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

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

Fig. 4 View Figure 4

Etymology.

“locitonitius” combines “loci,” signifying locality, with “tonitius,” the Latin word for thunder, to mean “of the locality of thunder,” denoting the location where the holotype was found.

Holotype.

KUN-L 0093723

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. Apothecia lirelliform, scattered or aggregated, erumpent, simple or irregularly branched, curved, and either terminally rounded or acute, measuring 0.5–2.5 mm long and 0.2–0.6 mm wide. Disc narrow to open, covered with a white pruina. Exciple uncarbonized, brown at apex, pale yellowish brown towards base. Epihymenium brown, 10–42 µm high. Hymenium hyaline, not inspersed, 180–350 μm high, I + weakly blue-violet. Paraphysis anastomosing, filiform, 1–2.5 µm wide. Asci fusiform, 112–260 × 30–81 μm, I –. Ascospores 1 / ascus, hyaline, richly muriform, peripheral cells distinctly smaller than central ones, 26–40 / 6 – 15 locular, (105 –) 117–189 (– 247) × (25 –) 33–60 (– 76) μm (x ̄ = 153 × 47 μm, n = 20), I –. Asexual moprh: not observed.

Chemistry.

Thallus K + reddish brown, C –, KC + orange, P + yellow, TLC: constictic acid, salazinic acid, norstictic acid.

Material examined.

China, • Guizhou Province, Leishan County, Leigong Mountain National Nature Reserve , 26°22'53.94"N, 108°11'46.76"E, 1771 m elev., on bark, 27 Oct. 2023, Ze Yang & Bo Liu, LGS 256-1 (holotype KUN-L 0093723 ) GoogleMaps .

Notes.

This species is characterized by its lirelliform apothecia, which are erumpent with narrow to open discs covered by a white pruina; the exciple is uncarbonized, and the hymenium is hyaline, not inspersed, and reacts I + weakly blue-violet. The ascospores, one per ascus, are hyaline, richly muriform, with peripheral cells distinctly smaller than central ones, containing 26–40 × 6–15 locular, measuring 117–189 × 33–60 μm, I –. Chemically, this species contains constictic, salazinic, and norstictic acids.

Phylogenetic analysis based on combined LSU and mtSSU sequence data places Diorygma locitonitrus as closely related to D. tiantaiense (Fig. 1 View Figure 1 ). However, nucleotide comparison of the LSU reveals a difference between D. locitonitrus of 0.80 % (6 / 758 bp) between the two species. The new taxon is chemically distinct from the presence of both norstictic and salazinic acids, while D. tiantaiense contains only norstictic acid. In addition, the hymenium of D. locitonitrus exhibits a weakly I + blue-violet reaction in Lugol’s solution, in contrast to the I – reaction in D. tiantaiense ( Cui et al. 2024) .

Diorygma locitonitrus is morphologically similar to D. chumphonense but differs in the larger ascospores (117–189 × 33–60 μm vs. 95–110 × 37–40 μm) and the iodine reaction of the hymenium (I –, vs. I + weakly violet). Additionally, the ascospores of D. locitonitrus are I –, in contrast to the I + violet reaction observed in D. chumphonense ( Sutjaritturakan et al. 2014) .