Stagonosporopsis lijiangensis

Stagonosporopsis lijiangensis G.C. Ren & K.D. Hyde, in Ren, Jayasiri, Tibpromma, Farias, Chethana, Faraj, Wanasinghe, Xu, Hyde & Gui, Mycosphere 15(1): 1006 (2024)

Index Fungorum number: IF 901351; Facesofungi number: FoF 13881

Saprobic on dead twigs of Quercus serrata. Sexual morph: Ascomata 120–140 μm high, 110–160 μm diam., (x̅ = 130 × 140 μm, n = 5), immersed to erumpent, solitary or scattered, globose to subglobose, uni-loculate, coriaceous, black, with short papilla. Ostioles central, short, slightly raised, 32–42 × 36–41 μm (x̅ = 36 × 38 μm, n = 5). Peridium 8–12 μm wide, 2–3 layered, composed dark brown cells of textura angularis. Hamathecium 2.2–4.4 μm wide, comprising branched, septate, hyaline, cellular pseudoparaphyses, constricted at the septa, embedded in a gelatinous matrix. Asci 46–59 × 8–10 μm (x̅ = 53 × 9 μm, n = 20), 8-spored, bitunicate, fissitunicate, cylindric, slightly curved, with a broadest truncate pedicel, apically rounded. Ascospores 14–14.7 × 3.8–4.6 μm (x̅ = 14.3 × 4.2 μm, n = 30), overlapping, 1–2-seriate, hyaline, fusiform, tapering towards rounded ends, straight to slightly curved, 1-septate, constricted at the septum, smooth-walled, guttules. Asexual morph: Undetermined.

Culture characteristics: Ascospores germinating on PDA within 24 h at room temperature (25 °C). Germ tubes produced from the basal and apical cell of ascospore. Colonies on PDA, reaching 50 mm diameter after two weeks at 20–25 ℃, mycelia superficial, circular, fimbriate, dense, flat, entire edge, surface rough, raised, grayish white; reverse, light brown.

Material examined: China, Yunnan Province, Lijiang, on dead woody twigs of Quercus serrata (Fagaceae), 30 August 2020, G.C. Ren, DQ10 (HKAS 122715, holotype), ex-type living culture KUMCC 21-0531.

GenBank numbers : LSU: OQ170849, ITS: OQ158929, SSU: OQ168205, rpb2: OR578559.

Notes: In our phylogenetic analysis, Stagonosporopsis lijiangensis clustered with Stagonosporopsis ailanthicola (MFLUCC 16-1439) and S. heliopsidis (CBS 109182), with 79% ML bootstrap support and 0.95 BYPP value. However, these two species are only reported from their asexual morph (Aveskamp et al. 2010, Tibpromma et al. 2017, Boggess et al. 2022), and our isolation is recorded with its sexual morph. Therefore, we could not conduct a morphological comparison among these three collections. However, S. lijiangensis shares similar morphology with Stagonosporopsis in having globose to subglobose ascomata, cylindrical to subclavate, 8-spored, biseriate asci and fusiform or obovoid, 1-septate, guttulate ascospores (Aveskamp et al. 2010). Sequence comparison for the ITS region between Stagonosporopsis lijiangensis (KUMCC 21-0531) and S. ailanthicola (MFLUCC 16-1439) showed a 2.9% (13/455 bp, without gaps) base pair difference in ITS region, 3.4% (20/595 bp, without gaps) base pair difference in rpb2 region, 0.7% (6/873 bp, without gaps) base pair difference in LSU region. Additionally, comparison for the ITS region between Stagonosporopsis lijiangensis (KUMCC 21-0531) and S. heliopsidis (CBS 109182) showed a 1.2% (6/488 bp, without gaps) base pair difference in ITS region, 3.2% (19/595 bp, without gaps) base pair difference in rpb2 region, 0.6% (5/876 bp, without gaps) base pair S. lijiangensis as a new species in Stagonosporopsis. Stagonosporopsis species are recorded from different host plant families (Amaranthaceae, Asteraceae, Campanulaceae, Caryophyllaceae, Cucurbitaceae, Fabaceae, Lamiaceae, Pinaceae, Ranunculaceae, Solanaceae and Valerianaceae) and represents serious plant pathogens, such as ray blight disease of pyrethrum, leaf spot and stem blight on Pogostemon cablin and leaf spot on whorled sunflower (Fox 1998, Vaghefi et al. 2012, Jayawardena et al. 2019, Boggess et al. 2022). Our novel species was isolated from the dead woody twigs of Quercus serrata (Fagaceae).

Figure 1: Phylogram generated from ML analysis based on LSU, ITS, rpb2, and tub2 sequence data representing Stagonosporopsis. Related sequences are obtained following Dong et al. (2021). Sixty-six strains are included in the combined analyses, which comprise 2388 characters for LSU, ITS, rpb2, and tub2 alignment. Two Allophoma piperis strains (PD 90.2011 and CBS 268.93) were used as the outgroup taxa. The best-scoring RAxML tree with a final likelihood value of -9973.267368 is presented. The matrix had 530 distinct alignment patterns, with 4.37% of undetermined characters or gaps. Estimated base frequencies were as follows; A = 0.244019, C = 0.238910, G = 0.272866, T = 0.244205; substitution rates AC = 2.397927, AG = 5.305500, AT = 1.951399, CG = 0.899750, CT = 14.000885, 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.