Flectospora Réblová & Hern.-Restr., in Réblová, Nekvindová & Hernández-Restrepo, Journal of Fungi 7(6, no. 438): 15 (2021)
MycoBank number: MB 839478; Index Fungorum number: IF 839478; Facesoffungi number: FoF14548;
Etymology – Flectus (L) bend, curved, spora (L) spore, referring to the curved conidia.
Type species – Flectospora laminata Réblová & Hern.-Restr.
Description – Colonies on the natural substrate effuse, hairy, mycelium semi-immersed, composed of conidiophores, occasionally ascomata. Asexual morph: Setae absent. Conidiophores macronematous, mononematous, solitary, erect, straight or slightly flexuous, cylindrical, unbranched, thick-walled, septate, smooth, brown. Conidiogenous cells integrated, terminal, mono- or polyphialidic with several lateral apertures, extending percurrently and sympodially, paler than the conidiophores, conidia formed on single conidiogenous loci; collarettes funnel-shaped. Conidia ellipsoidal to obovoid, slightly curved, aseptate, hyaline, accumulate in slimy colourless fascicles. Sexual morph: Ascomata perithecial, non-stromatic, superficial, subglobose to conical, papillate or with a rostrate neck, dark brown, glabrous. Ostiole periphysate. Ascomatal wall two-layered, carbonaceous. Paraphyses persistent, septate, hyaline. Asci unitunicate, cylindrical-clavate, short-stipitate, ascal apex with a non-amyloid apical annulus, 8-spored. Ascospores ellipsoidal-fusiform, hyaline, transversely septate, smooth.
Habitat and geographical distribution – Saprobes on decaying wood, known so far in New Zealand and Thailand.
Note – Flectospora is established for ascomycetes with phialidic dematiaceous hyphomycete anamorphs with macronematous, simple conidiophores and hyaline, ellipsoidal to obovoid, aseptate, slightly curved conidia accumulating in slimy heads. The teleomorphs have glabrous perithecial ascomata, unitunicate asci, paraphyses, and hyaline, septate ascospores. The genus accommodates two species.
Flectospora laminata was initially considered the chloridium-like anamorph of Chaetosphaeria hispida [19], characterised by scolecosporous, septate, hyaline ascospores and ascomata covered with short, opaque spines. The holotype of Ch. hispida contains conidiophores of the chloridium-like fungus growing near the ascomata. Identical, sporulating conidiophores were obtained in culture (strain CBS 112964), from which the DNA sequences were derived. However, phylogenetic analysis of ITS-28S sequences, including the chloridium-like anamorph, E. spinosa, members of Paragaeumannomyces and other mor- phologically similar species, have raised suspicions that the chloridium-like fungus is not the anamorph but likely a contamination. The isolation into axenic culture occurred during the fieldwork in the Khao Yai forest in Thailand. Although the strain was derived from ascospores, the conidia were probably removed from the natural material by accident.
Although Ch. hispida, E. spinosa and Paragaeumannomyces are remarkably similar in characters to ascomata, asci and especially ascospores, they grouped in distantly related clades. The ex-type strain of E. spinosa S.M.H. 2754 and Paragaeumannomyces spp. clustered in one clade, while the ex-type strain of Ch. hispida CBS 112964 nested in the Tainosphaeria clade. It is difficult to reconcile such different teleomorphic features with the revealed phylogenetic relationships. Known teleomorphs of the Tainosphaeria clade have glabrous ascomata and symmetrical, ellipsoidal to fusiform, 0–several-septate ascospores ([3], this study). The results of the phylogenetic analysis prompted the revision of the holotype of Ch. hispida and has been found to be a species of Paragaeumannomyces [7,20]. Based on the phylogenetic arguments and critical evaluation of teleomorphic and anamorphic characteristics, we conclude that the chloridium-like presumed anamorph of Ch. hispida does not belong to its life cycle. Therefore, the hyphomycete growing in the holotype of Ch. hispida is transferred to the new genus Flectospora as F. laminata and a new combination for Ch. hispida in Paragaeumannomyces is proposed below.
Species