Lobothallia complanata Lun Wang & Y. Y. Zhang, 2025

Wang, Lun, Feng, Yi-Shan, Wang, Li-Song, Wang, Xin-Yu & Zhang, Yan-Yun, 2025, An overview of the genus Lobothallia (lichenized Ascomycota, Megasporaceae) in China, MycoKeys 125, pp. 205-244 : 205-244

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

Fig. 3

Etymology.

The epithet refers to the flat thallus of this species.

Diagnosis.

Thallus appressed to the substrate, areolate with a flat and radiately lobate margin; upper surface orangish gray, covered by white pruina; apothecia lecanorine, orbicular, adnate, discs brown with orangish pruina; mature pycnidia protruding.

Holotype.

China • Sichuan Prov.: Aba Tibetan and Qiang Autonomous Prefecture, Li Co., Putou Vil. , 31°25'08.23"N, 103°04'10.85"E, alt. 2099 m, on rock, 4 September 2020, Li-Song Wang et al. 20-67554 ( KUN-L 75731 ) .

Description.

Thallus areolate with lobate margin, up to 5 cm across, closely appressed to the substrate, 0.3–1.5 mm thick. Areoles polygonal to suborbicular, (0.3 –) 0.5–1.2 (– 2.0) mm wide, interspaces between areoles 0.05–0.1 mm wide. Lobes flat, ca. 0.3 mm thick, elongate, 2–3 (– 3.5) mm long, 0.4–0.8 (– 1.0) mm wide at base, 0.6–1.5 mm wide at apex. Upper surface matt, orangish gray, covered by white pruina. Upper cortex paraplectenchymatous, even, 20–30 μm thick, with brown granules (soluble in K); epinecral layer 10–15 µm thick, with dense black granules (insoluble in K). Algal layer 75–125 µm thick, discontinuous; photobiont chlorococcoid, cells 8–20 µm diameter. Medulla opaque, filled with gray-black granules. Lower cortex absent.

Apothecia lecanorine, scattered, orbicular, (0.4 –) 0.8–2.0 (– 2.5) mm in diameter, adnate, constricted at base at maturity; disc plane to slightly convex, matt, brown with orangish pruina; apothecial margin entire, orange-gray, pruinose, persistent, 0.1–0.25 mm wide. Exciple narrow, widening to 20–60 μm in the uppermost part. Epithecium, hymenium and subhymenial layers combined 130–180 µm high; epithecium 10–15 µm high; epihymenium 10–20 μm high, with brown to dark brown granules (mostly soluble in K, leaving faint brown residue), N-; hymenium 75–100 µm high, hyaline, I + blue; subhymenial layers 40–75 μm high, hyaline, I + blue; algal layer discontinuous below hypothecium, 20–50 μm high; paraphyses simple, rarely anastomosed, septate, submoniliform, with 2–3 uppermost cells shorter and wider than the basal cells, 3–4 μm wide (basal cells ca. 2 μm wide); asci clavate, Aspicilia - type, hyaline, 8 - spored, 60–70 × 20–25 µm; ascospores simple, hyaline, broadly ellipsoid to spherical, (9.0 -) 9.5–10.4 – 11.3 (- 12.0) × (7.0 -) 7.7–8.7 – 9.8 (- 10.0) µm (n = 49), l / w ratio (1.0 -) 1.0–1.2 – 1.4 (- 1.6), wall ca. 1 µm thick. Pycnidia common, 0.2–0.5 mm diameter, distinctly protruding at maturity; ostiole brownish to dark brown; conidia bacilliform, hyaline, 4–6 × 1 µm.

Chemistry.

Cortex K + yellow to red, P-; Medulla K + yellow to red, P + yellow, C-, KC-; norstictic and connorstictic acids detected by TLC.

Habitat and distribution.

Saxicolous. Currently only known in Sichuan Prov., China.

Notes.

Lobothallia lobulata resembles the new species in the flat and appressed thallus. However, L. lobulata is readily distinguished by its light gray thallus surface bearing lobules, epruinose apothecial disc and the absence of secondary metabolites ( Zhang et al. 2024 a).

Additional specimens examined.

China • Sichuan Prov.: Aba Tibetan and Qiang Autonomous Prefecture, Li Co., Putou Vil. , 31°25'08.23"N, 103°04'10.85"E, alt. 2099 m, on rock, 4 September 2020, Li-Song Wang et al. 20-66561 ( KUN-L 74736 ) • Rangtang Co., 32°17'39.37"N, 101°00'44.83"E, alt. 3535 m, on rock, 4 September 2020, Xin-Yu Wang et al. XY 20-2551 ( KUN-L 78906 ) .

Figures

Figure 3. Lobothallia complanata (KUN-L 75731, holotype). A. Habitat; B. Thallus; C. Lobes; D, E. Apothecia; F. Protruding pycnidia; G, H. Section of thallus (H in K reagent); I. Vertical section of apothecium; J. Vertical section of pycnidium; K. Asci and ascospores (right in Lugol’s solution); L. Paraphyses (LCB); M. Conidia. Scale bars: 2 mm (B); 0.5 mm (E); 0.2 mm (C, D, F); 50 µm (G, H, I, J); 10 µm (K); 5 µm (L, M).