Cylichna, Loven, 1846

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 168

Cylichna ? sp. B

Figs 35 W–Y

2014 Cylichna sp. B Hansen & Surlyk: tab. 3.

Material. MGUH 33321, MGUH 33322 and two incomplete moulds with informal sample numbers SR.784.A–B and SR.990.B–C, all from the collections of the Natural History Museum of Denmark.

Occurrence. Lithified top of the Maastrichtian Højerup Member at Rødvig, Harvig and Stevns Fyr, Stevns Klint.

Description. Shell involute, bulbous ovoid with small, shallow spire pit not showing more than latest whorl. Aperture moderately narrow, higher than penultimate whorl. No columellar folds are present on juvenile specimen MGUH 33322. Teleoconch sculpture absent.

Measurements. Largest shell, MGUH 33321, 3.7 mm high and 2.4 mm wide.

Remarks. This taxon is distinguished from the other Danish cylichniid boundary taxa by the bulbous shell, which may not have a columellar fold. The lack of a columellar fold may, though, be due to the undeveloped juvenile condition of the studied specimen.

Figures

FIGURE 35. A–B. Pseudomalaxis sp., Silicone cast of MGUH 33306. Width 4.3 mm. C–D. Climacopoma? sp., Silicone cast of MGUH 33307. Width 13.1 and 9.9 mm respectively. E–I. Mathilda dania n. sp. E. Silicone cast of holotype MGUH 33308. Width 1.9 mm. F. Silicone cast of paratype MGUH 33309. Width 2.0 mm. G. Silicone cast of paratype MGUH 33310. Width 0.8 mm. H. Silicone cast of paratype MGUH 33311. Width 0.7 mm. I. Silicone cast of paratype MGUH 33312. Width 1.7 mm. J–K. Clathrobaculus sp., Silicone cast of MGUH 33313. Width 0.5 mm. L–P. Ringicula sp. L. Silicone cast of MGUH 33314. Width 7.0 mm. M–N. Silicone cast of MGUH 33315 and a partly hidden second specimen. Width 7.3 and 6.6 mm respectively. O–P. Silicone cast of MGUH 33316. Width 5.6, 5.3 mm respectively. Q–T. Cylichna stevniensis n. sp. Q. Silicone cast of holotype MGUH 33317. Width 1.4 mm. R–S. Internal mould of paratype MGUH 33318. Width 1.5 mm. T. Internal mould of paratype MGUH 33319. Width 2.8 mm. U–V. Cylichna? sp. A. Cast of MGUH 33320. Width 2.3, 2.4 mm respectively. W–Y. Cylichna? sp. B. W. Wax cast of MGUH 33321. Width 2.4 mm. X–Y. Inner mould of MGUH 33322. Width 1.3 mm. Z–AE. Roxania sp. Cast of MGUH 33323. Width 3.2, 3.3 mm respectively.