Neogregarithecium W.H. Tian, K.D. Hyde & Maharachch., in Tian, Liu, Jin, Chen, Zhou, Wu, Su, Guo, Wanasinghe, Hyde, Liu & Maharachchikumbura, Mycosphere 15(1): 1808 (2024)

Index Fungorum number: IF 851875; MycoBank number: MB 851875; Facesoffungi number: FoF16267

Etymology – Named after its morphological similarity to Gregarithecium.

Saprobic on the dead twigs of grass. Asexual morph: Hyphomycetous. Colonies on natural substrate velvety, superficial, brown to dark brown. Aerial hyphae septate, pale to dark brown, verrucose. Conidiophores micronematous, mononematous, arising laterally from superficial hyphae, simple or occasionally branched, aseptate, hyaline to pale brown, becoming paler or subhyaline towards the apex, verrucose, cylindrical to ampulliform, straight to slightly flexuous. Conidiogenous cells holoblastic, discrete, unbranched, straight, hyaline to pale brown, verrucose, inflated. Conidia holoblastic, acrogenous, catenate, in short acropetal chains, golden-brown to dark brown, verrucose, aseptate, globose. Conidial secession schizolytic. Sexual morph: Undetermined.

Type species – Neogregarithecium sichuanense W.H. Tian, K.D. Hyde & Maharachch.

Notes – Gregarithecium curvisporum HHUF 30134 was introduced as the type of Gregarithecium by Tanaka et al. (2015). However, G. curvisporum (MFLUCC 13-0853) is mistakenly regarded as the type strain (Boonmee et al. 2016, Shen et al. 2022). Gregarithecium curvisporum (MFLUCC 13-0853) is a strain with only sequence data in NCBI but no morphological description. Based on pairwise nucleotide comparisons, G. curvisporum (MFLUCC 13-0853) differs from G. curvisporum (HHUF 30134) by 61/472 bp (gaps: 28/472 bp) in ITS; 19/825 bp (gaps: 5/825 bp) in LSU; 20/978 bp in SSU. However, comparisons of the ITS, LSU, and SSU sequences of G. curvisporum (MFLUCC 13-0853) and Neogregarithecium sichuanense (HKAS 131988) revealed 99.03% sequence identity (508/513 bp, gaps:3/513 bp) in ITS, 100% sequence identity (771/771 bp, no gaps) in LSU and 100% sequence identity (978/978 bp) in SSU. Therefore, the isolate MFLUCC 13-0853 probably belongs to Neogregarithecium. According to the multi-locus phylogeny, Neogregarithecium sp. (MFLUCC 13-0853) and Neogregarithecium sichuanense (HKAS 131988) constitute a distinct clade sister to Gregarithecium curvisporum (HHUF 30134) and Gregarithecium bambusae (UESTCC 23.0290). The asexual morphology of Gregarithecium has only been observed in G. bambusae (UESTCC 23.0290). Neogregarithecium is distinct from Gregarithecium in the characteristics of conidiophores. Neogregarithecium has micronematous, simple or occasionally branched, aseptate, straight to slightly flexuous conidiophores. Gregarithecium has micronematous to semi-macronematous, branched, 1–4-septate, flexuous conidiophores. Moreover, based on pairwise nucleotide comparisons, N. sichuanense differs from the type species G. curvisporum (HHUF 30134) by 58/469 bp (gaps: 25/469 bp) in ITS; 19/772 bp (gaps: 5/772 bp) in LSU; 21/1025 bp (gaps: 1/1025 bp) in SSU. Thus, we introduce the new genus Neogregarithecium based on the morphology and multi-locus phylogeny.

Figure 1 – Phylogram of the best ML tree based on a combined dataset (ITS, LSU, SSU and tef1-α) of Dictyosporiaceae. The scale bar indicates 0.03 changes. The tree is rooted with Hysterium pulicare (CBS 123377) (Hysteriaceae, Hysteriales). The best ML tree with a final likelihood value of -17249.789 is presented. The alignment dataset comprises 50 taxa with 3313 sites, including 1063 distinct patterns, 303 singleton sites and 2408 constant sites. Ultrafast bootstrap values for the maximum likelihood analysis equal to or greater than 95% and posterior probability for Bayesian analysis equal to or greater than 0.95 are indicated at the nodes. Novel isolates are shown in red. Isolates from type materials are in bold.

Species