Neoxylaria arengae Konta & K.D. Hyde, in Konta, Hyde, Phookamsak, Xu, Maharachchikumbura, Daranagama, McKenzie, Boonmee, Tibpromma, Eungwanichayapant, Samarakoon & Lu, Mycosphere 11(1): 2638 (2020)

Index Fungorum number: IF 556651;MycoBank number: MB 556651; Facesoffungi number: FoF 03395;

Etymology – Refers to the name of the host genus, Arenga

Holotype – MFLU 15-0267

Saprobic on dead petiole of Arenga pinnata (Arecaceae). Sexual morph: Stromata (1.6–)4– 27(–30) × 0.5–1 mm (= 13 × 0.7 mm, n = 30), erect, coriaceous, solitary, cylindrical, simple to branched from the base, unbranched when immature, branching from the base at maturity with 3(– 5) branches, arising separately or in small bundles, stipes (stem) (1.7–)2.1–4.6(–7.1) × 0.4–1 mm (= 3.2 × 0.7 mm, n = 20, up to 12 mm), cylindrical, longitudinally, black, with a hairy-tomentose broadened base, smooth to downy to hairy-tomentose above; tomentum black to dark brown, fertile part (1.7–)2.5–18(–25) mm (= 9 mm, n = 20), bearing 29 to 35(–45) exposed perithecia, apex sterile, rarely find finely longitudinally furrowed delimiting narrow stripes, roughened with prominent ostiolar papillae, perithecia scattered along the stroma, arranged in a zigzag or in straight rows, without circumferential wrinkles isolating groups of perithecia, perithecial contours most often conspicuous, visible as black single or small fusiform ascoma, surface, outer crust, thick, coriaceous, cracked, interior solid, brown with white tissue surrounding perithecial layer, sterile apex attenuated conical, up to 1–2(–3) mm. Perithecia 400–620 × 260–570 μm (= 493 × 464 µm, n = 10), pale brown, immersed in stromatic tissues, globose to subglobose, ostiolate, papillate, slightly conspicuous, with periphyses. Peridium 80–130 µm wide (= 100 µm, n = 20), thick-walled, composed of several layers, outwardly, thick-walled, comprising dark brown cells of textura angularis and inwardly, thick-walled, comprising hyaline to pale brown cells of textura prismatica. Ostiole 150–215 × 150–285 μm (= 180 × 210 µm, n = 5), raised-discoid, brown to black surrounding disc appear on the surface; hyaline, papillate, with a central periphyses. Paraphyses 3–5(–7) µm wide (= 4 µm, n = 10), filamentous, cylindrical, septate, unbranched. Asci 74–160(–180) × 5–12 µm (= 115 × 7 µm, n = 20), 6–8-spored, unitunicate, cylindrical, long pedicellate, apically rounded, with a J+, apical ring, inverted hat-shaped. Ascospores 10–18(–22) × 3.5–6(–7.5) µm (= 15 × 5 µm, n = 20), uniseriate, hyaline to pale brown when immature, dark brown at maturity, broad fusoid, unicellular, a lot of small guttules when immature, two large guttules at maturity, smooth-walled, with a straight, full-length germ slit. Asexual morph: Undetermined. Appressoria 4–9 × 3–10 μm (= 6 × 6 μm, n = 20), solitary, hyaline, mostly globose, irregular in shape, thick-walled.

Culture characteristics – Ascospores germinated on MEA within 24 hours, and germ tube was produced from the germ slit. Mycelium immersed in the medium, septate, branched, and smooth-walled hyphae. Colonies on MEA, medium dense, irregular in shape, flowered-like, surface slightly rough with curled margin, radiating outward colony, flat, slightly raised at the centre, hairy fluffy, initially white, becoming white at the margin, greyish white near the centre, with black and white curled, radiated near the centre; reverse zonate, yellow and white, curled with black radiating outward colony; not produced pigmentation on medium.

Material examined – THAILAND, Phang-nga Province, on dead petiole of Arenga pinnata (Wurmb) Merr. (Arecaceae), 5 December 2014, S. Konta, PHR03d (MFLU 15-0267, holotype; KUN-HKAS 100698, isotype), ex-type living culture, MFLUCC 15-0292.

Notes Neoxylaria arengae resembles N. (syn. Xylaria) juruensis, but it has shorter stromata (fertile part) (1.6–)4–27(–30) mm vs 15–40 mm), forms branches at the base, smaller perithecia (0.4–0.6 diam. mm vs 0.7–0.9 diam. mm), slightly larger asci (74–160 × 5–12 µm vs 100–120 × 4–6 μm) and ascospores overlapping in size (10–18(–22) × 3.5–6(–7.5) µm vs 12–17 × 4–5 μm). However, N. arengae was found on a dead part of Arenga pinnata, while N. juruensis was reported from a rotten palm frond and on Arenga engleri (Arecaceae) (Hennings 1904, Hsieh et al. 2010, Becerril-Navarrete et al. 2018). Xylaria queenslandica is similar to Neoxylaria and is transferred in this paper. Neoxylaria arengae is similar to X. tucumanensis in the appearance of the stromata, but our new species has larger stromata (4–27 × 0.5–1 vs 12–15 × 0.5–0.6 mm), shorter stipes (2.1–4.6 × 0.4–1 vs 6–7 × 0.2–0.3 mm), forming 3(–5) branches at the base, while X. tucumanensis forms simple (unbranched), and larger numbers of perithecia (bearing 29–35 vs 9–17 perithecia per stroma) (Hladki & Romero 2010). Neoxylaria arengae also shares similar stomatal characters with X. diminuta, X. enteroleuca, X. filiformioidea, X. himalayensis, X. mellissi, and X. subgracillima, but differs in having branches at the base, having longer stromata (fertile part), and having more perithecia per stromata than other species (Cooke 1883, Hennings 1904, Martin 1970, Narula et al. 1985, Hladki & Romero 2010, Huang et al. 2014). We also cross-checked with X. diminuta, X. enteroleuca, X. filiformioidea, X. himalayensis, X. mellissi and X. subgracillima, but only X. enteroleuca has DNA sequence data; thus, we included X. enteroleuca in the phylogenic tree (not shown) and found that it did not form a branch close to Stilbohypoxyon or Neoxylaria.

Figure 3 Neoxylaria arengae (MFLU 150267, holotype). a–b Stromata on host substrate. c, e Perithecia and sterile apex strongly conical. d Stem with brown hair (Pubescent). f Section of a stroma. g Periphyses. h Peridium. i Paraphyses. j–l Asci. m–p Ascospores. q Ascospore with germ slit. r J+, apical ring in Melzer’s reagent. s Germinated ascospore. t Germinated ascospore with appressorialike structures. u–z Appressorialike structures. aa, ab Colony on MEA. Scale Bars: a = 5 mm, b, d, e = 0.5 mm, c = 2 mm, f, g = 0.1 mm, h, i, t = 20 μm, j–l = 50 μm, m–s = 10 μm, u–z = 5 μm.