Jahnula oblonga Senan. & K.D. Hyde, sp. nov.

Index Fungorum number: IF 900237; MycoBank number: MB 900237; Facesoffungi number: FoF 14166; Fig. 1

Etymology – based on the oblong-shaped ascospores.

Saprobic on submerged decaying wood. Sexual morph: Ascomata 350–380×310–345 μm (x=360×325 μm, n=5), erumpent to superficial with the immersed base, solitary, scattered, globose to subglobose, dark brown to black, coriaceous, papillate, ostiolate. Papilla central, short, lined with hyaline periphyses. Peridium 35–75 μm thick, comprising outer, 4–6 layers of large, brown, thick-walled cells of textura angularis and inner, 3–5 layers of compressed, hyaline, thick-walled cells of textura angularis. Hamathecium comprising 2–3 μm wide, septate, branched, filiform pseudoparaphyses, embedded in a gelatinous matrix. Asci 110–150×30–35 μm (x=125×32 μm, n=20), 8-spored, bitunicate, fissitunicate, oblong fusiform, short or apedicellate, apex rounded, with an indistinct ocular chamber. Ascospores 30–33 × 15–18 μm (x=32 × 16 μm, n =50), biseriate, oblong, 1-septate, slightly constricted at the septum, rough-walled, multi-guttulate, greenish-brown, apiculate. Asexual morph: undetermined.

Culture characteristics – Colonies on PDA reaching 2 cm diam., after 10 days in dark at 25 °C, flat, circular, with inner, concentric zonation around the centre with dark brown to greyish brown, woolly aerial mycelia with curled margin, then filamentous hyphae extend out to form paler, thin outer zone with filiform margin, reverse blackish brown, no pigments produced. Material examined: China, Guangdong Province, Guangzhou City, Baiyun Mountain, on submerged decaying wood, 16 August 2021, Jinzhen Fu, WBHS 12 (MHZU 22-0128, holotype), ex-type culture ZHKUCC 22-0223.

GenBank numbers – ITS: OR164944, OR164945, LSU: OR164972, OR164973.

Notes – In the combined gene analysis of ITS, LSU and SSU showed that our isolate (ZHKUCC 22-0223, MHZU 22-0128) grouped with Jahnula granulosa K.D. Hyde & S.W. Wong with ML/BI=100%/1.00 bootstrap support. The nucleotide differences of ITS, and LSU locus between our isolate and Jahnula granulosa revealed that 1.2%, and 0.9% respectively and sequences for SSU couldn’t obtained. Morphologically, Jahnula granulosa differs from our collection by ascomata attached to the base with a stalk-like strands and a few sparse hair-like projections arise around the base, unbranched pseudoparaphyses, pedicellate asci with an ocular chamber or faint ring, ellipsoid to fusiform ascospores with a germ pore, and surrounded by a thin mucilaginous sheath (Hyde and Wong 1999). Jahnula granulosa has been reported from China, South Africa and Thailand (Hyde and Wong 1999; Liew et al. 2000; Cai et al. 2002; Suetrong et al. 2011). Jahnula species are only found in freshwater mostly in relatively undisturbed streams (Calabon et al. 2022). Therefore, it is highly likely that at present Jahnula species will have evolved in isolated stream worldwide (Hyde et al. 2020a). We therefore, introduce a new species and expect many more discoveries (Fig. 2).

Figure 1 – Jahnula oblonga (MHZU 22-0128, holotype). a Ascomata on submerged wood. b Vertical section of ascoma. c Pseudoparaphyses. d Surface view of colony on PDA. e Reverse view of colony on PDA. f–h Asci. i–k Ascospores. Scale bars: b=200 µm, c=10 µm, f–h=60 µm, i–k=30 µm

Figure 2 –   Phylogram generated from maximum likelihood analysis based on combined ITS, LSU and SSU sequence data which comprised 2434 characters (ITS=543, LSU=866, SSU=1025). The best scoring RAxML tree with a final likelihood value of − 8034.098510 is presented. The matrix had 576 distinct alignment patterns, with 31.95% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.225508, C=0.330133, G=0.230543, T=0.213816; substitution rates: AC=1.338925, AG=2.498969, AT=1.195768, CG=0.746582, CT=5.928346, GT=1.0; gamma distribution shape parameter α=0.118818. 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 Aliquandostipite khaoyaiensis (ISAN100), A. khaoyaiensis (KUMCC 19-0083) and A. siamensis (SS0081)