the comparatively shallow and straight-sided whorl profile above the keel, the thin and edgy peristome, and the narrow umbilicus. These features distinguish Falsipyrgula ? coronata sp. nov. from similar species of Falsipyrgula, including the co-occurring F. cf. sieversi. The latter species shares the beaded keel, which is, however, consistently weaker and slightly lower positioned on the whorl, but the shell is ovoid, smaller, and has a stronger inclined, regularly ovoid aperture. Extant Falsipyrgula species have a lower positioned keel or multiple keels or otherwise differ in shape (Schütt and Yildirim 1999).

Prososthenia attica Fuchs, 1877 sensu Schütt and Besenecker (1973, pl. 1, fig. 7) from the Late Miocene (?) of Chios resembles F. ? coronata in terms of overall shell shape and presence of a subcentral keel, but the last whorl is tapered and the whorl profile above the keel is convex. Original P. attica from the Pliocene of Megara is more elongate and has only a week keel near the whorl base (Fuchs 1877) and is probably a different species as the Chios specimens.

Known only from the Early Pleistocene of the Denizli Basin.

Sample 2: 1 specimen (RGM 962610), 1 specimen (RGM 1310376), 27 partly incomplete specimens and fragments (RGM 1310861), 1 specimen (SNSB-BSPG 2023 XII 20); sample 3: 1 specimen (RGM 1310375).

Bank deposits of the Araks River near Nakhichevan’ Town, Azerbaijan (approximately 39°10'30"N, 45°21'41"E); extant.

Small, ovoid hydrobiid with 5 whorls. Protoconch consists of ~1 whorl, without discernible sculpture but clear P/T boundary (Fig. 12U). First teleoconch whorl smooth, soon weak, beaded keel with round, equally spaced nodules appears slightly below whorl center. Nodules increase slightly in intensity throughout ontogeny and form keel-like appearance on last whorl. Whorl profile weakly convex above nodules, convex below them, grading into weakly convex base. Last whorl attains ~70–76% (n = 3) of total shell height. Aperture ovoid, strongly inclined, faintly detached, leaving narrow umbilicus. Peristome continuous, not thickened or expanded, but weakly intensified abapical growth in final ontogeny typical of hydrobiids exposes shell layers at adapical tip.

4.66 × 2.97 mm (RGM 962610; Fig. 12M–O, U), 3.54 × 2.43 mm (RGM 1310376; Fig. 12G, H), 3.60 × 2.56 mm (SNSB-BSPG 2023 XII 20; Fig. 12P–R).

The available material shows high similarities and is perhaps conspecific with the extant Falsipyrgula sieversi (Boettger, 1881) from the Aras river in Nakhchivan (Azerbaijan). Sitnikova et al. (2018) recently studied and illustrated the holotype, which matches our specimens in terms of shell shape, size, whorl convexity, the position of the keel, the slightly convex base, and the shape and tilt of the aperture. The only difference is that the keel is not beaded as in the Denizli specimens. However, Sitnikova et al. (2018) also reported keel-less, fossil specimens of that species, confirming the variability of this trait in the Staja–Falsipyrgula species complex. Shells reported from the Early Pleistocene of the Pasinler Basin are considerably broader, nearly conical, and bear the keel at the base of the whorl (Vasilyan et al. 2014).

Other similar species include F. osmana (Bukowski, 1930) from the Quaternary of Burdur and Kirelia carinata Radoman, 1973b (classified as Falsipyrgula by Schütt and Yildirim 1999), both of which differs in the stronger, continuous keel and the slightly more elongate shell (Schütt and Yildirim 1999).

Falsipyrgula sieversi is known living and from Quaternary strata in Nakhchivan (Azerbaijan) (Sitnikova et al. 2018), the Early Pleistocene of Armenia (Tesakov et al. 2019), and the Pasinler Basin (Vasilyan et al. 2014).

1 shell (RGM 1310799) from sample 2.

4.25 × 2.56 mm.

