Phylogenetic relationships and biogeographic distribution of Termitomyces (Lyophyllaceae, Basidiomycota)

Abstract

Termitomyces (Lyophyllaceae, Basidiomycota) is a group of edible fungi that developed a mutualistic relationship exclusively with all members of Macrotermitinae, especially the Macrotermes. The phylogeny of the genus and its symbionts has already been established, but its relation to their biogeographic distribution needs to be better understood. In this paper, partial sequences of the small subunit ribosomal RNA (SSU rRNA) gene from the mitochondrial DNA (mitDNA) of 20 Termitomyces spp. were analyzed to infer its phylogeny and biogeographic distribution using maximum parsimony (MP), maximum likelihood (ML), Bayesian inference (BI), and statistical dispersal-vicariance analysis (S-DIVA). The constructed MP and ML trees show that all Termitomyces spp. are monophyletic with a bootstrap percentage of 91% and 63%, respectively, with several variations in the branching of other taxa, notably the polyphyly of the three formae of T. striatus. A few monophyletic groups in the MP tree were reconstructed as either polyphyletic or paraphyletic in the ML tree. The maximum clade credibility (MCC) tree inferred from BI split Termitomyces into two major clades (posterior probability, 1.00), unlike the topologies inferred from MP and ML. The BI also indicates that Termitomyces and its sister clade diverged from their most recent common ancestor (MRCA) around 36.17 M years ago (Ma) (posterior probability, 1.00). The divergence time dating of Termitomyces and its sister clade, Lyophyllum, shows strong support for the previously established divergence time. Results from the S-DIVA imply that all extant species of Termitomyces emerged from their MRCA in Africa through rapid adaptive radiation, primarily via dispersal rather than vicariance around 17 Ma. This was most likely driven by the Oligocene-Miocene transition and Cenozoic deformations in Asia, causing the genus to disperse across the Oriental region.