Robiniigena Bundhun, Camporesi & K. D. Hyde 2024, gen. nov.

Robiniigena Bundhun, Camporesi & K. D. Hyde gen. nov. Etymology: The name is based on the host genus Robinia, from which the fungus was isolated. Description. Saprobic on woody substrates. Sexual morph: Ascomata immersed, with black dots present on host surface or erumpent, scattered, solitary or growing in groups in a pseudostroma, perithecial, globose to subglobose, usually unilocular, brown to dark brown, ostiolate. Ostiolar neck papillate, composed of hyaline pseudoparenchymatous cells. Peridium comprising two regions, outer region multi-layered, composed of brown to dark brown, thick-walled cells of textura angularis; inner layer made up of lightly pigmented to hyaline cells. Hamathecium composed of hyaline, filiform, cellular, branched, indistinctly septate pseudoparaphyses. Asci bitunicate, fissitunicate, 8 - spored, hyaline, clavate to cylindric-clavate, thin-walled, short-pedicellate, apically rounded, with an ocular chamber. Ascospores overlapping 1–2 - seriate, hyaline, narrow to broadly fusiform, straight to slightly curved, euseptate, constricted at the septum, both ends conically rounded, smooth-walled, usually guttulate, surrounded by a thick or spreading mucilaginous sheath at maturity. Asexual morph: Undetermined. Type species. Robiniigena hyalinospora Bundhun, Camporesi & K. D. Hyde Notes. This monotypic genus forms a basal lineage in Pleomonodictydaceae with 99 % ML BS and 1.00 BYPP statistical support (Fig. 1). Robiniigena shares several characteristics with Inflatispora, in terms of cellular pseudoparaphyses, clavate to cylindric-clavate, short-pedicellate asci, and hyaline, septate ascospores surrounded by a mucilaginous sheath (Zhang et al. 2011; Tibpromma et al. 2017). The ascospores of Robiniigena are, however, narrow to broadly fusiform and sometimes contain few large guttules, while those of Inflatispora are mostly narrowly fusiform to almost cylindrical and are ornamented with small guttules (Zhang et al. 2011; Tibpromma et al. 2017). The two genera are also phylogenetically distinct, with Inflatispora grouping with Pleohelicoon and Pleomonodictys in a clade and Robiniigena forming a basal separate lineage (Fig. 1).