Gyalecta perithecioidea is a little-known species of saxicolous (rock-dwelling), crustose lichen in the family Gyalectaceae.

[1] It is found in Brazil, where it grows on sheltered limestone in the Atlantic Forest.

The type specimen was collected by the author from the Serra da Bodoquena (Mato Grosso do Sul at an elevation of 500 m (1,600 ft).

The hamathecium comprises unbranched paraphyses filled with yellow oil, which is a rare character in lichens.

Ascospores are hyaline, numbering eight per ascus, and they are densely irregularly muriform, with only the median septum horizontal.