Two new Lactarius species from a subtropical cloud forest in eastern Mexico

Abstract

Two species of Lactarius from the subtropical montane cloud forest of central Veracruz are described as new. Both species are placed in subgenus Lactarius based on an accurate study of macro- and micromorphological features and supported by molecular phylogenetic analyses of a single nuc rDNA ITS1-5.8S-ITS2 (ITS), a concatenated ITS, D1, and D2 domains of nuc 28S rDNA (28S), and part of the second largest subunit of the RNA polymerase II (rpb2) (6–7 region) sequence datasets. In the phylogenetic reconstruction presented, the two species appear nested in two clearly distinct, well supported clades that reveal their phylogenetic position among members of subgenus Lactarius (= subg. Piperites s. auct.), a complex group of which a worldwide phylogeny requires further study. According to field observations, both taxa are possible ectomycorrhizal associates of Quercus spp. and one of Fagus grandifolia var. mexicana. Taxonomic descriptions based on the study of specimens gathered during fieldwork from 2012 to 2014 are presented. Descriptions are accompanied with illustrations of macro and micromorphological characters and a discussion of related species is provided.