Plicatiformes fittoni fittoni (A. d'Orbigny, 1845)

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 : 23

Plicatiformes fittoni fittoni (d’Orbigny in Murchison et al., 1845)

Figure 3.11

1845 Cardium fittoni d’Оrbigny in Murchison, Verneuli and Keyserling, p. 499, pl. 43, figs. 38-39.

1932 Cardium fittoni (d’Оrbigny in Murchison, Verneuli and Keyserling); Davitashvili, p. 25, pl. 7, figs. 18-20.

1935 Cardium fittoni (d’Оrbigny in Murchison, Verneuli and Keyserling); Kolesnikov, p. 115, pl. 17, figs. 10-13.

1955 Cardium fittoni fittoni (d’Оrbigny in Murchison, Verneuli and Keyserling); Merklin, Nevesskaya, p. 49, pl. 11, figs. 1-5.

1969 Cardium (Cerastoderma) fittoni fittoni (d’Оrbigny in Murchison, Verneuli and Keyserling); Kojumdgieva, p. 50, pl. 16, figs. 15-19.

1976 Cerastoderma (Plicatiforma) fittoni fittoni (d’Оrbigny in Murchison, Verneuli and Keyserling); Iljina, Nevesskaya and Paramonova, pl. 2, figs. 3-8.

1993 Plicatiforma fittoni fittoni (d’Оrbigny in Murchison, Verneuli and Keyserling); Nevesskaya, Goncharova, Paramonova, Popov, Babak, Bagdasaryan and Voronina, p. 271, pl. 64, figs. 13-16.

2001 Plicatiformes fittoni fittoni (d’Orbigny in Murchison, Verneuli and Keyserling); Nevesskaja, Paramonova and Popov, p. 179.

Material. 15 specimens from layer 1 (11 left valves,

15 right valves) and 17 specimens from layer 3 (5

right valves, 17 left valves).

Description. Round-triangular shell (LS up to 26 mm; HS up to 28 mm; Con. up to 11 mm), equivalve. Closure of the valves is dense. Umbo is pointed, bent forward and have a central position. The anterior branch of the dorsal edge is almost horizontal and with blunt angle merging into a widely rounded anterior edge. The posterior branch of the dorsal edge forms a well-defined blunt angle with a slightly convex (almost straight) posterior edge. The ventral edge is slightly convex. Valves are almost equilateral, convex. The keel is expressed in the most developed rib.

The shell surface is covered with five well-developed ribs, which have scales and spines. The intercostal distance is much wider than the ribs. In the keel area, weakly developed ribs (radial striae) are visible, reaching the lower edge.

There are two cardinal teeth and one lateral tooth in the hinge of the right valve.

Short nymph is behind the umbo. The pallial line is whole. The scars of the anterior and posterior muscles are round-oval, equal in size. There are grooves corresponding to the ribs on the inner surface.

Region of distribution and age. Late Middle Sarmatian (Late Bessarabian) of the Eastern Paratethys (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).