Neridomus hemisphaerica (Roemer, 1836)

Gründel, Joachim & Nützel, Alexander, 2024, Late Jurassic (Upper Kimmeridgian) gastropods from Saal near Kelheim (Germany, Bavaria), Zitteliana 98, pp. 19-72 : 19-72

Neridomus hemisphaerica (Roemer, 1836)

Plate 6: figs 3–7

2019 Neridomidae oder Naticidae – Werner: 21, figs 15–16.

2019 Gastropode non det. – Werner: 21, fig. 17.

Material.

10 specimens (illustrated ones SNSB – BSPG 2016 XXI 651 , 1764–1765) from Saal.

Description.

Shell oblique oval in lateral view, somewhat wider than high, with convex whorls; periphery low on whorls; largest specimen 39 mm high; spire very low; very large body whorl, embracing most of previous whorls; sutures very shallow, indistinct; aside from growth lines, no sculpture visible; growth lines prosocline and weakly prosocyrt from adapical suture to center of the base; aperture teardrop-shaped with strongly and asymmetrically convex outer lip and almost straight inner lip; aperture pointed adapically and broadly rounded abapically; callus very wide with a concave-convex outer edge; color patterns of irregular patches preserved on several specimens.

Remarks.

It is possible that Neridomus hemisphaerica is identical with Neridomus sp. 1 as reported by Gründel et al. (2015) that had been only known from two poorly preserved specimens which are smaller and have an approximately evenly convex outer edge of the callus (maybe due to preservation). The numerous described but feature-poor Neridomus species show only few characters and can hardly be reliably distinguished from each other based on the literature. The present assignment to Neridomus hemisphaerica Roemer is not certain. Roemer (1836) described this taxon from the Portlandian. According to his illustrations, the present material could be identical with Roemer’s (1836) taxon. Hardly distinguishable forms have been repeatedly reported from the Upper Jurassic (e. g., Loriol 1881; Loriol in Loriol and Bourgeat 1886); Pčelintsev 1926; Cox 1965; Fischer and Weber 1997).

Figures

Plate 6. (1, 2) Parvulatopsis? sp. 1, SNSB – BSPG 2016 XXI 1759, lateral and apical views, width 12 mm. (3) Neridomus hemisphaerica (Roemer, 1836), SNSB – BSPG 2016 XXI 1764, lateral view, width 33 mm. (4, 5) Neridomus hemisphaerica (Roemer, 1836), SNSB – BSPG 2016 XXI 651, lateral views, height 35 mm. (6, 7) Neridomus hemisphaerica (Roemer, 1836) with color pattern, SNSB – BSPG 2016 XXI 1765, lateral and apical views, width 36 mm. (8–12) Neritopsis? rotundatus sp. nov., holotype, SNSB – BSPG 2016 XXI 1767, (8–10) abapertural, apertural and apical views, width 15 mm, (11) detail in oblique apical view, width 11 mm, (12) basal view, width 15 mm. (13, 14) Wallowiella (Plicaropsis) cancellata (Stahl, 1824) (adult), SNSB – BSPG 2016 XXI 1773, lateral and basal views, width 21 mm.