Nyhamnian. gen., a new monotypic cystiphyllid rugose coral genus from the Lower Silurian of Gotland

The new monotypic cystiphyllid genus Nyhamnia from the Lower Silurian of Gotland is here established. The genus is characterized by having a sharp separation between a narrow marginarium of dilated dissepiments and a broad pronounced tabularium, and by septa confined to the dissepimentarium. Nyhamnia is assigned to the family Holmophyllidae, and is compared to Holmophyllum Wedekind, Dentilasma Ivanovsky, and Microplasma Dybowski. Nyhamnia pusilla - type species - is fixosessile and has a very small corallite.