MOLECULAR TAXONOMY OF THE APHYLLOPHORALES

Ribosomal internal transcribed spacers (ITS1-5.8S-ITS2) sequences were used to evaluate the phylogenetic relationships within the Aphyllopho rales. The results indicate that, the Aphyllophorales represent differ ent independent lineages. In some cases phylogenetics support traditio nal taxonomic groups, e.g. Hericiales with amyloid spores. In other ca ses, among ''polypores'', ''corticioids'', or ''hydnaceous'' forms, se quence data suggest new, unfamiliar groupings chat require revision of the classification. Phylogenetic analysis of ITS sequence data gives insights into the branching structure in the tree; we have considered branchs - as independent evolutionary lineages - which merit formal ta xonomic status, e.g., order. About twenty orders hai-e been distinguis hed; five are proposed as new: Peniophorales, Phlebiales, Podoscyphale s, Trametales, and Vuilleminiales, like that five new families: Acanth ophysiaceae, Amylostereaceae, Gloiotheleaceae, Lophariaceae and Tramet aceae. Three new combinations have been also proposed: Scytinostroma i nsolitum (Boid. ,& Lanq.)n.c., Thanatephorus microsclerotius (Weber)n. c. and Vararia intexta (Boid. & Lanq.)n.c., The Lachnocladiales appear as a monophyletic group with a high bootstrap support; this implies t hat the diagnostic dextrinoid binding hyphae character is valid. In co ntrast, molecular data do not provide strong support for subgeneric di scrimination in the Peniophora or sections in the Hymenochaete. The ph ylogenetic situation is too unstable to formalize now Gloeophyllales a nd Phaeolales. The work of Hibbett & Donoghue (1995) based on ribosoma l small subunit senses as the basis for the discussion. With a combina tion of evidence from ITS sequence data available through GenBank and from intraspecific groups, we have divided Rhizoctonia solani (anamorp hic Ceratobasidiales) into four species: Thanatephorus cucumeris (Fran k)Donk, Thanatephorus praticola (Kotila)Flentje, Thanatephorus sasakii (Shirai)Tu & Kimbr. and Thanatephorus microsclerotius (Weber)c.v. ITS regions have rates of substitution that are useful for evaluating the species level relationships. For example, the ITS data indicated a ne ar contempory divergence of Central America Amylostereum ferreum and i ts two closest european relatives. There is little significant diverge nce within Peniophora quercina and simulans, less than 2 bases per ITS ; considering the conditions used here, the intraspecific diversity mi ght be a PCR artefact. Here we estimated the substitution rate variati on among species with different incompatibility systems. Sequences als o revealed information about the relationships among mycelia lacking b asidiocarps; examples are given with unidentified aphyllophorean fungi isolated from bamboos by Zhang et al.