The single specimen from Denizli closely resembles the extant Radomaniola caputlacus (Schütt & Şeşen, 1993), originally described as a species of Orientalina from eastern Anatolia. Both share the conical shape with weakly convex whorls and the simple ovate aperture. However, Radomaniola caputlacus is with 2.2 mm shell height (Schütt and Şeşen 1993) only about half the size of the Denizli shell. Larger species (up to 4 mm) of that genus are known from the Balkan Pensinula, where it is considerably more diverse, but these species differ clearly from the Denizli shell (Delicado and Hauffe 2022).

Figure 13. 

Hydrobiidae of the Kolankaya I fauna. A–C. Hydrobiidae sp. indet., RGM 1310799, sample 2. Scale bar: 1 mm.

Another similar species is the fossil Bithynia giralanensis Oppenheim, 1919 (pl. 10, fig. 1), described from the Denizli Basin. However, that species is much larger (10 × 8 mm) at about the same number of whorls and bears a weak subsutural band; also, the shell is slightly broader and has a shallower base. Given these features, classification in the genus Bithynia is unlikely. Considering the poor preservation of Oppenheim’s material as cast and the apparent loss of the type material (see Introduction), the name Bithynia giralanensis Oppenheim, 1919 should be considered a nomen dubium.

Yet another similar species is Bania urosevici (Pavlović, 1931) from the middle Miocene of Serbia in terms of general shape, the angulation, and the tilt of the aperture (Neubauer et al. 2020). The Denizli shell is, however, much larger (height of B. urosevici ~1.8 mm). Moreover, no Bania species is known until now from Turkey or deposits younger than Tortonian. The shell similarity may rather be due to convergence.

Finally, the species shares similarities with species of Shadiniinae, e.g., Persipyrgula saboori (Glöer & Pešić, 2009), which has a similar size, number of whorls, and shell shape, but more rounded whorls and a larger aperture (Delicado et al. 2016).

Given the poor preservation of our material and the overall difficulty of assigning fossil hydrobiids with few morphological characteristics to genera and even subfamilies, we refrain from a tentative placement in any of the abovementioned taxa.

Valvata cristata Müller, 1774; by subsequent monotypy.

1 specimen (RGM 962694) from sample 3.

6.25 × 6.15 mm.

This well-known extant species is a typical representative of Quaternary freshwater mollusk faunas. It is known for its morphological variability, especially concerning the outline shape, ranging from nearly conical to broadly ovoid, being a result of an inflated penultimate whorl (Glöer 2002, 2019; Welter-Schultes 2012). The apex is depressed, the aperture is nearly circular and the umbilicus is wide. All these features match well the Turkish specimen, which also shows an expanded penultimate whorl. Only, it is slightly larger than the average extant members of the species (up to 4.5 mm high and 5 mm broad; Glöer 2019).

Figure 14. 

Valvatidae of the Kolankaya I fauna. A–D. Valvata piscinalis (Müller, 1774), RGM 962694, sample 3. E–H, U, V. Valvata sp. 1, RGM 1365352, sample 1. I–L, W. Valvata sp. 1, RGM 962695, sample 2. M–P. Valvata gregaria Bukowski, 1896, lectotype (designated by Willmann 1981), IGUW 1895 XII/25, Skiadhi Monastery, Rhodes, Greece, Istrios Formation (Pliocene). Q–T. Valvata gregaria Bukowski, 1896, paralectotype, IGUW 1895 XII/26, same locality and stratum. Scale bars: 1 mm (A–T); 100 μm (U–W).

The material also resembles the depressed morphotype of the extant Valvata lilljeborgi Westerlund, 1897 in terms of the inflated penultimate whorl. That species comprises a broader range of morphologies, also including unusually high-spired forms (Vinarski et al. 2013). The species is today restricted to cold-temperate regions of the Baltic Sea Basin, the Dnieper Basin, and Western Siberia (Vinarski et al. 2013; Glöer 2019). Considering the above, we consider an identification with the more common V. piscinalis more likely.

