Cerithidea, Swainson, 1840

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 80-82

Cerithidea ? sp.

Figs 23 L–O

Material. The two external teleoconch moulds MGUH 33129 and MGUH 33130.

Occurrence. Lithified top of the Maastrichtian Højerup Member north of Holtug Quarry, Stevns Klint and from the upper metre of the lower Danian ‘dead layer’ at Vokslev Quarry, Northern Jutland.

Description. Protoconch unknown. Shell high turriform with weakly convex whorls separated by shallow but well marked suture. Whorls twice as wide as high. Periphery located slightly above fairly sharp transition to moderately flat base. Columella fairly short, terminating in rather deep and oblique, narrow siphonal canal. Columellar folds lacking. Growth lines opisthocline, nearly straight.

Teleoconch sculpture on early whorls dominated by around 20 to later 40 low and sharp-ridged, weakly opisthocline transverse ribs. Transverse ribs crossed by seven to nine narrow and weak spiral ribs, abapical most demarcating whorl base. Adapical rib beaded and stronger than succeeding ones, demarcated abapically by relatively wide spiral furrow crossing transverse ribs. Later whorls characterized by fine spiral ribs and furrows fading out centrally on whorl. Base smooth but for weak spiral ribs abaxially.

Measurements. MGUH 33130 measures 3.65 mm in width and 10.1 mm in height, consisting of at least eight teleoconch whorls. The original height was most probably around 11.0 mm.

Remarks. The taxon has an uncharacteristically deep and narrow siphonal canal, but otherwise agrees well with the diagnostic features of the Miocene to Recent genus Cerithidea . It is therefore tentatively assigned here.

Figures

FIGURE 23. A. Arene jakobseni n. sp., Silicone cast of paratype MGUH 33120. Preserved width 8.9 mm. B–E. Ataphrus (Ataphrus) knoesensis n. sp. B–C. Silicone cast of holotype MGUH 33121. Width 4.0 mm. D. Silicone cast of paratype MGUH 33122. Width 4.2 mm. E. Silicone cast of paratype MGUH 33123. Width 3.9 mm. F–H. Cerithium sp. F. Silicone cast of MGUH 33124. Width 10.7 mm. G. Silicone cast of MGUH 33125. Width 9.9 mm. H. Silicone cast of MGUH 33126. Width 10.7 mm. I. Pseudovertagus? sp., Silicone cast of MGUH 33127. Width 1.6 mm. J–K. Striovertagus? sp., Silicone cast of MGUH 33128. Width 2.5 mm. L–O. Cerithidea? sp. L–M. Silicone cast of MGUH 33129. Cast height on figure L 7.4 mm. Cast width on figure M 3.3 mm. N–O. Silicone casts of MGUH 33130. Width 3.7 mm. P–S. Cirsocerithium crassilabris (von Koenen, 1885). P–Q. Silicone casts of MGUH 33131. Width 5.0 mm. R. Lectotype MGUH 865. Upper Palaeocene Lellinge Greensand, Denmark. Height 12.7 mm. Photograph by S. L. Jakobsen. S. Lateral view of MGUH 33132. Upper Palaeocene Lellinge Greensand, Denmark. Width 4.4 mm. T–U. Turritellid genus et sp. indet, Silicone cast of MGUH 33133. Width 1.0 mm. V–W. Turritella cf. plana Binkhorst, 1861. Silicone cast of MGUH 33134. Whorl width at least 17.2 mm. Height of last whorl 17.8 mm. X–Y. Mesalia danica n. sp. X. Silicone cast of holotype MGUH 33135. Width 2.2 mm. Y. Silicone cast of paratype protoconch MGUH 33136. Width 0.7 mm. Z. Mesalia sp., Silicone cast of MGUH 33137. Width 0.6 mm. AE. Tenagodus sp., Silicone cast of MGUH 33138. Width 4.3 mm.