Ceratia rodvigensis, Hansen, 2019

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 100

Ceratia rodvigensis n. sp.

Figs 26 E–H

Diagnosis. Shell slender with slowly expanding and relatively flat whorls; apex blunt with low, obtusely conical protoconch and first teleoconch whorl; aperture distinctly lenticular. Teleoconch with very weak spiral striation.

Derivation of name. Refers to the type locality Rødvig at the southern end of Stevns Klint, Denmark.

Type material. Holotype MGUH 33167 is an external and internal mould from 10 to 20 cm below the top of the Cerithium Limestone Member at Rødvig . Paratype MGUH 33168 is an external and internal mould from the same locality and stratigraphic horizon as the holotype .

Additional material. ØSM.10042-108 and 16 external and internal moulds in the inofficially catalogued samples SH.140.A–B, SH.274.B, SH.416, SH.456.A–B, SH.479, SS.211.A–B, SR.152.A, SR.275, SR.395, SR.518, SR.591, SR.620.A, SR.628, SR.630 and SR.696.B–C are known from the Cerithium Limestone Member of Stevns Klint. A specimen in sample DN.28.A–B comes from the contemporaneous ‘dead layer’ in Dania Quarry, Northern Jutland. Additionally a single specimen, ØSM.10042-70, from the hardground about two metres above the base of the Korsnaeb Member at Stevns Klint was examined.

Type stratum and type locality. Uppermost part of the lower Danian Cerithium Limestone Member at Rødvig, Stevns Klint .

Occurrence. Ranges from 30 cm above the Cretaceous to the top of the lower Danian Cerithium Limestone Member at Rødvig and up to the hardground in the lower part of the succeeding Korsnaeb Member at Stevns Klint. It is furthermore found in the lower Danian ‘dead layer’ at Dania quarry, Northern Jutland.

Description. Spire blunt with smooth and obtusely conical protoconch consisting of 1 ½ convex whorls; transition to teleoconch rather gradual. Teleoconch with very finely spirally striated and fairly high whorls, the first rather weakly convex, the following becoming more convex with increasingly steeply inclined flanks. Growth lines weak, slightly opisthocline. Suture distinct but not deep.

Measurements. Minute gastropod, the largest specimen from sample SR.628 being just over 2 mm high and 0.95 mm wide and consisting of approximately 6 ½ whorls, protoconch included.

Remarks. Ceratia rodvigensis n. sp. is distinguished from most species belonging to this genus by the low, obtusely conical apex, the relatively flat whorls and the fairly slow whorl expansion. This species may superficially resemble the Palaeocene Ceratia sp. 2 and C. sp. 3 sensu Kollmann & Peel (1983) from Greenland but for the blunt apex and the less deep suture.

Figures

FIGURE 26. A–B. Alvania sp. A. Silicone cast of MGUH 33164. Width 1.5 mm. C. Alvania sp. B. Silicone cast of MGUH 33165. Width 0.8 mm. D. Zebina sp., Wax cast of MGUH 33166. Width 0.9 mm. E–H. Ceratia rodvigensis n. sp. E–F. Silicone cast of holotype MGUH 33167. Width 0.8 mm. G–H. Silicone cast of paratype MGUH 33168. Width 0.9 mm. I–J. Ceratia? sp. I. Mould of MGUH 33169. Width 0.9 mm. J. Silicone cast of MGUH 33170. Height 1.1 mm. K. Anchura sp., Silicone cast of MGUH 33171. Width 8.6 mm. L–M. Columbellaria tuberculosa (Binkhorst, 1861). Silicone cast of ØSM.10042-202-a–c. Width 5.2 mm, height 5.9 mm. N. Tylostoma? sp., inner mould MGUH 33172. Width 19.9 mm. O–P. Cassidae genus et sp. indet. Silicone cast and internal mould of ØSM.10042-315-a–b and c, respectively. Width 9.2 and 8.6 respectively. Q–U. Sassia faxense Ravn, 1933. Q. Detail of apex of MGUH 33173. Width of protoconch 1.4 mm. R. Silicone cast of MGUH 33174. Width 6.0 mm. S. Silicone cast of MGUH 33175. Width 6.5 mm. T. Silicone cast of MGUH 33176. Width 7.8 mm. U. Silicone cast of MGUH 33177. Width 5.2 mm. V–X. Hipponix sp. V–W. Internal mould MGUH 33178. Length 23.8 mm, width 19.5 mm. X. Inner mould MGUH 33179. Width 19.1 mm. Y–Z. Eulima? danica Ravn, 1933. Y. Silicone cast of MGUH 33180. Width 2.5 mm. Z. Silicone cast of MGUH 33181. Width 2.0 mm. AE. Eulima? sp., Mould MGUH 33182. Width 1.3 mm.