A new species, Gyalectidium yahriae Buck & Sérus., is described from collections made on twigs in Quercus woods in Florida (U.S.A.) and from decorticated wood in the montane forest zone of Papua New Guinea. Its ascocarps are unknown, but it is easily characterized by hyphophores composed of a circle of triangular lobes and by masses of moniliform hyphae producing long cilia on their outer cells; its generic position in the lichen family Gomphillaceae is uncertain.