Ochrolechia guizhouensis Zheng & Meng, 2025

Ochrolechia guizhouensis Zheng & Meng sp. nov.

Fig. 2 View Figure 2

Remark.

Ochrolechia guizhouensis is characterised by apothecia with rugose to rosulate discs presenting a distinct floral morphology. Chemically, lichesterinic acid is present in the apothecia, but absent in the thallus.

Type.

China • Guizhou, Qiandongnan Prefecture, Leigongshan Nat. Res , on bark, 1698 m elev., 2023, B. Liu and Z. Yang, LGS 219 ( KUN-L 96618 , holotype) .

Etymology.

The species epithet refers to Guizhou Province, the type locality where the species was collected.

Holotype.

KUN-L 96618 .

Description.

Thallus greyish-green, thick, rugose to verruculose, dull; prothallus indistinct, isidia and soredia absent.

Sexual morph. Apothecia frequent, scattered, sometimes crowded, sessile, round or irregular, 0.5–0.8 mm diam.; disc light yellowish-green or light brown, rugose to rosulate, epruinose; margins thick, smooth and taller than disc when young, becoming thin, verruculose and as tall as disc when older, exciple well developed even extending to the disc surface, concolorous with the thallus, shiny. Pycnidia are absent. Hymenium hyaline and colourless, 360–370 μm high, paraphyses are branched and anastomosing; epihymenium brown, 9–11 μm high; hypothecium pale brown (the colour of the epihymenium and hypothecium disappears in a 10 % KOH solution), 30–40 μm high; coccoid green alga, algae forming a continuous layer in the margin and in scattered clumps below the hypothecium. Asci clavate, (269) 272–284 (288) × (48) 49–60 (62) μm (n = 10). Ascospores hyaline, aseptate, broadly ellipsoid, (57) 60–78 (82) × (26) 28–32 (34) μm (n = 31).

Chemistry.

Thallus contains gyrophoric acid and lecanoric acid; ascomata contain gyrophoric acid, lecanoric acid and lichesterinic acid ( TLC). Thallus cortex: K + pale yellow, C + red, KC + red; medulla: C –; apothecia cortex: K + pale yellow, C + red, KC + yellow; medulla: C –; disc: C + red; thallus UV -.

Material examined.

China • Guizhou Province, Qiandongnan Prefecture City, Leigongshan National Nature Reserve , 26°22'43.24"N, 108°11'42.54"E, 1698 m elev., on bark, 27 October, 2023, Bo Liu and Ze Yang, LGS 219 ( KUN-L 96618 , holotype) GoogleMaps .

Notes.

In the phylogenetic tree, O. guizhouensis (LGS 219) and O. akagiensis (Hara Kojiro: 0007) are closely related although with weak bootstrap support (<70 %). The ITS sequence divergence between them is 6.35 % (33 / 520 bp). Morphologically, the two species differ distinctly: O. guizhouensis lacks isidia on the thallus and produces pale yellow, smaller apothecia ( 0.5–0.8 mm in diameter), whereas O. akagiensis bears isidia and develops pinkish, larger apothecia ( 0.8–1.5 mm in diameter). Chemically, the apothecia of O. guizhouensis contain lichesterinic acid, while the presence of this compound has not been reported in O. akagiensis ( Park et al. 2019) .

Although Ochrolechia guizhouensis resembles O. trochophora in some morphological and chemical characteristics, the two species differ notably in several features. The apothecia of O. guizhouensis are smaller ( 0.5–0.8 mm diam.), whereas those of O. trochophora are larger (1–3 (4) mm diam.) ( Brodo 1991). In addition, the apothecia of the latter lack lichesterinic acid. Phylogenetic analyses further indicate that this new species is distantly related the two O. trochophora vouchers (AFTOL-ID 880 and J. Vondrak 15442), supported by sequence divergences of 13.76 % (67 / 487 bp) in the ITS region and 4.97 % (35 / 704 bp) in the mtSSU region between O. guizhouensis (LGS 219) and O. trochophora (J. Vondrak 15442).

The difference with another similar species O. margarita , based on the identification key of Ren (2017), is that this species has a very thin thallus and its apothecia become subglobose when mature. Moreover, the algal layer forms a continuous layer below the hymenium, containing only gyrophoric acid and a trace of lecanoric acid.