Mid Miocene–Last Interglacial Callitris (Cupressaceae) from south-eastern Australia

Abstract

Callitris Vent., is the most speciose of the Southern Hemisphere Cupressaceae (conifer) genera, with species indigenous to Australia and New Caledonia. While most other Southern Hemisphere conifers are restricted to wet climates, Callitris species occupy a broad range of habitats, from the margins of rainforests to arid Australia. This study examines fossilized Callitris foliage collected from three south-eastern Australian sites ranging in age from middle Miocene to the Last Interglacial. The oldest, middle Miocene, fossils are from Yallourn, southern Victoria and represent a new (extinct) species, Callitris blackburnii. Much younger, early Pleistocene (~1.59 Ma), fossils are from four slightly different aged horizons within the Stony Creek Basin, western Victorian uplands. One of these specimens is consistent with extant C. rhomboidea R.Br. ex Rich. & A. Rich. in both morphology and size. Specimens from other depths in the Stony Creek sediments are assigned to another extant species, C. columellaris F. Muell., but are smaller in size than the extant species. The youngest fossil specimens (Last Interglacial (~110 ka) Yarra Creek, King Island) are assigned to extant C. rhomboidea. The findings of this study enhance the previously sparse fossil record of Callitris and further indicate that two widespread extant Callitris species have been present in south-eastern Australia for at least ~1.5 million years.