Host and geographical distribution ofVerticicladium trifidum,Thysanophora penicillioides, and similar fungi on decaying coniferous needles

摘要

Dematious hyphomycetes such asVerticicladium trifidumandThysanophora penicillioidesare examples of equivalent species occupying the same ecological niche in different fungal successions. These two species fructify through the stomata of coniferous needles a few months after litter fall. Litter samples of 23 coniferous species from different European sites were examined to explain the fungal distribution.Thysanophora penicillioidescolonizedAbies,Picea,Pseudotsuga, andTsuganeedles, whereasV.trifidumwas restricted toPinusandCedrus. Sometimes other fungal species occupied the stomata: onPinus pineaneedles, the niche was occupied byCladosporiumspp. andAlternaria alternata;Chaetopsina fulvahave been found only onPseudotsuganeedles andThysanophora canadensisonPicea.Verticicladium trifidumwas apparently absent onPinuslitters from cold climates (high altitude or latitude) and probably from warm mediterranean regions, suggesting a climatic determinism. However, coexistence ofVerticicladiumandThysanophorain some samples or colonization of somePinuslitter byThysanophorasuggests that these distributions result from competition rather than strict host specificity.Key words: ecological niche, equivalent species, conifers, needles,Verticicladium trifidum,Thysanophora penicillioides.