Genetic and morphological variations of the lichenized fungus Steinera intricata (Arctomiaceae, Lecanoromycetes) from southern South America to Antarctic Peninsula

摘要

Steinera (Arctomiaceae, Lecanoromycetes) is an Austral genus of lichenized fungi that form symbiotic associations with cyanobacteria, producing small and inconspicuous thalli. Most species of Steinera present a high degree of endemism restricted to sub-Antarctic islands except S. intricata which occurs from southern South America to the Antarctic Peninsula and presents remarkable phenotypic variation along its distribution range. In this study, an integrative approach was used to explore the extent of intraspecific diversity of S. intricata throughout its distribution. Morphological and anatomical descriptions and the phylogenetic analyses of three genomic regions were performed with specimens collected from seven Antarctic islands and in the Tierra del Fuego National Park (Argentina). Genetic data revealed species-level lineages are not associated with the differences observed in the thalli shape, which probably are related to distinct microhabitats and substrates as well as to the development stage. Molecular clock analyses estimated that S. intricata originated at about 0.24 Myr and that the diversification of the Antarctic lineages occurred at about 0.16 Myr. This study revealed that there is probably an unknown diversity of new members of Steinera in southern South America and that the evolutionary history of these cyanolichens may contribute to the understanding of the phylogeographic connections between members of the Austral-Antarctic flora.