Gyalectidium corticola sp. nov. is described from Costa Rica. It is the first corticolous lichen to be formally described in this primarily foliicolous genus. The structure of the ascocarps and their pattern of development is similar to the type species of the genus but it also shows some resemblance to other genera in the Asterothyriaceae in different features. Of particular note is the production of conidia within the massive muriform ascospores.