Ringicula, Deshayes in Deshayes & Milne-Edwards, 1838

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 165

Ringicula sp.

Figs 35 L–P

Material. MGUH 33314, MGUH 33315, MGUH 33316, and an additional specimen sitting together with MGUH 33315.

Occurrence. The lower Danian ‘dead layer’ exposed in the Dania Quarry, Northern Jutland.

Description. Protoconch apparently conical in outline, 0.8 mm wide with smooth, convex whorls separated by deep suture.

Teleoconch low spired, rotund with flattened, adpressed spire whorls; whorls nearly four times as wide as high. Last whorl evenly convex all the way to anterior canal, taking up more than 80 % of shell height. Aperture narrow, outer lip strengthened by strong varix reaching from anterior canal to adapical suture of transition between last whorl and penultimate whorl. Outer lip carrying five stronger, elongated teeth on abapical part, succeeded adapically by several more, but very weak teeth fading out completely adapically. Inner lip with moderately wide callus and two sinuses separated by a strong and furrowed ridge. Adapical parietal region carrying strong but low and ridged transverse thickening of the shell.

Teleoconch sculpture consisting of around 20 moderately weak spiral grooves, which continue onto the varix.

Measurements. Most complete specimen MGUH 33314 is 6.0 mm wide and more than 6.9 mm high, but lacking anterior canal and protoconch apex. It consists of the final protoconch whorl and 3 ½ teleoconch whorls.

Remarks. This species differs from the Danian Ringicula pinguis Glibert, 1973 from Belgium by the much more rotund outline, adpressed whorls and furrowed lower ridge on the inner lip. It differs from the Campanian R. abundanta Kiel & Bandel, 2001a and R. multidentata Kiel & Bandel, 2001a from Spain by the rotund shape and from the latter also by a different tooth pattern on the outer lip. It differs from the Palaeocene R. erratica Roedel, 1937 from Northern Europe by its lower spire and more flattened spire whorls.

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.