Phylogeny reconstruction of 'Callitris' Vent. (Cupressaceae) and its allies leads to inclusion of 'Actinostrobus' within 'Callitris'

Abstract

Relationships between 'Callitris', 'Actinostrobus' and 'Neocallitropsis', members of the southern hemisphere "callitroid clade" (Callitroideae 'sensu' Gadek et al. 2000) of Cupressaceae, are estimated using a database of 42 morphological and anatomical characters. 'Callitris' is paraphyletic, with 'Actinostrobus' being closer to a large well supported clade of 15 Australian species of 'Callitris' than are 'C. baileyi', 'C. macleayana' and the New Caledonian taxa. The New Caledonian unispecific endemic, 'Neocallitropsis', is sister to the clade comprising all 'Callitris' and 'Actinostrobus' species. There are marked differences between this estimate of the phylogeny and two recent estimates based on nuclear encoded DNA sequence data and non-molecular data, respectively, but some similarities to the molecular estimate are highlighted and lead us here to formally include 'Actinostrobus' within 'Callitris'. Further molecular data are needed to test these results and explore the cause of the conflict between these estimates of the phylogeny within the group, and the status of 'Neocallitropsis'.