Relationships among Tasmanian Tertiary Nothofagus (Nothofagaceae) populations

Three leaf and two cupule forms of Nothofagus from the Early Oligocene deposit at Lea River are assigned to the previously described species Nothofagus tasmanica, N. lobata, N. gunnii, N. glandularis and N. bulbosa. A single leaf specimen is possibly referable to Nothofagus subgenus Brassospora. Nothofagus microphylla, previously described from Monpeclyata, is separated into two species. These two species are N. microphylla and a new deciduous species named Nothofagus martinii. N. microphylla is transferred from the Nothofagus subgenus Lophozonia to subgenus Nothofagus, based upon cuticular characteristics. Nothofagus bulbosa and Nothofagus gunnii are also present at Monpeclyata. It is proposed that both N. lobata and N. microphylla have heterophyllous shoots and thus two leaf morphologies. Evolutionary and environmental relationships between Nothofagus species at Lea River, Monpeclyata and Little Rapid River are discussed. Large scale disturbance and increased seasonality are predicted to have caused the extinction of Nothofagus subgenus Nothofagus in Australia.