Pseudomalaxis, Fischer, 1885

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 163

Pseudomalaxis sp.

Figs 35 A–B

Material. MGUH 33306 and three fragmentary specimens with the informal sample numbers SH.9, SR.1080 and SR.1081, all belongs to the Natural History Museum of Denmark.

Occurrence. The specimens were collected from the lithified top of the Tor Formation at Rødvig, Holtug Quarry, Harvig and Højerup Church, Stevns Klint.

Description. Protoconch not preserved. Shell consisting of 3 ½ very slightly widening subrectangular and weakly to moderately convex whorls with two sharply distinct, unbeaded keels located at whorl periphery and umbilical margin respectively. Height and width of whorl largely equal. Umbilical keel is in contrast to the peripheral keel completely free of the following whorl. Shell surface smooth except for a few very indistinct spiral cords and weak growth lines.

Measurements. The most complete specimen, MGUH 33306, is 4.3 mm in diameter with a whorl height of 1.0 mm on the third whorl.

Remarks. This species differs from other species of this genus by the clearly convex spire and the nearly smooth and moderately inflated whorls carrying continuous, unbeaded keels. It resembles somewhat the Late Cretaceous Pseudomalaxis ? stantoni Sohl, 1960 from Tennessee, but differs in the distinctly more angular cross-section of the whorls; the absence of a third spiral cord on the outer whorl face and in the slightly more convex apex.

Figures

FIGURE 35. A–B. Pseudomalaxis sp., Silicone cast of MGUH 33306. Width 4.3 mm. C–D. Climacopoma? sp., Silicone cast of MGUH 33307. Width 13.1 and 9.9 mm respectively. E–I. Mathilda dania n. sp. E. Silicone cast of holotype MGUH 33308. Width 1.9 mm. F. Silicone cast of paratype MGUH 33309. Width 2.0 mm. G. Silicone cast of paratype MGUH 33310. Width 0.8 mm. H. Silicone cast of paratype MGUH 33311. Width 0.7 mm. I. Silicone cast of paratype MGUH 33312. Width 1.7 mm. J–K. Clathrobaculus sp., Silicone cast of MGUH 33313. Width 0.5 mm. L–P. Ringicula sp. L. Silicone cast of MGUH 33314. Width 7.0 mm. M–N. Silicone cast of MGUH 33315 and a partly hidden second specimen. Width 7.3 and 6.6 mm respectively. O–P. Silicone cast of MGUH 33316. Width 5.6, 5.3 mm respectively. Q–T. Cylichna stevniensis n. sp. Q. Silicone cast of holotype MGUH 33317. Width 1.4 mm. R–S. Internal mould of paratype MGUH 33318. Width 1.5 mm. T. Internal mould of paratype MGUH 33319. Width 2.8 mm. U–V. Cylichna? sp. A. Cast of MGUH 33320. Width 2.3, 2.4 mm respectively. W–Y. Cylichna? sp. B. W. Wax cast of MGUH 33321. Width 2.4 mm. X–Y. Inner mould of MGUH 33322. Width 1.3 mm. Z–AE. Roxania sp. Cast of MGUH 33323. Width 3.2, 3.3 mm respectively.