Abstract
Pyrenothrix mexicana Herrera-Campos, Huhndorf & Lücking spec. nova is described from leaves in the upper montane rainforest of Oaxaca State, Mexico. It is the second species in the genus Pyrenothrix Riddle, established at the beginning of the twentieth century for the single species, P. nigra Riddle, a corticolous lichen restricted to southeastern United States. Both taxa have the same thallus and perithecial morphology and anatomy, but P. mexicana differs by its longer, transversally septate ascospores. The perithecial anatomy of Pyrenothrix is documented and its systematic affinities are discussed, and we conclude that the family Pyrenothrichaceae Zahlbr. should be placed in the order Chaetothyriales.
This study was financially supported by a grant of the Mexican CONACYT (no. 35008-V) to M.A. Herrera-Campos and R. Lücking. We would like to thank the Instituto de Biología (UNAM) for logistic support, Rosa Emilia Pérez, Paola Martínez Colín and Álvaro Campos for their assistance in the field, and our colleagues at UNAM, in particular M. Ulloa and C. Delgadillo, for scientific advice.