Re-appraisal of the taxonomy of Acacia holosericea, including the description of a new species, A. Colei, and the reinstatement of A. Neurocarpa

Abstract

The taxonomic status of Acacia holosericea A. CUM. ex Don is re-appraised in the light of recent isozyme, chromosome and field studies, as well as from a critical examination of specimens at BM, BRI, K, DNA and PERTH. Accordingly, A. holosericea, as traditionally defined, is now regarded as comprising three distinct species, each corresponding to a dierent level of ploidy. Acacia holosericea A. Cum. ex Don (tetraploid) is widespread, principally in tropical/subtropical areas of Western Australia, the Northern Territory and Queensland. Acacia neurocarpa A. Cunn. ex Hook. (diploid), occurs in tropical/subtropical Western Australia and the Northern Temtory and until now has been regarded as conspecific with A. holosericea. Acacia colei Mash & Thomson (hexaploid) is described as a new species which appears to have evolved as an allopolyploid hybrid between A. neurocarpa and A. cowleana (tetraploid). It is widespread and common in subtropical/arid Western Australia, the Northern Territory and Queensland. These four species are illustrated, mapped and their principal discriminating features given in tabular form and in a key. Acacia holosericea is neotypified to exclude A. neurocarpa, and A. neurocarpa is lectotypified to exclude A. dunnii (Maiden) Turrill.