Epichloë guerinii is a hybrid asexual species in the fungal genus Epichloë.
A systemic and seed-transmissible grass symbiont first described in 2007,[1] Epichloë guerinii is a natural allopolyploid of Epichloë gansuensis and a strain in the Epichloë typhina complex.
Epichloë guerinii is found in Europe, where it has been identified in the grass species Melica ciliata and Melica transsilvanica.