Bandelopsis, Fryda, Blodgett, and Stanley, 2003

Monari, Stefano, Valentini, Mara & Conti, Maria Alessandra, 2011, Earliest Jurassic patellogastropod, vetigastropod, and neritimorph gastropods from Luxembourg with considerations on the Triassic-Jurassic faunal turnover, Acta Palaeontologica Polonica 56 (2), pp. 349-384 : 361

Bandelopsis ? sp.

Fig. 8C .

1988. Neritopsis cf. hebertan [sic] d’Orbigny; Meier and Meiers 1988: 26, pl. 2: 6a, b.

Material.— One specimen: MNHNL BR 367, Brouch, Upper Hettangian ( Schlotheimia angulata Zone , Schlotheimia complanata Subzone ).

Dimensions.—See Table 2.

Description.—Neritiform, globose, moderately small−sized shell. Spire composed of about four rapidly expanding whorls. Early spire with relatively high and convex whorls. Last whorls exhibiting a spiral angulation which delimits a wide ramp. Ramp almost flat, slightly inclined, becoming feebly convex on the last whorl. Base globose. Umbilicus absent or reduced to a narrow axial fissure. Aperture subcircular and slightly elongated at the junction of the inner lip with the basal lip. Peristome continuous, with a rather thick parietal lip. Outer lip strengthened by an outer varix and smoothly passing to the inner lip. Inner lip strong, seemingly simple and smooth. Ornament composed of collabral ribs crossed by spiral threads. Collabral ribs originating from peristomal varices. They are prosocline, quite strong, evenly sized and spaced, and tend to fade out towards the upper suture. About ten collabral ribs on the last whorl. Spiral ornament composed of primary spiral threads alternating with secondary spiral threads. During the growth the secondary spiral threads appear into the interspaces between the primary spiral threads. Outer angulation of the ramp bearing a row of nodes. Growth lines prosocline, prosocyrt on the ramp, almost straight on the whorl side, straight to slightly opisthocyrt on the base.

Remarks.—The specimen differs from those ascribed here to Bandelopsis ? cf. exigua ( Terquem, 1855) in having a smaller size, a higher W/H ratio, and a less prominent spire. Moreover, the ramp is narrower and less sloping, and it lacks a spiral ornament. Finally, the collabral ribs are stronger. The presence in the material of a single specimen prevents further comparisons and the determination of the species variability.

Figures

Fig. 8. Neritopsoideans from Brouch (Mersch, Grand−Duchy of Luxembourg), Late Hettangian (Schlotheimia angulata Zone, Schlotheimia complanata Subzone), Early Jurassic. A, B. Bandelopsis? cf. exigua (Terquem, 1855). A. MNHNL BR880, dorsal (A1), and apical (A2) views. B. MNHNL BR700, dorsal (B1), apertural (B2), and apical (B3) views. C. Bandelopsis? sp., MNHNL BR367, apical (C1), apertural (C2), and dorsal (C3) views.