Thermutopsis jamesii Henssen gen. et sp. nov. (Lichinaceae) is described from calcareous rocks in Antigua. The new species resembles in habit Thermutis velutina but differs in the internal stucture and development of thallus and fructifications. The cyanobiont is a poorly lichenized species of Tolypothrix; the fructifications arise within the the gelatinous sheath of the algal filaments. The ascocarps are thallinocarps of a special type; the hymenium stains deep blue in iodine; young paraphyses are thick and richly branched; the prototunicate, non-amyloid asci contain 8 simple, colourless spores. The pycnidia are ellipsoid, producing small rod-shaped, acrogenous conidia.