Morphological and molecular evidence for major re-circumscriptions in and eight new species of Melichrus R.Br. (Ericaceae subfam. Epacridoideae) in eastern Australia

The genus Melichrus R.Br. has received very little taxonomic attention and treatments have largely disagreed on species delimitation. The eastern Australian clade of Melichrus was last revised in 1958. Over 60 years later we present new, in-depth evidence for species delimitation. A morphological dataset (90 individuals from 68 populations, scored for 26 characters) was analysed using NMDS ordination with Bayesian Inference cluster modelling (mclust) and UPGMA hierarchical clustering to detect morphological discontinuities in the genus that may indicate species boundaries. Discontinuities in the morphological analyses were compared with those apparent in clustering (principal component analysis, SplitsTree Neighbour-Net, STRUCTURE and conStruct) and statistical analyses (HE, HO, FIS and FST) of a DArTseq SNP dataset of 548 samples from 110 populations of Melichrus. These new lines of evidence form the basis of detailed recommendations for a revised species taxonomy of Melichrus including the description of eight new species, recircumscription of previously described species and the correction of a longstanding nomenclatural misapplication.