Molecular phylogenetic relationships reveal taxonomic and biogeographic clades in Dianella (flax lilies; Asphodelaceae, Hemerocallidoideae)

Abstract

A phylogeny of Dianella is presented based on Bayesian and maximum parsimony analyses of a combined molecular data set using three chloroplast markers (trnQ^UUG–5'rps16, 3'rps16–5'trnK^(UUU) and rpl14–rps8–infA–rpl36) and two nuclear markers (ITS and ETS). Accessions included most Dianella species, including all species from Australia, the centre of diversity for the genus, and related outgroup genera Eccremis, Stypandra, Thelionema and Herpolirion. The phylogeny showed Stypandra sister to Herpolirion + Thelionema, and confirmed the monophyly of Dianella. Within Dianella, a number of clades were resolved that revealed biogeographic relationships. Accessions from south-western Australia (extending into South Australia) formed the earliest diverging clade, followed by D. serrulata from New Guinea, sister to all other clades of Dianella from Australia and other regions. Tropical North Queensland species, including the D. pavopennacea complex, were related to a clade of accessions from New Caledonia and the Hawaiian Islands in the Pacific, and a clade that included samples of D. carolinensis (Caroline Islands) and the widespread D. ensifolia from South-East Asia and across the Indian Ocean to Mauritius and Madagascar. However, D. ensifolia is not monophyletic, with accessions from Japan and Taiwan related to a clade of Queensland samples that are part of the D. revoluta complex. Three New Zealand species (diploid, 2n = 16) were found to be related to Norfolk Island D. intermedia (type locality; octoploid, 2n = 64). In contrast ‘D. intermedia’ from Lord Howe Island was resolved as sister to the eastern Australian D. caerulea complex. The phylogenetic results indicate the need for taxonomic revision, particularly revision of the species ‘complexes’ D. longifolia and D. caerulea in Australia, and recognition of more than one species within D. ensifolia and within D. sandwicensis on the Hawaiian Islands.

Key words:

• Australia
• biogeography
• Dianella
• flax lilies
• molecular phylogeny
• monocots

Acknowledgements

The following people provided support to K. Muscat with botanical or locality information, advice on molecular analyses, field collecting or plant material: Gill Brown, Geoff Carr, Barry Conn, John Conran, David Fell, Fred and Sue Fetherston, Paul Forster, Colin Gibson, Bruce Gray, Peter Heenan, Rod Henderson, Ailsa Holland, Shelley James, Goro Kokubugata, Erin May, John McCabe, Ian Menkins, Robert Miller, Bill Molyneux, Laurence Muscat, Theresa Muscat, Daniel Ohlsen, Park Rangers (Dorrigo National Park, Moreton Island National Park and Townsville region), Oscar Parraga, Andrew Perkins, Sook Ngoh Phoon, Jenny Reid, Gary and Nada Sankowsky, Tanja Schuster, Val Stajsic, Neville Walsh, Sarder Uddin. Research on the Hawaiian Islands was supported by staff from Bishop Museum and National Tropical Botanical Garden, Kauai, Tim Flynn, Joel Lau, David Lorence, Anna Palomino, Forest and Kim Starr, Kenji Suzuki, Natalia Tangalin, Rae Williams. Thanks also to Larry Dorr and Warren Wagner, Smithsonian Institute (USA), for discussions about Hawaiian flora. Henry C. Méra, Michaela Plein, and Peter Bostock assisted with translations of documents from French, Latin, and German to English. For access to loans: Australian Herbaria, CANB, PERTH, CNS, MEL, DNA, BRI and HO; National Tropical Botanical Garden Kauai (PTBG); Herbarium Pacificum (BISH); National Museum of Nature and Science, Japan (TNS); Singapore Botanic Gardens (SING); Bangladesh National Herbarium (DACB); Auckland Museum (AK); Missouri Botanical Garden (MO); Universidad Central de Venezuela (MYF); IRD Noumea (Nou); and United States National Herbarium (US), Smithsonian Institute, Washington.

Disclosure statement

The authors declare no conflicts of interest.

Supplemental data

Supplemental data for this article can be accessed here: https://dx.doi.org/10.1080/14772000.2019.1607617.

Associate Editor: Nadia Bystriakova

Additional information

Funding

This research was suppported by a University of Melbourne Postgraduate Research Scholarship; Capacity Building and Bush Blitz grants (Australian Biological Resources Study, ABRS); McBryde Grant (Smithsonian Institute, USA); and a Travel Award from The University of Melbourne Botany Foundation.