Today present throughout the Palearctic, also introduced to North America (Welter-Schultes 2012; Glöer 2019). Common in Upper Miocene to Pleistocene deposits across Europe (Wenz 1923).

Sample 1: 1 specimen (RGM 1365352), 1 specimen (SNSB-BSPG 2023 XII 21); sample 2: 1 specimen (RGM 962695), 1 specimen (SNSB-BSPG 2023 XII 22).

1.60 × 2.48 mm (RGM 962695; Fig. 14I–L, W), 1.48 × 2.18 mm (RGM 1365352; Fig. 14E–H, U, V).

This species is characterized by a small, low-trochiform shell with relatively large, nearly circular aperture, slightly raised, bulbous apex, wide umbilicus, and moderately distinct growth lines. The protoconch bears the typical valvatid pattern, with numerous distinct spiral ridges crossed by weaker axial, u-shaped ridges, creating a wavy impression (Fig. 14U, V).

The material closely resembles the Pliocene Valvata gregaria Bukowski, 1896 (p. 25–28, pl. 8, figs 7, 8) from Rhodes in terms of the shell size and shape, the relatively large aperture, and low number of whorls (see also Willmann 1981, p. 77, textfig. 25). However, the lectotype and paralectotype of that species (designated by Willmann 1981) show a depressed and unevenly coiled spire (Fig. 14M–T), while the Denizli specimens has a bulbous, almost pointy apex and a slightly more ovoid aperture.

Given the low amount of specimens available for comparison and assessing morphological variability, the perhaps not fully adult state of the specimens, as well as the low number of features, we do not describe a new species, although we could not detect any extant or late Cenozoic species that matches our material.

1 specimen (RGM 962690) from sample 1.

4.60 × 4.97 mm.

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.

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.B41478, 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).

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.

1 specimen (RGM 962697) from sample 2.

2.79 × 2.92 mm.

As for the previous species, this one is only known from a single specimen. It is characterized by a relatively small, globular shell with short apex and bulbous, regularly convex body whorl. The aperture is broken but appears to be nearly circular, the umbilicus is wide and the shell surface bears distinct orthocline growth lines. The protoconch is about half a whorl, weakly heterostrophic and bears weak signs of an originally spiral sculpture. The transition to the teleoconch is marked by a broad, shallow furrow and the onset of regular coiling.

The spherical shape with short apex and distinct growth lines reminds of the extant Valvata montenegrina Glöer & Pešić, 2008 from Lake Skadar and Podgorica (Montenegro). The Balkan species is, however, much larger (6–7 mm high, 6.2–6.8 mm wide; Glöer 2019) and slightly less broad than the Turkish specimen. Our specimen also reminds of juvenile V. piscinalis, but the shape is too conical and the umbilicus to wide with a too long straight upper flank. Given the generally large variability of Valvata piscinalis we cannot exclude the option that the specimen belongs to that species, but we consider it unlikely. The Turkish Quaternary species Valvata orientalis Fischer, 1866 (see above) shares the broad shape but has a higher apex and a relatively smaller aperture (Fig. 15E–G).

Although we could not find any species with which this one can be identified, we refrain from introducing a new name because of the low amount of material available, the incompleteness of the shell, and the small number of distinct morphological features.

Corymbina rhodensis Bukowski, 1892; by subsequent designation (Wenz 1923).

1 juvenile specimen (RGM 962696) from sample 2.

Italy; no further details known—Cantraine wrote: “Je ne connais cette espèce qu’à l’état fossile, le seul individu que je possède m’a été donnée par mon ami M. Rossi de Livourne, qui a’en connaissait pas exactement la provenarco.” [I only know this species in the fossil state, the only individual I have was given to me by my friend Mr. Rossi from Livorno, who didn’t know exactly where it came from.].

Shell comprises protoconch and about 0.75 teleoconch whorls. Initial part of protoconch smooth, followed by quarter whorl bearing faint riblets. P/T boundary not clearly visible, but probably coincides with weak angulation and onset of growth lines. Soon distinct, sharp ribs develop, which soon become broader and bulgier, leading to an irregular, wavy surface. Aperture fragmented, parts of outer lip missing; originally apparently elliptical. Umbilicus narrow.

