Expansion of Lordhowea, and a new genus for scapose, alpine Australian species of Senecioneae (Asteraceae).
The Senecioneae are one of the largest tribes of Asteraceae, with more than 3000 species and a global distribution. They also contain a large number of invasive species such as fireweed (Senecio madagascariensis), cape ivy (Delairea odorata), and ragwort (Jacobaea vulgaris). Although sequence data are available for many species, published phylogenies are for the most part restricted to specific subgroups, and the most broadly sampled phylogenies have limited coverage in depth. Fifty-two of 126 native Australian or introduced species remain unsequenced. As a consequence, the phylogenetic relationships of introduced and native Australian taxa remain difficult to assess, hampering research in biocontrol. We inferred ribosomal and chloroplast phylogenies of the Senecioneae incorporating all available data for the four most frequently sequenced gene regions (nrITS, nrETS, psbA-trnH, trnL) and generated sequence data for 32 additional species to inform the assembly of biocontrol test lists. Our results indicate that nine newly sequenced species currently classified as Senecio are phylogenetically distant from that genus. Although initially unexpected, the inferred affiliations of eight of these species are also supported by morphology, biogeography and chromosome numbers, together providing strong evidence in favour of taxonomic changes. Three species are added to previously phylogenetically isolated and monotypic Lordhowea, and the new genus Scapisenecio is created to accommodate five species characterised by a rosette habit with scapose capitulescences occurring in alpine to subalpine habitats of southeastern Australia.