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

Fig. 3 A – K

Type.

China • Sichuan Prov.: Ganzi Tibetan Autonomous Prefecture, Xinlong County, along road G 227 ; 31 ° 25 ′ 52.77 ″ N, 100 ° 8 ′ 52.04 ″ E; 3296 m elev.; on rock; 11 July 2022; ZYY 22-819 (Holotype: KUN-L 0082392 !; Isotype: AHUB - 00673 !) .

Diagnosis.

The species Lobothallia lobulata is characterised by its conspicuously radiate marginal lobes, pruinose upper surface with lobules, the aspicilioid apothecia when immature, lecanorine to zeorine at maturity with epruinose, shiny discs and the absence of secondary metabolites.

Etymology.

The epithet refers to its lobules along the upper surface.

Description.

Thallus placodioid, circular in outline, up to 3 cm in diameter, tightly adnate to the substratum; central areoles contiguous, angular to irregular, plane to slightly convex, 0.3–1 mm across; marginal lobes radiate, plane, 1–5 mm long, 0.5–1 mm wide, ca. 0.3 mm thick, apex rounded, irregularly divided, usually with a black rim. Upper surface light grey to greyish-olive, lightly and discontinuously pruinose, pruina on the apex of lobes thicker than the centre. Lobules common, 0.1–0.3 mm, divided, heavily pruinose. Upper cortex paraplectenchymatous, even, ca. 30 μm thick, filled with pale brown (insoluble in K) and dark brown (partly soluble in K) granules; epinecral layer 10–20 μm thick, containing dark granules when pruina is present (POL +, insoluble in K); algal layer discontinuous, interrupted by fungal tissue, forming separated groups, 50–150 μm high, containing black substance (soluble in K), algae cells ca. 5–10 μm in diam.; medulla filled with black substance (POL +, insoluble in K). Lower cortex absent.

Apothecia aspicilioid when immature, lecanorine to zeorine at maturity, common, initially 1–2 per areole, usually one per areole, scattered to slightly grouped, adnate, rounded, 0.5–1 mm in diam.; disc brown to brownish-black, shiny, epruinose, concave at first, plane at maturity; thalline margin entire, ca. 0.1 mm wide, slightly pruinose or epruinose, cortex identical with upper cortex (POL –), 30–50 μm thick; proper exciple conspicuous in mature apothecia, 20–150 μm thick. Hymenium hyaline, I + blue, 100–120 μm high; epihymenium 5–10 μm thick, with pale brown (insoluble in K) and brown (soluble in K) granules; paraphyses simple, moniliform at upper part, with 3–6 cells, apex thickened, 4–6 µm wide; hypothecium 25–50 μm thick, hyaline, I + blue; asci 8 - spored, clavate, Aspicilia - type, 70–80 × 15–20 µm; ascospores hyaline, simple, broadly ellipsoid, (9.0 –) 10.5–11.5 – 12.5 (– 13.0) × (7.0 –) 8.0–8.5 – 9.5 (– 10.0) µm (n = 64), wall ca. 1.0 µm. Pycnidia common, convex, ostioles dark brown, shiny; conidia hyaline, bacilliform, 5–6 × ca. 1 μm.

Chemistry.

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

Distribution and ecology.

This new species grows on exposed calcareous rocks at elevations of 3262–3296 m elev. in Sichuan Province, China.

Notes.

This species shares morphological features with the closely-related Lobothallia radiosa : both have placodioid thallus, areolate in central parts and conspicuously radiate marginal lobes. Lobothallia radiosa has three chemotypes: parasitica with stictic acid, subcircinata with norstictic acid and radiosa with or without a trace amount of norstictic acid ( Ryan 2004; Reyim et al. 2012; Paukov et al. 2019). The new species shares the chemotype of some specimens of radiosa , but differs in the presence of lobules, the aspicilioid apothecia when immature, lecanorine to zeorine at maturity and in its phylogenetic position. Lobothallia hydrocharis also has a placodioid thallus with secondary metabolites absent, but differs by its aspicilioid apothecia with black and matt discs and its distribution, which is restricted to Sardinia, Italy ( Nimis and Poelt 1987; Nimis 2016; Nascimbene et al. 2023).

Additional specimens examined.

China • Sichuan Prov.: Xinlong Co., along road G 227 ; 31 ° 25 ′ 53 ″ N, 100 ° 8 ′ 53 ″ E; 3282–3296 m elev.; on rock; 11 July 2022; ZYY 22-822 ( KUN-L 0082395 , AHUB - 00676 ), ZYY 22-824 ( KUN-L 0082397 , AHUB - 00678 ), ZYY 22-829 ( KUN-L 0082402 , AHUB - 00683 ) • Shadui Vi. ; 31 ° 25 ′ 52 ″ N, 100 ° 8 ′ 54 ″ E; 3262–3263 m elev.; on limestone rock; 11 July 2022; Li S. Wang et al.; 22-73395 ( KUN-L 0087873 ), 22-73396 ( KUN-L 0087874 ) .

Figures

Figure 3. Lobothallia lobulata A thallus and apothecia B apothecia C lobules D cross-section of thallus E cross-section of thallus under polarised light F vertical section of apothecia G vertical section of apothecia under polarised light H, I ascus J ascospores K conidia. All sections were mounted in water, except where otherwise stated. Scale bars: 2 mm (A); 0.4 mm (B); 1 mm (C); 20 µm (D, E); 50 µm (F, G); 5 µm (H, I, J, K).