Ditretus sp., cf. rostellaria ( Buvignier, 1852 )

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

Ditretus sp., cf. rostellaria ( Buvignier, 1852)

Plate 9: figs 1–4

? 1931 Ditretus valenensis n. sp. – Yin: 46, pl. 4, figs 1–3.

2019 Ditretus sp. , cf. rostellaria ( Buvignier, 1852) – Gründel, Keupp and Lang: 110, pl. 4, figs 4–7.

Material.

11 specimens, SNSB-BSPG 2016 XXI 1808 –1818.

Description.

The description is based on specimens with relatively stout shell shape; shell acutely trochiform, stout, with few whorls; last whorl higher than spire; a specimen is 23 mm high (apex missing); whorl face of spire whorl low; shell sides straight (side view); whorl face with subsutural row of large, rounded nodes (approximately 10 nodes per whorl) with steep adapical slope producing ramp that accentuates suture; whorls including nodes covered with numerous weak spiral lirae; transition from whorl face to base rounded; nodular spiral cord at transition to base and a weaker one below it are more or less clearly developed (probably intraspecific variation); base also covered with spiral lirae; fully grown specimens with distinctly widened, large and rounded aperture; inner and outer lip strongly thickened and broadened; columellar inner lip is also thickened and somewhat detached; short abapical canal hardly visible in apertural view because canal is almost closed.

Remarks.

Ditretus rostellaria Buvignier, 1852 differs in having whorls that are angulated at a row of nodes, its shell is more slender, the columellar inner lip is neither thickened nor detached according to the illustrations. Diatinostoma germaini Étallon sensu Yin (1931) largely lacks spiral cords and its aperture is unknown. Ditretus valenensis Yin, 1931 is similar (identical?) to the variant with a knobby spiral cord at the transition from whorl face to base. Ditretus thurmanni Loriol in Loriol and Koby sensu Gründel et al. (2022) is more slender and has more whorls.

Figures

Plate 9. (1, 2) Ditretus sp., cf. rostellaria (Buvignier, 1852), SNSB SNSB-BSPG 2016 XXI 1808, (1) lateral view, height 25 mm, (2) detail of ornament, height 12 mm. (3, 4) Ditretus sp., cf. rostellaria (Buvignier, 1852), SNSB-BSPG 2016 XXI 1809, lateral views, height 23 mm. (5) Cryptoptyxis? spinosus sp. nov., holotype, SSNSB-BSPG 2016 XXI 1824, apertural and abapertural lateral views, height 22 mm. (6, 7) Coninoda strekwera Gründel, Keupp & Lang, 2019, SNSB-BSPG 2016 XXI 1827, lateral view and longitudinal section, height 33 mm. (8, 9) Tropacerithium cumaritum Gründel, Keupp & Lang, 2019, SNSB-BSPG 2016 XXI 1830, (8) detail of last whorl, height 4 mm, (9) lateral view, height 7 mm. (10–12) Exelissa? aff. corallense (Buvignier, 1843), SNSB-BSPG 2016 XXI 1835, locality 1985, above coral stock, level 2 (“ Fundort 1985, über Korallenstock, Sohle 2 ”), (10) lateral view, height 12 mm, (11) apex in lateral view, height 5 mm, (12) last two whorls in lateral view, height 7 mm. (13, 14) Exelissa ursicina (Loriol in Loriol and Koby 1889), SNSB-BSPG 2016 XXI 1836, (13) l ateral view, height 10 mm, (14) basal view, width 4.5 mm. (15–17) Turritella lucagrita sp. nov., holotype, SNSB-BSPG 2016 XXI 1840, (15) lateral view, height 75 mm, (16) earliest preserved whorls in lateral view, height 40 mm, (17) last whorls in lateral view, height 46 mm. (18) Nudivagus? sp. 2, SNSB-BSPG 2016 XXI 1844, lateral view, height 35 mm. (19) Neuburgensia angulata sp. nov., paratype, SNSB-BSPG 2016 XXI 1848, collection Lang, last whorl with aperture, height 6 mm.