Systematics of New Zealand Pimelea (Thymelaeaceae)

Abstract

Pimelea Banks and Sol. ex Gaertn. is a genus of shrubs, sub-shrubs and herbs belonging to the eudicot family Thymelaeaceae. First described 1769, the genus initially contained four species but has since grown to contain 126 species which are distributed around Australia, New Zealand and Lord Howe Island. New Zealand has 35 endemic Pimelea species, and numerous subspecies bringing the total to 51 taxa which are distributed across the North and South Islands, as well as offshore. The most recent revision of the genus Pimelea was conducted by Colin Burrows throughout a series of five papers published from 2008 to 2011. Burrows (2011), as well as Motsi (2010), theorized that New Zealand’s Pimelea initially originated from Australia. Motsi (2010) went on to hypothesise that these species were monophyletic and that the diversity present occurred via speciation and radiation. The conclusions drawn by these two papers, however, have their limitations. Burrows (2011) based his solely on the morphology of species across New Zealand Pimelea, while Motsi (2010) only studied the molecular sequences of four New Zealand Pimelea species. Burrows, throughout a number of his papers, also studied the molecular systematics of Pimelea and attempted to organize its taxonomy but similarly only based his findings on morphological traits. This project has four key aims, the first is to assemble and review the literature currently available about Pimelea and in particular, the New Zealand Pimelea. Due to the absence of previous research which considers both morphology and molecular phylogenetics of Pimelea, this project will include all New Zealand Pimelea taxa and will use both morphological traits and molecular analysis of the DNA sequence variation off the nuclear ribosomal inter transcriber spacer regions (ITS). Using these, this research intends to 1) test the classification of the genus sensu Burrows, 2) infer biogeographic relationships between Pimelea species within New Zealand and 3) infer the number of colonization events of Pimelea in New Zealand and hence test its monophyly.