A new species of Stigmatodiscus (Ascomycota, Dothideomycetes, Stigmatodiscaceae) from Juan de Nova (Mozambique Channel, Scattered Islands, French Southern and Antarctic Lands)

Abstract

Stigmatodiscus touroultii (Stigmatodiscaceae, Stigmatodiscales) is described and illustrated from corticated dead twigs of Salvadora angustifolia collected in Juan de Nova (Scattered Islands, Mozambique Channel). It is characterized by the irregularly shaped pruinose hymenial disc without distinct black marginal lips and a calcium oxalate crystal layer in the epithecium. Phylogenetic analyses of a multigene matrix containing a representative selection of Dothideomycetes from four genes (nucSSU-ITS-LSU rDNA, RPB2, TEF1 and TUB2) revealed a highly supported placement within Stigmatodiscus as sister species to Stigmatodiscus oculatus. Micromorphology of the sexual and asexual morph matches the genus Stigmatodiscus. A key to all known species worldwide is provided.