Extinct conifers and conifer diversity in the Early Pleistocene of western Tasmania

Abstract

Generic conifer diversity is now relatively high in western Tasmania, with seven genera in the region, but was higher in the Early Pleistocene with at least eight genera in a single catchment at the same time, and even higher during the Tertiary. Specific diversity was also probably higher in the Early Pleistocene than at present. Generic diversity had probably decreased to modern levels by the Middle Pleistocene. Western Tasmania is a refugium for conifers. Two new, extinct species of conifer are described from Early to possibly Middle Pleistocene sediments at Regatta Point, western Tasmania. Dacrycarpus carpenterii Jordan, sp. nov. (Podocarpaceae) has morphological similarities to extant D. dacrydioides from New Zealand. Dacrycarpus is extinct from Australia, but many species are known from the Tertiary in southern Australia. Callitris strahanensis Jordan, sp. nov. (Cupressaceae) has morphological similarities to C. macleayana, the only extant wet forest species of a widespread and prominent genus in drier vegetation in Australia. Their extinctions may have been due to dryness during glacial periods.