Vexillum, Roding, 1798

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 140

Vexillum ? sp.

Fig. 31H

Material. A single external mould, MGUH 33264.

Occurrence. Lithified top of the Maastrichtian Højerup Member at Højerup, Stevns Klint.

Description. Protoconch high conical, 1.1 mm high and 1.0 mm wide, consisting of close to four smooth, weakly convex whorls. Transition to teleoconch sharp.

Teleoconch fusiform with moderately convex and high whorls separated by shallow suture. Whorl width corresponding to just over 1.5 times the height. Whorls with pronounced shoulder and adapical restriction, giving the spire a stepped outline. Whorl periphery located slightly abapically of mid-whorl. Last whorl corresponding to approximately 75 % of shell height, ending abapically in short and fairly broad canal. Aperture unknown.

Teleoconch sculpture dominated by 9–10 coarse and rounded costae beginning just below adapical restriction and continuing down onto shell base, where they fade out at transition to canal. Costae crossed by spiral lirae numbering around eight on spire whorls, but covering the whole last whorl evenly. Lirae fading somewhat out on costae, but this may be due to wear. Growth lines very weakly sigmoid.

Measurements. MGUH 33264 is 7.3 mm high and 3.5 mm wide, consisting of protoconch and 2 ½ teleoconch whorls.

Remarks. The taxon looks very similar to the Danien Vexillum ? rosenkrantzi n. sp. described above and more material may perhaps show them to be conspecific. Vexillum ? sp. differs by having four protoconch whorls and a slightly higher number of transverse ribs. The adapical whorl collar may also be slightly more pronounced.

Figures

FIGURE 31. A–C. Vexillum tenestolidum n. sp. A–B. Silicone cast of holotype MGUH 33259. Width of protoconch 0.7 mm. Width of last whorl 3.4 mm. C. Silicone cast of paratype MGUH 33260. Width 5.8 mm. D–G. Vexillum? rosenkrantzi n. sp. D–E. Silicone cast and inner mould of holotype MGUH 33261. Width 1.9 and 1.6 mm respectively. F. Silicone cast of paratype MGUH 33262. Width 3.2 mm. G. Silicone cast of paratype MGUH 33263. Width 2.9 mm. H. Vexillum? sp. Silicone cast of MGUH 33264. Width 3.5 mm. I. Columbarium heberti (Briart & Cornet, 1880). Silicone cast of last whorl MGUH 33265. Width 7.7 mm. Photograph by S.L. Jakobsen. J. Columbarium sp. Silicone cast of MGUH 33266. Width 13.3 mm. K–N. Conomitra glabra (Ravn, 1902). K. Silicone cast of MGUH 33267. Width 3.6 mm. L–M. Silicone cast of MGUH 33268. Width 3.6 and 3.9 mm respectively. N. External cast of syntype MGUH 116. Height 8.2 mm. Photograph by S.L. Jakobsen. O. Volutomitra cf. quinqueplicata Ravn, 1902. Silicone cast of MGUH 33269. Width 11.6 mm. P. Volutomitra quinqueplicata Ravn, 1902. External cast representing last whorl of type specimen MGUH 117. Middle Danien Faxe Formation, Denmark. Height 38.6 mm. Photograph by S.L. Jakobsen. Q–R. Spirancilla milthersii (Ravn, 1902). Q. Silicone cast of holotype MGUH 33270. Width 3.3 mm. R. Silicone cast of MGUH 33271. Width 3.1 mm. S–T. Exilia sp., Silicone cast of MGUH 33272. Width 1.6 mm. U–W. Latiromitra? sp. External cast and inner mould of MGUH 33273. Width 4.6 mm for casts and 4.0 mm for mould.