Neohelicascus W. Dong, H. Zhang & Doilom, Fungal Divers (2020).
Saprobic on submerged wood. Sexual morph: Pseudostromata scattered, comprising brown to black fungal material growing in cortex of host, unil- or multi-loculate, flattened at the basal region, horizontally arranged under the pseudostroma, visible on the host surface as blackened ostiolar dots. Locules immersed, lenticular to ampulliform, ostiolate. Ostiole converging at the centre, uniting into one common, central pore, periphysate. Peridium of locules comprising several layers of brown, thin-walled angular cells, paler inwardly, fusing with the host cells. Pseudoparaphyses numerous, cellular, hypha-like, hyaline, septate, embedded in a gelatinous matrix. Asci 8-spored, bitunicate, fissitunicate, clavate, long pedicellate, base of endoascus long, narrow and coiled within ectoascus, ectoascus uncoiling to form a long tail-like extension, apically rounded with a cylindrical ocular chamber. Ascospores mostly biseriate, straight or slightly curved, ellipsoidal to broadly fusiform, with rounded ends, 1-(2-3)-septate, apical cell slightly larger than basal cell, brown, thin-walled, smooth- or rough-walled, with or without a deliquescing sheath (Zhang et al. 2013a). Asexual morph: Coelomycetous. Pycnidia solitary, superficial, with the base immersed, uniloculate, globose to subglobose, brown, coriaceous, central ostiolate, with minute papilla. Peridium composed of brown, thin-walled cells of textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells holoblastic, determinate, cylindrical to subcylindrical, hyaline, smooth. Conidia ellipsoid to obovoid, hyaline, aseptate, occasionally two-celled, smooth, thin-walled, without sheath or appendage (Adapted from Zhang et al., 2013 and Dong et al., 2020).
Type species: Neohelicascus aquaticus (H. Zhang & K.D. Hyde) W. Dong, K.D. Hyde & H. Zhang
Notes: Neohelicascus was introduced by Dong et al. (2020) with N. aquaticus as type species. Neohelicascus is characterized by scattered pseudostromata, fissitunicate, clavate, long pedicellate asci and ellipsoidal to broadly fusiform ascospores. The asexual morph is characterized by solitary, superficial pycnidia with the base immersed, holoblastic, determinate, cylindrical to subcylindrical, hyaline conidiogenous cells and ellipsoid to obovoid, hyaline, aseptate conidia. Neohelicascus differs from Aquihelicascus in having brown ascospores, a long, narrow endoascus base twisted inside the ectoascus which unwinds to form a long tail-like extension while Aquihelicascus has hyaline ascospores and an uncoiled endoascus. Neohelicascus is phylogenetically distinct from Neohelicascus. Among taxa of Neohelicascus, N. egyptiacus and N. elaterascus possess a gelatinous sheath around the ascospores which is lacking in N. unilocularis (Zhang et al., 2013; 2015; Dong et al., 2020). Neohelicascus gallicus is unique among the taxa in having fugacious mucilaginous remnants in ascospores when they are just released from the asci (Zhang et al., 2014; Dong et al., 2020). Neohelicascus aquaticus is the only taxa reported with an asexual morph in culture (Zhang et al., 2013a; Dong et al., 2020). Neohelicascus is morphologically and phylogenetically a distinct genus in Morosphaeriaceae.