Search on : Taxa descriptions


 Add this item to the list  Pirex Hjortst. & Ryv. gen. nov.
Description type:Original description 
Description:Pirex Hjortst. & Ryv. gen. nov.
Typus generis: Radulum concentricum Cooke & Ellis
Basidiocarp resupinate, effuse, moderately thick, in the type-specimen approximately 2-5 mm, hymenium subceraceus, odontoid to hydnoid or subporoid. Hyphal system monomitic, with clamps on all hyphae. Subiculum distinct, cottony, brown, hyphae moderately thick-walled, ramified and irregularly interwoven, yellowish brown, other hyphae more or less hyaline, with oily contents in the protoplasm. Cystidia absent but hyphal elements (cystidioles) may occur in the hymenium. Basidia typically clavate, slightly constricted and basally narrowing, with 4 sterigmata and a basal clamp. Spores ellipsoid to narrowly ellipsoid, thin-walled, smoooth, moderately sized (6-9 µm), acyanophilous, non-amyloid, non-dextrinoid.
Remarks. Pirex is well characterized by its conspicuous brown subiculum, which is very striking in the central part of the aculei. Of further important diagnostic value are the hymenial configuration, the club-shaped basidia, and the thin-walled, smooth spores. The reddish colour change in KOH (which in the type is very slight, see Gilbertson, 1963) is very obvious in fresh specimens, but also in well-developed and properly dried specimens. Microscopically, the generic type is somewhat like Cylindrobasidium evolvens (Fr.) Jiilich, especially by its oil-rich hyphae and the shape of the basidia. For further information of Radulum concentricum, see Gilbertson 1963 and 1964.
Taxon name: