Three new species of Rhytidhysteron (Dothideomycetes, Ascomycota) from Mexico

The genus Rhytidhysteron is characterised by forming navicular to apothecial hysterothecia, exposing the green, yellow, orange, red, vinaceous or black colours of the hymenium which generally releases pigments in the presence of KOH. The exciple is smooth or striated, the asci bitunicate and ascospores have 1–5 transverse septa. To date, twenty-six Rhytidhysteron species have been described from the Tropics. The present study aims to describe three new species in the Neotropics of Mexico based on molecular methods and morphological features. Illustrations and a taxonomic key are provided for all known species of this genus. Rhytidhysteron cozumelense from the Isla Cozumel Biosphere Reserve, R. esperanzae from the Sierra Juárez, Oaxaca and R. mesophilum from the Sierra Madre Oriental, Hidalgo are described as new species. With the present study, the number of species of Rhytidhysteron known from Mexico is now increased to eight.