CLASSIFICATION AND PHYLOGENY IN THE ARTHONIALES (LICHENIZED ASCOMYCETES)

The current classification of the Arthoniales and phylogenetic hypothe ses for the order are discussed. The available phylogenetic analyses o f the order lend to a better understanding of certain groups, particul arly the Roccellaceae and Chiodecton sensu late. However, numerous gen era in these groups contain a low number of species, whereas the major ity of the ca 1,200 species in the order is found in only three genera : Arthonia, Arthothelium and Opegrapha. Other formerly large genera e. g., Schismatomma, Lecanactis, and Chiodecton, have already been split into smaller units, but the classification of Arthonia and Arthotheliu m is still unsettled. A phylogenetic analysis is included to elucidate the position of Cryptothecia, Chrysothrix, and additional species of Arthonia and Arthothelium in the order. Selected morphological charact ers used in the classification and phylogeny of the Arthoniales are re viewed and a key to the better known genera is presented.