Gastropods from the Cretaceous-Palaeogene boundary in Denmark Author Hansen, Thomas text Zootaxa 2019 2019-08-12 4654 1 1 196 journal article 26049 10.11646/zootaxa.4654.1.1 9ce1d103-9234-4fbe-9544-f1c294bb8783 1175-5326 3365803 CFD82CC0-3110-472E-972B-7ADC0C523A04 Mesalia danica n. sp. Figs 23 X–Y 2014 Mesalia sp. Hansen & Surlyk: tab. 3. Diagnosis. Protoconch broad and low with four whorls. Teleoconch spire relatively low with weakly beaded spiral ribs and a smooth, flattened base. Derivation of name. danica (Latin) =Danish. Type material. Holotype MGUH 33135 is a well preserved external mould of the protoconch and teleoconch spire . Paratype MGUH 33136 is an external mould of the protoconch from the same stratigraphic level at Højerup, Stevns Klint . Additional material. Two fragmentary external moulds from the uncatalogued old collections at the Natural History Museum of Denmark , and a complete external mould ( ØSM .10042-335-a and b) from the collections at Østsjaellands Museum. Type stratum and type locality. Lithified top of the Højerup Member of the upper Maastrichtian Tor Formation at Holtug Quarry , Stevns Klint . Occurrence. Lithified top of the Tor Formation at Højerup Church, Mandehoved and Holtug, Stevns Klint. Description. Protoconch low conical, consisting of four smooth whorls with a very tiny initial chamber. Height and width equal, measuring between 0.5 and 0.6 mm . Teleoconch whorls sharply convex with flattened upper shoulder and keel-like periphery. Shoulder carrying three to four secondary spiral ribs, followed by three primary spiral ribs intercalated by two secondary ones around the keel. Spiral ribs crossed by strong opisthocyrt growth lines forming weak, diffuse tubercles at connecting points. Broad growth line sinus located just above keel. Base flattened, smooth. Aperture rounded subrectangular. Measurements. Shell height of MGUH 33135 larger than 4.2 mm and width larger than 2.3 mm . Remarks. Mesalia danica n. sp. differs from other species of this genus by the broad and low protoconch with its four whorls; the relatively compact teleoconch shell and the weakly beaded spiral ribs. It shows some resemblance to the slightly younger Mesalia instabilis ( Briart & Cornet, 1873 ) from the Danian of Belgium , but is separated by the more compact shell with a higher number of spiral ribs and a smooth, flattened base. Mesalia danica n. sp. differs from the Danian M. virginiae Stilwell et al ., 2004 from Antarctica and the Middle Palaeocene Mesalia sp. 1 and Mesalia sp. 2 sensu Kollmann & Peel (1983) from West Greenland by the convex whorls with weak tuberculation. It is distinguished from the Maastrichtian M . ( Woodsalia ) jovisammonis ( Quaas, 1902 ) from Libya by the more compact shell with its tuberculated spiral ribs.