Leucorhynchia, Crosse, 1867

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 75

Leucorhynchia sp.

Figs 22 J–K

Material. Specimen MGUH 33115 is an incomplete external mould.

Occurrence. Lithified top of the Højerup Member of the Maastrichtian Tor Formation at Holtug Quarry, Stevns Klint.

Description. Shell very low trochiform with flattened spire. Nearly planispiral protoconch 0.55 mm wide, consisting of approximately two smooth and only slowly widening flat whorls; whorls separated by deep sutures. Transition to teleoconch not visible.

Teleoconch with around two fairly rapidly widening, adapically flattened whorls. Deep suture situated just above sharply rounded periphery of preceding whorl. Base weakly convex. Aperture and umbilical area unknown. Teleoconch sculpture consisting of a single distinct adapical furrow.

Measurements. Specimen MGUH 33115 is 1.6 mm high and at least 2.4 mm wide, consisting of 3 3/4 whorls.

Remarks. This taxon differs from the middle Danian Leucorhynchia marginata Ravn, 1933 from Denmark by a slightly higher shell and lower protoconch, but seems otherwise quite similar.

Figures

FIGURE 22. A. Phorcus sp., Silicone cast of MGUH 33109. Exposed width 2.2 mm. B–C. Stomatella sp., External mould of MGUH 33110. Figure B has been colour inverted and mirrored to show it in positive. Width 1.5 mm. D–F. Solariella sp. D–E. Silicone cast of MGUH 33111. Width 6.2 mm. F. Silicone cast of aperture of MGUH 33112. Width 5.95 mm. G–I. Skenea sp. G–H. Inner mould of MGUH 33113. Width 5.2 mm. I. Inner mould of MGUH 33114. Width 10.2 mm. J–K. Leucorhynchia sp., Silicone cast of MGUH 33115. Width 2.4 mm. L–N. Tectus? indecorus n. sp., L. Umbilical view of inner mould of paratype ØSM.10042-327-b. Width 19.7 mm. M–N. Silicone cast of holotype MGUH 33116. Width 1.7 mm. O–P. Homalopoma sp., Silicone cast and inner mould of MGUH 33117. Width 9.6, 6.9 mm respectively. Q. Calliomphalus (Calliomphalus) sp., Silicone cast of MGUH 33118. Width 3.1 mm. R–U. Arene jakobseni n. sp. R–T. Silicone cast of holotype MGUH 33119. Width 8.6 mm. U. Silicone cast of paratype MGUH 33120. Width of aperture 4.8 mm.