Several genera now classified in the Pleurotheciales appear polyphyletic based on molecular phylogenies. Helicoön farinosum, which has hyaline, coiled, septate conidia formed holoblastically on short denticles, is the only representative with helicosporous conidia in the Pleurotheciales and in the whole CPS clade. It was experimentally linked with its sexual state Ascotaiwania hughesii (Fallah et al. 1999) and in our phylogeny it is nested in Clade I as a sister to Brachysporiella setosa. We confirmed the phylogenetic position of H. farinosum (DAOM 241947) with collections, cultures and sequences made in Canada (Réblová et al. 2012). Although the correct species epithet for this holomorphic fungus would be ‘farinosum’, whether the generic assignment should be Helicoön is unclear pending confirmation of the phylogenetic placement and classification of the type species H. sessile. The genus Helicoön sensu Goos et al. (1986) was shown to be polyphyletic with DNA sequences of two nuc rDNA loci by Tsui & Berbee (2006), but H. sessile was not included. The only available ITS rDNA sequence of this species (U72605, Pfister et al. 1997) shows 99 % similarity with the ITS sequence of Sarocladium kiliense of the Hypocreales (KP132606, Irinyi et al. 2015), an unlikely relationship suggestive of a mislabelled or contaminated culture. Other species of Helicoön were placed in the Pleosporales, Tubeufiales and Venturiales of the Dothideomycetes (Tsui & Berbee 2006).

Phaeoisaria is a dematiaceous hyphomycete genus with species producing indeterminate synnemata with septate or nonseptate ellipsoidal, obovoidal, fusiform-cylindrical or falcate conidia formed on a sympodially extending rachis, occurring on decaying wood, plant debris or soil sediments (e.g. Sutton 1973, Deighton 1974, Castañeda et al. 2002, Seifert et al. 2011, Mel’nik 2012, Cheng et al. 2014, Crous et al. 2015). The genus was proposed by Von Höhnel (1909) with the only species Ph. bambusae. It was originally described as an asexual state of Neopeckia bambusae, inferred from the intimate juxtaposition of synnemata and ascomata. Based on his revision of type and herbarium material, Deighton (1974) considered Ph. bambusae a synonym of Ph. clematidis. He compiled an extensive synonymy of the latter species, distinguishing it from morphologically similar Ph. magnifica, which has broader conidia. Deighton’s concept of Ph. clematidis seems to represent a complex of several phylogenetic species. Phaeoisaria now includes 19 species, five of which were analysed in our study. The sampled species form a strongly supported monophyletic clade in the Pleurotheciales that includes species with synnemata and conidiophores formed in fascicles.

Taeniolella exilis, the type of the genus, is commonly found on decaying wood and bark of Betula (Hughes 1958, Ellis 1971). During a revision of the type material of T. exilis by Jones et al. (2002), a penicillately branched conidiophore was observed as an extension of the terminal macroconidia. A similar penicillate conidiophore was observed in two other species, T. longissima and T. rudis (Hughes 1980, Jones et al. 2002). The latter taxon was shown to be closely related to Sterigmatobotrys macrocarpa of the Pleurotheciales, whose asexual state is characterised by similar penicillate conidiophores with several series of branches and metulae terminating macronematous conidiophores (Réblová & Seifert 2011). However, brown, septate Taeniolella macroconidia were not observed in axenic cultures obtained from conidia or ascospores of S. macrocarpa.