Latiromitra, Locard, 1897

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 146

Latiromitra ? sp.

Figs 31 U–W

Material. A single external and internal mould, MGUH 33273.

Occurrence. Extremely rare in the Cerithium Limestone Member. Skeldervig at Stevns Klint.

Description. Protoconch with low dome-like apex; composed of between 1 and 3 smooth whorls. Transition between protoconch and teleoconch not pinpointed, but located at change in spire angle around 1 and 1 ½ whorls from apex or at beginning of weak spiral three whorls from apex.

Teleoconch moderately slender, the whorls flattened with narrow shoulder demarcating deep adapical suture. Whorl height just surpassing whorl width. Aperture narrow with adapical channel, smooth outer lip and two moderately developed and widely spaced columellar folds; aperture and short siphonal canal corresponding to just over a third of the shell height.

Teleoconch sculpture dominated by 14–16 low but sharp, weakly opisthocline and opisthocyrt transverse ribs per whorl, disappearing on last whorl. Spiral sculpture consisting of two adapical spiral cords and furrows and additional spiral cords on siphonal part of last whorl. Indistinct growth lines very weakly sigmoid, adapically following pattern of transverse ribs.

Measurements. The nearly complete specimen MGUH 33273 is 12.9 mm high and 4.6 mm wide, consisting of nine whorls in total.

Remarks. This specimen with its fusiform shell and predominantly axial sculpture shouldered at intersection between axial ribs and spiral cord (see Bouchet & Kantor 2000), closely resembles species in the genus Latiromitra Locard, 1897 , to which it is tentatively assigned. More knowledge of the aperture and protoconch is needed for a confident assignment.

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.