Acteon cf. pinguis d’Orbigny, 1852

Thivaiou, Danae, Harzhauser, Mathias & Koskeridou, Efterpi, 2019, Early Miocene Gastropods from the Felli Section (Proto-Mediterranean Sea NW Greece), Geodiversitas 41 (8), pp. 323-366 : 346

Acteon cf. pinguis d’Orbigny, 1852

(Fig. 7 B1, B2)

cf. Acteon pinguis d’Orbigny, 1852 : no. 521, 36. — Peyrot 1932: 157, no. 1376, pl. 11, figs 55-57, pl. 14, figs 12, 13. — Lozouet et al. 2001: 79. — Harzhauser 2002: 125, pl. 12, fig. 7.

MATERIAL EXAMINED. — Sample F10: AMPG ( IV) 2479-2481 (three specimen); sample F11: AMPG ( IV) 2482, 2483 (two specimens); sample F12: AMPG ( IV) 2484-2487 (four specimens) .

DIMENSIONS. — Maximum height: 1.85 mm.

DISTRIBUTION. — Early Miocene. Aquitanian. NE Atlantic: France (Aquitaine Basin) ( Peyrot 1932; Lozouet et al. 2001); Proto-Mediterranean: Greece (this paper). — Burdigalian. NE Atlantic: France (Aquitaine Basin) ( Peyrot 1932); Paratethys: Austria (Harzhauser 2002).

DESCRIPTION

Juvenile and incomplete specimens with intorted smooth protoconch.Apical angle of 55°.Two teleoconch whorls, sculpture typi- cal with regularly-spaced pitted grooves, suture deeply impressed; aperture tear-drop shaped, no umbilicus, outer lip regularly convex.

REMARKS

A single species of ‘ Acteon ’ has been found, represented mainly by juveniles. The sculpture, apical angle coincide with those of A. pinguis but the juvenile and incomplete specimens does not allow a clear identification. Variation in sculpture consists of the grooves that bear less prominent pits and have a smoother aspect abapically. The last whorl of the specimens observed has slightly deeper grooves which could possibly be a feature dominating the sculpture of later whorls.

The shape of the shell and the convexity of the whorls are reminiscent of Acteon semistriatus (Férussac, 1822) . The sculpture and overall morphology of the recovered specimens is most similar to A. pinguis d’Orbigny, 1852 . Nevertheless, the protoconch seems slightly wider and less inflated, which could be due to intraspecific variability. Moreover, specimens recovered show various traces of predation from molluscs and possibly decapods.

Figures

FIG. 7. — A1-A3, Mathilda sp., AMPG(IV) 2478; B1, B2, Acteon cf. pinguis d’Orbigny, 1852: B1, AMPG(IV) 2479 (SEM image); B2, AMPG(IV) 2479, detail of microsculpture (SEM image); C1, C2, Ringicula minor (Grateloup, 1838), AMPG(IV) 2488; D1-D3, Retusa truncatula (Bruguière, 1792): D1, D2, AMPG(IV) 2541; D3, AMPG(IV) 2542 (SEM image); E1, E2, Pyrunculus sp., AMPG(IV) 2545; F1, F2, Volvulella acuminata (Bruguière, 1792), AMPG(IV) 2547; G1-G3, Pyramidella cf. plicosa Bronn, 1838: G1, G2, AMPG(IV) 2554; G3, AMPG(IV) 2555 (SEM image); H1-H3, ‘Odostomia’ sp. 1, AMPG(IV) 2557; H3, AMPG(IV) 2557 (SEM image); H4, AMPG(IV) 2557, apex (SEM image). Scale bars: A1-A3, C1, C2, E1, E2, F1, F2, G1, G2, H1, H2, 1 mm; B1, 200 µm; B2, H4, 100 µm; D1, D2, H3, 500 µm; D3, G3, 400 µm.