Understanding Diversity and Systematics in Australian Fabaceae Tribe Mirbelieae

Abstract

Australia has a very diverse pea-flowered legume flora with 1715 native and naturalised species currently recognised. Tribe Mirbelieae s.l. includes 44% of Australia’s peas in 24 genera with 756 recognised species. However, several genera within the Pultenaea alliance in tribe Mirbelieae are considered to be non-monophyletic and two main options have been proposed: option one is to merge ca. 18 genera containing ca. 540 species (the largest genus, Pultenaea has nomenclatural priority); and option two is to re-circumscribe some genera and describe new genera as required to form monophyletic groups. At the species level, option one would require 76% of names to be changed; whereas based on available data, option two is likely to require, at most, 8.3% of names to change. Option two therefore provides the least nomenclatural disruption but cannot be implemented without a robust phylogenetic framework to define new generic limits. Here we present novel analyses of available plastid DNA data (trnL-F) which suggest that option two would be feasible once sufficient data are generated to resolve relationships. However, the reticulate evolutionary histories or past rapid speciation suggested for this group may prevent the resolution of all nodes. We propose targeted use of Next-Generation Sequencing technology as the best way to resolve relationships between the key clades in the tribe and present a framework for such a study. An overview of current taxonomy in the tribe is presented, along with the state of taxonomic knowledge and availability of published descriptions for electronic flora treatments. Several new combinations and typifications are published in an appendix.