Latirulus, Cossmann, 1889

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 137-138

Latirulus ? sp.

Figs 30 R–T

Material. MGUH 33255 , MGUH 33256 , a mould in the informally catalogued sample SH.287.A–B, and three fragmentary external and internal moulds without numbers are found in the collections of the Natural History Museum of Denmark. Of the latter three two have been collected by A. Rosenkrantz at Skeldervig (22–28 July 1943) and Rødvig (1924), while the third was collected by S, B. Andersen at Holtug (21 July 1970) .

Occurrence. A rare species occurring in the Cerithium Limestone Member from Stevns Klint, and in the contemporaneous ‘dead layer’ at Vokslev, Northern Jutland.

Description. Protoconch low conical with 2 ½ apparently smooth and moderately convex whorls.

Teleoconch spire moderately slender with strongly convex whorls and a fairly shallow sinuous suture. Siphonal canal at least as high as aperture. Outer lip of aperture smooth. Columella carrying four weak columellar folds arranged two and two.

Teleoconch sculpture dominated by strong and moderately narrow transverse ribs with no constriction at adapical suture. Ribs numbering 9 or 10 on early whorls, becoming fewer on later whorls. Transverse ribs crossed by very strong and sharp spiral cords, adapical three weaker than succeeding ones on whorl periphery. Peripheral spiral cord, generally number four from adapical suture, widest and most pronounced, succeeded by two slightly weaker cords abapically on spire whorls. Spiral cords coarse on base. Growth lines nearly orthocline, with weak prosocyrt sinus at adapical suture.

Measurements. Protoconch measures 0.65 mm in width and 0.65 mm in height on MGUH 33255.

Remarks. The assignment to Latirulus is very tentative due to the presence of four instead of three columellar folds, and as many as 2 ½ protoconch whorls.

Figures

FIGURE 30. A–B. Amaea sp.A. Details of protoconch on external mould of MGUH 33242 shown in natural view and mirrored with inverted colours. Width of protoconch 0.6 mm. C–D. Amaea sp. B. C. Silicone cast of protoconch MGUH 33243. Width 0.6 mm. D. Silicone cast of protoconch MGUH 33244. Width 0.4 mm. E. Amaea? sp. C, Silicone cast of ØSM.10042-373. Width 5.5 mm. F–G. Acirsa torensis n. sp. F. Silicone cast of holotype MGUH 33245. Width 0.8 mm. G. Silicone cast of paratype MGUH 33246. Width 1.1 mm. H. Acirsa sp., Silicone cast of MGUH 33247. Height 6.2 mm. I–K. Opaliopsis carlsbergi n. sp. I. Silicone cast of holotype MGUH 33248. Height 2.2 mm. J. Silicone cast of paratype MGUH 33249. Height 1.7 mm. K. Silicone cast of paratype MGUH 33250. Height 3.0 mm. L–M. Fusinus schnetleri n. sp. L. Silicone cast of holotype MGUH 33251. Height 23.9 mm. M. Silicone cast of paratype MGUH 33252. Height 13.4 mm. N–O. Streptochetus sp. A. Silicone cast of MGUH 33253. Width of figure N 2.7 mm. Width of teleoconch 3.5 mm. P–Q. Streptochetus? sp. B. Silicone cast of MGUH 33254. Teleoconch width 2.6 mm.Width of protoconch 0.6 mm. R–T. Latirulus? sp. R–S. Silicone cast of MGUH 33255. Width of protoconch 0.7 mm. Height of teleoconch 10.5 mm. T. Silicone cast of MGUH 33256. Width 3.7 mm. U–W. Dolicholatirus lorenzi n. sp. U. Silicone cast of holotype MGUH 33257. Height 30.8 mm. V–W. Silicone cast of paratype MGUH 33258. Width of teleoconch 5.5 mm. Width of protoconch 0.7 mm. X. Vexillum tenestolidum n. sp., Silicone cast of holotype MGUH 33259. Width of teleoconch 4.3 mm.