The corticolous and lignicolous species of Bacidia and Bacidina in North America

This is a taxonomic revision of the corticolous and lignicolous taxa of the genera Bacidia and Bacidina (Lecanoraceae, Lecanorales, lichenized Ascomycotina) in the continental United States and Canada. Twenty-seven species of Bacidia (one of which is divided into two subspecies) and twelve species of Bacidina are recognized. The morphology, secondary chemistry, ecology, and phytogeography of these species are discussed, and a key is provided. Apothecium pigmentation, thallus composition, presence of crystals in the proper exciple, hymenium height, thickness of paraphyses, spore shape and size, in Bacidina sometimes also conidial type and tholus structure, have proved to be the most important characters to distinguish between species. Circumscriptions of Bacidia and Bacidina are attempted. Tholus structure, cell structure of the proper exciple, presence of goniocysts, presence of crystals in the thallus cortex, and size of conidiogenous cells are the most valuable characters in the delimitation of these genera. Nine new taxa are described: Bacidia diffracta, B. helicospora, B. salmonea, Bacidina aenea, Bn. californica, Bn. crystallifera, Bn. ramea, Bn. squamellosa, and Bn. varia. Twelve new combinations are introduced: Bacidia campalea, Bacidia laurocerasi subsp. idahoensis, Bacidina assulata, Bn. egenuloidea, Byssoloma meadii, Fellhanera floridana, Herteliana alaskensis, Lecania stigmatella, L. subfuscula, Pachyphiale gyalizella, Ropalospora phaeoplaca, and Ophioparma rubricosa. In addition to the newly described species, 12 species of Bacidia and four species of Bacidina are correctly reported from the study area for the first time. The genera Psorella and Toniniopsis are reduced into synonymy with Bacidia.