Coprinellus radicellus, a new species with northern distribution

A new coprophilous species, Coprinellus radicellus, is presented and described on the basis of morphological characters and a species phylogeny inferred from ITS1–5.8S–ITS2 and beta-tubulin gene sequences. The species is characterized by lageniform pileo- and caulocystidia, 8- to 11-μm long ellipsoid basidiospores with a central germ-pore, globose cheilocystidia, an often rooting stipe, the lack of pleurocystidia and velar elements. These characters distinguish C. radicellus from all other described species in subsection Setulosi. It comes closest to C. brevisetulosus (Arnolds) Redhead, Vilgalys & Moncalvo and C. pellucidus (P. Karst.) Redhead, Vilgalys & Moncalvo both morphologically and phylogenetically, but is distinct from both. Another five representatives of morphologically recognizable groups of subsection Setulosi were included in the phylogenetic analyses and found were distinct from C. radicellus, both morphologically and phylogenetically. To date, this new species is known only from Scandinavia, which is surprising in view of the uniform geographical distributions of most setulose Coprinellus species. A key to coprophilous taxa of Coprinellus with pileo- and caulocystidia is presented. Three new combinations are proposed.