The class Dothideomycetes is one of the largest groups of fungi with a high level of ecological diversity. Species in this class are characterized by bitunicate asci (asci with two wall layers) with fissitunicate dehiscence property, a thick extensible inner layer (endotunica), a thin inextensible outer layer (ectotunica) and ascolocular ascoma development (Schoch et al. 2009, Hyde et al. 2013). They are also characterized by the presence of hamathecium or centrum defined as the tissues and cells subjugating the cavity of ascomata. These characters can demarcate ordinal classification in Dothideomycetes, such as Pleosporales, Dothideales, and Myriangiales (Luttrell 1955, Kirk et al. 2001, Schoch et al. 2009). Several studies have been carried out in this class of fungi providing preliminary data towards a natural classification of Dothideomycetes (Boonmee et al. 2011, 2012, Chomnunti et al. 2011, Liu et al. 2011, 2012, Schoch et al. 2009, Nelsen et al. 2009, 2011, Zhang et al. 2011, 2012, Hyde et al. 2013). Till now, more than 105 families, 22 orders, 1300 genera and over 19,000 species have been described in this class of fungi (Wijayawardene et al. 2018). Most of them are saprobes, exhibiting both sexual and asexual morphs. Some are endophytes, epiphytes, fungicolous, lichenized, or lichenicolous fungi. They are highly diverse and occur worldwide on terrestrial, freshwater and marine habitats. Members in the Dothideomycetes share a number of similar morphological characters with other fungal classes and its taxonomy has been strongly influenced by classifications based on the development and morphology of the sexual structures (e.g., bitunicate asci or meiosporangia). It was earlier described as loculoascomycetes (Lutrell 1955) based on the developmental pattern of the ascomata or ascostromata (Berbee & Taylor 1995, Spatafora et al. 1995). Previous findings showed that morphological characters of Dothideomycetes fungi either maintain ancestral traits or they display convergence due to similar selection pressures. One of the main challenges in the Dothideomycetes systematics is which species should be members of the class based on morphology alone (Schoch et al. 2009). Moreover, the taxonomy of Dothideomycetes is often confused since it is based mostly on a limited number of morphological characters (Schoch et al. 2009). Dual names have been applied to the same species leading to confusion among scientists (Wijayawardene et al. 2014). Majority of fungi hypothesized to be members of Dothideomycetes remain under-sampled within a systematic framework (Preito et al. 2013). Several studies performed during past years have increased our understanding of these fungi, but phylogenetic relationships of the saprobes and asexual species remain poorly studied. Molecular data has been recently incorporated into studies and a more natural phylogeny of the group is emerging, however more research is warranted in this group of fungi. Dothideomycetes taxonomy needs to keep pace with rapid advances being made in molecular systematics as well as assess diversity accurately and allow mycologists to have access to an agreed set of taxonomic names to aid communication (Schoch et al. 2009).
In this paper we deal with the genera of Dothideomycetes as currently recognized and bring together recent published data and attempt to link morphological data to the findings resulting from molecular analysis. This work is a continuation of the papers “Families of Dothideomycetes” (2013) in which we compile a treatment of the class Dothideomycetes. The present treatment is needed as our knowledge has rapidly increased, from 105 families and 1138 genera (238 Genera incertae sedis) in 2013 to ca 202 families and 1495 genera (242 Genera incertae sedis) at the time of publication. In this treatment we provide notes on each genus. We provide up-to-date trees. The new genus ***, and new species **** are introduced with illustrations and descriptions, while ** new records are provided. We also list ** taxa that are transferred to Sordariomycetes and provide short notes. For each genus we provide a general description and illustrate the type species, the latter where the placement is confirmed with molecular data. Both the sexual and asexual morphs representative of a genus are provided where available. A key to the genera is also provided unless this was not feasible. Notes on ecological and economic considerations are also given.
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