Amaea, H. Adams & A. Adams, 1853

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 131

Amaea ? sp. C

Fig. 30E

Material. Specimen ØSM.10042-373 represents a fragmentary external mould of the teleoconch.

Occurrence. The taxon belongs to the Maastrichtian Tor Formation and here probably from the basal Højerup Member or the uppermost Sigerslev Member, where it is cut by the early Danian lithified hardground layer in the northern part of Stevns Klint.

Description. Protoconch unknown. Teleoconch very slender, turriculate, with strongly convex whorls separated by deep suture; whorls 1.6 times as wide as high. Distinct carina delimiting basal disc just visible above abapical suture. Varices narrow and frequent, tending to appear after every whorl.

Teleoconch sculpture reticulate, consisting of more than 30 transverse ribs per whorl, crossed by slightly weak- er spiral threads. Transverse ribs sharp-ridged, opisthocyrt, bending forward adapically; ribs continuing down onto basal disc. Spiral threads close-spaced, numbering around 18 on spire whorls; adapical five to six very weak and closely spaced, succeeding ones stronger, alternating between coarser and finer threads. Connecting points between spirals and transverse ribs marked by weak tubercle. Basal disc covered by fine and closely spaced spiral threads on at least marginal part.

Measurements. Specimen ØSM.10042-373 consists of eight teleoconch whorls and measures 20.2 mm in height and more than 6 millimetres in width.

Remarks. As pointed out by Squires and Saul (2003b) the high frequency of varices is somewhat unusual for taxa belonging to Amaea . Allowing for the lack of the protoconch this taxon seems in all other respects to belong within this genus to which it is provisionally assigned. Amaea ? sp. C has a strong resemblance to Amaea elegans ( Ravn, 1902) from the middle Danian Coral Limestone at Faxe, Denmark. It is readily distinguished by the much finer and close-laying transverse ribs.

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.