|Publication Type:||Journal Article|
|Year of Publication:||2018|
|Authors:||Holstein, N., M. Gottschling|
|Journal:||Australian Systematic Botany|
Halgania (Ehretiaceae, Boraginales) comprises 20 species of ericoid shrubs endemic to Australia. The current taxonomic concepts based on morphology are confusing and are sometimes based on misidentification or lack of information about the type material. We describe the morphological diversity and infer relationships using molecular phylogenetics. The five petals in all Halgania species are blue to violet (rarely white). The yellow or yellow-purple anthers are connected into a cone surrounding the single style. Differences among the species are mainly found in the indumentum of the plants, the leaf margin (i.e. degree of serration), the sepals (being either of equal or of unequal size) and the length of the beak-like anther appendages. A phylogenetic tree mainly based on ITS sequences retrieves three highly supported groups. The H. andromedifolia clade uniquely has sepals of unequal size, and the H. anagalloides clade exhibits dolabriform trichomes. The remaining taxa (constituting the H. littoralis clade) lack such diagnostic morphological traits, but are reliably retrieved as sister group to the H. anagalloides clade. As a first step towards the taxonomic revision of Halgania, we have compiled a nomenclatural list of all validly published names (at the species level and below), provide information about herbarium deposition of original material and discuss the current use of the names.