Gregarithecium bambusae W.H. Tian, K.D. Hyde & Maharachch., in Tian, Liu, Jin, Chen, Zhou, Wu, Su, Guo, Wanasinghe, Hyde, Liu & Maharachchikumbura, Mycosphere 15(1): 1803 (2024)

Index Fungorum number: IF 851874; MycoBank number: MB 851874; Facesoffungi number: FoF02295

Etymology – Named after the host genus from which the holotype was collected, Bamboo.

Holotype – HKAS 131989

Saprobic on the dead branch of bamboo. Asexual morph: Hyphomycetous. Colonies on natural substratum velvety, superficial, brown to dark brown. Aerial hyphae septate, pale to dark brown, verrucose. Conidiophores micronematosa to semi- macronematous, mononematous, arising laterally from superficial hyphae, branched, 1–4-septate, hyaline to pale brown, becoming paler or subhyaline towards the apex, verrucose, cylindrical to ampulliform, flexuous, 10–48 × 3–5 μm (x̅ = 25 × 4 μm, n = 25). Conidiogenous cells holoblastic, sympodial, discrete, retrogressive, branched, straight or slightly flexuous, septate, constricted at septa, hyaline to pale brown, verrucose, inflated, 6–14 × 3–6 μm (x̅ = 9 × 4 μm, n = 25). Conidia holoblastic, acropleurogenous, catenate, in short, acropetal chains of 1–4, golden-brown to dark brown, verrucose, aseptate, globose, 3 – 5 μm (x̅ = 4 μm, n = 30) diam., with single germ pore ca 0.7 – 2 μm (x̅ = 1.5 μm, n = 20) diam.; conidial secession schizolytic. Sexual morph: Undetermined.

Culture characteristics – Colony on PDA reaching 12 mm diam. in 10 days at 25 °C in the dark, colonies from above: irregular circular, white, uneven entire, raised in centre, with denser mycelium at the center; from below: white, pale brown in the centre, margin undulated.

Material examined – China, Sichuan Province, Chengdu City, Yunqiao Wetland, N 30°52’32”, E 103°53’23”, elevation 570 m, 10 July 2022, on dead branch of bamboo, W.H. Tian YQ0710021 (HKAS 131989, holotype), ex-type CGMCC 3.25698 = UESTCC 23.0290.

GenBank numbers – ITS: PP294644, LSU: PP213251, SSU: PP213255, tef1-α: PP213050

Notes – Gregarithecium curvisporum was described by Tanaka et al. (2015) based on its sexual morphology and phylogenetic analyses. Multi-locus analyses of combined ITS, LSU, SSU, and tef1-α sequence data showed that our collection (UESTCC 23.0290) is sister to the type strain of G. curvisporum (HHUF 30134). A comparison of sequence data of the ITS, LSU and SSU between G. curvisporum (HHUF 30134) and our strains (UESTCC 23.0290) show 93.26% sequence identity (318/341 bp, gaps: 10/341 bp) in ITS, 98.74% sequence identity (786/796 bp, no gaps) in LSU, and 99.03% sequence identity (1019/1029 bp, gaps: 3/1029 bp) in SSU. Consequently, we have identified our collection as a new species in Gregarithecium, marking it as the first known asexual morphic species within the genus.

Figure 1 – Gregarithecium bambusae (HKAS 131989, holotype). a Specimen. b, c Mycelium on the host surface. d–f Conidiophores with lateral conidia. g, h Developing conidia in short acropetal chains. i Conidia. j Germinating conidium. k, l Culture characteristics. Scale bars: d = 20 μm, e–j = 10 μm.