Proliferodiscus longisporus
Proliferodiscus longisporus C.J.Y. Li, K. D. Hyde & Q. Zhao
Index Fungorum number: IF 559356; Facesoffungi Number: FoF 12760
Etymology – The specific epithet refers to the long ascospores.
Holotype – HKAS 124390.
Parasitic on the bark of Liquidambar formosana. Sexual morph: Apothecia 1–2.5 mm wide × 0.3–0.5 mm high (x̅ = 1.7 × 0.4 mm, n = 20) when fresh, gregarious or scattered, disc-shaped, stipitate, growing on the superficial bark or proliferating from the center of the old apothecia. Disc flat and circular with light orange (5A3-5A4) or persion orange (6A6-6B6) when fresh, and brownish-orange (6C8) when dry. Receptacle pulvinate, reddish white to reddish-grey (7A2-7B2) with bushy hairs. Stipe 0.5–0.7 mm wide × 0.1–0.4 mm long (x̅ = 0.6 × 0.3 mm, n = 20), short and broad with white hairs. Hairs 167–185 μm long × 2.4–3.1 μm wide (x̅ = 180 × 2.8 mm, n = 20), rising from the outermost cells of ectal excipulum, cylindric, irregularly curled, hyaline, pale brownish-orange (5A5) on receptacle, white on stipe, septate, thin-walled, smooth, apex covered by irregular hyaline resinous materials. Hymenium 114–128 μm, pale orange (5A3). Ectal excipulum 77–93 μm thick, comprised of thin-walled, hyaline to pale brownish-orange (5A5) cells of textura prismatica, non-gelatinous. Medullary excipulum 110–160 μm thick, comprised of thin-walled, hyaline to pale brownish-orange (5A5) cells of textura intricata, non-gelatinous. Subhymenium not obvious. Paraphyses 2–3 μm (x̅ = 2.7 μm, n = 20) wide, hyaline, filiform, cylindrical, rounded apex, branched and septate at base, extending beyond the asci. Asci 92–114 × 7–10 μm (x̅ = 101 × 8 μm, n = 40), 8-spored, cylindric or subclavate, rounded to subconical apex with J+ apical ring in Melzer’s reagent, tapering to subtruncate base, observed croziers at the stipitate base. Ascospores (21–)22–30(–40) × (2.9–)3.1–4.3(–4.7) μm (x̅ = 25.5 × 3.7 μm, n = 100), Q = (4.8–)5.5–9.1(–10) μm, Qm = 7.0 ± 1.1 μm, overlapping uniseriate or biseriate, fusoid-clavate with blunt ends, hyaline, slightly asymmetrical and sinuous, thin-walled, smooth, 0–3-septate, with multiple granules in the living state and four or more large guttules when dry.
Asexual morph – Undetermined.
Culture characteristics – Colonies growing on PDA medium, reaching 3 cm diam. in 6–7 weeks at 25℃, circular, umbonate elevation, entire margin, rough surface, white mycelia in the front view, reverse view brownish-yellow in suitable humidity and some red mycelium appear in medium with low humidity, white at the margin, center dark brown; no sporulation.
Material examined – China, Yunnan Province, Kunming City, Panlong District, altitude 1918m, on the bark of Liquidambar formosana, 14 September 2021, Cuijinyi Li, LCJY-286 (HKAS 124390, holotype) – ex-type living culture KUNCC22-12441; ibid, Yeya lake, altitude 1900m, on the bark of Liquidambar sp., 3 July 2021, Cuijinyi Li, LCJY-123 (HKAS 124388, paratype).
Notes – Proliferodiscus longisporus is characterized by its disc-shaped, light orange apothecia, receptacles covered with pale brownish orange hairs, short stipe covered with white hairs, filiform, septate and branched paraphyses, large cylindric asci with amyloid pore and large fusoid-clavate ascospores. Morphologically, Proliferodiscus longisporus resembles P. tricolor in having similar-sized apothecia, shorter stipes, bushy hairs and cylindric asci, but differs by having light orange discs when fresh and pale brownish orange discs when dry, pale brownish orange hairs with resinous material on receptacles, branched paraphyses and larger ascospores (P. longisporus 22–30 × 3.1–4.3 μm vs. P. tricolor 10–14 × 3–3.5 um) (Popov 2013). Phylogenetically, our collections formed a clade sister to Proliferodiscus tricolor with 99% ML bootstrap support and 1.00 Bayesian probability in nLSU-ITS multi-gene phylogeny.
Proliferodiscus longisporus (HKAS 124390, holotype). a–d Fresh ascomata on the bark. e Dried ascomata on the bark. f Vertical section of ascoma. g–h Hairs. i–j Excipulum. k Paraphyses. l–n Asci (m–n Asci in Meltzer's reagent). o–t Ascospores (s–t Ascospores in Meltzer’s reagent) u–w Colonies on PDA. Scale bar: c = 1 mm, d = 500 μm, e 1500 μm, f = 600 μm, g = 100 μm, h = 30 μm, i = 100 μm, j = 40 μm, k = 80 μm, l = 50 μm, m–n = 40 μm, o–t = 15 μm, u–v = 3 cm, w = 1.5 cm 
Maximum likelihood tree generated from RAxML analyses based on the combined dataset of nLSU and ITS sequences, showing the phylogenetic position of Erioscyphella latispora and Proliferodiscus macrospora. The ML bootstrap proportions (ML-BP) higher than 90% and Bayesian posterior proportions (BI-PP) higher than 0.95 are shown above the branches on the phylogenetic tree with the order ‘ML/ BI’. Newly generated sequences are shown in blue. Ex-types are shown in bold black.
References:
Li CJY, Chethana KWT, Lu ZY, Zhao Q 2022 – Two novel species of Lachnaceae (Helotiales, Leotiomycetes) from southwestern China. Current Research in Environmental & Applied Mycology (Journal of Fungal Biology) 12(1), 333–345, Doi 10.5943/cream/12/1/20
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