Molecular and morphological analyses support recognition of Prostanthera volucris (Lamiaceae), a new species from the Central Tablelands of New South Wales

Abstract

Research into the systematics of Prostanthera recently revealed close evolutionary relationship among P. phylicifolia sens. str., the critically endangered P. gilesii, and a population of uncertain identity from the Central Tablelands of New South Wales (NSW), Australia. Previous analyses were unable to establish whether genetic boundaries separated these taxa. This study assessed species boundaries among these three taxa by using a combination of single-nucleotide polymorphisms (SNPs) sampled at the population-scale and multivariate analysis of morphological characters. Ordination, model-based clustering, F-statistics, neighbour-network analysis, phylogenetic analysis, and ancestry coefficient estimates all provided support for discrete genetic differences among the three taxa. Morphological phenetic analysis recovered congruent morphological clusters and identified a suite of corresponding diagnostic characters. This congruence of molecular and morphological evidence supports the presence of three independently evolving lineages, two of which correspond with the previously described P. gilesii and P. phylicifolia sens. str. The third taxon, represented by a single population from the Central Tablelands of NSW, is here described as P. volucris R.P.O’Donnell. A detailed description, diagnostic line drawings and photographs are provided. We evaluate P. volucris as satisfying criteria to be considered Critically Endangered.

Using molecular and morphometric data as operational criteria for the analysis of a threatened rainforest species complex shows interspecific variation, with implications for cryptic-species delimitation and conservation

“…DArTseq has been successfully applied to define a range of taxonomically challenging plant groups (Sansaloni et al 2011;Steane et al 2011;O'Donnell et al 2023), including Fontainea (Brunton et al 2022). Also, notably, the chromosome count and ploidy status of Fontainea are currently unknown and have not been investigated in the study species.…”

“…There are several Australian examples that have explored the patterns of population divergence using an integrateddata approach to recover the relationships among closely related, threatened species (Robins et al 2021;Wilson et al 2022;O'Donnell et al 2023). These studies highlighted various outcomes, such as subspecies recognition (Robins et al 2021), designation of new species (O'Donnell et al 2023) and the merging of some species (Wilson et al 2022), that all contributed to updated conservation priorities. However, overestimating morphological diversity within species of taxonomic uncertainty can divert attention and has often restricted resources away from populations that are in greater need of conservation focus (Wilson et al 2022).…”