Hyalorbilia yunnanensis C.J.Y. Li & K.D. Hyde sp. nov.

Index Fungorum number: IF 902392; Mycobank number: MB 902392; Facesoffungi number: FoF 16058 Fig. 1

Etymology – named according to the geographical origin, Yunnan province.

Holotype – HKAS 126582

Saprobic on decayed wood. Apothecia fresh 1.5–3 mm diam., dried 0.21–0.24 mm high (x̅= 1.97 × 0.23 mm, n = 23), scattered or gregarious, superficial, flatted or inverted discoid, pale cream yellow when fresh, yellowish orange when dry, translucent. Disc flat and circular, smooth, margin thin; almost sessile. Excipulum 140–170 μm, hyaline, wall thin, at base comprised of textura angularis cells, 14–17.9 × 11.3–15.4 μm (x̅= 16.3 × 13.1 mm, n = 20), at middle comprised of large, loosely disordered textura angularis-prismatica cells, 20.8–29.6 × 14.9–21.2 μm (x̅= 24.3 × 17.5 mm, n = 20), at flank of horizontally oriented textura prismatica, 15.7–26.7 × 8–11.2 μm (x̅=22.2 × 9.5 mm, n=20). Hymenium 31–35 μm, hyaline. Paraphyses 1.4–1.7 μm wide at tips, filiform, hyaline, unbranched, aseptate, scarcely extending beyond the asci. Asci 26–33×3.1–5.4 μm (x̅=29.2×4.4 μm, n=30), 8–spored, short clavate, hemispherical apex, short and thick stalk arising from croziers. Ascospore (1/1/4) (7.9–)8–9. 7(–10.1)×(1–)1.3–1.9(–2) μm (x̅=8.8×1.6 μm, n=50),
Q = (4.3)4.6–7(–8.9) μm, Qm = 5.67 ± 0.9 μm, overlapping uniseriate to biseriate, clavate with narrowly rounded ends, thin-walled, smooth, aseptate or 1-septate. Anchoring hyphae very abundant, 3.6–5.2 μm wide, wall thin, radiating, twining, multi-septate. Exudate 0.3–0.5 μm thick, covering asci and paraphyses, continuous, smooth, pale yellow. Asexual morph: not observed.

Material examined – China, Yunnan Province, Tengchong City, altitude 1550 m, on decayed wood, 20 August 2022, Cuijinyi Li, LCJY-1129 (HKAS 126582, holotype).

GenBank numbers – ITS: OQ158979

Notes – The phylogenetic analysis of ITS data and typical morphological features indicates that our collection belongs to Hyalorbilia. The ITS region of Hyalorbilia yunnanensis (HKAS 126582) is similar to Hyalorbilia juliae (strain 6449) (449/506 with 25 gaps) and Hyalorbilia citrina (H.B. 8012, C.L. 5247) (349/414 with 29 gaps). Hyalorbilia yunnanensis formed an individual clade between Hyalorbilia arcuate (strain H.B. 8578b) and Hyalorbilia citrina (H.B. 8012, C.L. 5247) with 84% ML bootstrap and 0.99 Bayesian probability. Hyalorbilia yunnanensis is mainly characterised by typically pale cream yellow and translucent apothecia, horizontally oriented prismatica cells and large, loosely disordered angularis to prismatica cells, low thickness proportion of hymenium, thin paraphyses, short and broad asci with long ascospores. Morphologically, Hyalorbilia yunnanensis is similar to Hyalorbilia polypori in vertical section features (hymenium and excipulum) and short broad asci, but the latter distinct Hyalorbilia yunnanensis by having shorter ascospores (8–9.7×1.3–1.9 μm vs. 5.5–8.5×1.5–1.9 μm) and septate paraphyses (Baral et al. 2020). Hyalorbilia arcuata and Hyalorbilia citrina were sister to Hyalorbilia yunnanensis based on the phylogenetic analysis but can be distinct by curved ascospores (Baral et al. 2020).

Figure 1 – Hyalorbilia yunnanensis (HKAS 126582, holotype). a Fresh ascomata on natural habitat. b Vertical section of ascomata. c Excipulum. d Anchoring hyphae at apothecial base. e Paraphyses. f–j Asci (f–i Asci in phloxine reagent). k–p Ascospores (k–n Ascospore in phloxine reagent). Scale bar: b=800 μm, c=130 μm, d=25 μm, e–j=15 μm, k–p=5 μm