Lobothallia subdiffracta var. rimosa 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 subdiffracta var. rimosa Lun Wang & Y. Y. Zhang var. nov.

Fig. 4 A – J

Type.

China • Xinjiang Uygur Autonomous Region: Hami Ci. , Balikun Co.; 43 ° 41 ′ 39 ″ N, 92 ° 17 ′ 48 ″ E; 2031 m elev.; on rock; 04 July 2022; ZYY 22-647 (Holotype: KUN-L 0082221 !, isotype: AHUB 00501 !) .

Diagnosis.

Lobothallia subdiffracta var. rimosa is characterised by its areolate thallus with slightly radiated marginal areoles, rimose and white pruinose upper surface, lecanorine apothecia with black and pruinose discs, its crenate thalline margin when immature and entire at maturity and the absence of secondary metabolites.

Etymology.

The epithet refers to the rimose upper surface.

Description.

Thallus areolate, usually circular in outline, up to 4 cm in diam., 2–5 mm thick, central areoles continuous, angular and slightly convex, 0.5–2.5 mm across, marginal areoles slightly radiate with a rounded apex. Upper surface greyish to clay coloured, rimose and pruinose. Upper cortex paraplectenchymatous, uneven, (25.0 –) 36.5–53.5 – 70.5 (– 85.0) μm (n = 20) thick, upper part brownish, insoluble in K; epinecral layer uneven, (10.0 –) 21.5–45.5 – 69.0 (– 95.0) μm (n = 30) thick, containing dark brown granules (POL +, insoluble in K); algal layer discontinuous, interrupted by fungal tissue, forming algal stacks, 100–200 μm high, with dark granules (partly soluble in K), algae 8–15 μm in diam.; medulla containing black substance (POL +, insoluble in K). Lower cortex absent.

Apothecia lecanorine, numerous, initially 1–2 per areole, then one per areole, dispersed to grouped, rounded, (0.2 –) 0.7–1.5 (– 2) mm in diam.; disc slightly concave to plane, matt, black, pruinose; thalline margin 0.1–0.15 mm wide, crenate when young, entire with age, pruinose, concolorous with upper surface, cortex identical with upper cortex (POL +), 40–75 μm thick; proper exciple inconspicuous. Hymenium hyaline, I + blue, 100–125 μm high; epihymenium 5–15 μm thick, with pale brown (insoluble in K), brown (soluble in K) granules and hyaline plate-like crystals (insoluble in K); paraphyses simple to rarely anastomosed, submoniliform to moniliform at the upper part, with 3–5 cells, apex thickened, 4–6 µm wide; hypothecium 50–60 μm thick, hyaline, I + blue; asci 8 - spored, clavate, Aspicilia - type, 60–80 × 20–30 µm; ascospores hyaline, simple, broadly ellipsoid, (8.0 –) 10.0–11.0 – 12.5 (– 13.0) × (7.0 –) 7.0–8.0 – 9.0 (– 10.0) µm (n = 50), wall ca. 1.0 µm. Pycnidia common, with punctiform ostiole, dark brown; conidia hyaline, bacilliform, 5–7 (– 8) × ca. 1 μm.

Chemistry.

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

Distribution and ecology.

This species grows on exposed calcareous rocks at elevations of approximately 2000 m in Xinjiang Uygur Autonomous Region, China.

Notes.

Lobothallia subdiffracta var. rimosa , L. subdiffracta var. subdiffracta and “ L. helanensis ” were sympatric in north-western China and neighbouring regions and also phylogenetically closely interrelated ( Kou et al. 2013; Paukov et al. 2019). “ Lobothallia helanensis ” was previously synonymised with L. subdiffracta , because both shared the morphological characters of non-lobate thallus and apothecia with incised margins, with similar sequences in the ITS and mtSSU regions ( Paukov et al. 2019). Our materials differ from both var. subdiffracta and “ L. helanensis ” by their characters of lecanorine apothecia, permanent thalline margin, pruinose discs and the slightly radiate marginal areoles. Therefore, we treat these specimens as a new variety within Lobothallia subdiffracta . Table 2 presents a brief comparison of these taxa. Another taxon Lobothallia recedens may be confused with L. subdiffracta var. rimosa due to its thick, areolate, non-lobate thallus and the absence of secondary metabolites. However, the former differs in its densely clustered apothecia (3–6 per areole) and its shorter conidia 3–5 × ca. 1 μm ( Paukov et al. 2019; Cannon et al. 2023; Martellos et al. 2023).

Additional specimens examined.

Lobothallia subdiffracta var. rimosa . China • Xinjiang Uygur Autonomous Region: Hami Ci., Balikun Co., along road G 335 , 43 ° 41 ′ 35.55 ″ N, 92 ° 17 ′ 46.81 ″ E, 2036 m elev., on limestone rock, 04 July 2022, Li S. Wang et al. 22-72975 ( KUN-L 0087453 ) .

Lobothallia subdiffracta var. subdiffracta . China • Xinjiang Uygur Autonomous Region: Fukang Ci., Chengguan Vi. ; 44 ° 09 ′ 36.52 ″ N, 87 ° 58 ′ 42.00 ″ E; 500–600 m elev.; on sandstone; 04 July 2022; Yin A. C. & Chen H. X.; 22-72347 ( KUN-L 0086973 ) • Turpan Ci. , Tuokexun Co.; 43 ° 06 ′ 15.85 ″ N, 87 ° 34 ′ 52.51 ″ E; 2473 m elev.; on rock; 02 July 2022; ZYY 22-628 ( KUN-L 0082202 , AHUB - 00482 ) .

“ Lobothallia helanensis ”. China • Inner Mongolia: Bayan Hot Vi. , Helan Mountain; 1500–2000 m elev.; on rock; 19 Aug 2011; Wang H. Y. 20122708; Kou X. R. 20123833, Wang P. M. 20123198, Dong D. B. 20123040 ( SDUN) .

Figures

Figure 4. Lobothallia subdiffracta var. rimosa A thallus and apothecia B thalline margin crenate when immature and entire at maturity C slightly radiate arrangement of marginal areoles D cross-section of thallus E cross-section of thallus under polarised light F vertical section of apothecia G ascus H ascus (Lugol’s solution) I ascospores J conidia. All sections were mounted in water except where otherwise stated. Scale bars: 2 mm (A); 1 mm (B, C); 100 µm (D, E); 20 µm (F); 5 µm (G, H, I, J).