Melichrus adpressus sensu Paterson

Melichrus adpressus sensu Paterson View in CoL

In the genus-wide morphological analyses, segregates of M. adpressus sensu Paterson were spread across three distinct clusters. Melichrus sp. Gurulmundi clustered with M. urceolatus , due to similarities in both vegetative and floral morphology. Melichrus sp. Gurulmundi was found to be reliably diagnosable through a combination of several characters. Molecular evidence decisively demonstrated the genetic distinctiveness and as such we consider that this should be described as a new species.

Samples of M. adpressus sensu Paterson clustered with the single M. sp. Wahlmoorum sample in morphological analyses based on the shared floral morphology but in molecular analyses M. sp. Wahlmoorum did not group with any M. adpressus sensu Paterson segregates. This may indicate some divergence but is more likely an artefact due to inadequate sampling of M. sp. Wahlmoorum. We therefore recommend not recognising the entity as a distinct species until further information is available and we exclude this from the updated Melichrus taxonomy.

The third group recovered in the morphological analyses contained Melichrus sp. Herberton, M. sp. Kroombit Tops, M. sp. Boonoo Boonoo and M. sp. Yuraygir. Analysis of a subset of the morphological data containing only samples from this cluster demonstrated M. sp. Yuraygir to be morphologically distinct. Discontinuities in the results of the molecular analyses also supported M. sp. Yuraygir and M. adpressus sensu Paterson as distinct species. Melichrus sp. Herberton and M. sp. Kroombit Tops clustered tightly in all molecular analyses, despite the geographic disparity. Melichrus sp. Boonoo Boonoo clustered closely with M. sp. Kroombit Tops and near to M. sp. Herberton in morphological analyses but not in the DArTseq PCA and SplitsTree analyses. In the STRUCTURE analysis, the single population of M. sp. Boonoo Boonoo drew from two ancestral populations shared by M. sp. Yuraygir and M. adpressus sensu Paterson respectively. The discontinuities observed in the morphological analyses could not be readily reconciled with those observed in the molecular analyses. We recommend that M. sp. Boonoo Boonoo be excluded from taxonomic revision until further information is available. Denser sampling, particularly in northern New South Wales and southern Queensland may reveal a more detailed picture of species boundaries in this group.