A study of the taxonomic diversity and a phylogenetic assessment of New Zealand Sun Orchids (Thelymitra) : a thesis presented in partial fulfilment of the requirements of the degree of Master of Science in Biological Sciences at Massey University, Manawatū, New Zealand. EMBARGOED until 9th April 2027
Loading...
Date
2025
DOI
Open Access Location
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Massey University
Rights
The author
Abstract
The sun orchids, otherwise known as Thelymitra, are a diverse genus of terrestrial orchids found in the South Pacific. Within New Zealand they are represented by approximately 15 species, although there has long been debate on the exact number, due to the existence of species complexes and suspected undescribed taxa, some of conservation concern. Historically taxonomists have struggled to accurately document diversity of this genus in NZ, and recent and rapid taxonomic revision of Australian species has left the taxonomy of NZ sun orchids lagging behind, and in desperate need of an update. In this thesis I present the most complete plastid marker-based phylogeny of New Zealand sun orchids to date, comprising 15 species and six entities known informally by tag names and thought to be undescribed species. This is paired with a nuclear marker phylogeny, with sequences obtained through a novel application of Oxford Nanopore Sequencing that has enabled the identification of putative allopolyploid species which had previously only been hypothesised. Finally, I present an analysis of the T. longifolia complex, investigating nuclear and chloroplast genome variations within it, and how those relate to the forms commonly reported in the national botanical literature. The findings of this work support the existence of new species of Thelymitra within NZ, although further morphological study is needed to circumscribe these. Evidence suggesting an allopolyploid origin for at least four species present in NZ, which had previously only been hypothesised, was detected in nuclear sequence data. Suggestions for future work is also made, particularly with regard to filling the gaps in understanding still remaining for the undescribed forms in this genus.
Description
Embargoed until 9th April 2027
Figures are reused with permission.