Nigrospora ficuum Senan., sp. nov.

Index Fungorum number: IF 900458;  MycoBank number: MB 900458; Facesoffungi number: FoF 14211; Fig.  2

Etymology: based on the host genus Ficus.

Saprobic, isolated from dead twigs of Ficus sp. Sexual morph: Not observed. Asexual morph: Sporulate on PDA after four weeks, dark brown to black spore masses visible on cultures and host substrates. Hyphae 2–6 μm diam., initially hyaline, turn to olivaceous to pale brown with time, branched, thick-walled, septate. Conidiophores 18–25 × 2–4 μm (x=20 × 3 μm, n=25), straight, pale brown, aseptate, unbranched. Conidiogenous cells 5–10×1–2 μm (x=8×1.5 μm, n=25), holoblastic, monoblastic, hyaline, cylindrical, straight, discrete, aseptate, smooth-walled. Conidia 8–12×10–12 μm (x=10×10 μm, n = 20), dark brown, globose to subglobose, smooth-walled, with a longitudinal germ slit.

Culture characteristics: Colonies on PDA reaching 5 cm diam. after 5 days in dark at 20 °C, floccose, edge entire, initially white, becoming black when sporulate, reverse off-white with black patches due to sporulation.

Material examined: China, Guangdong Province, Guangzhou City, Baiyun Mountain (23° 09′ 35″ N 113° 17′ 40″ E), dead twigs of Ficus sp., 23 September 2021, I.C. Senanayake, 14 (MHZU 22-0068, holotype), ex-type cultures ZHKUCC 22-0125, ZHKUCC 22-0143.

GenBank numbers: ITS: OR164910, OR164911; β-tubulin: OR166317, OR166318.

Notes: The sequence data of ITS, LSU, β-tubulin and tef1-α of our collection (MHZU 22-0068) gives species in Nigrospora as the closest matches with NCBI. The phylogenetic analysis (Fig. 2) showed that our collection is genetically close to N. bambusae, but genetically distinct forming a clade with MP/BI=91%/0.90 statistical support. Morphologically, our collection is different from N. bambusae by cylindrical, solitary conidiogenous cells and small conidia while N. bambusae has globose to ampulliform conidiogenous cells aggregated in clusters on hyphae and large conidia (Wang et al. 2017). Therefore, we introduce our collection as a new species, Nigrospora ficuum.

Figure 1 – Nigrospora ficuum (ZKUH 22-0068, holotype). a examined Specimen. b Conidial mass on substrate. c Upper view of culture on PDA. d Reverse view of culture on PDA. e–f Conidiogenous cells attached to the conidia. g–j Conidia. Scale bars: e–j=10 µm

Figure 2 – Phylogram generated from maximum likelihood analysis based on combined ITS, LSU, β-tubulin and tef1-α sequence data of 190 taxa, which comprised 2694 characters (ITS=565, LSU=862, β-tubulin=444, tef1-α=823). The best scoring RAxML tree with a final likelihood value of − 20,488.974413 is presented. The matrix had 917 distinct alignment patterns, with 25.57% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.229550, C=0.267919, G=0.242735, T=0.259795; substitution rates: AC=1.447018, AG=2.737139, AT=1.353872, CG=1.119023, CT=4.157776, GT=1.0; gamma distribution shape parameter α=0.215582. Bootstrap support for maximum likelihood (ML) equal to or greater than 50% and clade credibility values greater than 0.90 (the rounding of values to 2 decimal proportions) from Bayesian inference analysis are labelled at each node. Ex-type strains are in bold, while the new isolate is indicated in blue bold. The tree is rooted to Sporocadus trimorphus (CBS 114203)

Figure 2 – (continued)

Figure 2 – (continued)