Vermetus, Daudin, 1800

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 107

Vermetus sp.

Figs 27 C–E

Material. MGUH 33184 , MGUH 33185 , MGUH 33186 , ØSM.10042-134-a, ØSM.10042-187, ØSM.10042-188, ØSM.10042-386, ØSM.10042-388-b and ØSM.10042-393. The collection of the Natural History Museum of Denmark furthermore contains several specimens lacking numbers. These may be grouped into 14 very fragmentary external teleoconch moulds from the upper Maastrichtian Højerup Member (samples: SH.4, SR.773, SR.914, SR.921, SR.924.A, SR.1039, SR.1067.A–B, SR.1069.A–B, SR.1086.A–B, SR.1091.B, SR.1092.A–B, SR.1105, SR.1107, SR.1114.A) and 52 fragmentary moulds from the Lower Danian Cerithium Limestone Member (informal sample numbers: SH.80.B, SH.84, SH.149.B–C, SH.169.A, SH.174, SH.191, SH.234, SH.254, SH.277, SH.297.A–B, SH.302.A, SH.415.B, SH.454, SH.455, SH.458.A–B, SH.468.A, B, SH.483.A–B, SH.483.B–C, SR.143, SR.146, SR.189, SR.211.A–B, SR.250, SR.253, SR.281 (2 specimens), SR.285, SR.291, SR.295, SR.312, SR.331, SR.372, SR.383, SR.384, SR.389.A–B, SR.400, SR.404.A–B, SR.450, SR.458, SR.586.A–B, SR.597, SR.616 (2 specimens), SR.622, SR.632, SR.642.A–B, SR.648, SO.90.A–B, SO.101, SO.176, and two without number from the old collections at the Natural History Museum of Denmark) .

Occurrence. Lithified top of the upper Maastrichtian Højerup Member at Rødvig and Højerup Church. Low- er Danian Cerithium Limestone Member at Rødvig, Højerup Church, Skeldervig and Holtug, Stevns. The lower Danian ‘dead layer’ at Vokslev, Northern Jutland. The lower hardground (‘krabbelaget’) in the Korsnaeb Member at Korsnaeb, Stevns Klint. The best exposed protoconch possibly comes from the infilling of Korsnaeb Member into a burrow in the lower middle part of the Cerithium Limestone Member at Højerup Church.

Description. Protoconch 0.65 to 0.9 mm high and 0.5 to 0.55 mm wide and regularly coiled trochispiral with 3 ½ to 4 whorls. Surface without sculpture. Teleoconch uncoiled, irregular with few unevenly distributed and moderately sharp spiral ribs and fairly strong, irregularly distributed growth increments. Older specimens may have a denser spiral sculpture with more rounded ribs. Aperture tube-shaped.

Measurements. Largest specimen from Holtug with a largest whorl diameter of 6.6 mm and aperture width of 2.6 mm.

Remarks. Except for the protoconch specimen, which is located inside a bryozoan colony, none of the vermetid tubes studied is attached to a substrate. Most probably they have been associated with poriferans, which based on the numerous spicules present in the rock must have been quite abundant in the palaeo-environment.

Vermetus sp. differs from the Maastrichtian Vermetus alternans Kaunhowen, 1898 from Belgium by the sparser sculpture, which does not show any alternation between coarser and finer spiral ribs. Whether any of these diagnostic features separating the taxa could be solely ecophenetic is unclear, and at present it is deemed wisest to leave the Danish taxon under open nomenclature.

Figures

FIGURE 27. A–B. Melanella? sp., Silicone cast of MGUH 33183. Width 1.4 mm. C–E. Vermetus sp., C. Silicone cast of attached tube MGUH 33184. Largest diameter 6.6 mm. D. Inner mould of protoconch and initial teleoconch inside bryozoan ball. MGUH 33185. Protoconch 0.5 mm wide. E. Silicone cast of MGUH 33186. Width 3.5 mm. F–J. Thylacodes contendis n. sp. F. Attached holotype mould MGUH 33187. Width 2.4 mm. G–H. Silicone cast of paratype MGUH 33188. Width 2.9 mm. I. Silicone cast of paratype MGUH 33189. Width 3.0 mm. J. Silicone cast of free whorl paratype MGUH 33190. Tube diameter 1.8 mm. K–M. Thylacodes? sp., Silicone cast of MGUH 33191. Width 2.4 mm. N. Dendropoma sp., Protoconch and initial teleoconch tube of MGUH 33192. Width 1.7 mm. O. Laxispira sp., Silicone cast of MGUH 33193. Width 3.6 mm. P–R. Epetrium s.l. skeldervigensis n. sp. P. Silicone cast of holotype MGUH 33194. Width 2.4 mm. Q. Silicone cast of paratype MGUH 33195. Width 4.0 mm. R. Silicone cast of paratype MGUH 33196. Width 3.6 mm. S. Triphoridae genus et sp. indet. Sinistrally coiled protoconch MGUH 33197. Width 0.7 mm. T–W. Cerithiopsis restemlongis n. sp. T. Silicone cast of holotype MGUH 33198. Width 1.0 mm. U. Silicone cast of paratype MGUH 33199. Width 1.5 mm. V. Silicone cast of paratype protoconch MGUH 33200. Width 0.5 mm. W. Silicone cast of paratype protoconch MGUH 33201. Width 0.6 mm and height 1.1 mm. X. Cerithiopsis? sp., Silicone cast of MGUH 33202. Width 0.6 mm. Y–AE. Thereitis carlsbergi n. sp. Y–Z. Silicone cast of holotype specimen MGUH 33203. Width of protoconch 0.6 mm and teleoconch 1.4 mm. AE. Silicone cast of paratype MGUH 33204. Width 0.7 mm.