Amphisphaeria guttulata J.Y. Zhang & Y.Z. Lu, sp. nov.
Index Fungorum number: IF 900043; Mycobank number: MB 900043; Facesoffungi number: FoF 13259; Fig. 1
Etymology – refers to the ascospores with guttules.
Holotype – MFLU 22-0078.
Saprobic on dead branch. Sexual morph: Ascomata 193–268 μm high×104–208 μm in diam. (x = 225×161 μm, n=8), immersed, visible as black spots, surrounded by a grey halo area, solitary, scattered or aggregated, globose to subglobose, dark reddish brown, centric ostioles with periphyses. Hamathecium composed of paraphyses, septate, unbranched, 2.5–5 μm wide, not anastomosing, hyaline. Perridium comprising 4–7 layers of dark brown cells of textura angularis, 12.5–24 μm wide, thick-walled. Asci 77–88×8.5–12.5 μm (x = 81 × 10.5 μm, n=15), 8-spored, unitunicate, cylindrical, sessile, thin-walled, apically round. Ascospores 12–16 × 4.5–5.5 μm (x = 14 × 5 μm, n=20), uniseriate, partly overlapping, oblong or narrowly fusiform, 1-septate,
2-celled, slightly constricted at the septum, guttulate, pale brown, smooth-walled. Asexual morph: undetermined.
Culture characteristics – Ascospores germinated on WA within 12 h at 25–28 °C. The hyaline germ tube germinates from a point of one cell of the ascospores. Colonies growing on PDA, reaching 19 mm in diam. after two weeks at 25 °C, flat, section to fan shape at the surface, fimbriate margin with
a smooth surface, yellowish white from above; cream yellow mycelium in the middle and brown yellow mycelium in the outer ring in reverse, and not producing pigment in the culture.
Material examined – Thailand, Loei Province, Chang Wat, Phu Kradueng, Tambon Huai Som (16° 55′ 9″ N, 101° 55′ 21″ E), on dead branch in a forest, 27 February 2020, J.Y. Zhang, Y196 (MFLU 22-0078, holotype); extype living culture, MFLUCC 22-0052.
GenBank numbers – MFLU 22-0078: LSU=OQ101583, ITS=OQ101582.
Notes – The morphological characteristics of the new isolate match well with the generic concept of Amphisphaeria and is most similar to Amphisphaeria micheliae in the shape of asci and ascospores (Samarakoon et al. 2020). However, it is recognized from A. camelliae by its shorter asci (77–88×8.5–12.5 μm vs. 92–135×7–10.5 μm) and smaller ascospores (12–16×4.5–5.5 μm vs. 15.5–21×6–7.5 µm, Samarakoon et al. 2020). The phylogenetic tree showed that the new collection formed a separate clade within the genus Amphisphaeria, and is sister to A. yunnanensis (Fig. 2). Therefore, we introduce the new collection as Amphisphaeria guttulata sp. nov.
Figure 1 – Amphisphaeria guttulata (MFLU 22-0078, holotype). a, b Ascomata on the substrate. c, d Vertical section of ascoma. e ostiole. f paraphyses. g peridium. h–k asci. l–r ascospores. s Germinating ascospore. t, u Colony on PDA from above and below. Scale bars: a, b=1000 μm, c–e=50 μm, g–k=20 μm, f, l–s=10 μm
Figure 2 – Phylogram generated from maximum likelihood analysis based on combined LSU and ITS sequence data. 26 taxa were included in the combined analyses, which comprised 1782 characters (LSU: 1160 bp, ITS: 622 bp) after alignment. The best scoring RAxML tree with a final likelihood value of -7242.965669 is presented. The matrix had 614 distinct alignment patterns, with 17.29% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.257803, C=0.216953, G=0.269172, T=0.256073; substitution rates: AC=0.829912, AG=2.560479, AT=1.266564, CG=0.816478,
CT=4.838135, GT=1.000000; gamma distribution shape parameter α=0.264935. Bootstrap support values for ML equal to or greater than 50% and
BYPP equal to or greater than 0.90 are given above the nodes. The tree is rooted with Bartalinia pondoensis CBS 125525 and B. pini CBS 143891. The newly-generated strain is shown in blue and bold. Ex-type strains are indicated by black and bold