Byssoloma Trevis.
Thallus crustose, effuse, ecorticate. Photobiont green, species of Chlorococcaceae. Apothecia adnate or sessile, ± round, lecideine. Paraphyses simple or slightly branched. Asci thick-walled, 8-spored. Ascospores colourless, 1-3-septate. Pycnidia sessile, ± globose, usually covered by a layer of loosely intricating hyphae. Conidia simple, pear- to flask-shaped.
Species of Byssoloma are predominantly foliicolous although some grow on bark or stone. The foliicolous species are monographed by Santesson [ Symb. bot. upsal. 12: 477-494 (1952)] who records one species from New Zealand.
