AbstractRiccia atlanticaSérgio&Perold,sp. nov., described from Madeira, is a diminutive species with conspicuous and enlarged epithelial cells, which give a crystalline and shiny appearance when fresh. It is also distinguished by the inconspicuous hyaline scales, the absence of cilia and the spore ornamentation, areolae on the distal face have indistinct walls, the unperforated marginal angles, the triradiate mark on the proximal face being almost imperceptible, and the inconspicuous wing.