Sordariales Chadefaud ex D. Hawksworth & O.E. Eriksson, Syst. Ascomycet. (1986) is characterised by superficial ascomata, either perithecial or cleistothecial, non-amyloid and shallow ascal ring, black spores often with a gelatinous sheath or appendages (Lundqvist, 1972; Kirk et al., 2001). Members of this Order can be coprophiliac, fungicolous, herbicolous, lignicolous or soil-inhabiting. According to the recent compilation (Eriksson et al., 2006), the Sordariales contains three accepted families: the Chaetomiaceae, Lasiosphaeriaceae and Sordariaceae.
Historically, up to 14 families have been placed in the Sordariales based on the putative ascomal ontogenetic characters involved in centrum development (Luttrell, 1951). Two of the families (Batistiaceae, Catabotrydaceae) are monotypic, and nine others (Annulatascaceae, Boliniaceae, Cephalothecaceae, Ceratostomataceae, Chaetomiaceae, Coniochaetaceae, Helminthosphaeriaceae, Nitschkiaceae, Sordariaceae) contain fewer than 15 genera each (Eriksson et al., 2003). The Lasiosphaeriaceae is by far the largest and most morphologically diverse family in the Order. 53 genera have been referred to this family (Eriksson & Hawksworth, 1998) but recently it has been redefined and circumscribed with 27 genera (Eriksson, 2006). Sordariaceae, on the other hand, is one of the well-known and best-studied families, as it consists of some notable taxa such as Neurospora crassa and Sordaria fimicola, model organisms that are widely used in molecular and genetic studies (Perkins, 1992; Taylor et al., 1993; Kalogeropoulos & Thuriaux, 2001).
Familial delineation of taxa to Lasiosphaeriaceae and Sordariaceae has been very unclear in the past. Genera within these two classes have been combined under one family (Munk, 1953; Carroll & Munk, 1964; Dennis, 1968), then separated into two families with two subfamilies in Lasiosphaeriaceae (Lundqvist, 1972) or split into a third family, Tripterosporaceae (Cain, 1956; Barr, 1990). This ambiguity is now resolved with molecular phylogenetics. In the recent study by Huhndorf et al. (2004), most of the families that have been previously placed in Sordariales were evaluated. They concluded that the Order is a coherent group with morphologies that vary along well-defined lines, including large ascomata with large-celled membraneous or coriaceous walls and ascospores that show wide variation in the kinds of appendages or sheaths. As a result of their study, only Chaetomiaceae, Lasiosphaeriaceae and Sordariaceae are retained in the Order Sordariales, others including Annulatascaceae, Boliniaceae, Batistiaceae, Catabotrydaceae, Cephalothecaceae, Ceratostomataceae, Chaetomiaceae, Coniochaetaceae, Helminthosphaeriaceae and Nitschkiaceae were either placed into a new Order, in other existing Orders, or in Sordariomyetidae incertae sedis.