A new species and a new record of Diatrypaceae from Panama.

Based on opportunistic collections of fungi in Panama, two species of Diatrypaceae (Xylariales) are described and illustrated. One of them, Eutypella semicircularis, found twice on branches probably belonging to Alnus acuminata, is new to science. It differs from known species of Eutypella and Peroneutypa with strongly allantoid or semicircular ascospores, such as E. crustata and P. curvispora, in having larger ascospores that sometimes almost form a circle and broader stromata, among other differences. Molecular data of the ITS rDNA region show that the new species is a sister taxon of Eutypella cerviculata, the type species of the genus Eutypella. Diatrype bermudensis on stems of Guadua angustifolia is reported from Panama for the first time, being known up to now apparently only from Bermuda.