Dimerella Trevis.
Thallus crustose, effuse, decorticate, thin, shining, yellowish-green to dark green or olive-green, on bark, mosses or rarely on rock. Photobiont green, Trentepohlia. Apothecia sessile, scattered, rounded, ± lecideine, pale to intensely yellow or orange. Hypothecium colourless. Paraphyses simple, with thickened apices. Asci cylindrical to clavate, thin-walled, 8-spored. Ascospores colourless, 1- or 2-septate, spindle-shaped to ellipsoid.
Dimerella, included in the family Gyalectaceae is a genus of c. 20 species best developed in tropical or subtropical regions. At least five species are foliicolous [Santesson Symb. bot. upsal. 12: 391-403 (1952)]. One species is recorded from New Zealand.
