Revision of the species Astraeospongium Patina Roemer, 1861, based on Ordovician bedrock specimens from Estonia

Specimens of Astraeospongium patina Roemer, 1861 from Lower-Middle Ordovician (Arenig-Llanvirn) and from Upper Ordovician (Caradoc) deposits in Aluvere and in the Maardu region, Estonia, are described, demonstrating the validity of the species. These are the first bodily preserved specimens reported from Baltic bedrock, and the oldest representatives of the Astraeospongiidae known to date. Previous reports by Roemer (1861), Kiaer (1908) and Reitner (1992) are discussed, and a comparison of A. patina Roemer, 1861 with A. meniscum (Roemer, 1848) is given. Spicules in comparable parts of A. patina are considerably smaller (about 1 mm) than in those of A. meniscum (6-7 m).