Mitochondrial and nuclear ribosomal DNA data do not support the separation of the Antarctic lichens Umbilicaria kappenii and Umbilicaria antarctica as distinct species

The Antarctic endemics Umbilicaria kappenii and U. antarctica are morphologically close, but mainly distinguished by their reproductive strategies. Umbilicaria antarctica propagates by means of thalloconidia. Umbilicaria kappenii lacks thalloconidia, but exhibits a variety of asexual propagules: soredia, adventive lobes and thallyles. We have now employed molecular data from three gene regions to examine the phylogenetic relationships of these two morphotypes. The phylogeny often samples and four outgroup taxa (Umbilicaria decussata, U. krascheninnikovii, U. nylanderiana, U. umbilicaiioides) was reconstructed using Bayesian and maximum parsimony analyses of a combined data set of nuclear ITS, nuclear LSU rDNA and mitochondrial LSU rDNA sequences. Forty two new partial sequences of 14 specimens were generated. Our results indicate that all samples morphologically referred to U. antarctica and U. kappenii form a monophyletic group. A topology separating the two morphotypes as phylogenetic species is significantly rejected with the data set. It is proposed to place U. kappenii into synonymy with U. antarctica.