Phylogenetic analysis of Trichaptum based on nuclear 18S, 5.8S and ITS ribosomal DNA sequences

Phylogenetic relationships of Trichaptum were studied using DNA sequences from nuclear 18S rDNA and 5.8S rDNA and their internal transcribed spacers, ITS1 and ITS2. Eight strains of four Trichaptum species were investigated. Using parsimony and neighbor-joining methods, phylogenetic trees were constructed for 18S rDNA and for the combined data sets of rDNA and ITS. Phylogenetic analyses of 18S rDNA sequences showed that Trichaptum species were closer to Inonotus (Hymenochaetaceae) than to other genera of the Polyporaceae sensu Donk. Strains of each species formed a monophyletic group except for IT: abietinum which formed polyphyletic subgroups, indicating that each Trichaptum species is phylogenetically distinct but that ir: abietinum may be in the process of divergence. Our results suggest similar conclusions for both 185 rDNA and ITS1-5.8S-ITS2 analyses.