GIBBULA Risso, 1826

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 : 7

Subgenus GIBBULA Risso, 1826

Gibbula (Gibbula) pseudoangulata (Sinzov, 1875)

Figure 4.9 , Figure 8.2

1875 Trochus pseudoangulatus Sinzov , p. 52 [erroneously written Trochus pseudoanulatus ], pl. 4, figs. 17-18.

1935 Trochus pseudoangulatus Sinzov ; Kolesnikov, p. 142-143, pl. 20, figs. 1-3.

2017 Gibbula (Gibbula) pseudoangulata (Sinzov) ; Sladkovskaya, p.1537-1538, pl.

4, figs. 25-27.

Material. 2 specimens from layer 1 and 1 specimen from layer 3.

Description. The shell is conical with a sharp spire (HS is 12 mm; WS is 11 mm), moderately high (WS/HS is 0.85-0.9), consists of seven convex whorls separated by an almost horizontal surface suture. Near-suture very narrow flat areas are visible. The last whorl is about 0.7 of the height of the shell (HLW/HS). Aperture is round, slightly carved by the penultimate whorl (WA/HA is 0.8), and is approximately 0.45-0.55 of the total shell height (HA/HS). The outer edge of aperture is thin; the inner one is thickened. Umbilicus is like a puncture; it can be slightly covered by the inner edge of aperture.

The shell surface sculpture appears after the protoconch and consists of spiral ribs (17 on each whorl). There is a well-developed keel on the periphery of the last whorl. The base of the shell is slightly convex and covered with the same spiral ribs. Growth lines are visible on some shells.

Remarks. The subgenus attribution follows Sladkovskaya (2017).

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).

FIGURE 8. Assemblage of the redeposited Miocene marine and terrestrial molluscs. 1, Dorsanum sp. 2, Gibbula (Gibbula) pseudoangulata (Sinzov, 1875). 3, Anisus cf. spirorbis (Linnaeus, 1758). 4, Blinia cf. angulata (d’Orbigny, 1844). 5, Cardiidae indet. (cf. Obsoletiformes). 6, Cardiidae indet. 7, Barbotella intermedia (Radovanović et Pavlović, 1893).