Hybrid fungal endophytes symbiotic with the grass Lolium pratense

Classification of endophytes inhabiting Lolium pratense (= Festuca pratensi s) based on morphological and molecular phylogenetic characteristics is rep orted. From an extensive survey of L. pratense collected throughout Europe, we concluded that the overwhelmingly predominant endophyte was Neotyphodiu m x uncinatum. We constructed phylogenies based on three unlinked, nuclear genes and analyzed allozymes to evaluate the relationship of N. x uncinatum to Epichloe endophytes. Our results suggest that N. x uncinatum is an inte rspecific hybrid of two Epichloe species. A second, much rarer hybrid endop hyte was isolated from L. pratense which may have shared one of its two Epi chloe ancestors with N. x uncinatum. This second isolate is a previously un described species for which we propose the name Neotyphodium x siegelii.