Filelloides cretacea n. g. n. sp., ein durch Bioimmuration überlieferter Vertreter der Ordnung Hydroida (Hydrozoa) aus der Maastrichter Tuffkreide (Obermaastrichtium)

A new thecate hydroid from the Maastrichtian Chalk (Upper Maastrichtian) preserved by bioimmuration is described asFilelloides cretacea n. g. n. sp. It comprises five hydrothecae of a hydrozoan colony settling upon an algae sheet, which were overgrown by a disc-shaped cyclostome bryozoan colony of the genusActinopora. Its basal face shows the negative relief of the throughout annulated hydrothecae which are extremely well molded in all details. Among Recent colonial Hydroida the genusFilellum Hincks of the family Lafoeidae is the nearest relative, our specimen differs from the latter in that the hydrothecae are not connated with the hydrocaulus or the hydrorhiza.Filelloides n. g. is one of the few non-mineralized Cretaceous hydrozoan genera. Their rare record in the Mesozoic contrasts with their fairly common occurrence in the Palaeozoic.