Nigrograna heveae R.F. Xu & Tibpromma, Mycosphere 14: 663–744 (2023).

Index Fungorum number: IF 559985; MycoBank number: MB 559985; Facesoffungi number: FoF 12908; Fig. 1

Holotype – ZHKU 22-0152.

Saprobic on dead branch. Sexual morph: undetermined. Asexual morph: Coelomycetous. Conidiomata immersed in natural host, visible as black spots, solitary, scattered or aggregated, globose to depressed globose, papillate. Conidiophores arising from the wall, up to 28 µm long, and mainly 3 µm wide, in palisadic arrangement, filiform, septate, 1 to 3-celled, hyaline, unbranched or sparsely branched. Conidiogenous cells 4–12.5 × 1–3 µm (x = 7.5 × 2.5 µm, n = 10), terminal phialide, cylindrical, hyaline. Conidia 3–4 × 1.5–2 μm ( x = 3.5 × 1.8 µm, n = 20), oblong to cylindrical, unicellular, with 1–2 small guttules, hyaline, smooth-walled.

Culture characteristics – Conidia germinating on PDA within 12 h and germ tube produced from conidia. Colonies growing on PDA, reaching 20 mm diam. in 10 days at 25 °C, circular, flat, entire edge with a protuberance in the center, brown to yellowish towards the edge in reverse and not producing pigment in culture.

Material examined – Thailand, Chiangrai Province, Mae Fah Luang University, on dead branch in a forest, 07 January 2019, J.Y. Zhang, TF01-2 (MFLU 19-1393), living culture, ex-type living culture, MFLUCC 22-0051 (new record for Thailand).

GenBank number – LSU=OQ101584, ITS=OQ101581, TEF1α=OQ054804.

Notes – Morphologically, our collection (MFLUCC 22-0051) matches with generic concept of Nigrograna and is similar to N. fuscidula in the shape of conidiophores, conidiogenous cells and conidia (Jaklitsch & Voglmayr 2016). However, our collection differs from N. fuscidula in having shorter conidiophores (up to 28 μm vs. up to 55 μm, Jaklitsch & Voglmayr 2016). In the phylogenetic tree, our isolate (MFLUCC 22-0051) clustered as sister taxon to the strains of Nigrograna heveae (ZHKUCC 22-0284 and ZHKUCC 22-0285) with support (100% ML/1.00 PP, Fig. 2). The comparison of LSU, ITS, and TEF1α sequences between our isolate and type strain (ZHKUCC 22-0285) showed 99.77% (850/852 bp), 99.34% (907/913 bp) and 99.79% (939/941 bp) sequence similarity, respectively. Based on the molecular evidence and phylogenetic result, we recognize they are the same species. Nigrograna heveae was introduced with its ascomycetous sexual morph on the stem of Hevea brasiliensis (Euphorbiaceae) in China (Hyde et al. 2023). In this study, we identify our collection as N. heveae with coelomycetous asexual morph and report a new record of the species in Thailand.

FFigure 1 – Nigrograna heveae (MFLU 19-1393). a Superficial conidiomata on inidentified plant substrate. b Section of conidioma. c–e Conidiophores and conidiogenous cells. f Conidia. g Germinating conidium. h Colony on PDA. Scale bars: a=1000 μm, b=50 μm, c–g=10 μm

Figure 2 – Phylogram generated from maximum likelihood analysis based on combined ITS and TEF1α sequence data. 40 taxa were included in the combined analyses, which comprised 1382 characters (ITS: 493 bp, TEF1α: 889 bp) after alignment. The best scoring RAxML tree with a final likelihood value of -5723.168531 is presented. The matrix had 441 distinct alignment patterns, with 15.59% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.224465, C=0.293279, G=0.250321, T=0.231935; substitution rates: AC=2.046193, AG=3.037116, AT=2.343899, CG=0.810670, CT=9.890958, GT=1.000000; gamma distribution shape parameter α=0.176114. Bootstrap support values for ML equal to or greater than 50% and BYPP equal to or greater than 0.95 are given above the nodes. The tree is rooted with Occultibambusa bambusae MFLUCC 13-0855 and O. pustula MFLUCC 11-0502. The newly-generated strain is shown in blue. Ex-type strains are indicated
by black and bold