A Synopsis of the Taxonomy of Teleomorphs Connected with Rhizoctonia S.L.

The genus Rhizoctonia s.l., was originally characterized by the presence of sclerotia different from those of Sclerotium and the ability to infect living plant tissue (DeCandolle, 1815). This has already served to exclude the saprophytic ascomycetous genera Ascorhizoctonia (teleomorph: Tricharina, Yang and Korf, 1985; Moore, 1987) and Oedocephalum p.p. (teleomorph: Iodophanus, Gamundi and Ranalli, 1964; Stalpers, 1974) and to restrict it to the basidiomycetes. Duggar (1915) and Parmeter and Whitney (1970) listed additional characteristics to delimit Rhizoctonia s.l., among them hyphal constrictions at septa, hyphal branching at right angles just before septa, and production of monilioid cells. Unfortunately, these criteria are not sufficiently diagnostic to delimit a homogeneous taxon, and the teleomorphs of Rhizoctonia s.l. (as far as known) are now classified in various basidiomycete orders. A natural concept, in which anamorph taxonomy reflects teleomorph taxonomy, is now also being adopted in Rhizoctonia (Moore, 1987).