Two species of Lactarius are documented from fragments of tropical lowland oak forest in central Veracruz. Lactarius trichodermoides, described here as new, was found in association with Quercus sapotifolia and Lactarius subplinthogalus with Quercus glaucescens. Both Lactarius species were identified morphologically and supported by phylogenetic analyses of nuc rDNA internal transcribed spacers (ITS1-5.8S-ITS2) and D1-D2 domains of nuc 28S rDNA sequences. Confirmation of mycobionts in ectomycorrhizal (ECM) associations was verified by molecular identification of ECM root tips. Detailed macroscopic and microscopic descriptions and photographs and illustrations of basidiomes and ectomycorrhizas are presented. The new binomial Lactarius chiangmaiensis is proposed for L. subplinthogalus var. chiangmaiensis.
Keywords: 2 new taxa; Ectomycorrhizal ecology; Russulales; oak forest; taxonomy.