Arceuthobium M.Bieb. (Viscaceae) parasitizing an angiosperm: the unique case of A. azoricum Hawksw. & Wiens in the Azores islands.

Arceuthobium azoricum Wiens & Hawksw. is a rare Azorean endemic epiphytic hemiparasite (mistletoe), that typically parasitizes branches of the gymnosperm Juniperus brevifolia (Hochst. ex Seub.) Antoine (Cupressaceae), also an Azorean endemic. Here we describe one population of A. azoricum, on Pico Island, parasitizing Erica azorica Hochst. ex Seub (Ericaceae) also an Azores endemic. Our molecular analysis (using nuclear ribosomal ITS) showed no differences between individuals parasitizing Erica and Juniperus. Moreover, a preliminary analysis showed no differences in morphological characters between accessions sampled from the different hosts. Given that this is the first bona fide record of Arceuthobium parasitizing an angiosperm, this population represents a unique host shifting event and its conservation is important because it may allow new insights into host recognition mechanisms in mistletoes. Immediate attention should be given to characterize this Pico Island population using appropriate molecular methods and additional morphological analyses.

Multiplexed shotgun genotyping (MSG) data resolve phylogenetic relationships within and among archipelagos in Macaronesian Tolpis.

PREMISE: Plants endemic to oceanic archipelagos are suitable for studying evolution, being isolated on substrates of different ages. Evolution has been recent, rendering traditionally employed sequences insufficiently variable for resolving relationships. This study includes sampling in the genus Tolpis (Asteraceae) from the Azores, Madeira, and Cape Verde, and expands upon an earlier study demonstrating the efficacy of multiplexed shotgun genotyping (MSG) for resolving relationships in Canarian Tolpis. METHODS: Genomic libraries for 90 accessions of Tolpis and two from the outgroup were generated for genotyping individuals using MSG. Loci were de novo assembled with iPyrad, which clusters MSG loci within and between samples. A maximum likelihood phylogeny was generated with RAxML. Ancestral area reconstruction was inferred using R package BioGeoBEARS. RESULTS: MSG data recovered a highly resolved phylogeny from population to inter-archipelago levels. Ancestral area reconstruction provided biogeographic hypotheses for the radiation of Macaronesian Tolpis. CONCLUSIONS: Four major clades were resolved. The Madeiran endemic T. macrorhiza is sister to other Tolpis. Species from the Canaries, Cape Verdes, and the continent are sister to T. succulenta from Madeira, which has a sister subclade of Azorean populations composed of T. succulenta and T. azorica. Population-level resolution suggests unrecognized taxa on several archipelagos. Ancestral reconstruction suggests initial dispersal from the continent to Madeira, with dispersal to the Azores, then dispersal from Madeira to the Canary Islands, with both subsequent dispersal to the Cape Verdes and back-dispersal to the continent. Single-island radiations and inter-island dispersal are implicated in divergence in Macaronesian Tolpis.