Helminthosphaeriaceae Samuels, Cand. & Magni, Mycologia 89(1): 144 (1997)
Index Fungorum number: IF 81913; MycoBank number: MB 81913; Facesoffungi number: FoF 01142; 140 species.
Saprobic on wood or decorticated branch in terrestrial and aquatic habitats, some fungicolous. Sexual morph: Ascomata perithecial, gregarious or scattered, dark brown to black, solitary, superficial or immersed, ovoid, globose to subglobose, rough, tuberculate, smooth or with setae, papillate or ostiole indistinct, the apex collapsing when dry. Ostioles periphysate. Peridium composed of two layers, outer layer comprises brown cells of textura angularis or prismatica, carbonaceous or membranaceous; inner layer comprising hyaline cells of textura prismatica, thin, membranaceous. Paraphyses numerous, septate, persistent or deliquescing, swollen, filiform or cylindrical. Asci 8-spored, unitunicate, thin or thick-walled, cylindrical to clavate, pedicellate, apex truncate, J-, apical ring refractive or indistinct. Ascospores 2-seriate, hyaline or brown or becoming dark colored in part, allantoid, clavate, cylindrical to ellipsoid, 0–3-septate, smooth-walled, with or without guttules or pores. Asexual morph: Hyphomycetous. Conidiophores macronematous, mononematous, scattered or gregarious, brown, straight, septate, unbranched, smooth-walled. Conidiogenous cells mono- or polyblastic, terminal, intercalary, integrated, percurrently elongating; conidiogenesis tretic. Conidia solitary, acrogenous, brown, aseptate or septate, obclavate, globose to fusiform to cylindrical, straight, subtruncate to obtuse at the apex, truncate or swollen at the base, sometimes with guttules.
Type genus – Helminthosphaeria Fuckel
Notes – Helminthosphaeriaceae was introduced by Samuels et al. (1997) for taxa with black, setose ascomata and cylindrical asci containing brown ascospores and included the only genus Helminthosphaeria (Fuckel 1870). Tengiomyces was added to the family by Réblová (1999a) based on similar characters to Helminthosphaeria, viz. setose ascomata. Echinosphaeria, Hilberina, Ruzenia and Synaptospora, many of which are Lasiosphaeria segregates, were included based on analysis of LSU sequence data and characters (Miller & Huhndorf 2004, Miller et al. 2014). Endophragmiella was accepted as the asexual morph of Echinosphaeria (Hughes 1979). Helminthosphaeriaceae forms a well-supported clade in Chaetosphaeriales, with Chaetosphaeriaceae as a sister clade (Maharachchikumbura et al. 2015). Currently seven genera are accepted in the family based on morphological and phylogenic analyses of LSU, SSU, tef1 and rpb2 sequence data (Fig. 8). Although we include Tengiomyces here, it lacks molecular data, which is needed to confirm its placement.
Figure 8 – Phylogram generated from maximum likelihood analysis based on combined LSU and ITS sequence data of Chaetosphaeriales and Tracyllalales taxa. Ninety-six strains are included in the combined analyses which comprised 1695 characters (1081 characters for LSU, 614 characters for ITS) after alignment. Neurospora crassa MUCL 19026 and Gelasinospora tetrasperma CBS 178.33 (Sordariaceae, Sordariales) are used as outgroup taxa. Single gene analyses were carried out and the phylogenies were similar in topology and clade stability. Tree topology of the maximum likelihood analysis is similar to the Bayesian analysis. The best RaxML tree with a final likelihood value of – 23777.689886 is presented. Estimated base frequencies were as follows: A = 0.231060, C = 0.264793, G = 0.308265, T = 0.195882; substitution rates AC = 1.388486, AG = 1.836207, AT = 1.649563, CG = 0.971659, CT = 6.316962, GT = 1.000000; gamma distribution shape parameter a = 0.460297. Bootstrap support values for ML greater than 75% and Bayesian posterior probabilities greater than 0.95 are given near the nodes. Ex-type strains are in bold. The newly generated sequences are indicated in blue.