Sequence data support greater taxonomic diversity and a complicated history of hybridisation in New Zealand’s sun orchids - Thelymitra (Orchidaceae)

Abstract

Thelymitra, commonly known as sun orchids, is a genus of orchids present in New Zealand (NZ), known for their radially symmetrical and brightly coloured flowers. A long history of nomenclatural changes, and a recent and rapid circumscription of Australian (AU) taxa has left our understanding of this genus in NZ lagging. In this study we report two phylogenies of NZ Thelymitra species, based on nuclear (LFY) and plastid (ycf1) sequence data. The phylogenies identify support for several taxa currently only known by tag-names as being distinct from those that are currently described both in NZ and AU, as well as evidence supporting an extensive history of hybrid speciation in this genus in NZ, which had been hypothesised previously for six species. This work has also found evidence for species complexes within NZ Thelymitra that need further molecular and taxonomic work to fully resolve species boundaries. In this study we also demonstrate a novel application of nanopore sequencing of amplicons, that enables the recovery of multiple sequence copies in allopolyploid taxa without the prior need for cloning.