Xylaria atrosphaerica (Cooke & Massee) Callan & J.D. Rogers, Mycotaxon

Wu, You-Peng, Pi, Yin-Hui, Long, Si-Han, Liu, Li-Li, Zhang, Xu, Long, Qing-De, Lin, Yan, Kang, Ying-Qian, Kang, Ji-Chuan, Wijayawardene, Nalin N. & Li, Qi-Rui, 2022, Morphology and phylogeny reveal two novel Xylaria (Xylariaceae) species from China, Phytotaxa 550 (2), pp. 130-146 : 134

Xylaria atrosphaerica (Cooke & Massee) Callan & J.D. Rogers, Mycotaxon 36 (2): 349 (1990) ( Fig. 2 )

Synonymy:

Hypoxylon atrosphaericum Cooke & Massee, Grevillea 22(no. 103): 68 (1894)

Penzigia atrosphaerica (Cooke & Massee) J.N. Mill., Monograph Univ. Puerto Rico, Series B 2: 212 (1934) Kretzschmaria atrosphaerica (Cooke & Massee) P.M.D. Martin, Jl S. Afr. Bot. 36(2): 79 (1970)

Kretzschmaria atrosphaerica (Cooke & Massee) P.M.D. Martin, Jl S. Afr. Bot. 42(1): 74 (1976)

MycoBank number: MB 127393

Saprobic on dead wood, forming on the host surface. Sexual morph: Stromata semiglobular or irregularly globose, pulvinate, 0.4‒1.8 mm high × 1.4‒3.2 mm broad (x = 1.4 × 2.3 mm, n = 10), with flattened or slightly convex top. Exterior grey dark to black, roughened by fine cracks and ostioles; interior whithish to light grey. Perithecia 0.3‒0.8 mm diam., completely immersed, sphaerical. Ostioles inconspicuous. Asci 182‒288 × 12.3‒20 μm (x = 237 × 16.1 μm, n = 30), unitunicate, 8-spored, cylindrical, long-stipitate, apically rounded, with a J+, wedge-shaped apical ring, blue staining in Melzer’s reagent, 7–12 μm (x = 10 μm, n = 30) high, 3.5–7 μm (x = 5.4 μm, n = 30) wide. Ascospores 20.5–25.5 × 6.5–10 μm (x = 22.7 × 7.8 μm, n = 30), brownish-black, unicellular, ellipsoid to inequilateral, with broadly rounded ends, smooth, with a sigmoid germ slit nearly half spore-length, lacking appendages and sheaths. Asexual morph: Undetermined.

Specimens examined: CHINA, Guizhou Province, Duyun City, Doupengshan Nature Reserve (26.223062°N, 107.22846°E), elev. 1086 m, on dead wood of unidentified plant, June 2021, Youpeng Wu, 2021DPS13 (GMB0077, KUN-HKAS 122633; living culture, GMBC 0077).

Culture characteristics: Colonies on OA reaching 4–5 mm diam. after 2 weeks at 25 °C. White at first, with regular margins, becoming moderately radiating furrows spreading toward the edge, medium becoming black from central; reverse greyish black ring in the center, white marginal area. After 4 weeks, colonies on OA reaching 9 cm diam., white, velvety, appressed with entire margins; reverse dark black. No conidia were observed.

Notes: Hypoxylon atrosphaericum Cooke & Massee collected from Queensland was described originally by Cooke (1894). Rogers et al. (1987) described the asexual morph of Penzigia atrosphaerica collected from Indonesia. However, based primarily on the nature of cultures, Callan & Rogers (1990) placed them in the genus Xylaria . Morphologically, our new collection (GMB0077) is congruent with X. atrosphaerica having semi-globular or irregularly globose stromata, grey dark to black, internally white; surface roughened by fine cracks and ostioles and perithecial mounds inconspicuous, brownish-black, ellipsoid-inequilateral, smooth ascospores (17–25 × 6–10 μm), with oblique to spiral germ slit, nearly 1/2 spore-length, lacking sheaths and appendages. Phylogenetic analyses showed that GMB0077 resembles with X. atrosphaerica (HAST 91111214) with high statistical support (100% ML, 1.00 BYPP; Fig. 1 ).

Figures

FIGURE 1. RAxML tree based on analysis of a combined dataset of β-tubulin, rpb2 and α-actin sequence dataset from selected species of Xylariales. Bootstrap support values for maximum likelihood (ML) greater than 50%, and Bayesian posterior probabilities (BYPP) greater than 0.90 are given at the nodes. Strain numbers are noted after the species names. Ex-type strains are in bold. Newly generated taxa are in red. The tree is rooted to the outgroup of Camillea obularia (ATCC 28093).

FIGURE 2. Xylaria atrosphaerica (GMB0077).A. Stromata on the surface of host. B. Close-up of stromata surface. C. Transverse section of stroma. D. Longitudinal section of stroma. E. Ascus apex with a J+, apical ring (stained in Melzer’s reagent). F. Culture on OA from above. G. Culture on OA from below. H–J. Asci with ascospores. K–N. Ascospores. O. Ascospores with indehiscent perispore in 10% KOH. Scale bars: B = 200 μm, C, D = 150 μm, E= 10 μm, H–O = 10 μm.