PROGRESS TOWARD A PHYLOGENETIC CLASSIFICATION OF THE POLYPORACEAE THROUGH PARSIMONY ANALYSIS OF MITOCHONDRIAL RIBOSOMAL DNA-SEQUENCES

We used sequence data from mitochondrial small-subunit ribosomal DNA t o infer phylogenetic relationships of the Polyporaceae. We examined 62 species representing 14 families of Aphyllophorales and Agaricales. P arsimony analyses of these sequences suggest that the Polyporaceae are polyphyletic. Higher order relationships are poorly resolved, but sev en groups of species are generally well supported (as measured by boot strapping) or are congruent with previous taxonomic hypotheses. Group 1 includes Polyporus s.str., seven other genera of Polyporaceae, Lenti nus, and Ganoderma. Because this clade contains the type species of Po lyporus, it may serve as the core for a future recircumscription of th e Polyporaceae. Group 2 is morphologically and ecologically diverse, b ut all members have amyloid, ornamented spores (with the possible exce ption of Heterobasidion). This group includes Bondarzewia, Heterobasid ion, Hericium, Echinodontium, Lentinellus, Auriscalpium, and Russula. Group 3 includes five exemplars of the Hymenochaetaceae, as well as Ox yporus and Trichaptum. Trichaptum and members of the Hymenochaetaceae are unusual among the holobasidiomycetes in their possession of imperf orate parenthosomes. Group 4 represents the Boletaceae and includes Bo letus and Suillus. Group 5 includes Bjerkandera, which is a polypore, and Pulcherricium and Phanerochaete, which are corticioid. In Group 5 the corticioid habit may have been derived by reduction. Group 6 inclu des Fomitopsis, Piptoporus, acid Daedalea, all of which are brown rot polypores with bipolar mating systems. Group 7 includes Laetiporus and Phaeolus. Laetiporus is classified in Polyporaceae, but Phaeolus has been placed in both the Polyporaceae and Hymenochaetaceae. In general, our results suggest that macromorphology is evolutionarily flexible, but that certain anatomical and physiological characters, while not fr ee from homoplasy, contain clues to higher order relationships of poly pores.