Nothofagus beardmorensis (Nothofagaceae), a new species based on leaves from the Pliocene Sirius Group, Transantarctic Mountains, Antarctica

Leaves from the Late Pliocene Sirius Group at Oliver Bluffs in the Dominion Range, Transantarctic Mountains, are assigned to the new species Nothofagus beardmorensis Hill, Harwood et Webb, sp. nov. The plant which produced the leaves was winter deciduous, and it is probable that the wood and pollen of Nothofagus that co-occur in the sediments are conspecific with N. beardmorensis. The presence of this species in Antarctica in the Pliocene suggests a much different climate than at present, since no extant Nothofagus species can survive temperatures below about -22°C in winter, and temperatures must have been substantially above 0°C for a relatively long period during the growing season for the growth and reproductive effort observed. A preliminary estimate of a 13-15°C temperature difference between fossil deposition and the present day is inferred.