Spratt and Forbes (1847) mentioned the name Limneus [sic] adelina along with an illustration, making the name available. However, they clearly referred it to be the same species as Adelina elegans Cantraine, 1841, rendering Lymnaea adelina a junior objective synonym of Corymbina elegans. The specimen they illustrated has a much larger aperture, but the species has an extremely variable shell (see also Willmann 1981).

Corymbina bicarinata (Fuchs, 1877) from the Early Pleistocene of Livanates (Phthiotis, Greece) has a Radix-like appearance, with broad ovoid, attached aperture, an angulated last whorl, slender ribs, and small, pointy spire (Neubauer 2023b). Specimens from the same deposits identified by Fuchs (1877) as L. adelinae [= C. elegans] differ considerably from the phenotypes shown by Cantraine (1841), Spratt and Forbes (1847), and Willmann (1981). They rather resemble C. bicarinata, yet with a keel at the angulation. More data on the variability of both species is needed to disentangle their taxonomy and synonymies. We tentatively associate our single juvenile specimen with C. elegans given the general match in shell shape and sculpture as well as the known stratigraphic and geographic distribution of the species.

The Late Miocene Corymbina rhodensis Bukowski, 1892 is smaller and has a more slender shell, often with reduced sculpture (Willmann 1981). In both C. elegans and C. rhodensis specimens occur with the last whorl partly or entirely uncoiled (Willmann 1981). Corymbina aegaea (Oppenheim, 1919) from Upper Miocene (?) deposits near Harmancık (NW Turkey) has a more elongated shell (Schütt and Kavusan 1984). The Early Sarmatian (Serravallian, Middle Miocene) Corymbina coronata (Marinescu, 1992) from Romania differs from C. elegans in the more angulated body whorl and the ribs being reduced to elongated knobs at the uppermost whorl portion.

Corymbina rhodensis senestris İnal, 1975 from supposedly Pliocene sediments at Gürleyik SE Afyonkarahisar (c. 170 km ENE Denizli) shows a similar type of sculpture, but it is a rare case of a sinistral representative (İnal 1975). It is questionable, however, if it represents a distinct species or simply an aberrant morphotype of an existing species.

Corymbina elegans has been reported from the Pliocene of the Denizli, Eşen, and Çameli basins in Turkey (Spratt and Forbes 1847; Oppenheim 1919; Wenz 1923), the Early Pliocene of central Italy (Esu and Girotti 2018), and the Pliocene–Pleistocene of Greece (Wenz 1923; Schütt and Besenecker 1973; Gillet et al. 1979). Records from the Late Miocene (Chios Island; Schütt and Besenecker 1973) are probably based on an outdated stratigraphy.

Figure 16. 

Lymnaeidae of the Kolankaya I fauna. A–C. Corymbina elegans (Cantraine, 1841), RGM 962696, sample 2. D–F. Radix sp., RGM 1310798, sample 2. Scale bars: 1 mm.

Radix auriculatus Montfort, 1810 [unnecessary substitute name for Radix auricularia (Linnaeus, 1758)]; by original designation.

1 juvenile specimen (RGM 1310798) from sample 2.

The single available specimen contains about 2 whorls, with a small, bulbous protoconch and a large, inflated, and convex body whorl. The aperture is broad and semi-circular. Although a more precise identification is not possible, these features suggest a classification in the genus Radix.

Mytulus [sic] polymorphus Pallas, 1771; by monotypy.

The dreissenid material at hand is very much broken and displays huge variability in shape and ornamentation. We have found it nearly impossible to distinguish species within the material. Our distinction of two morphotypes below will require confirmation by further designated collecting of entire specimens and populations in the region.

Sample 2: 5 valves (RGM 962698–962702), c. 690 valves (RGM 1310845), 2 valves (SNSB-BSPG 2023 XII 23); sample 3: 28 valves (RGM 1310846).

