AGRESTIA ZEROVII (MEGASPORACEAE, LICHEN-FORMING ASCOMYCETES), A NEW SPECIES FROM SOUTH EASTERN EUROPE PROVED BY ALTERNATIVE PHYLOGENETIC ANALYSIS

Agrestia zerovii is described, illustrated, and compared here with closely related taxa. It is a member of the A. hispida complex of the steppe zone of Ukraine, southeastern Europe, and diff ers from A. hispida s. str. in having much thicker main thalline lobes, in forming thick “horizontal crust”, and in the lack of black tips of secondary branchlets. Th e position of the newly described A. zerovii in the alternative combined phylogenetic tree of the Megasporaceae with all members for which reliable data on the nrITS, nrLSU, and mtSSU sequences are hitherto available is discussed. Four new robust branches and their taxonomic diversity are discussed, i.e.: the Agrestia, the Chlorangium, the Sphaerothallia s. str., and the “Circinaria” lacunosa clades being in separate position from the Circinaria s. str. clade (additionally to fi ve genera of the Megasporaceae, i.e. Aspicilia, Circinaria, Lobothallia, Megaspora and Sagedia accepted by previous authors). Th e genera Agrestia, Chlorangium, and Sphaerothallia, proposed to be resurrected, and a number of aspicilioid lichens the status of which are in need of revision are discussed. Five new combinations for the species of the genus Chlorangium (C. alpicola, C. aschabadense, C. asperum, C. gyrosum, and C. sphaerothallinum) are proposed.