Phylum: Ascomycota Family: Leptosphaeriaceae
Leptosphaeria acuta (Fuckel) P. Karst.
Nettle Rash
Widespread on the dead stems of common nettle (Urtica dioica)
References:
Ellis, M.B. & Ellis, J.P (1997 new enlarged edition) Microfungi on Land Plants: An Identification Handbook
Dennis, R.W.G. (1978) British Ascomycetes