Dorsanum ignobile (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 ignobile (Kolesnikov, 1932)

Figure 4.8

1932 Buccinum ignobile Kolesnikov , p. 112, pl. 4, figs. 33-36.

1935 Buccinum ignobile Kolesnikov ; Kolesnikov, p. 269, pl. 31, figs. 39-40.

1939 Duplicata ignobile (Kolesnikov) ; Zhizhchenko in Kolesnikov, 1939.

2012 Duplicata ignobile (Kolesnikov) ; O. Anistratenko and V. Anistratenko, p. 122.

Material. 5 specimens from layer 1.

Description. The shell is conical with a pointy apex (HS is 28-30 mm; WS is 16-18 mm), moderately high (WS/HS is 0.6) and consists of 7 slightly convex whorls separated by a slightly sloped surface suture. The last whorl is 0.7-0.75 of the height of the shell (HLW/HS). Aperture is oval, pointed in the upper part (WA/HA is 0.52), and is about 0.5 of the total shell height (HA/HS). The outer edge of aperture is thin; the inner one is tightly adjacent to the shell, forming a thickening. There is a well-developed siphonal canal in the lower part of aperture. Shell surface sculpture appears from the second whorl and consists of radial rows of tubercles connected in ribs. The upper tubercle row forms a keel inflection. The surface of the whorls above the tubercles is smooth. In addition to the keel row one more row of tubercles is usually visible on the spire. Up to four such rows can be traced on the last whorl as well. There are two spiral rows of tubercles on adumbilicus, which form actually the lower part of the radial rows. Adumbilicus is also covered with coarse growth lines.

Region of distribution and age. Middle Sarmatian (Bessarabian) of the Eastern Paratethys (O. Anistratenko and V. Anistratenko, 2012).

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).