Neoacanthostigma Boonmee, Bhat & K.D. Hyde, gen. nov.,Index Fungorum number: IF550576.

Etymology: neo – a new genus similar to Acanthostigma.

Saprobicon dead wood. Sexual state:Ascomata superficial, solitary, scattered, globose to subglobose, reddish-brown to dark brown, to black, surrounded by black shining setae, tapering towards an acute tip, ostiolate. Peridium composed of several layers of brown cells of textura angularis. Hamathecium comprising numerous,filiform, septate, branched, hyaline pseudoparaphyses. Asci 8-spored, bitunicate, cylindric-clavate, with a short rounded pedicel, with thick and rounded apex, ocular chamber not observed. Ascospores fasciculate, cylindrical, narrowly fusiform, tapering towards narrow, subacute ends, trans-septate, hyaline, smooth-walled. Asexual state:hyphomycetous, helicosporous.Conidiophores micronematous, holoblastic, polyblastic, dentate on creeping hyphae, up to 5 µm long, hyaline. Conidiahelicosporous, coiled in 1–2½ dimensional times, tapering towards rounded ends, multiseptate, hyaline, with mucilaginous pads at ends.

Type species:Neocanthostigma fusiforme Boonmee, Bhat & K.D. Hyde

Notes: The type species of Neoacanthostigma, N. fusiforme, clusters with the type strain of Acanthostigma septoconstrictum Promp. & A.N. Mill. in an individual clade in the multigene analysis (Clade M, Fig. 2)with highsupport (99% BS and 1.00 PP).These taxa appear to be related, therefore, we synonymize Acanthostigma septoconstrictumunder Neoacanthostigma based on phylogenetic suggestion.Two strains of Acanthostigmafiliforme(ANM101, ex-type and ANM514) also cluster in Clade M, although with weak support (Fig. 2) and is synonymised under Neoacanthostigma.Neoacanthostigma is similar to Acanthostigma in that ascomata are covered with setae, asci are bitunicate, ascospores are cylindrical to narrowly fusiform and the asexual state is helicosporous (Réblová and Barr 2000). Species in this genus would previously have been referred to Acanthostigma, while their asexual states are helicoma-likeor helicomyces-like. These genera are morphologically distinct. In Neoacanthostigma the ascomata have long setae and the ascospores are narrowly fusiform to symmetrical, while in Acanthostigma the ascomatal setae are short and the ascospores are asymmetrical, fusiform to clavate (Réblová and Barr 2000; Bonmee et al. 2011). The hyaline conidiophores are moniliaceous and micronematous formed directly from mycelium, not typical ofHelicoma, Helicomycesor Helicosporium.

 Species