Symmetrocapulus, Dacque, 1934

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 59

Symmetrocapulus ? sp.

Fig. 19H

Material. Specimen MGUH 33082, representing a fragmentary mould.

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

Description. Shell low cap-shaped, apex located close to steep posterior margin. Protoconch 0.7 mm wide, obtusely conical to dome-shaped with at least 1.5 smooth whorls. Protoconch located at apex approximately 1/5 shell length from posterior margin, forming wide, somewhat bulbous beak over short, steep posterior margin. Adult shell thin, sub-circular, smooth, the only sculpture represented by weak, irregular growth lines.

Measurements. MGUH 33082 is 2.6 mm long and 0.8 mm high. The width is unknown but seemingly nearly as great as the length.

Remarks. This taxon differs from the typical Symmetrocapulus by the small size, lack of shell sculpture and the anterior location of the shell apex, and is consequently only tentatively assigned this genus. It may represent the youngest known species of this genus.

Figures

FIGURE 19. A–C. Acmaea selandica n. sp. A. Inner mould of holotype MGUH 33077. Length 5.9 mm. B. Paratype MGUH 33078. Length 2.6 mm. C. Internal mould of paratype MGUH 33079. Length 4.45 mm. D–E. Acmaea? sp. Wax cast of now lost specimen MGUH 33080. Length 19.7 mm. F–G. Cocculina? sp. Silicone cast of MGUH 33081. Exposed length 5.7 mm. H. Symmetrocapulus? sp., external mould MGUH 33082. Length 2.4 mm. I–K. Emarginula coralliora Lundgren, 1867. I–J. Silicone cast of MGUH 33083. Length 2.9 mm, height 1 mm. K. Inner mould of MGUH 33084. Length 7.8 mm. L–Q. Cranopsis cretacea n. sp. L–O. Silicone cast and inner mould of holotype MGUH 33085. Length 3.6 mm, width 2.6 mm. P–Q. Silicone cast and inner mould of paratype MGUH 33086. Length 2.1 mm. R–S. Palaeoloxotoma sp., Silicone cast of MGUH 33087. Length 17.2 mm.