The extrabasinal elements in Lower Pennsylvanian floras of the Maritime Provinces, Canada: Description of Adiantites, Pseudadiantites and Rhacopteridium

Resumen

Adiantites adiantoides (Lindley and Hutton) Kidston, Pseudadiantites sessilis (Roehl) Gothan and Pseudadiantites rhomboideus (Ettingshausen) comb. nov. are figured and described as well as Rhacopteridium speciosum (Ettingshausen) Hirmer, as part of a revision of lower Pennsylvanian floras of Nova Scotia. These species show a foliar branching structure which is described as "pseudopinnate" as against the fully planated pinnate structure of the Palaeozoic fern and pteridosperm fronds. Their systematic affinity is unknown. A discussion is presented of the genera Adiantites, Pseudadiantites, Aneimites, Palaeopteridium, and Triphyllopteris, and the problematic nature of the history of Adiantites is emphasised. The four species described are rare though rather more widespread than previous records suggested. Their occurrence is apparently linked to habitat and local palaeogeography rather than to considerations of general palaeogeographic distribution.