Gantechinobathra vulcani ( Brongniart, 1823 )

Islamoğğlu, Yeşşim, Dominio, Stefano & Kowalke, Thorsten, 2011, Early Eocene Caenogastropods (Mollusca, Gastropoda) from Haymana-Polatl Basin, Central Anatolia (Turkey): taxonomy and palaeoecology, Geodiversitas 33 (2), pp. 303-330 : 320

Gantechinobathra vulcani ( Brongniart, 1823) ( Fig. 6 K-M)

Terebra vulcani Brongniart, 1823: 67 , pl. 3, fig. 11. Cerithium vapincense – d’Orbigny 1850: t. 2, 367, fig. 588.

Cerithium (Potamides) vulcani – De Gregorio 1896: 72, pl. 8, fig. 31.

Cerithium vulcani – Boussac 1911: 305, 306.

MATERIAL EXAMINED. — Five specimens, MTA- Y. İ.-2007 -54 to 58.

LOCALITY AND HORIZON. — Grey siltstone, KIrkkavak Formation (Macunköy: samples G2, G3).

PALAEOGEOGRAPHIC DISTRIBUTION. — Nigeria: Early Eocene; Romania, Hungary: Lutetian; Roncà ( Italy): Bartonian.

DESCRIPTION

Shell is medium to large sized, wide-conical shaped with 30 ° apical angle bearing more than six flat whorls. The ornamentation of each whorl consist of prominent, thick, wide-spaced and slightly orthocline axial ribs lined up together. They attain their maximum strength in the posterior part of the whorls.Up to seven blunt axial ribs are accompanied by huge varices causing an angular outline of the shell and angular outline of the apertural margin. Axial ribs run by spiral cords which become thicker in the last whorl. Last whorl more convex and rounded in the posterior, but having angular corner in the anterior side. Aperture is narrow, diagonal, quadrangular-ovate, siphonal canal is short.

REMARKS

Our samples have been compared to the specimens of Gantechinobathra vulcani from Roncà, Italy (MNHN.F.B22659). On first appearance, the pyramidial shape and flat whorls are very similar to those of Pyrazus pyramidatus Deshayes, 1833 from the Cuisian of the Paris Basin ( Cossmann & Pissarro 1910: t.2, pl. 29, fig. 151-2). However, it differs by its wider conical angle and clear difference between spire and last whorl width. Cerithium fodicatum Bellardi, 1852 from the Late Eocene (Auversian) of Turin Basin ( Italy) displays similar strong axial ribbing. However, its apex angle is smaller, axial ribs are convex and not lined up one with the other whorls ( Bellardi 1852: t. 4, 226, pl. 14, fig. 10; Boussac 1911: 289, pl. 17, figs 55, 56). On the other hand our specimens also closely resemble those of the samples from Early Eocene units of Nigeria (MNHN.F.B44487).

Figures

FIG. 6. — Caenogastropods (deposited in the repositories of the General Directorate of Mineral Research and Exploration, Ankara): A, Cerithium puigcercosensis (Cossmann,1897) n. comb.;B-F, Vicinocerithium cf.subacutum (d’Orbigny,1850); G, S, Bellatara ankaraensis n. sp., holotype;H, I, Tympanotonos turris (Deshayes,1833); J, Cerithium cf.anguloseptum Rauff,1884; K-M, Gantechinobathra vulcani (Brongniart, 1823); P-R, “Crommium” sp. 2. Scale bars: 1 cm.