A new species, Flammulina mexicana, grows on woody Senecio cinerarioides at
high elevation on Mexican volcanoes. A tetrapolar mating system and other
cultural features are described. Flammulina mexicana is compared to its clo
sest ally, F. callistosporioides, based on type studies. Both species have
hymeniform pileipelli and gelatinized subhymenia.