Distribution and species composition of Laccaria (Agaricales) in tropical and subtropical America

Species of Laccaria (Agaricales) form a conspicuous component of forests dominated by Pinaceae and Fagaceae in tropical and subtropical America. Seventeen species have been reported from this region. Five species are widely distributed in the region with the others being more narrowly distributed. Laccaria fraterna is an introduced species associated with Eucalyptus. Species have not been reported from other forest types in the Neotropics following extensive field work by a number of workers in many areas of tropical South America and the Caribbean. Similarities among mycotas (fungal equivalent of flora and fauna) were assessed by comparing taxon lists and by calculating the Simpson Coefficient of Similarity between pairs of areas. Similarities between North America north of Mexico and Colombia/Costa Rica were calculated as 80% and 71.5%, respectively. This is higher than coefficients for other compared areas. Species composition in a particular area within this region appears to be influenced by the available ectomycorrhizal hosts, along with climatic and geographic factors and history.