Lecidea tibetica Z. J. Ren, Xin Y. Wang & Lu L. Zhang, 2025

Lecidea tibetica Z. J. Ren, Xin Y. Wang & Lu L. Zhang sp. nov.

Fig. 4 View Figure 4

Diagnosis.

Lecidea tibetica is characterized by a well-developed thallus, I + violet medulla, hyaline to pale straw-colored hypothecium, and the presence of 2 ’ - O - methyperlatolic acid as the major secondary metabolite.

Type.

China • Tibet Prov., Chayu Co., Zhuwagen Town Mont. Pass , 28°43'17.75"N, 97°42'21.01"E, alt. 4685 m, on siliceous rock, 13 Jul. 2019, X. Y. Wang et al. XY 19-659 ( KUN, holotype; GenBank PV 698370 ) GoogleMaps .

Etymology.

The epithet “ tibetica ” refers to the type location, Tibet Province, China.

Description.

Thallus: crustose, areolate to rimose-areolate, flat to bullate, thick (up to 1.1 mm); prothallus: black, obvious at the margin of the thalli; areoles: dispersed, irregular, flat to convex, sometimes expand into a tuberous structure; surface: gray to bluish gray or whitish gray (the shady side), esorediate; cortex: 12–20 μm thick; medulla: white, I + violet; algal layer: 50–100 μm thick; photobiont trebouxioid, cells (5.5 –) 7.5–13 μm diam. Apothecia: black, immersed to subimmersed, lecideine, up to 4.5 mm in diam.; disc: black, flat to slightly convex, epruinose, often irregularly cracked in old apothecia; proper margin: dull, often dark grey, persistent, sometimes undulate. In section: exciple: dark brown outside, unpigmented inside, with large crystals insoluble in K and N; epihymenium: olive-brown (N + orange-brown, K –), 15–25 μm thick; hymenium: hyaline, 70–85 μm tall; paraphyses: simple, occasionally scarcely branched and anastomosing; subhymenium: hyaline, poorly distinguishable from the hymenium; hypothecium: hyaline to pale straw colored, c. 200 μm; asci: clavate, Lecidea - type or Porpidia - type (occasionally observed in immature asci), 8 - spored; ascospores: hyaline, simple, ellipsoid, 11.5–13 × 6–8 μm, length-width index: 1.6–2 (n = 20). Conidiomata: immersed, graphidoid; conidia: bacilliform, (14 –) 15–18 (– 19) × 1 μm.

Chemistry.

Cortex and medulla K + yellow, C –, KC –; thallus UV –; 2 ’ - O - methyperlatolic acid and confluentic acid (trace) were detected by TLC.

Additional specimens examined.

China • Tibet Prov., Chayu Co., Yixiula Puerto , 28°44'16.62"N, 97°42'7.98"E, alt. 4492 m, on siliceous rock, 25 Sep. 2014, L. S. Wang et al. 14-46952 ( KUN) GoogleMaps .

Distribution.

This species is associated with Rhizocarpon sp. and has been documented so far only in the Tibet Province of China, where it grows on non-calcareous rocks in high-altitude areas.

Discussion.

Lecidea tibetica is morphologically similar to L. confluens (Weber) Ach. , L. tessellata Flörke , and Porpidia speirea (Ach.) Kremp. , as they all have a well-developed and grayish thallus, I + violet medulla, and immersed to sub-immersed apothecia. However, among the latter three species, all exhibit smaller apothecia (generally less than 2 mm), conidia measuring 8–13 × 1–1.3 μm (vs. [14 –] 15–18 [– 19] × 1 μm), and contain confluentic acid as the primary secondary metabolite. Specifically, Lecidea confluens has a brown to dark brown hypothecium, while L. tessellata lacks conspicuous apothecial margins. Porpidia speirea can be distinguished by the presence of prominent dark parathecial margins, halonate ascospores, and a dark brown hypothecium. Like Lecidea tibetica , L. stratura K. Knudsen & Lendemer also has a white to grayish thallus, I + medulla, and contains 2 ’ - O - methyperlatolic acid. However, it has a blue to blue-green epihymenium, a shorter hypothecium (70–100 μm vs. 200 μm), smaller ascospores (8–9.5 × 3.0–5.5 μm vs. 11.5–13 × 6–8 μm), and a distinctly thin thallus (usually 0.2–0.5 mm thick) rather than a thick thallus (up to 1.1 mm thick) like L. tibetica ( Knudsen et al. 2017).