Endophyte-Host Associations in Grasses. XIX. A Systematic Study of Some Sympatric Species of Epichloë in England

Systematic studies were conducted on populations of Epichloë species on host grasses Agrostis capillars, Dactylis glomerata, and Holcus lanatus. Three species of Epichloë are described and two, E. baconii and E. clarkii, are proposed as new, being distinguishable from the type by disarticulation of ascospores to form uniquely shaped part-spores. The type species E. typhina does not form part-spores. Reproductive compatibility between fungi was examined. Intraspecies crosses were found to yield a dense layer of perithecia that differentiated asci and ascospores internally. Interspecies crosses gave one of three results, including no reaction, necrotic browning, or perithecia that did not mature. Cultural features of these fungi are compared. Isolates are seen to exhibit differences in growth rates on sugars and hydrolysis of milk protein and corn starch. Generic limits of Epichloë are discussed and several species are excluded. It is proposed that a biological species concept be adopted to aid definition of species within this genus.