Diorygma weii Wei Wu & S. B. Fu, 2025

Wu, Wei, Jiang, Shu-Hao, Chai, Lin-Shan, Bo, He-Yun, Jayawardena, Ruvishika S., Fu, Shao-Bin & Meng, Qing-Feng, 2025, Four new species of the lichen genus Diorygma (Graphidaceae, Ostropales) from Guizhou, China, MycoKeys 121, pp. 111-142 : 111-142

Diorygma weii Wei Wu & S. B. Fu sp. nov.

Fig. 5

Etymology.

The species epithet “ weii ” honors Professor Jiangchun Wei (Chinese Academy of Sciences), a venerable lichenologist, for his pioneering contributions to lichenology in China.

Holotype.

KUN-L 0093727

Description.

Sexual morph: Thallus corticolous, crustose, thin, tightly attached to the substratum, milky white, with a slight greenish tint, rough, dull, lacking isidia and soredia, prothallus absent. Apothecia lirelliform, prominent, stellately branched, curved, and either terminally rounded or acute, measuring 2–7 mm long and 0.1–0.4 mm wide. Disc closed to slit-like, covered with a thin white pruina. Proper margin conspicuous. Exciple uncarbonized, brown at apex, pale yellowish brown towards base. Hymenium hyaline, not inspersed, 150–210 μm high, I + violet. Paraphysis anastomosing, filiform, 1–2 µm wide. Asci fusiform, 60–155 × 18–45 μm, I – or I + violet. Ascospores 1 / ascus, hyaline, richly muriform, peripheral and central spore locules of ± equal size, ends with gelatinous caps, 24–28 / 6 – 9 locular, (55 –) 73–119 (– 142) × (11 –) 18–35 (– 41) μm (x ̄ = 96 × 27 μm, n = 20), I + violet. Asexual moprh: not observed.

Chemistry.

Thallus K + reddish brown, C –, KC + yellow, P + yellow, TLC: Norstictic acid.

Material examined.

China, • Guizhou Province, Leishan County, Leigong Mountain National Nature Reserve , 26°20'33.94"N, 108°17'23.94"E, 831 m elev., on the bark, 25 Oct. 2023, Ze Yang & Bo Liu, Coll. No. LGS 57 (holotype KUN-L 0093727 ) .

Notes.

This new species is characterized by its lirelliform apothecia, which are prominent with a closed-to-slit-like disc covered by a thin white pruina. The exciple is uncarbonized, and the hymenium is hyaline, not inspersed, and reacts I + violet. Spores are single per ascus, hyaline, richly muriform, with peripheral and central spore locules of approximately equal size, 24–28 × 6–9 locular, measuring 73–119 × 18–35 μm, I + violet. Chemically, this species contains only norstictic acid.

Phylogenetic analysis based on the combined data of LSU and mtSSU sequences indicates that D. weii forms a clade with D. karnatakense (Fig. 1 ). However, nucleotide divergence in mtSSU between the two species is 3.52 % (23 / 653 bp). Morphologically, D. weii has asci containing a single spore, versus 1–8 - spored asci in D. karnatakense . Chemically, D. weii only produces norstictic acid, whereas D. karnatakense contains both norstictic and salazinic acids ( Ansil et al. 2023).

Diorygma weii shares morphological similarities with Diorygma inaequale and D. dealbatum B. O. Sharma & Makhija. However , both D. inaequale and D. dealbatum contain both salazinic and norstictic acids, whereas the new species produces only norstictic acid ( Sharma and Makhija 2009 a).

Figures

Figure 1. RAxML analysis based on combined LSU and mtSSU sequence data. Bootstrap support values for maximum likelihood (ML ≥ 75 %) and Bayesian posterior probabilities (PP ≥ 0.90) are shown near the nodes as ML / PP. Glyphis cicatricosa (Lücking 28047 F and Lumbsch 19528 o F) is used as the outgroup taxon. Newly generated sequences are shown in bold. Type strains are indicated as T.

Figure 5. Diorygma weii (KUN-L 0093727, holotype). A – C. Thallus with ascomata; D. Cross section of apothecium; E. Cross section of apothecium (in IKI); F – H. Ascus; I, J. Ascospores (in water); K. Ascospore (in IKI). Scale bars: 1 mm (A – C); 50 µm (D); 100 µm (E); 20 µm (F – K).