Revision of Acacia tumida (Leguminoseae: Mimosoideae) and close allies, including the description of three rare taxa

Acacia tumida F.Muell ex. Benth. is a wide-ranging species in north-western Australia, with high morphological variability. Overseas it is cultivated for firewood, windbreaks and sand stabilisation. To assist in its domestication, the taxonomy of A. tumida is revised and its close allies, A. difficilis Maiden and A. retinervis Benth., circumscribed. The following six new taxa in the A. tumida group are described: A. areolata M.W.McDonald, A. dissimilis M.W.McDonald, A. seclusa M.W.McDonald (syn. A. tumida var. pubescens Maiden), A. tumida var. extenta M.W.McDonald, A. tumida var. kulparn M.W.McDonald and A. tumida var. pilbarensis M.W.McDonald. A lectotype is designated for A. retinervis. A key to the group, which also includes A. brassii Pedley, A. eriopoda Maiden & Blakely, A. meiosperma (Pedley) Pedley, A. mountfordiae Specht & A. torulosa Benth., is presented. Genetic variation and phylogeny in A. areolata and A. seclusa on the basis of allozymes are briefly discussed. On the basis of present knowledge, three of the new taxa (A. dissimilis, A. seclusa, A. tumida var. extenta) have restricted distributions and warrant formal legislative protection.