“Kairandere zwischen Bosalan und Bulladan” [Kairandere between Bozalan and Buldan], Denizli Basin, Turkey.

Variably shaped Dreissena with outlines ranging from mytiliform to flat, wide, and broad with apparent intermediate shapes. Dorsal margin usually curved but in some specimens can be straight. Ventral margin slightly curved, lacks byssate inflection. Semidiameter located toward ventral margin in adult stages. External ornamentation remarkably variable. Most specimens contain some sort of fanning out (axial) ribs. Number, shape, and length of these ribs highly variable; smooth specimens also occur. Typically 1–3 ribs develop almost immediately below umbo; often most prominent rib located at dorsal margin forms distinct dorsal angle. Ribs can fade within short distance or run entire shell length. Irregular small secondary ribs occur in some specimens. Hinge plate variable in strength. Plane of symmetry appears to be flat.

All material is broken, but measurements from cracked specimens in the field gave maximum dimensions of approximately 25 × 21 × 9.5 mm (width × height × semidiameter) for adult valves.

Our material concerns a hugely variably shaped species for which additional study is required to determine whether it is a single species or consists of multiple species. Our juvenile and broken adult material does not enable making such a distinction. The flat plane of symmetry, the lack of a byssate inflexion on the shells exterior, and the relative prominence of the posterodorsal ridge in many of the specimens makes a close relationship with the Dreissena polymorpha Pallas, 1771 species group possible.

The species differs from the co-occurring Dreissena sp. 1 particularly in the shifting position of the semidiameter through ontogeny, which runs with an almost straight line 45° from the umbo toward the posterior margin, and the generally more curved shell. Dreissena phrygica Oppenheim, 1919 and D. hierapolitana Oppenheim, 1919, both also described from the Denizli Basin, seem to differ from Dreissena kairanderensis mostly in size, shell curvature, and/or the presence of additional keels. Given the variability we observe in our material, these names probably only signify morphological varieties of a single, polymorphic species. However, further studies are required to verify their taxonomic status. The same applies to other Denizli dreissenids, i.e., Dreissena lycophila Oppenheim, 1919, Dreissena filifera Andrusov, 1893, sensu Taner, 1974b, Congeria prekairenderensis Taner, 1974b, and C. spathulata minor Taner, 1974b [non Congeria minor Fuchs, 1877], all of which require investigation.

Figure 17. 

Dreissenidae of the Kolankaya I fauna. A, B. Dreissena kairanderensis (Oppenheim, 1919), RGM 962699, sample 2. C, D. D. kairanderensis, RGM 962701, sample 2. E, F. D. kairanderensis, RGM 962702, sample 2. G, H. D. kairanderensis, RGM 962700, sample 2. I, J. D. kairanderensis, RGM 962698, sample 2. K, L. Dreissena sp. 1, RGM 962703, sample 2. M, N. Dreissena sp. 1, RGM 962704, sample 2. Scale bar: 2 mm.

Endemic to the Denizli Basin.

Sample 2: 2 valves (RGM 962703, 962704), 49 valves (RGM 1310847), 2 valves (SNSB-BSPG 2023 XII 24); sample 3: 6 valves (RGM 1310848).

Shell large, wide, and distinctly flat. Exterior smooth, apart from fine growth lines. Dorsal margin long, almost straight, with robust but rounded posterodorsal angle. Through ontogeny, semidiameter shifts with almost straight line 45° from umbo toward posterior margin (which is broken in all specimens). In some specimens, slight byssal inflection may be developed on ventral margin, which is otherwise almost straight. Plane of symmetry between valves appears to be not entirely flat. Hinge plate robust, wide, and flat.

Length c. 20 mm (all material is broken).

The smooth appearance and the presence of a very slight byssate inflection are characters that may point to a relationship with the Pontocaspian Dreissena rostriformis Deshayes, 1838 species group (Wesselingh et al. 2019). However, the very wide nature of specimens is unknown from this group and resembles superficially Congeria species.

Dreissena sp. 1 is only known from the Lower Pleistocene Kolankaya Formation of the Denizli Basin.