Annulatascaceae S.W.Wong et al., Syst. Ascom. 16(1–2): 18 (1998)

Index fungorum number: IF81939; 38 species

Saprobic on submerged wood; sometimes on bamboo and on other substrates in terrestrial habitats. Sexual morph: Ascomata perithecial, scattered or densely aggregated in patches, immersed, partially superficial, brown to black, ostiolate, unilocular, rarely clypeate, globose to subglobose, ellipsoidal, smooth or rough-walled with short setose-like hyphae on the outside. Ostiolar necks cylindrical to conical, black, black at the base and pale yellow or lighter at the apex in some genera, glabrous, rarely with setae, hyphae or hairs. Peridium carbonaceous or coriaceous composed of cells of textura angularis, textura intricata, textura epidermoidea or textura prismatica with compressed cells. Paraphyses numerous, septate, branched or unbranched, tapering. Asci 8-spored, unitunicate, cylindrical, pedicellate, usually with a massive J-, refractive, cylindrical to flaring, doughnut-shaped, apical ring. Ascospores usually uniseriate, sometimes overlapping, hyaline to pale yellow or brown, ellipsoidal to oval or fusiform or lunate or citriform, unicellular or septate, septa mostly transverse, smooth or roughed, with or without appendages, mucilaginous sheath and germ pores. Asexual morph: Hyphomycetous. taeniolella-like for Chaetorostrum where Conidiophores are micronematous, mononematous. Conidia monoblastic, elongate cylindrical, trans-septate, euseptate, brown, paler near the apex. Conidial secession schizolytic (adapted from Maharachchimbura et al. 2016)

Type: Annulatascus K.D. Hyde

Notes: The family Annulatascaceae was introduced by Wong et al. (1998) to accommodate saprobic, lignicolous, freshwater genera of ascomycetes viz. AnnulatascusAscotaiwania, Clohiesia, Frondicola, Proboscispora and Submersisphaeria. Wong et al. (1998) considered that Annulatascus could be best placed in Lasiosphaeriaceae due to the presence of tapering paraphyses and within the order Sordariales. Using LSU rDNA molecular data, Ranghoo et al. (1999) showed that Annulatascaceae is a separate family, which has relationships with Sordariales. Ho and Hyde (2000) reviewed the ultrastructural studies on Annulatascaceae and concluded that more taxa need to be sequenced and analyzed to strengthen data for this family and that the ultrastructural data supports descriptions of new genera. Based on LSU rDNA sequence data, Réblová and Winka (2001) showed that that Annulatascaceae had affinities outside Sordariales. Kirk et al. (2001, 2008) placed Annulatascaceae in Sordariomycetidae families incertae sedis, which was further supported by molecular analyses using LSU rDNA datasets (Campbell and Shearer 2004; Huhndorf et al. 2004a). The family Annulatascaceae is polyphyletic (Raja et al. 2003; Campbell and Shearer 2004; Huhndorf et al. 2004a; Vijaykrishna et al. 2005). Clohiesia was placed in Annulatascaceae by Tsui et al. (1998) based on morphology but was shown to have a phylogenetic affinity with Lasiosphaeriaceae and Sordariaceae (Raja et al. 2003; Duong et al. 2004). The genus Chaetorostrum produces a taeniolella-like asexual morph in culture and is the first record of an asexual morph for Annulatascaceae (Zelski et al. 2011). The family currently comprises 18 genera and members of this family are reported from temperate and tropical regions and in both terrestrial as well as freshwater habitats. All genera need further study at the molecular level to clarify phylogenetic relatedness and possibly determine their evolution. Maharachchikumbura et al. (2015) formally placed it in Annulatascales based on phylogenetic analyses. Many genera, having a relatively massive apical ring, were placed in Annulatascaceae as listed in Maharachchikumbura et al. (2016b). Zhang et al. (2017a) excluded some genera to other families and Diaporthomycetidae genera incertae sedis based on phylogenetic analyses and divergence estimates. Currently, ten genera are accepted in this study (as listed below). Annulatascaceae species clustered in a distinct clade, but with low bootstrap support as shown in Luo et al. (2019) and this study.

Ecological and economic significance of Annulatascaceae
Annulatascaceae species are generally saprobic on submerged wood in freshwater, sometimes on bamboo and on other substrates in terrestrial habitats (Maharachchikumbura et al. 2016b). Annulusmagnus triseptatus produces soft-rot cavities on balsa wood in culture (Campbell & Shearer 2004). Species are involved in nutrient cycling (Tsui et al. 2000).