Creniturbo gibbosus, Gründel & Nützel, 2024

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

Creniturbo gibbosus sp. nov.

Plate 4: figs 12–15

Etymology.

Latin gibbus – nodes; for the abapical row of large nodes.

Holotype.

SNSB – BSPG 2016 XXI 1738 (pl. 4, figs 14–15), collection Lang.

Paratypes.

6 specimens from Saal ( 4 specimens collection Lang: SNSB–BSPG 2016 XXI 1739 –1742 , 2 specimens collection Sylla: SNSB–BSPG 2016 XXI 1743 –1744 )

Other material.

A questionable specimen from Saal, collection Lang.

Type locality and stratum.

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

Diagnosis.

Shell broadly trochiform, gyroscopic; whorl face slightly concave, with several weak spiral lirae; suture shallow, inconspicuous; edge at transition from whorl face to base with 10–13 large rounded nodes, visible slightly above suture in spire whorls; aperture has circular lumen; tongue-shaped callus covers center of base.

Description.

Only juvenile specimens at hand are relatively well-preserved; fully grown but poorly preserved specimens up to 16 mm wide; shell broadly trochiform, gyroscopic; whorl face slightly concave; edge at transition from whorl face to base with 10–13 large rounded nodes, visible slightly above suture in spire whorls; suture wavy due to nodes; whorl face covered with very faint spiral lirae (usually not visible due to preservation); it is not certain whether spiral lirae are also present on nodes; base slightly convex and set off from whorl face at an angle; growth lines on base opisthocyrt; spiral lirae probably also present on base, but obscured by preservation; aperture has circular lumen, slightly tapering adapically; tongue-shaped callus covers center of base.

Remarks.

Creniturbo dirce (d’Orbigny) , the type species and the only other species assigned to Creniturbo , has a double row of nodes at the basal edge and it has a much stronger spiral cords.

Figures

Plate 4. (1) Heliacanthus sp. 1, SNSB – BSPG 2016 XXI 1726, basal view, width 12 mm. (2–6) Heliacanthus? sp. 2, SNSB – BSPG 2016 XXI 1730, (2, 5) lateral and apical view, width 20 mm, (3) apex in lateral view, height 11 mm, (4) shell detail in lateral view, height 11 mm, (6) detail apical view, width 15 mm. (7) Heliacanthus? sp. 2, SNSB – BSPG 2016 XXI 1731, apertural view, height of aperture 19 mm. (8–11) Nododelphinulidae? gen. and sp. indet., SNSB – BSPG 2016 XXI 1731, (8, 10) lateral and lapical views, width of specimen 17 mm, (9) apex in lateral view, height 10 mm, (11) detail of base, width 14 mm. (12, 13) Creniturbo gibbosus sp. nov. (specimen lost), collection Lang, apical and lateral views. (14, 15) Creniturbo gibbosus sp. nov., holotype, SNSB – BSPG 2016 XXI 1738, (collection Lang), oblique basal and lateral views, width 6.5 mm.