Species of the Silurian operculate rugose coral genera Araeopoma and Rhytidophyllum

The operculate rugose coral genera Araeopoma Lindström and Rhytidophyllum Lindström, represented in Silurian sequences on Gotland, are here revised and redescribed. These genera belong to the subfamily Araeopomatinae which is characterized by undifferentiated opercular septa. The affinities between Araeopoma and other operculate genera including Goniophyllum is discussed. The species treated in this paper are Araeopoma prismaticum (type species), Araeopoma elongation and Rhytidophyllum pusillum, all of which appear to be endemic on Gotland. Araeopoma has a rhabdacanthine septal microstructure, while that of Rhytidophyllum is unknown.