Setoarthopyrenia jinghongensis

Setoarthopyrenia jinghongensis G.C. Ren & K.D. Hyde, Mycosphere 15(1): 1046 (2024)

Index Fungorum number: IF 901360; FacesofFungi number: FoF13892

Saprobic on dead twigs of Ehretia acuminata. Sexual morph: Ascomata 120–345 μm high, 87–197 μm diam., (x̅ = 200 × 129 μm, n = 5), immersed to erumpent, solitary or scattered, coriaceous, uni to bi loculate, oval or obpyriform, black. Ostioles central. Peridium 15–25 μm wide, 2–4-layered, composed of hyaline or light brown cells of textura angularis. Hamathecium 1.6–2.3 μm wide, hyaline, comprising numerous, filamentous, branched, septate, cellular pseudoparaphyses, embedded in a gelatinous matrix. Asci 90–120 × 10–11 μm (x̅ = 107.4 × 10.6 μm, n = 10), 8 spored, bitunicate, fissitunicate, clavate or cylindrical, slightly curved, short pedicellate, apically rounded. Ascospores 14.5–18.5 × 5.5–6.7 μm (x̅ = 16.5 × 6 μm, n = 30), overlapping uniseriate, ellipsoid, straight, initially hyaline, becoming yellowish brown to dark brown when mature, 1 septate, 2 celled, slightly constricted at the septum, guttulate. Asexual morph: Undetermined.

Culture characteristics: Ascospores germinating on PDA within 24 h at room temperature (25 °C). Germ tubes produced from one cell of the ascospore. Colonies on PDA, reaching 50 mm diameter after two weeks at 20–25 ℃, mycelia superficial, circular, dense, filamentous, flat, slightly raised at the center, circular zonate on the surface, white at the margin, light brown at the center; reverse, pale yellow at the margin, dark brown at the center.

Material examined: China, Yunnan Province, Xishuangbanna Dai Autonomous Prefecture, Jinghong, Xishuangbanna Tropical Botanical Garden (21°55.19'N, 101°15.24'E), on dead woody twigs of Ehretia acuminate (Boraginaceae), 4 March 2020, G.C. Ren, JH31 (HKAS 122740, holotype), ex type culture KUMCC 21 0580. ibid., living culture KUMCC 21 0581.

GenBank numbers:  KUMCC 21 0580: SSU: OQ168231, LSU: OQ170880, ITS: OQ158958, tef1-α: OR613444; KUMCC 21 0581: SSU: OQ168232, LSU: OQ170881, ITS: OQ158959.

Notes: In the phylogenetic analyses, our isolates formed a sister clade to S. chromolaenae with 100% ML bootstrap support and 1.00 BYPP value. Setoarthopyrenia jinghongensis fits well with the generic concept of Setoarthopyrenia in having immersed, coriaceous, black ascomata, clavate or cylindrical, slightly curved, short pedicellate asci, ellipsoid, 1 septate ascospores with guttulate (Mapook et al. 2020), but distinct from S. chromolaenae in having oval or obpyriform ascomata, clavate or cylindrical asci, uniseriate, ellipsoid, brown to dark brown ascospores, while S. chromolaenae has globose ascomata with brown to dark brown setae, cylindric clavate asci, biseriate, hyaline, ellipsoid to obovoid ascospores (Mapook et al. 2020). Sequence comparison for the ITS region between Setoarthopyrenia jinghongensis (KUMCC 21-0580) and S. chromolaenae (MFLUCC 17 1444) showed 8.2% (39/475 bp, without gaps) base pair difference in ITS region, and 3.9% (35/890 bp, without gaps) base pair difference in the tef1-α region. Based on distinct morphology and phylogenetic position, Setoarthopyrenia jinghongensis is introduced as a new species.

Figure 1.  Phylogram generated from ML analysis based on LSU, ITS, tef1-α, and rpb2 sequence data, representing Roussoellaceae. Related sequences are obtained following Zhang et al. (2020b). Sixty strains are included in the combined analyses, which comprise 3136 characters for LSU, ITS, tef1-α, and rpb2 alignment. Torula herbarum (CBS 111855) and T. hollandica (CBS 220.69) were used as the outgroup taxa. The best-scoring RAxML tree with a final likelihood value of -22805.534061 is presented. The matrix had 1172 distinct alignment patterns, with 25.96% of undetermined characters or gaps. Estimated base frequencies were as follows; A = 0.240512, C = 0.264779, G = 0.272734, T = 0.221974; substitution rates AC = 1.942253, AG = 5.228557, AT = 2.132197, CG = 1.362679, CT = 10.344711, 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.