Abstract
Aciphylla latipinna Perrie, Glenny, & L.D.Sheph. is newly described after testing the morphological and genetic distinctness of a long‐recognised unresolved taxonomic entity whose informal names include Aciphylla aff. horrida (a) (CHR 511521; Lomond). Analyses of genetic data from ddRADseq DNA sequencing found A. latipinna to be only distantly related to A. horrida but closer to A. aurea . When hybrids were accounted for, A. latipinna was distinct from A. aurea across sampling sites spanning about 140 km, even though it was nested within the latter's greater genetic diversity in some analyses. Morphologically, A. latipinna can be distinguished from A. aurea and A. horrida by its wider leaf rachises and leaflets, and shorter sheath leaflets. Its often glaucous leaves are another clear difference from the never glaucous A. horrida . Aciphylla latipinna is principally a species of western Otago, but reaches both Canterbury and Southland. It usually occurs in Chionochloa ‐dominated grasslands and shrublands above 1000 m. While A. latipinna occurs in central parts of its distribution without A. horrida or A. aurea , it abuts the former to the west and overlaps extensively with the latter to the east, although A. latipinna generally occupies higher elevations. Hybridisation between A. aurea and A. latipinna is widespread and can be locally common. While hybridisation can make morphological identification of some individuals difficult, Aciphylla latipinna remains genetically and morphologically distinct across its range, including where it overlaps with A. aurea , such that they should be recognised as separate species.