Planorbarius cf. cornu ( Brongniart, 1810 )

Harzhauser, Mathias, Neubauer, Thomas A. & Hoşgör, İzzet, 2018, Oligocene-Miocene freshwater gastropods from the Oltu-Narman Basin in eastern Turkey, Acta Palaeontologica Polonica 63 (2), pp. 357-369 : 364-366

Planorbarius cf. cornu ( Brongniart, 1810)

Fig. 5C–E .

cf. 1810 Planorbis Cornu ; Brongniart 1810: 371, pl. 22: 6.

Material.— Seven specimens: NHMW 2018 /0019/0022 ( Fig. 5C ); NHMW 2018 /0019/0023 ( Fig. 5D ); NHMW 2018 / 0019/0024 ( Fig. 5E ); NHMW 2018 /0019/0024a (4 specimens) from the upper Susuz Formation ( upper Oligocene or lower Miocene ) at Kömürlü, Oltu-Narman Basin, northeastern Turkey .

Remarks.—Only fragmentary specimens consisting of few whorls are available showing a shell with strongly convex whorls and deep suture ( Table 5). The protoconch displays traces of spiral rows of pits, which are replaced by delicate spiral cords on the first teleoconch whorl whereas the later whorls are smooth. These features correspond fully to specimens of Planorbarius cornu as described by Harzhauser et al. (2014b) from the early Miocene of the Czech Republic. Although the very high whorls support the identification, a separation from the early to late Miocene Planorbarius mantelli ( Dunker, 1848) is difficult based on fragments only see Harzhauser et al. 2014a, b). Moreover, the status of Planorbarius cornu is problematic and would need revision based on topotypic specimens from the Meulières de Montmorency in France (see Kadolsky 2015 for discussion). Therefore, we discuss the Turkish species in open nomenclature.

Planorbarius cornu was originally described from the Rupelian of the Paris Basin and is frequently recorded in Europe from Oligocene and lower Miocene deposits ( Wenz 1923).

Figures

Fig. 5. Physid (A, B) and planorbid (C–I) gastropods from upper Oligocene–lower Miocene Susuz Formation, Kömürlü, Turkey. A, B. Aplexa cf. subhypnorum Gottschick, 1920. A. NHMW 2018/0019/0020, in dorsal (A1) and apertural (A2) views; detail of sculpture (A3). B. NHMW 2018/0019/0021, in apertural view. C–E. Planorbarius cf. cornu (Brongniart, 1810). C. NHMW 2018/0019/0022, in apical view, specimen with characteristic protoconch microsculpture; C1 detail of C2. D. NHMW 2018/0019/0023, in apical view, specimen with prominent spiral cords. E. NHMW 2018/0019/0024, in lateral view. F–I. Gyraulus sp. F. NHMW 2018/0019/0025, in umbilical (F1), apical (F2), and lateral (F3) views. G. NHMW 2018/0019/0026, in umbilical (G1), apical (G2), and lateral (G3) views. H. NHMW 2018/0019/0027, in umbilical (H1) and apical (F2) views. I. NHMW 2018/0019/0028, in lateral view. Scale bars A1, A2, B, 5 mm; C1, 200 μm; A3, C2, D, E, 1 mm, F–I, 500 μm.