Fuscostagonospora banksiae

Fuscostagonospora banksiae Crous & Carnegie, Fungal Systematics and Evolution 3: 82 (2019)

Index Fungorum number: IF 829304; Facesofungi number: FoF 13882

Saprobic on dead woody twigs of Rhododendron rubiginosum. Sexual morph: Ascomata 400–530 μm high × 600–650 μm diam., (x̅ = 460 × 640 μm, n = 5), immersed to erumpent, solitary or scattered, coriaceous, ampulliform, dark brown, multiloculate, with 2–3 locules, cells of ascostromata composed of several layers of dark brown cells of textura angularis. Locules 160–300 μm high × 200–320 μm diam., (x̅ = 260 × 250 μm, n = 10), globose to subglobose. Ostiolar neck clypeate, central, short papillate, 60–80 × 70–90 μm (x̅ = 70 × 80 μm, n = 5). Peridium of locules 12–17 μm wide, 3–4-layered, comprising pale brown cells of textura angularis. Hamathecium 1.5–2 μm wide, comprising cylindrical, septate, branched and anastomosed pseudoparaphyses, embedded in a hyaline, gelatinous matrix. Asci 64–78 × 7.6–9.8 μm (x̅ = 72 × 8.6 μm, n = 15), bitunicate, 8 spored, cylindrical clavate, straight, slightly curved at the end, apically rounded, pedicellate. Ascospores 11–14 × 3–4 μm (x̅ = 12.7 × 3.5 μm, n = 30), uniseriate, ellipsoidal, hyaline, 1 septate, constricted at the septum, guttulate, thick and smooth walled, upper cell wider than lower cell, without a gelatinous sheath. Asexual morph: Conidiomata solitary, pycnidial, globose, brown, 180–200 μm diam, exuding a milky white conidial mass. Conidiophores lining the inner cavity, reduced to conidiogenous cells or with a supporting cell, branched at base or not, 5–12 × 3–4 μm. Conidiogenous cells ampulliform to doliiform, hyaline, smooth, 5–7 × 3–4 μm, proliferating indisttnctly percurrently at apex. Conidia solitary, aseptate, hyaline, smooth, guttulate, ellipsoid, apex obtuse, base bluntly rounded, (3–)4(–5) × (2–)2.5(–3) μm (Crous et al. 2019).

Culture characteristics: Ascospores germinating on PDA within 24 h at room temperature (25 °C). Germ tubes produced from the basal and apical cells of ascospore. Colonies on PDA, reaching 20–30 mm diameter after two weeks at 20–25 ℃, mycelia superficial, circular, grey, smooth, downy, fimbriate; reverse dark grey.

Material examined: China, Yunnan Province, Diqing, Xianggelila, Nixi, on dead woody twigs of Rhododendron rubiginosum (Ericaceae), 31 August 2020, G.C. Ren, NX10 (HKAS 122762), living culture KUMCC 21 0640.

Known distribution: Banksia sp. (Proteaceae) in Australia (Crous et al. 2019), on dead woody twigs of Rhododendron rubiginosum (Ericaceae) in China (This study).

GenBank numbers: LSU: OQ170851, ITS: OQ158931, SSU: OQ168207, tef1-α: OR613429.

Notes: According to the multi-gene phylogenetic analyses of a combined SSU, LSU, ITS and tef1-α sequence dataset, the new isolate (KUMCC 21-0640) nested together with Fuscostagonospora banksiae (CBS 144621), which was isolated from Banksia sp. (Proteaceae) in Australia (Crous et al. 2019) with 100% ML bootstrap support and 1.00 BYPP value. However, there were no sexual morphs reported for F. banksiae (Crous et al. 2019). The characteristics of the new strain (KUMCC 21-0640) fit with the generic description of Fuscostagonospora by having immersed, scattered ascomata, pale brown peridium, branched and anastomosed pseudoparaphyses embedded in a hyaline, gelatinous matrix, cylindrical asci with pedicellate, hyaline, septate ascospores (Tanaka et al. 2015). The new isolate and F. banksiae (CBS 144621) clustered closer to F. camporesii with 88% ML bootstrap support and 1.00 BYPP value. The characteristics of the new strain (KUMCC 21-0640) resemble F. camporesii in having semi-immersed to erumpent, subglobose to globose ascomata, cylindric-clavate, short pedicellate asci and 1-septate, ellipsoid to obovoid ascospores (Hyde et al. 2020b). However, the new isolate can be distinguished from F. camporesii in having multiloculate ascostromata and hyaline ascospores, whereas F. camporesii has uni-loculate ascomata and light brown ascospores (Hyde et al. 2020b).

Figure 1. Phylogram generated from ML analysis based on SSU, LSU, ITS, and tef1-α sequence data representing Fuscostagonosporaceae. Related sequences are obtained following Hyde et al. (2020b). Fifty-one strains are included in the combined analyses, which comprise 3368 characters for SSU, LSU, ITS, and tef1-α alignment. Periconia byssoides (MFLUCC 18-1548) and P. thailandica (MFLUCC 17-0065) were used as the outgroup taxa. The best-scoring RAxML tree with a final likelihood value of -21124.171380 is presented. The matrix had 1176 distinct alignment patterns, with 24.30% of undetermined characters or gaps. Estimated base frequencies were as follows: A = 0.238450, C = 0.247333, G = 0.272652, T = 0.241565; substitution rates AC = 1.491762, AG = 2.507287, AT = 1.659077, CG = 1.294230, CT = 7.094483, 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.