Cucurbitaria lijiangensis
Cucurbitaria lijiangensis G.C. Ren & K.D. Hyde, in Ren, Jayasiri, Tibpromma, Farias, Chethana, Faraj, Wanasinghe, Xu, Hyde & Gui, Mycosphere 15(1): 1000 (2024)
Index Fungorum number: IF 901350; Facesofungi number: FoF 13879
Saprobic on dead twigs of Rhododendron rubiginosum. Sexual morph: Ascomata 420–510 μm high, 400–450 μm diam., (x̅ = 470 × 430 μm, n = 5), clustered, immersed to erumpent through the host periderm, visible as raised, globose to subglobose, uni-loculate, coriaceous, black, ostiolate .Ostioles central, 150–200 μm high, 140–170 μm diam., (x̅ = 171 × 161 μm, n = 5). Peridium 25–85 μm wide, sometime thick at the base, comprising 4–9 layers, composed of dark outer layers, inner layers comprising hyaline to reddish-brown, flattened, thick-walled cells of textura angularis. Hamathecium 1.5–2.5 μm wide, comprising numerous, branched, filamentous, septate, hyaline pseudoparaphyses. Asci 170–225 × 24–31 μm (x̅ = 200 × 27.3 μm, n = 30), 6–8-spored, bitunicate, fissitunicate, cylindrical to cylindric-clavate, short-pedicellate, apically rounded, with a minute ocular chamber .Ascospores 33–43 × 14–19 μm (x̅ = 39 × 17 μm, n = 40), uniseriate, muriform, ellipsoidal to broadly fusiform, hyaline to pale brown when young, becoming dark brown at maturity, paler at the extreme ends, with 6–15 transverse septa and 2–6 longitudinal septa, slightly constricted at the central septum, lower part larger than the upper part, guttulate in each cell, ends remaining cone-shaped, with acute ends. Asexual morph: Undetermined. RAxML tree with a final likelihood value of -5781.224323 is presented. The matrix had 285 distinct alignment patterns with 25.91% of undetermined characters or gaps. Estimated base frequencies were as follows; A = 0.245250, C = 0.217613, G = 0.282353, T = 0.254784; substitution rates AC = 2.091807, AG = 3.145516, AT = 3.237090, CG = 0.505851, CT = 9.326419, GT = 1.0000. The tree topology of the ML analysis is similar to the Bayesian analysis. Bootstrap values for ML equal to or greater than 70% and BYPP values greater than 0.95 (the rounding of values to 2 decimal proportions) are labelled on the nodes. Strains of the newly described species are in blue, while type strains are in bold.
Culture characteristics: Ascospores germinating on PDA within 24 h at room temperature (25 °C). Germ tubes produced from every cell of the spore. Colonies on PDA, reaching 10–20 mm diameter after two weeks at 20–25 ℃, mycelia superficial, irregular, grey to greenish brown, floccose, umbonate, flat, lobate edge; reverse, white, light yellow at center.
Material examined: China Yunnan Province, Lijiang, on dead woody twigs of Rhododendron rubiginosum (Ericaceae), 30 August 2020, G.C. Ren, DQ11 (HKAS 122716, holotype), ex-type living culture KUMCC 21-0532.
GenBank numbers: SSU: OQ168203, LSU: OQ170847, ITS: OQ158927, tef1-α: OR613428.
Note: In our phylogenetic analysis, Cucurbitaria lijiangensis clustered basal to the strains of C. oromediterranea and C. berberidis with 94% ML bootstrap support and 1.00 BYPP value. The BLASTn search of the ITS sequence showed that close match of the ITS sequence with 97.25% and 96.89% similarities with C. oromediterranea (CB2) and C. berberidis (CB, CB 39 and CBS 394.84), respectively. Cucurbitaria berberidis is the type species of Cucurbitaria, and many generic synonyms are listed under Cucurbitaria (Doilom et al. 2013, Species Fungorum 2024). Cucurbitaria lijiangensis differs from C. oromediterranea and C. berberidis in having large ascospores and clearly shows changing the transverse septa with maturity. Furthermore, ascomata of C. oromediterranea and C. berberidis are seated on a thick-walled basal pseudostroma; however, in C. Lijiangensis, a basal pseudostroma is absent (Doilom et al. 2013, Jaklitsch et al. 2018).
Figure 1. Phylogram generated from ML analysis based on SSU, LSU, and ITS sequence data representing Cucurbitariaceae. Related sequences obtained following Jayawardena et al. (2019) and Dayarathne et al. (2020). Thirty-nine strains are included in the combined analyses, which comprise 1645 characters for SSU, LSU, and ITS alignment. Neophaeosphaeria agaves (CPC 21264) and N. filamentosa (CBS 102202) were used as the outgroup taxa. The best-scoring RAxML tree with a final likelihood value of -5781.224323 is presented. The matrix had 285 distinct alignment patterns with 25.91% of undetermined characters or gaps. Estimated base frequencies were as follows; A = 0.245250, C = 0.217613, G = 0.282353, T = 0.254784; substitution rates AC = 2.091807, AG = 3.145516, AT = 3.237090, CG = 0.505851, CT = 9.326419, GT = 1.0000. The tree topology of the ML analysis is similar to the Bayesian analysis. Bootstrap values for ML equal to or greater than 70% and BYPP values greater than 0.95 (the rounding of values to 2 decimal proportions) are labelled on the nodes. Strains of the newly described species are in blue, while type strains are in bold.
Figure 2. Cucurbitaria lijiangensis (HKAS 122716, holotype). a The host twig. b, c Appearance of ascomata on host substrate. d Section of ascoma. e Peridium. f Pseudoparaphyses. g–k Asci. l–p Ascospores. q Germinated ascospore. r, s Culture characters on PDA (r = from above, s = from below). Scale bars: d = 250 μm, e = 50 μm, f = 20 μm, g–k = 100 μm, l–q = 20 μm, r, s = 30 mm.
References
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