Australian Systematic Botany Australian Systematic Botany Society
Taxonomy, biogeography and evolution of plants

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Taxonomic resolution of the Tetratheca hirsuta (Elaeocarpaceae) species complex using an integrative approach

Elizabeth Joyce , Ryonen Butcher , Margaret Byrne , Pauline Grierson , Maggie Hankinson , Kevin Thiele

Abstract

The Tetratheca hirsuta Lindl. species complex from south-west Western Australia is one of the last unresolved complexes in this Australian endemic genus, and comprises the highly variable T. hirsuta, two rare, phrase-named taxa, and the closely allied T. hispidissima Steetz. An integrative approach incorporating multivariate morphometric analysis and molecular phylogenetic and phenetic analyses of nrDNA (ETS) and cpDNA (ndhF-trnL, rpl16, trnS-trnG5’2S) was used to investigate taxonomic boundaries within the complex. Morphological data showed clear divergence within the complex, and allowed a number of taxonomically uncertain individuals to be assigned. Phenetic and phylogenetic analyses of ETS showed substantial congruence with morphology, indicating that the groups recognised through morphometric analyses are also genetically divergent. By comparison, the chloroplast regions yielded incongruent gene trees, perhaps due to incomplete lineage sorting, hybridisation, or slow evolution of cpDNA. These results support the recognition of four taxa: a morphologically and geographically expanded T. hispidissima, which is highly divergent from the remainder of the complex, and a closer grouping of T. hirsuta subsp. boonanarring Joyce & R.Butcher subsp. nov., T. hirsuta subsp. viminea (Lindl.) Joyce comb. et stat. nov., and T. hirsuta subsp. hirsuta.

SB16040  Accepted 09 November 2016

© CSIRO 2016