Polititapes vitalianus (d’Orbigny, 1844)

Frolov, Pavel D., Danukalova, Guzel A. & Osipova, Eugenia M., 2018, Late Miocene molluscs of the Morskaya 2 site (Azov Sea region, Russia), Palaeontologia Electronica (a 20) 23 (1), pp. 1-32 : 20-21

Polititapes vitalianus (d’Orbigny, 1844)

Figure 3.3-4

1844 Tapes vitaliana : d’Orbigny, p. 486, pl. 5, figs. 22-25.

1969 Tapes vitalianus d’Orbigny ; Kojumdgieva, p. 52, pl. 17, figs. 11, 16.

1993 Venerupis (Polititapes) vitaliana vitaliana (d’Orbigny) ; Nevesskaya, Goncharova, Paramonova, Popov, Babak, Bagdasaryan and Voronina, p. 187, pl. 46, figs. 5-8.

2013 Polititapes vitalianus (d’Orbigny) ; Neubauer, Harzhauser and Mandic, p. 322.

2013 Polititapes vitalianus (d’Orbigny) ; Schnei- der, Mandic and Harzhauser, p. 195.

Material. 49 specimens from layer 1 (38 left valves, 49 right valves).

Description. Oval-quadrangular shell (LS up to 30.1 mm; HS up to 26 mm; Con. up to 9 mm), large, rather thick-walled, equivalve. Closure of valves is dense. Umbo is high, strongly shifted, and turned towards the anterior edge. The anterior branch of the dorsal edge merges smoothly into a narrowed rounded anterior edge. The posterior branch of the dorsal edge is long, slightly inclined, and with a blunt angle, merging into a widely rounded posterior edge. Ventral edge convex merges smoothly into adjacent edges without visible angles. The valves are inequilateral, slightly convex. There is a very weak rounded keel located in the direction from the umbo to the lower posterior corner. However, a keel may be absent. Growth lines are clearly visible, they become rougher downwards, and coarser growth stop lines are also clearly visible. Coloration in the form of horizontal zigzag-like bands can rarely remain on the shells. Nymph occupies about half of the posterior branch of the dorsal edge.

Hinge area is wavy curved. Hinge is massive. Both, the right and the left valves consists of three cardinal teeth, lateral teeth are absent. The central tooth is most developed, larger than others, divided by a shallow groove. The anterior tooth of the right valve and the posterior of the left valve are smaller; a groove may be developed. The posterior tooth of the right valve and the anterior tooth of the left valve are the weakest; a groove is absent.

The inner surface of the shell shows a clear pallial line, the sinus reaches the posterior third of the shell. Muscular scars are oval, deep, and approximately equal in size. Small oval-rounded muscular scars arranged in a semicircle are clearly visible under the umbo.

Region of distribution and age. Middle-Late Miocene of Europe, Western and Central Ciscaucasia (Nevesskaya et al., 1993).

Figures

FIGURE 3. Assemblage of the Middle Sarmatian (Bessarabian) marine bivalves (layer 1). 1-2, Polititapes ponderosa (d’Orbigny, 1844). 3-4, Polititapes vitaliana (d’Orbigny, 1844). 5-6, Sarmatimactra fabreana (d’Оrbigny, 1844). 7-8, Obsoletiformes obsoletum ingratum (Kolesnikov, 1929). 9-10, Obsoletiformes obsoletum obsoletum (Eichwald, 1830). 11, Plicatiforma fittoni fittoni (d’Orbigny in Murchison et al., 1845). 12-13, Ervilia dissita dissita (Eichwald, 1830).

FIGURE 4. Assemblage of the Middle Sarmatian (Bessarabian) marine gastropods (layers 1 and 2). 1, Acteocina lajonkaireana (Basterot, 1825). 2, Acteocina okeni (Eichwald, 1850). 3, Retusa melitopolitana (Sokolov, 1899). 4, Hydrobia elongata Eichwald, 1830. 5, Pseudamnicola nympha (Eichwald, 1850). 6, Dorsanum duplicata opinabile (Kolesnikov, 1932). 7, Dorsanum corbiana (d’Orbigny, 1844). 8, Dorsanum ignobile (Kolesnikov, 1932). 9, Gibbula (Gibbula) pseudoangulata (Sinzov, 1875). 10, Gibbula (Sarmatigibbula) podolica (Du Bois de Montpéreux, 1831).