Neoaquastroma ehretiae
Neoaquastroma ehretiae G.C. Ren & K.D. Hyde. Mycosphere 15(1): 1039 (2024)
Index Fungorum number: IF 901357; Facesoffungi Number: FoF 13888
Saprobic on dead woody twigs of Ehretia acuminate. Sexual morph: Ascomata 360–420 μm high, 380–430 μm diam., (x̅ = 390 × 410 μm, n = 5), solitary, scattered, immersed under small, blackened pseudoclypeus, uni loculate, obpyriform or globose to subglobose, brown to dark brown, glabrous, ostioles central. Peridium 24–33 μm wide, comprising two layers, outer layers composed of reddish to dark brown, thick walled cell of textura angularis fused with host tissues, inner layer composed of hyaline cells of textura angularis. Hamathecium composed of dense, 1.2–2.4 μm wide, filamentous, branched, septate cellular pseudoparaphyses, embedded in a gelatinous matrix. Asci 115–135 × 30–36 μm (x̅ = 126 × 33 μm, n = 20), 4–8 spored, bitunicate, fissitunicate, clavate, apically rounded with an ocular chamber and a short pedicel. Ascospores 50–60 × 10–13 μm (x̅ = 56 × 11 μm, n = 20), overlapping biseriate, hyaline, fusiform, straight to curved, narrow towards the apex, 5–7 transversely septate, deeply constricted at the middle, smooth walled with small to large guttules, surrounded by a distinct mucilaginous sheath. Asexual morph: Not observed.
Culture characteristics: Ascospores germinating on PDA within 24 h at room temperature (25 °C). Germ tubes produced from the around cell of ascospore. Colonies on PDA, reaching 30 mm diameter after two weeks at 20–25 ℃, mycelia superficial, circular, dense, flat, entire edge, band, dark grey at the center with greyish white margin, white grey; reverse, greenish grey at center, pale yellow at margin.
Material examined: China, Yunnan Province, Xishuangbanna, on dead woody twigs of Ehretia acuminate (Boraginaceae), 4 March 2020, G.C. Ren, JH48 (HKAS 122743, holotype), ex-type living culture KUMCC 21 0588, KUMCC 21 0589.
GenBank numbers: KUMCC 21 0588: LSU: OQ170869, ITS: OQ158947, tef1-α: OR613441; KUMCC 21 0589: LSU: OQ170870, ITS: OQ158948.
Notes: In the phylogenetic analyses of the present study, our strains (KUMCC 21 0588, KUMCC 21 0589) formed a sister clade to N. krabiense (MFLUCC 16 0419, type species) with 100% ML bootstrap support and 1.00 BYPP value. Our species differs from N. krabiense in having immersed, small, blackened pseudoclypeus, apapillate ascomata, and a peridium of 24–33 μm wide, while N. krabiense has semi-immersed to immersed ascomata with short hyphae projecting from peridium, which is 8–25 μm wide (Phukhamsakda et al. 2018). Sequence comparison for the ITS region between Neoaquastroma ehretiae (KUMCC 21 0588) and N. krabiense (MFLUCC 16 0419) showed a 5.4% (25/462 bp, without gaps) base pair difference in ITS region, 1.6% (14/903 bp, without gaps) base pair difference in the tef1-α region, 1% (7/689 bp, without gaps) base pair difference in LSU region. Here in, Neoaquastroma ehretiae is introduced as a new species based on its distinct morphology and the phylogeny of the combined SSU, LSU, ITS, and tef1-α dataset.
Figure 1. Phylogram generated from ML analysis based on SSU, LSU, ITS, and tef1-α sequence data, representing Nigrogranaceae. Related sequences are obtained following Xie et al. (2022) and Phookamsak et al. (2023). Thirty-five strains are included in the combined analyses, which comprise 3311 characters for SSU, LSU, ITS, and tef1-α alignment. Corynespora cassiicola (CBS 100822) was used as the outgroup taxa. The best-scoring RAxML tree with a final likelihood value of 13584.772234 is presented. The matrix had 871 distinct alignment patterns, with 10.96% of undetermined characters or gaps. Estimated base frequencies were as follows: A = 0.235255, C = 0.258240, G = 0.273696, T = 0.232809; substitution rates AC = 1.077058, AG = 2.178658, AT = 1.107003, CG = 1.470438, CT = 6.032092, 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. Neoaquastroma ehretiae (HKAS 122743, holotype). a Material examined. b, c Appearance of ascomata on the host substrate. d Section of an ascoma. e Peridium. f Pseudoparaphyses. g–i Asci. j–o Ascospores. p Germinated ascospore. q, r Culture characters on PDA (q = from above, r = from below). Scale bars: d = 200 μm, e, g–i = 100 μm, f, j–p = 50 μm, q, r = 30 mm.
- Ren GC, Jayasiri SC, Tibpromma S, De Farias ARG, et al. (2024) Saprobic ascomycetes associated with woody litter from the Greater Mekong Subregion (Southwestern China and Northern Thailand). Mycosphere 15(1), 954–1082, Doi 10.5943/mycosphere/15/1/8
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