Bittium larrieyense Vignal, 1911

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 : 331

Bittium larrieyense Vignal, 1911

(Fig. 4 A1-A3)

Bittium vignali var. larrieyensis Vignal, 1911: 160 , pl. 8, fig. 19.

Bittium vignali – Vignal 1911: 158 , pl. 8, fig. 18. — Cossmann & Peyrot 1922: 284, no. 615, pl. 7, figs 31, 32, 47-50.

Bittium reticulatum – Vignal 1911: 157 .

Bittium asperulatum – Cossmann & Peyrot 1922: 288, no. 618, pl. 7, figs 66-69.

Bittium larrieyense – Lozouet et al. 2001: 24, pl. 6, figs 6a-c.

MATERIAL EXAMINED. — Sample F10: AMPG ( IV) 1607-1645 (39 specimens); sample F11: AMPG ( IV) 1646-1890 (245 specimens) ; sample F12: AMPG ( IV) 1891-2071 (181 specimens) .

DIMENSIONS. — Maximum height: 3.80 mm.

DISTRIBUTION. — Early Miocene. Aquitanian. NE Atlantic in France ( Cossmann & Peyrot 1922; Lozouet et al. 2001) and Greece (this paper). —?Burdigalian. NE Atlantic in France ( Cossmann & Peyrot 1922).

DESCRIPTION

Turreted shell, minute, with six slightly convex teleoconch whorls. Protoconch of 225-250 µm in diameter, consisting of 2.5 whorls; first whorl low conical, convex; second whorl with mid-whorl angulation coinciding with weak spiral cord. Two faint spiral threads appear close above the abapical suture. Transition into teleoconch marked by deep sinusigera above angulation. Early teleoconch starts with two prominent spiral cords, a third cord appears on the second teleoconch whorl and a fourth on the fifth; regularly spaced axial ribs form pointed nodes at intersections with spiral cords. Broad varix formed on last (preserved) whorl. Microsculpture consisting of spirally arranged small granules, present on entire teleoconch.Sutures linear, impressed.Sculpture very constant, with a fourth spiral cord always forming between the first (adapical) and the second cords on the fifth whorl. A sixth spiral cord forms on the sixth whorl above the abapical suture; for the largest specimens more cords form with new ones added always above the abapical suture. Base with two additional spiral cords; aperture drop-shaped, siphonal canal short.

REMARKS

The specimens available are fragmentary; the largest fragment consists of eight teleoconch whorls. The shape can vary in width and whorl height; when present, tubercules are not numerous and not very prominent. Whorls are more convex for wider specimens, with an illusion of deeper sutures due to relatively more prominent sculpture.

This species is the most abundant in all the marine beds of Felli. Previously, it was only known from the Early Miocene of France. Morphologically, the Greek specimens are almost identical to the French type and specimens of collection, thus showing stability in the morphological characters and their variation.

The high variability of this species led to the description of several species and variations by Vignal (1911) and Cossmann & Peyrot (1922), such as B. vignali Dollfus, 1909 , Bittium subclathratum (d’Orbigny, 1852) and Bittium asperulum Cossmann & Peyrot, 1922. As discussed by Lozouet et al. (2001) these taxa seem to represent only morphotypes of B. larrieyense .

Figures

FIG. 4. — A1-A3, Bittium larrieyense Vignal, 1911: A1, AMPG(IV) 1891 (SEM image); A2, A3, AMPG(IV) 1646; B1-B3, Granulolabium plicatum (Bruguière, 1792): B1, AMPG(IV) 2089 (SEM image); B2, B3, AMPG(IV) 2167; C1-C3, Gibborissoia varicosa (de Basterot, 1825): C1, AMPG(IV) 2239 (SEM image); C2, C3, AMPG(IV) 2240; D, Mesohalina margaritacea (Brocchi, 1814), AMPG(IV) 2294 (SEM image); E1-E3, Terebralia lignitarum (Eichwald, 1830), AMPG(IV) 2304; F1-F3, Terebralia subcorrugata d’Orbigny, 1852, AMPG(IV) 2306; G1-G4, Finella perpusilla (Grateloup, 1827): G1, G2, AMPG(IV) 2308; G3, AMPG(IV) 2309 (SEM image); G4, AMPG(IV) 2309, protoconch (SEM image); H1-H4, Turritella turris de Basterot,1825:H1, H2, AMPG(IV) 2404;H3, AMPG(IV) 2405 (SEM image); H4, AMPG(IV) 2405, protoconch (SEM image). Scale bars: A1, C2, C3, G1, G2, H1-H3, 500 µm; A2, A3, D, 1 mm; B1, G3, C1, 400 µm; B2, B3, 5 mm; E1-E3, 10 mm; F1-F3, 2 mm; G4, H4, 200 µm.