Eunerinea? biplicata (Quenstedt, 1858)

Gruendel, Joachim, Keupp, Helmut, Lang, Fritz & Nuetzel, Alexander, 2022, Late Jurassic (Upper Kimmeridgian) Heterobranchia (Gastropoda) of the coral-facies of Saal near Kelheim and the viciniy of Nattheim (Germany), Zitteliana 96, pp. 179-221 : 179

Eunerinea? biplicata (Quenstedt, 1858)

Plate 16: figs 3-9

*1858 - Nerinea biplicata - Quenstedt: 766, pl. 94, fig. 11.

1881-1884 - Nerinea biplicata - Quenstedt: 529, pl. 205, figs 76-77.

Material.

Five specimens from Saal, collection Lang, four of which are illustrated (SNSB-BSPG 2021 XV 75-77, 107).

Description.

The largest fragment is 58 mm high. The shell is slender. The whorls increase regularly in width. The sutures are situated in the middle of a bulge that is formed by two neighbouring whorls. The whorl face is distinctly concave. The whorl face is ornamented with broad, orthocline axial ribs that reach from suture to suture in early whorls but may be reduced on late whorls except of nodes. They are thickened and node-like near the sutures. The whorls are deepened and pit-like between the axial ribs at mid-whorl. Juvenile specimens have two spiral cords between the nodes. The base is flat, smooth, and distinctly umbilicated. The transition from base to whorl face is sharply angulated. Sections show that the aperture is rhomboid and has two columellar plaits, a parietal, a palatal, and a basal plait.

Relationships.

Nerinea or else Cossmannea (Eunerinea) sculpta Étallon sensu Loriol in Loriol and Bourgeat (1886-1888), Cossmann (1898) and Hägele (1997) has stronger and probably also more axial ribs, a more strongly concave whorl face and, according to Loriol, lacks an umbilicus. Nerinea bicincta Bronn sensu Goldfuss (1844) has stronger axial ribs, lacks spiral cords and seemingly also lacks an umbilicus. Nerinea wosinskiana Zeuschner, 1849 has lower whorls, stronger nodes and it allegedly has only two plaits. Nerinea wosinskiana Zeuschner sensu Gemmellaro (1870) has an only weakly concave whorl face, lacks spiral cords and has only a columellar plait. Nerinea haidingeri Peters, 1855 is slenderer, has higher whorls which increase less rapidly in width, lacks spiral cords, has stronger knobs, and lacks an umbilicus. Nerinea incisa Étallon sensu Cossmann (1898) has a slenderer shell, higher whorls, a more distinctly concave whorl face, and more spiral cords; the presence of an umbilicus was not mentioned for that species.

Figures

Plate 16. (1 - 2) Eunerinea? sequana (Bronn ex Thirria, 1836), SNSB-BSPG 2021 XV 74, Saal (collection Lang); (1) lateral view, height 42 mm; (2) base, width 13 mm. (3 - 9) Eunerinea? biplicata (Quenstedt, 1858). (3 - 4) SNSB-BSPG 2021 XV 75, Saal (collection Lang); (3) lateral view, height 36 mm; (4) shell detail, height 17 mm. (5) SNSB-BSPG 2021 XV 76, Saal (collection Lang), oblique view of base, width 16 mm. (6 - 7) SNSB-BSPG 2021 XV 77, Saal (collection Lang), lateral view and section, height 58 mm. (8 - 9) SNSB-BSPG 2021 XV 107, Saal (collection Lang), height 57 mm; (8) columellar section; (9) lateral view showing concave whorl face encrusted by colonial coral. (10 - 13) Eunerinea sp. nov. 1. (10 - 11) collection Sauerborn, Nattheim area; (10) lateral view, height 46.5 mm; (11) aperture, width 10 mm. (12 - 13) Collection Sauerborn, Nattheim area; (12) lateral view, height 120 mm; (13) detail of ornament, height 26 mm. (14) Eunerinea sp. 2; SNSB-BSPG 2021 XV 79 (collection Lang), lateral view, height 32 mm.