Population genetic structure and range limits ofProstanthera cineolifera(Lamiaceae), a vulnerable shrub with a patchy distribution

AbstractIntegrating molecular data is essential for clarifying the distributions and genetic structures of species that have histories of misidentification and misapplication of names. There has been confusion about the species limits of the VulnerableProstanthera cineoliferawith respect to morphologically similar specimens in the Hunter Valley, New South Wales Australia and morphologically dissimilar specimens in the Lower Hawkesbury Valley New South Wales and from northeastern New South Wales. To test the species limits ofP. cineoliferaand related taxa specimens were collected from across the range and augmented with herbarium specimens. We used morphometric analysis of 18 morphological characters across 51 operational taxonomic units. Using the DArTseq reduced representation sequencing platform, 9,559 single-nucleotide polymorphisms (SNPs) across 122 individuals were recovered for molecular analysis. Both morphological and molecular analyses produced three concordant clusters (1)P. cineolifera, (2) a group sharing similarities withP. sp. Hawkesbury (B.J.Conn 2591), and (3) a group allied withP. lanceolataandP. ovalifolia. These results indicate that the specimens form northeastern New South Wales are more likely to beP. lanceolata, notP. cineolifera, and that specimens from the Lower Hawkesbury are of an undescribed species with the phrase nameP. sp. Hawkesbury (B.J.Conn 2591). WithinP. cineoliferathere was pronounced genetic differentiation among populations. Little evidence of inbreeding was observed, but the newly recognised, more isolated populations had the lowest genetic diversity. This study provides new information about the range of the species and its genetic structure that informs the conservation priorities for this species.