ORIGINAL ARTICLE Evolution and biogeography of the austral genus Phyllocladus (Podocarpaceae) Steven J. Wagstaff INTRODUCTION The southern conifers are well represented in the fossil record and have persisted since the Mesozoic, but the level of diversity in this ecologically important group has diminished through time (Hill, 1995). Some 200 species of conifers are presently recognized that have a largely austral distribution. The geographical range of many of these is often quite restricted and few dominate forests or treelines in the Southern Hemisphere. Phyllocladus (Podocarpaceae) is one of the most intriguing genera among the southern conifers. Because of the charac- teristic appearance of its foliage, it is often given the common names ‘celery pine’ or ‘celery-topped pine’. According to Page (1990), five species are currently recognized in the genus: P. aspleniifolius is endemic to Tasmania, P. alpinus, P. toatoa, (formerly P. glauca, Molloy, 1996), and P. trichomanoides are endemic to New Zealand, and P. hypophyllus is found in Malaysia from New Guinea to Luzon and Borneo (Fig. 1). They vary from lofty trees to dwarf shrubs and play an important functional role in indigenous forests ranging from sea level to nearly alpine elevations. The roots of Phyllocladus possess nodules that host nitrogen-fixing bacteria enabling the plants to occupy relatively infertile sites (Keng, 1978). The reproductive biology of Phyllocladus is quite unusual (Tomlinson et al., 1997). The species are either monoecious or dioecious and wind-pollinated. Pollination drops are secreted by the ovules of Phyllocladus and are exuded through the micropyle. During the early spring pollen is released in great abundance. The grains have vestigial sacci and are wettable so that they sink upon entering a pollination drop. Airborne pollen entering a drop stimulate it to withdraw back into the Allan Herbarium, Landcare Research, Lincoln, New Zealand Correspondence: Steven J. Wagstaff, Allan Herbarium, Landcare Research, PO Box 69, Lincoln 8152, New Zealand. E-mail: wagstaffs@landcareresearch.co.nz ABSTRACT Aim To infer evolutionary relationships within the genus Phyllocladus and among its close relatives by phylogenetic analysis of DNA sequences. Interpret the inferred relationships in association with the fossil record to examine the origin and diversification of the genus. Location Australasia. Methods Phylogenetic analyses of rbcL, matK and internal transcribed spacer (ITS) sequences representing all of the extant species of Phyllocladus and a selection of outgroups from Podocarpaceae and Araucariaceae. Results The rbcL and matK sequences exhibit little variation within Phyllocladus, but ally its members to Podocarpaceae although its immediate sister remains unclear. The ITS sequences resolve all five species of Phyllocladus and two intraspecific ecotypes of P. alpinus. Main conclusions Phyllocladus forms a distinct lineage that diverged early in the evolutionary history of Podocarpaceae. The fossil record indicates that the genus was more widely distributed and morphologically diverse during the early Tertiary than at present. Although of Mesozoic origin, the level of sequence variation within Phyllocladus suggests that the extant species radiated during the late Tertiary c. 6.3 ± 0.9 Ma. New Zealand is the present centre of species diversity. Keywords Araucariaceae, Australasia, DNA sequences, ITS, matK, New Zealand, Phyllo- cladus, phylogeny, Podocarpaceae, rbcL. Journal of Biogeography (J. Biogeogr.) (2004) 31, 1569–1577 ª 2004 Blackwell Publishing Ltd www.blackwellpublishing.com/jbi 1569