Diorygma leigongshanense Wei Wu & S. B. Fu 2025, sp. nov.

Diorygma leigongshanense Wei Wu & S. B. Fu sp. nov. Fig. 3 Etymology. The specific epithet “ leigongshanense ” refers to the location where the holotype was collected. Holotype. KUN-L 0093725 Description. Sexual morph: Thallus corticolous, crustose, thin, tightly attached to the substratum, pale grey to greenish grey, rough, dull, lacking isidia and soredia, prothallus absent. Ascomata lirellate, numerous, oblong to long, ± flexuous, simple or with a few branches, measuring 0.7–2.5 mm long and 0.4–1.2 mm wide. Disc surrounded by entire raised thalline margins, widely open, covered with a thin, pale yellowish pruina. Exciple uncarbonized, basally and laterally brownish. Epihymenium brown, 15–41 µm high. Hymenium hyaline, not inspersed, 160–350 μm high, I –. Paraphysis anastomosing, filiform, 1–2.5 µm wide. Hypothecium brown, 20–48 µm high. Asci fusiform, 106–202 × 28–58 μm, I –. Ascospores 1 / ascus, hyaline, richly muriform, peripheral and central spore locules of ± equal size, 20–42 × 5–10 locular, (95 –) 119–170 (– 194) × (22 –) 27–46 (– 54) μm (x ̄ = 144 × 37 μm, n = 20), I –. Asexual moprh: not observed. Chemistry. Thallus K + reddish brown, C –, KC + yellow, P + yellow, TLC: stictic acid, salazinic acid, norstictic acid. Material examined. China, • Guizhou Province, Leishan County, Leigong Mountain National Nature Reserve, 26°22'43.16"N, 108°11'42.65"E, 1681 m elev., on bark, 27 Oct. 2023, Ze Yang & Bo Liu, LGS 207 (holotype KUN-L 0093725). Notes. This species is characterized by its erumpent lirelliform apothecia, with discs surrounded by entire, raised thalline margins that are widely open and covered with a thin, pale yellowish pruina. The exciple is uncarbonized, and the hymenium is hyaline, non-inspersed, and I –. Spores are single per ascus, hyaline, richly muriform, with peripheral and central spore locules of approximately equal size, 20–42 × 5–10 locular, measuring 119–170 × 27–46 μm. Chemically, this species contains stictic, salazinic, and norstictic acids. Phylogenetic analysis based on combined LSU and mtSSU sequence data places D. leigongshanense as closely related to Diorygma tiantaiense (Fig. 1). However, Diorygma leigongshanense differs chemically by the presence of stictic and salazinic acids (vs. only containing norstictic acid). Morphologically, D. leigongshanense has lirelliform apothecia, in contrast to the oval, open, and raised ascocarps of D. tiantaiense (Cui et al. 2024). Diorygma leigongshanense is morphologically similar to D. rufopruinosum (A. W. Archer) Kalb, Staiger & Elix. However, it can be distinguished by its ascospore septation pattern: in D. leigongshanense, the peripheral cells and central cells are of similar size, whereas in D. rufopruinosum, the peripheral cells are noticeably smaller. Diorygma leigongshanense contains stictic, salazinic, and norstictic acids, while D. rufopruinosum produces protocetraric acid and lacks stictic acid (Kalb et al. 2004). Morphologically, Diorygma leigongshanense also shares similarities with D. chumphonense Sutjaritturakan & K. Kalb, but it can be distinguished by having longer ascospores (119–170 μm vs. 95–110 μm), peripheral cells of equal size to the central ones (vs. peripheral cells distinctly smaller), lacking stictic acid (vs. presence), and the I – (vs. I + blue-violet) (Sutjaritturakan et al. 2014).