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A new attempt to classify the families of the Helotiales
The Helotiales are one of the larger orders of Ascomycota, including about 330 genera and roughly 2,500 species (other estimates give >3,000 spp.). This circumscription excludes the Leotiales (a paraphyletic group comprising Geoglossaceae and Leotiaceae), Phacidiales (in an extended concept including Phacidiaceae, Tympanidaceae and Helicogoniaceae), Rhytismatales, and Erysiphales. Nannfeldt (1932) distinguished only three families to correspond to this restricted circumscription (Dermateaceae, Hyaloscyphaceae, Helotiaceae). Korf (1973) recognized three additional families (Ascocorticiaceae, Hemiphacidiaceae and Sclerotiniaceae). Since then some further families have been proposed (Gelatinodiscaceae S.E Carp. 1976; Loramycetaceae Dennis ex Digby & Goos 1988; Vibrisseaceae Korf 1990; Rutstroemiaceae Holst-Jensen, L.M. Kohn & T. Schumach. 1997; Roesleriaceae Y.J. Yao & Spooner 1999; Lachnaceae Raitviir 2004). Here we recognize 25 families within the order. In addition to those mentioned above, these are: Ascodichaenaceae, Arachnopezizaceae, Calloriaceae, Cenangiaceae (=Hemiphacidiaceae), Chaetomellaceae, Chlorociboriaceae, Cordieritidaceae, Drepanopezizaceae, Godroniaceae, Heterosphaeriaceae, Mitrulaceae, Mollisiaceae, Pezizellaceae, Ploettnerulaceae. Some of them have been proposed already in the 19th century but had not yet received approval. The circumscription of some families is substantially changed based on presently available data. Several families or subfamilies turned out to be wastebaskets, particularly the Dermateaceae, Encoelioideae, and Helotiaceae. We also propose five undescribed lineages: Bryoglossum, Discinella-Pezoloma, Hysteropezizella, Stamnaria, Strossmayeria. These results are based on the study of morphological characters of sexual and asexual state, combined with molecular data; thereby paraphyletic groups were accepted if supported by morphology. Molecular data are still lacking for many genera, and further families need to be recognized in the future. Some striking correlations between molecular and morphological data became apparent. One of them concerns the ionomidotic reaction (IR), another an attribute of living cells, the refractive vacuolar bodies (VBs). To date neither of these two characters had been found associated in a single species. IR occurs with significant frequency in the Cordieritidaceae, and VBs in the Hemiphacidiaceae, here tentatively included in Cenangiaceae. Baral (1987) and Verkley (1992–95) have shown that ascus apical structures serve as valuable markers at the genus or family level, and current molecular studies confirm the taxonomic value of these amyloid ring types.