Cladistics, Phenetics and Biogeography of Populations of Boronia inornata Turcz. (Rutaceae) and the Eucalyptus diptera Andrews (Myrtaceae) Species Complex in Western Australia

Abstract

Numerical cladistic and phenetic analyses were undertaken on morphometric data from 22 Western Australian populations of the southern Australian shrub Boronia inornata and from the southern Western Australian tree Eucalyptus diptera and its unnamed allies. The E. diptera species complex includes four taxa, three of which are at present unnamed. These species are largely allopatric, although in one location the ranges of two species overlap. Two subspecies of Boronia inornata are described and one of them, subsp. leptophylla, contains three informal variants. Subsp. inornata and two of the variants of subsp. leptophylla are restricted to Western Australia. One variant of subsp. leptophylla is sympatric with subsp. inornata in Western Australia and also occurs in southern South Australia. The events which gave rise to the four species of the E. diptera complex and to the subspecies and variants of B. inornata occurred within the semiarid mallee zone of Western Australia, probably during the Quaternary. Speciation has occurred in a replacement pattern across the southern transitional rainfall zone, which is reflected in at least one other, unrelated taxon.