Pyramidella cf. plicosa Bronn, 1838

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 : 349-350

Pyramidella cf. plicosa Bronn, 1838

(Fig. 7 G1-G3)

cf. Pyramidella plicosa Bronn, 1838: 1026 , pl. 40, fig. 24.

cf. Pyramidella plicosa – Landau et al. 2013: 304 , pl. 52, fig. 5 (cum syn.).

MATERIAL EXAMINED. — Sample F11: AMPG ( IV) 2554-2556 (three specimens).

DIMENSIONS. — Maximum height: 5.00 mm, diameter. 2.20 mm.

DISTRIBUTION. — Early Miocene. Proto-Mediterranean Sea: Italy ( Sacco 1892), Greece (this paper).

Middle Miocene. Proto-Mediterranean Sea: Turkey ( Landau et al. 2013); North Sea Basin: Belgium ( Glibert 1952), Denmark, Germany ( Landau et al. 2013), the Netherlands (A.W. Janssen 1984).

Late Miocene. Central Mediterranean: Italy ( Sacco 1892); North Sea Basin: Denmark, Belgium ( Landau et al. 2013).

Early Pliocene. Western Mediterranean ( Landau et al. 2013); central Mediterranean ( Malatesta 1974); North Sea Basin ( Glibert 1958).

Late Pliocene. Central Mediterranean: Italy ( Sacco 1892); North Sea Basin ( Marquet 1998).

Early Pleistocene. Central Mediterranean: Italy (Cerulli-Irelli 1914).

DESCRIPTION

Small, moderately slender, high conical shell; apical angle 30°. Protoconch of type A, partially immersed.Teleoconch consisting of seven, flat whorls with narrowly incised suture, resulting in faintly gradate spire.Transition into convex base weakly angulated. Aperture tear-shaped with 3 columellar folds and a narrow canal.

REMARKS

A complete list of synonymy is provided by Landau et al. (2013). Several varieties have been created due to the morphological variability of the species; the length, the angulation and width of the last whorl, and the strength of the three columellar folds. In the present material, only one protoconch was preserved, of type A and partially immersed, therefore no variability can be observed. There is a variation with size of the columellar teeth of the Greek specimens, the smallest specimen bears more prominent folds in contrary to the largest specimen for which they are moderately developed.

The species differs from Pyramidella grateloupi (d’Orbigny, 1852) from the type region (SW France, Aquitaine) in being more slender, having a less incised suture and having a less cyrtoconoid outline.

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.