Lobothallia crenulata Lun Wang & Y. Y. Zhang, 2024

Zhang, Yanyun, Wang, Lun, Yu, Xinmeng, Cheng, Su, Liu, Junlan & Wang, Xinyu, 2024, Three new taxa of the lichen genus Lobothallia (Megasporaceae, Ascomycota) from China, MycoKeys 108, pp. 351-369 : 351-369

Lobothallia crenulata Lun Wang & Y. Y. Zhang sp. nov.

Fig. 2 A – J

Type.

China • Xizang Autonomous Region: Shigatse Ci. , Sa′gya Co.; 29 ° 12 ′ 01.28 ″ N; 88 ° 23 ′ 09.65 ″ E; 3924 m elev.; on schist rock in a desert environment; 14 June 2022; ZYY 22-301 (Holotype: KUN-L 0081882 !, Isotype: AHUB - 00157 !) .

Diagnosis.

Lobothallia crenulata is characterised by its placodioid, thickly pruinose thallus, rimose upper surface, aspicilioid to lecanorine apothecia with a crenate thalline margin, concave, black and pruinose disc and the absence of secondary metabolites.

Etymology.

The epithet refers to the crenate thalline margin of the apothecia.

Description.

Thallus placodioid, circular to irregular in outline, up to 2 cm in diameter; central areoles contiguous, angular to rounded, flat to slightly convex, 0.5–2 mm wide; marginal lobes closely attached, 0.5–2 mm long, 0.2–1 mm wide, with an irregularly arranged and divided apex. Upper surface white to light grey, covered with white, thick and discontinuous pruina (see Fig. 2 D ). Upper cortex paraplectenchymatous, hyaline, 20–50 μm thick; epinecral layer 20–70 μm thick, consisting of dark granules (POL +, insoluble in K); algal layer discontinuous, interrupted by fungal tissue, forming separated groups, 50–150 μm high, diffuse dark granules (soluble in K), algae ca. 10–20 μm in diam.; medulla with dark brown granules (POL +, insoluble in K). Lower cortex absent.

Apothecia aspicilioid to lecanorine, numerous, 1–2 per areole, dispersed to crowded, rounded to flexuous, 0.1–1.25 mm in diam.; disc concave, black and thinly pruinose; thalline margin crenate, concolorous with the thallus, 0.05–0.125 mm wide; proper exciple inconspicuous. Hymenium hyaline, 75–120 µm high, I + blue; epihymenium 10–20 µm high, with inspersed pale brown (insoluble in K) and brown (soluble in K) granules and coarse hyaline plate-like crystals (insoluble in K); paraphyses simple, submoniliform at upper part, with 2–4 apical cells, apex thickened, 3–5 µm wide; hypothecium 30–60 μm high, hyaline, I + blue; asci 8 - spored, clavate, Aspicilia - type, 70–80 × 20–30 µm; ascospores hyaline, simple, broadly ellipsoid to ellipsoid, (8.0 –) 11.0–13.0 – 14.5 (– 17.0) × (7.0 –) 8.5–9.0 – 10.0 (– 11.0) µm (n = 56), wall ca. 1.0 µm. Pycnidia uncommon; conidia bacilliform, 5–6 × 1–1.5 µm.

Chemistry.

K –, C –, KC –. No substances were detected by TLC.

Distribution and ecology.

This new species grows on calcareous schist rocks at elevations of 3924–4304 m in Xizang Autonomous Region, China.

Notes.

The new species is similar to Lobothallia iqbalii Zulfiqar, Khalid & Paukov and L. pakistanica Razzaq, Fayyaz, Khalid & Afshan in its placodioid thallus, white to light grey upper surface and the absence of secondary metabolites. Lobothallia iqbalii differs in its lecanorine apothecia with plane to convex disc and an entire and thick thalline margin ( Zulfiqar et al. 2022). Lobothallia pakistanica differs in its rarely cracked central areoles, thinner epinecral layer (8–16 µm), slightly concave to flat, rarely pruinose disc and the absence of thalline margin ( Zulfiqar et al. 2022). Lobothallia subdiffracta shares some features with L. crenulata : rimose and pruinose thallus. However, L. subdiffracta differs in its grey thallus with thinner and uneven pruina and its non-lobate thallus ( Magnusson 1944; Kou et al. 2013; Paukov et al. 2019). Another taxon, Lobothallia pruinosa , also has a placodioid and pruinose thallus and pruinose discs, but differs from L. crenulata in its entire thalline margin and the presence of norstictic and constictic acids ( Kou et al. 2013).

Additional specimens examined.

China • Xizang Autonomous Region: Shigatse Ci., Dingri Co., along road G 219 ; 28 ° 35 ′ 10.03 ″ N, 87 ° 3 ′ 42.56 ″ E; 4304 m elev.; on weathered schist rock; 16 June 2022; ZYY 22-331 ( KUN-L 0081892 , AHUB - 00187 ) .

Figures

Figure 2. Lobothallia crenulata A thallus and apothecia B apothecia C marginal lobes D cross-section of thallus (LCB) E cross-section of thallus under polarised light (LCB) F vertical section of apothecia G, H ascus I ascospores J conidia. All sections were mounted in water, except where otherwise stated. Scale bars: 1 mm (A, C); 0.4 mm (B); 100 µm (D, E); 20 µm (F); 5 µm (G, H, I, J).