R. W. G. Dennis (Royal Botanic Gardens, Kew) Existence of the taxonomically very isolated fungus genus Cyttaria , with species confined to and parasitic on Nothofagus in the southern Andes, Tierra del Fuego, New Zealand, Tasmania and eastern Australia but not in New Guinea or New Caledonia supports the contention that Nothofagus originated, or became differentiated, at some centre in the south temperate zone, where the fungus genus evolved with it. There is also an Agaric genus, Descolea , family Cortinariaceae, with similar association and distribution.