Aquapteridosporaceae K.D. Hyde & Hongsanan, fam. nov.
MycoBank number: MB 557980; Index Fungorum number: IF 557980; Facesoffungi number: FoF 09410
Type genus: Aquapteridospora Jing Yang, K.D. Hyde & Maharachch
Saprobic on decaying wood submerged in freshwater. Asexual morph: Colonies on the substrate effuse, hairy, dark brown. Mycelium superficial or partly immersed, composed of branched, septate, pale brown to brown, smooth, thin‑walled hyphae. Conidiophores macronematous, mononematous, cylindrical, solitary, erect, unbranched, straight, or slightly flexuous, septate, smooth, dark brown, paler towards apex. Conidiogenous cells polyblastic, terminal becoming intercalary, integrated, with several sympodial proliferations, bearing tiny, protuberant, circular scars. Conidia acropleurogenous, solitary, fusiform, smooth, obtuse at both ends, euseptate, slightly constricted at septa, with pale to dark brown central cells and subhyaline end cells, guttulate, sometimes with sheaths. Sexual morph: Undetermined.
Notes: Aquapteridospora was established by Yang et al. (2015) based on an asexual species, Aquapteridospora lignicola. Phylogenetic analysis showed that this genus is close to species of Ellisembia and Sporidesmium (Yang et al. 2015). Aquapteridospora is morphologically distinct from Ellisembia and Sporidesmium by the polyblastic conidiogenous cells and euseptate conidia (Yang et al. 2015). With more species introduced, Aquapteridospora formed a stable and well‑supported clade within Distoseptisporales sister to Distoseptisporaceae (Luo et al. 2019; Hyde et al. 2020a). Our phylogenetic analysis obtained similar results, and the divergence estimate for this genus is around 110 MYA (Fig. 3), which falls within the family level range (50–130 MYA, Hyde et al. 2017). Aquapteridospora is similar to Distoseptispora in having macronematous, mononematous, unbranched conidiophores, mono‑ or polyblastic, holoblastic, conidiogenous cells and acrogenous, solitary conidia. However, Aquapteridospora can easily be distinguished from Distoseptispora by its terminal, conidiogenous cells which later become intercalary with circular scars. In addition, Aquapteridospora has long conidiophores and fusiform, 3‑euseptate conidia with obtuse ends and sometimes with a sheath. While, conidiogenous cells of Distoseptispora are terminal, lack circular scars, conidiophores are short, conidia are longer than conidiophores, obclavate, rostrate, and tapering towards apex and truncate at their bases. Based on the unique characters, phylogenetic analysis and divergence estimates being in the family range (50–130 MYA), we, introduced a new family Aquapteridosporaceae to accommodate the genus and place this family in Distoseptisporales. Currently, two species are included in this family and both were collected from freshwater habitats.
Fig. 3 The accepted families and orders in Diaporthomycetidae with divergence time estimations are shown in the MCC tree