Abstract
Two new species of Trichoglossum are described from south Mexico based on morphological and molecular evidence. Trichoglossumcaespitosum is characterized by the caespitose ascomata, rough and coiled paraphyses and the ascospores with 9-11 septa. Trichoglossumtropicale is characterized by the capitate ascomata, clavate and straight paraphyses and the ascospores with 10-12 septa. Both species grow in the tropical forests of the Yucatán peninsula. Here we provide descriptions and photographs for these species, together with a phylogenetic analyses based on the DNA sequences of nuc rDNA (ITS region and 28S gene) and a comparative table for the species known for America.