Pseudorhytidopilus? quadratus sp. nov.

Plate 1: figs 9–11

Etymology.

Latin quadratus – due to the quadratic outline of the shell.

Holotype.

SNSB–BSPG 2016 XXI 1607 (Plate 1: figs 9–10).

Paratypes.

6 specimens SNSB–BSPG 2016 XXI 1608 –1613.

Diagnosis.

Shell thin, with trapezoidal to subquadratic outline with rounded edges in dorsal view; apex approximately in central position; shell ornamented with irregular concentric bulges.

Type locality and stratum.

Upper Jurassic (Kimmeridgian) reefal limestones from the locality Saal near Kelheim, Lower Bavaria (Gründel et al. 2015, 2022).

Description.

Large specimen has a diameter of 21 mm; shell very thin, shallowly cap-shaped in lateral view; trapezoidal (one side of shell slightly narrower than the other side) to subquadratic outline with rounded edges in dorsal view; apex approximately in central position; shell ornamented with irregular concentric bulges.

Remarks.

Species with a similar ornament of bulges (e. g., P.? ledonii (Haber, 1932) sensu Gatto and Monari 2010, Fabercapulus semisculptus Monari et al. 2017) have an elliptic outline in dorsal view and a radial furrow. Other species with an oval outline in dorsal view lack a furrow and an ornament of bulges ( P. latissima (Sowerby, 1816) sensu Munt in Martill and Etches 2020, Berlieria maeotis (Eichwald) sensu Gerasimov, 1992 and others).

Brunonia annulata (Yokoyama, 1890) from the Cretaceous of Japan is also cap-shaped and has a similar ornament but its type species is much larger and has a rounded, oval outline in dorsal view (Kase 1988; Dieni 1990). Patella (Helcion) sculptilis Zittel, 1873 has a straight shell end in lateral view, weak concentric wrinkles and numerous radial ribs.