Strophomenate Brachiopods from the late Ordovician Boda Limestone of Sweden: their systematics and implications for palaeogeography

Brachiopods of the superfamilies Strophomenoidea, Plectambonitoidea and Chilidiopsioidea are revised and described from the late Ordovician (Middle Ashgill) carbonate mud mounds of the Boda Limestone of Sweden. The fauna is compared and contrasted with those from mud mounds of comparable age in England (the Keisley Limestone) and Ireland (the Kildare and Portrane Limestones). New strophomenoidean genera are Trondomena and Ungulomena (both Glyptomenidae), the latter within the new subfamily Ungulomeninae. A new subgenus is Leptaena (Ygdrasilomena) (Rafinesquinidae), and new strophomenoid species are Gunnarella magnifica, Holtedahlina suedica, Katastrophomena (Costistrophomena)? magna, Luhaia candelabra, Leptaena (Leptaena) bergstroemi, Leptaena (Ygdrasilomena) roomusoksi, Kiaeromena (Kiaeromena)? grandis, Trondomena bella, Ungulomena lindstroemi and Christiania dalarnensis; new plectambonitoidean species are Bimuria popovi, Leangella (Leangella) longae, Anoptambonites williamsi and Ptychoglyptus ingenuus. Ten more unnamed and probably new species and at least two more new genera are described under informal nomenclature (A to J). The Strophomenoidea, with at least 20 named and unnamed species in the Boda Limestone, are found to have been much more diverse and endemic than the Boda Plectambonitoidea and the Chilidiopsoidea: the latter two superfamilies include no definite endemic genera and those that occur are relatively cosmopolitan in the low latitudes in which the Baltica Terrane was situated in the late Ordovician. Some faunal links are established with the neighbouring terranes of Avalonia, Laurentia and Siberia, but, in contrast to the plectambonitoideans and chilidiopsoideans, the relative endemicity of the Boda Strophomenoidea is striking and that local radiation was probably caused by the mid-Ashgill Boda Warming Event.