Dorsanum duplicata opinabile (Kolesnikov, 1932)

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 : 10

Dorsanum duplicata opinabile (Kolesnikov, 1932)

Figure 4.6

1932 Buccinum opinabile Kolesnikov , p. 84, pl.

2, figs. 17-22.

1935 Buccinum opinabile Kolesnikov ; Kolesnikov, p. 247, pl. 21 figs. 24-26.

2011 Duplicata duplicata opinabile (Kolesnikov) ;

Kravchenko, p. 17.

Material. 34 specimens from layer 1.

Description. Fusiform shell with a pointy apex (HS is 20 mm; WS is 10 mm), moderately high (WS/HS varies from 0.4 to 0.6, usually 0.5), consisting of 6 slightly convex whorls separated by a slightly sloping surface suture. The last whorl is about 0.7 of the shell height (HLW/HS). Aperture is oval, pointed in the upper part (WA/HA is 0.45-0.55), and is about 0.45 of the total shell height (HA/HS). The outer edge of aperture is thin; the inner one is tightly adjacent to the shell. There is a well-developed wide siphonal canal in the lower part of aperture.

The shell surface sculpture appears from the second whorl and consists of radial ribs. It is clearly seen on the upper whorls that they consist of 2-3 rows of tubercles connected by spiral lines. The upper row of tubercles forms a keel inflection. The upper whorls surface above this row is smooth. Starting from the fourth whorl, an additional row of tubercles separated from ribs appears in the suture area.

On the last and penultimate whorls tubercles in ribs are not distinguishable, ribs are weakly Sbended. In the normal position of the shell 6-8 ribs are visible on the last whorl. Adumbilicus is covered by coarse growth lines and separated from the fold of the column by a shaft.

Region of distribution and age. Early and Middle Sarmatian of the Eastern Paratethys (Kolesnikov, 1935).

Figures

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).