Twisted flowers and tales to match: phylogenetic inference of Australian Caesia (Asphodelaceae, Hemerocallidoideae).

Aiden T. Webb (University of Melbourne); Joanne L. Birch (University of Melbourne); Russell L. Barrett (National Herbarium of New South Wales); Terry D. Macfarlane (Western Australian Herbarium).

Caesia R.Br. (Asphodelaceae, Hemerocallidoideae) is a predominantly Australian, tepaloid monocot genus with high species diversity in the east and south-west. It contains 14 species and at least eight additional entities recognised by phrase names. Identification and morphological analysis of Caesia from herbarium material is challenging, due to a paucity of distinguishing features retained on specimens (e.g. flower colour, roots). The phylogeny of Australian Caesia was inferred, based on five chloroplast regions generated using targeted amplicon sequencing. Caesia is polyphyletic, as Western Australian ‘rigid-leaved’ species are more closely related to Corynotheca F.Muell. ex Benth. Caesia species relationships are elucidated. Caesia parviflora is polyphyletic, with C. parviflora var. vittata more closely related to C. calliantha and C. chlorantha. Caesia walalbai, a south-east Queensland endemic, is newly described, segregated from the C. parviflora complex. Caesia calliantha is also polyphyletic. Northern species, Caesia chlorantha and C. setifera, represent species complexes; each is monophyletic and includes lineages with distinct morphological features or geographic distributions. Caesia sp. Mt Zeil (NT), C. sp. Foster Cliff (NT) and C. sp. Wheatbelt (WA) are each monophyletic and their relationships are inferred. Further work and additional collections are required to clarify species complexes in Australian Caesia.