Heteroradulum

Heteroradulum Lloyd ex Spirin & Malysheva, in Malysheva & Spirin, Fungal Biology 121(8): 709 (2017)

Diagnosis: Basidiocarps annual or perennial, orbicular, often fusing together, in one species effused-reflexed, leathery. Hymenophore smooth, as a rule with pink or red tints, with occasional fertile outgrowths or covered by regularly arranged sterile spines. Hyphal structure mono- or dimitic, hyphae clamped, sometimes irregularly inflated, coloured in subiculum and trama. Cystidia/gloeocystidia present. Basidia narrowly ovoid to obconical, longitudinally septate, constantly four-celled, embedded, often with a well-developed enucleate stalk. Basidiospores hyaline, cylindrical to broadly cylindrical, sometimes curved, with oily inclusions and thick, blunt apiculus. On dry branches

Index Fungorum number: IF818028

Type species: Heteroradulum kmetii (Bres.) Spirin & Malysheva, in Malysheva & Spirin, Fungal Biology 121(8): 711 (2017)

Notes: The genus name Heteroradulum was introduced by Lloyd (1917) although invalidly (as ‘McGinty’ – see Stevenson & Cash 1936). While discussing this possible new genus, Lloyd mentioned Radulum kmetii as its single representative. In addition, he correctly noticed possible close connections of the latter species with Radulum deglubens and R. spinulosum – they both were treated as members of Heteroradulum in Malysheva & Spirin (2017). Therefore, Malysheva & Spirin (2017) decided to validate Lloyd’s genus.

Morphologically, Heteroradulum is a well-defined genus. Tough basidiocarps, rather brightly coloured (pinkish or reddish) hymenium, irregularly inflated hyphae, and large, obconical basidia are the best hints for recognizing it. In two temperate – boreal species, H. deglubens and H. kmetii, hymenial surface remains smooth for a long time and obtains irregularly arranged, sharpened outgrowths only at late stages of the basidiocarp existence. In contrast, five warm temperate tropical species of Heteroradulum have spiny, Heterochaete-like hymenophore.