Anemonastrum tenuicaule and A. antucense (Ranunculaceae), new combinations for a New Zealand endemic species and its South American relative

A rational taxonomic circumscription of genera in tribe Anemoneae (Ranunculaceae) is briefly discussed. It is concluded that, in view of the morphological diversity of the group and recent molecular phylogenetic findings, a moderately narrow approach to the re-circumscription of genera earlier included in Anemone sensu lato is preferable, in particular, with the recognition of the lineage with the base chromosome number x = 7 (Anemone subgen. Anemonidium) as two genera, Hepatica sensu stricto and Anemonastrum in an expanded circumscription (including Anemonidium, Arsenjevia, Jurtsevia, and Tamuria). Following these conclusions, new nomenclatural combinations are proposed for two related species endemic to New Zealand and South America, respectively: Anemonastrum tenuicaule (= Anemone tenuicaulis, Ranunculus tenuicaulis) and Anemonastrum antucense (= Anemone antucensis). Information on typification is updated: the lectotype of Anemone antucensis is the specimen from P and not a specimen from G, and the lectotype of Ranunculus tenuicaulis is a specimen from AK. Biogeographic scenarios already proposed to explain the relationship of these two species and some other South America – New Zealand distribution patterns are discussed. It is concluded that the long-distance dispersal scenario fits best the available data for Anemonastrum. Two host-specific and geographically restricted species of Urosystis parasitizing A. tenuicaule and A. antucense are briefly discussed.