Abstract
A new species of Diderma (Physarales, Didymiaceae) was recorded in the Mata Estrela Private Nature Reserve, Rio Grande do Norte state. It is characterized by sessile sporangia, white globose columella, capillitium irradiating from the peridium, forming three layers, the middle part strongly calcareous, the outer layer cartilaginous and the inner layer membranous. A key to species of sessile sporangia Diderma with triple peridium is presented.
Key words:
Didymiaceae; Neotropic; triple peridium