Abstract
Clavaria species with dark basidiomata occurring in Europe were analysed using morphological and molecular methods. Morphological analyses revealed four groups containing seven Clavaria species with dark basidiomata. Phylogenetic analysis of the LSU nrDNA region confirmed the separate positions of all seven Clavaria species within the genus. All sequences were grouped in four well-supported clades, mostly corresponding to defined morphological species. The results of the molecular study are inconsistent with the infrageneric classification of Clavaria based on the presence or absence of clamps on the bases of basidia and two widely accepted subgenera. Clavaria and Holocoryne appear to be polyphyletic. A new approach in species delimitation is presented: 1) C. asperulispora and C. atrofusca are two distinct species recognized by the shape of their spores, and the name C. neo-nigrita is a possible synonym of C. asperulispora; 2) species with clustered fragile basidiomata, C. fumosa and Clavaria cf. fuscoferruginea, which are almost identical in shape and size of spores differing only in the darker basidiomata of the latter, are phylogenetically unrelated; 3) Clavaria atrobadia is a dubious species, the name being most likely a synonym of C. fuscoferruginea; 4) two species with close morphological and phylogenetic affinity, C. atroumbrina and C. pullei, are distinguished based on the more oblong and narrower spores of the former. Comparison of European and North American material suggests the transatlantic nature of the distribution of C. asperulispora, C. atroumbrina and C. fumosa.