Zebinella selandica, Hansen, 2019

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 96-97

Zebinella selandica n. sp.

Figs 25 S–U

Diagnosis. Shell slender with rounded apex, moderately convex whorls and well defined transverse ribs terminating at the whorl periphery. Transverse ribs numbering around 20 on first teleoconch whorl. Suture line well impressed.

Derivation of name. Refers to the Danish island Sealand from where it derives.

Type material. Holotype MGUH 33162 is a nearly complete external mould.

Additional material. The collections at the Natural History Museum of Denmark includes 11 moulds with the unofficial sample numbers SH.12, SR.730, SR.745, SR.746.A, SR.748.B–C, SR.1043.A, SR.1047, SR.1063, SR.1089.A, SR.1093 and SR.1126.

Type stratum and type locality. Lithified top of the Højerup Member of the upper Maastrichtian Tor Formation at Rødvig, Stevns Klint .

Occurrence. Lithified top of the Højerup Member of the Maastrichtian Tor Formation at Rødvig and Højerup, Stevns.

Description. Shell small to medium-sized, slender with an elongated conical spire. Protoconch obtusely conical, 0.55 mm high and 0.55 mm wide, consisting of approximately 3 ¾ smooth, convex whorls. Transition to teleoconch moderately sharp.

Teleoconch with weakly convex whorls more than twice as wide as high and divided by moderately deeply impressed linear suture located immediately abapically of preceding whorl periphery. Last whorl corresponding to less than half the shell height. Base convex. Aperture slightly flaring with thickened outer lip. Abapical part of aperture and columella not known. Teleoconch sculpture consisting of closely spaced, fine and slightly opisthocline, weakly opisthocyrt transverse ribs reaching from adapical suture to whorl periphery; number of ribs just surpassing 20 on first teleoconch whorl increasing to about 40 on third whorl. Base covered by weak spiral lirae, around nine on third whorl.

Measurements. Holotype MGUH 33162 0.8 mm wide and 2.1 mm high, consisting of protoconch and 3 ½ teleoconch whorls.

Remarks. Zebinella selandica n. sp. differs from the two Selandian taxa figured by Kollmann & Peel (1983) as Zebinella sp. 1 and Z. sp. 2 from Greenland by the teleoconch sculpture with the transverse ribs terminating at the periphery and by the more rounded outline of the spire top. It differs from the Danian Z. nuda Briart & Cornet, 1887 and Z. tenuicancellata Briart & Cornet, 1887 from Belgium by the presence of distinct teleoconch sculpture and well impressed suture line (see Cossmann 1924; Glibert 1973). The lack of both of these characters may indicate that the two Belgian species most likely do not belong to this subgenus.

Figures

FIGURE 25. A–G. Natica sp. A. A–B. Silicone cast of MGUH 33154. Width 7.9 mm. C–D. Silicone cast of MGUH 33155. Width 1.4 mm. E–G. Silicone cast of MGUH 33156. Width 2.1 mm. H–I. Natica sp. B. Silicone cast of MGUH 33157. Width 2.3 mm. J–N. Polinices sp. A. J–L. Silicone cast of MGUH 33158. Width 3.0 mm. M–N. Silicone cast of MGUH 33159. Width 5.2 mm. O–P. Polinices? sp. B. Silicone cast of MGUH 33160. Width 5.0 mm. Q–R. Rissoina? sp., Silicone cast of MGUH 33161. Width 0.6 mm. S–U. Zebinella selandica n. sp., Silicone cast of holotype MGUH 33162. Width 0.8 mm. Width of protoconch 0.55 mm. V. Alvania sp. A. Silicone cast of MGUH 33163. Width 1.2 mm.