Fusinus schnetleri, Hansen, 2019

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 135-136

Fusinus schnetleri n. sp.

Figs 30 L–M

Diagnosis. Teleoconch moderately slender with eight strongly convex and rounded transverse ribs per whorl, the ribs forming weak rounded shoulder. Transverse ribs crossed by sharp spiral riblets with moderately broad interspaces.

Derivation of name. In honour of K.I. Schnetler, who has contributed much to our knowledge of the Cainozoic gastropod faunas from Denmark.

Type material. Holotype MGUH 33251 is an external and internal mould lacking protoconch . Paratype MGUH 33252 is a teleoconch from the dead layer in Dania Quarry , Northern Jutland .

Additional material. Five external moulds from Stevns Klint are located in the collections of the National History Museum of Denmark. A mould catalogued by the informal sample number DN.9.A–B comes from Dania Quarry, Northern Jutland. Another three specimens from the same locality and belonging to the private collection of K.I. Schnetler have been examined.

Type stratum and type locality. Cerithium Limestone Member south of Stevns Fyr , Stevns Klint .

Occurrence. Sporadically occurring in the Cerithium Limestone Member along the southern part of Stevns Klint (Skeldervig to slightly south of Stevns Fyr) and contemporaneous dead layer in Dania Quarry, Northern Jutland.

Description. Protoconch unknown. Teleoconch moderately high-spired, consisting of weakly convex whorls; whorls low, their height corresponding to nearly half their width. Narrow suture located in distinct angle between succeeding whorls, or slightly below widest part of preceding whorl. Height of last whorl corresponding to around 60 % of shell. Aperture elongated ovoid with moderately gradual transition to narrow siphonal canal. Inner and outer lips and columella smooth, with no folds.

Teleoconch sculpture dominated by around eight strong, rounded transverse ribs partly aligned from whorl to whorl. Ribs giving the whorls a more convex outline. Interstices wider than ribs. Spiral riblets strong and sharp; strongest and least crowded four ribs running at whorl periphery. Around four smaller ribs are located between these and adapical suture on some specimens, while others have fewer and stronger ribs. Transverse ribs fading out at transition to base, which is dominated by close lying spiral riblets, becoming gradually finer towards distal end of canal.

Measurements. Most complete specimen, MGUH 33252, 13.6 mm high and 6.2 mm wide, consisting of initial six teleoconch whorls, but lacking tip of siphonal canal.

Remarks. This taxon differs from the middle Danian Fusinus faxensis ( Ravn, 1902) from Faxe Quarry, Denmark, by the slightly stronger and more closely spaced transverse ribs and the less crowded spiral riblets. It resembles the Early Palaeocene Fusinus sp. (sensu Kollmann & Peel 1983) from Greenland, but differs by a less tapering siphonal canal and a slightly more compact spire.

It appears distinctly more common in the ‘dead layer’ of Northern Jutland than in the Cerithium Limestone of Stevns Klint, suggesting a preference for a more deep-water and muddy environment than inhabited by most of the gastropods from the Danish area.

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.