Subclass Chaetothyriomycetidae Doweld, Prosyllabus Tracheophytorum, Tentamen Systematis Plantarum Vascularium (Tracheophyta) (Moscow), LXXVIII (2001)

Index Fungorum number: IF 90739; Facesoffungi number: FoF 14243

The subclass Chaetothyriomycetidae was first described for the order Chaetothyriales (Dowell 2001), but the two primarily lichenised orders Verrucariales and Pyrenulales were soon also shown to belong to this subclass (Lutzoni et al. 2001, 2004; Geiser et al. 2006; Gueidan et al. 2008). These three orders are characterised by ostiolate perithecial ascomata with evanescent to fissitunicate bitunicate asci. They, however, differ in their hamathecial structures. In Verrucariales, interascal filaments are absent at maturity, replaced by a gelin with a blue reaction to potassium-iodine. Short pseudoparaphyses are present in the upper part of the perithecial cavity and ostioles are bordered with periphyses. Chaetothyriales also have short apical pseudoparaphyses (or periphysoids) and often have periphyses in the ostioles. In Pyrenulaceae, the hamathecium is generally formed by narrow trabeculate pseudoparaphyses, subsequently replaced by unbranched paraphyses. These groups also differ by their ecology. Both Pyrenulales and Verrucariales are mostly lichenised, but Pyrenulales are associated with the green algal genus Trentepohlia and are mostly found on tree bark in the wet tropics, whereas Verrucariales have a broad range of algal associates (except for Trentepohlia) and are particularly diverse on rock substrates in temperate regions. Chaetothyriales is a diverse assemblage of oligotrophic species found on various substrates (e.g., rocks, plants, indoor environments) or different animal hosts (invertebrates and vertebrates, including humans).