PHYLOGENY OF THE ATTINE ANT FUNGI BASED ON ANALYSIS OF SMALL-SUBUNIT RIBOSOMAL-RNA GENE-SEQUENCES

Complete 16S-like ribosomal RNA coding regions were obtained from the fungal symbiont of five genera of attine (leaf-cutting) ants and two f ree-living fungi. Phylogenetic analyses with distance matrix, maximum likelihood, and parsimony methods revealed that the attine fungal symb ionts are homobasidiomycetes in the order Agaricales. Comparison of th e topology of the attine fungal symbiont phylogenetic tree with a tree based on attine ant morphology revealed a congruent branching pattern of the more derived attine ants and their fungal symbionts. The paral lel branching pattern suggests a long-term coevolution of derived leaf -cutting attine ants and their fungal symbionts.