Lecanora chondroderma Zahlbr., in Handel-Mazzetti, Symb. Sinic. 3: 174 (1930).

Zhang, Yan-Yun, Wang, Xin-Yu, Li, Li-Juan, Printzen, Christian, Timdal, Einar, Niu, Dong-Ling, Yin, An-Cheng, Wang, Shi-Qiong & Wang, Li-Song, 2020, Squamarina (lichenised fungi) species described from China belong to at least three unrelated genera, MycoKeys 66, pp. 135-157 : 135

Lecanora chondroderma Zahlbr., in Handel-Mazzetti, Symb. Sinic. 3: 174 (1930). Fig. 5A, B

≡ Squamarina chondroderma (Zahlbr.) J.C. Wei, Enumeration of Lichens in China: 231 (1991).Type: China, Sichuan Province, 3600-3900 m elev., 1914, Heinrich Frh. von Handel-Mazzetti 497 (W-holotype!)

Description.

Thallus to 6 cm across, squamulose or lobate, growing on moss over rock or on the meadow; squamules 0.5-2 mm across, convex, continuous to slightly overlapped; marginal lobes branched, convex, 0.5-2 mm wide, 2-4 mm long; the apex of squamules and lobes rounded, bent downwards; upper surface smooth, pale green to straw, covered by white pruina; lower surface pale to dark brown in the centre and white to pale brown at the margin; rhizinose strands blackish-brown. Upper cortex very thin, ca. 16 μm, filled with yellowish-brown granules dissolving in KOH; algal layer continuous, 48-60 μm thick, medulla filled with grey to pale brown granules, 129-161 μm high, medullary hyphae very loose, more or less hollow in centre; lower cortex well separated from medulla, evenly thick with strongly gelatinised and anticlinally arranged hyphae, ca. 80 μm thick, colourless, hyphae at lower part brown. Apothecia lecanorine, sessile, with constricted base, rounded, scattered or in small groups, up to 3 mm in diam.; disc pruinose, reddish to dark brown, slightly concave when young, slightly convex with age; thalline margin concolorous with thallus, entire to flexuose, forming a well-delimited cortex consisting of strongly gelatinised and anticlinally arranged hyphae; hymenium colourless, 58-80 μm; epihymenium filled with yellowish-brown granules, 10-15 μm; paraphyses simple, evenly septate; ascus Lecanora -type, 8-spored; ascospores colourless, ellipsoid to slightly ovoid, 7-13 × 6.5-9 μm.

Chemistry.

Upper cortex K-, C-, P + yellow, medulla K+ yellow, C-, P-; usnic acid and zeorin present in each sample, placodiolic and isousnic acids also present in most samples.

Ecology and distribution.

Growing on moss over rock or in meadow at 3600-4968 m elevation in the alpine zone. Worldwide distribution: China, India and Nepal. China: Sichuan Prov., reported here as new to Yunnan and Xizang provinces.

Notes.

The holotype of Lecanora chondroderma consists of several fragments, containing numerous apothecia.

Lecanora chondroderma was originally described by Zahlbruckner (1930) and transferred to Squamarina by Wei (1991). We transfer this species back to Lecanora temporarily because of its Lecanora -type ascus and phylogenetic position being closely related to the genera Rhizoplaca and Protoparmeliopsis (Fig. 4 ). Although Lecanora chondroderma is highly supported as a basal clade of the genus Rhizoplaca in our topology, it differs in dwelling on moss and meadow and having numerous rhizinose strands. Given that there are still many taxa of Lecanora which have not been included in our analyses and the phylogenetic relationships between Rhizoplaca and its related genera have still not been thoroughly resolved, we prefer to retain this species in Lecanora temporarily, rather than treat it as Rhizoplaca . Lecanora chondroderma is only known from the Himalayan region at elevations between 3600-4968 m. The morphology of the species varies amongst localities, with samples growing on moss over rock in Yunnan and Sichuan provinces, having broad (1-2 mm) and pale green lobes and samples from meadows at higher altitudes in Xizang Prov. developing narrower (0.5-1 mm) and more branched lobes with a yellowish appearance. These populations, however, share a pruinose thallus, convex lobes with rounded and downwards bent apices, a loose medulla, a well-delimited cortex of the thalline margin and lower cortex and the presence of usnic acid and zeorin.

Lecanora geophila (Th. Fr.) Poelt is similar to L. chondroderma in morphology, chemistry and habitat, whereas the former forms a yellowish crustose, squamulose to placodioid thallus with loboid projections or phyllidia or terete lobes and epruinose, pale, flat to convex apothecia, including usnic acid, zeorin and methylplacodiolic acid ( Brodo 1981; Obermayer and Kantvilas 2003); the latter presents a totally pruinose, squamulose to lobate thallus that never forms phyllidia and terete lobes, pruinose, reddish-brown to black apothecia, numerous rhizinose strands and absence of methylplacodiolic acid.

Specimens examined (all in KUN-L unless otherwise noted).

China: Sichuan Province: 4650 m elev., 1915, Heinr. Frh. & Handel-Mazzetti 1353 (W). Yunnan Province: Shangri-La Co., Mt. Hong Shan, 4470 m elev., 28°07'N, 99°54'E, on soil, 2018, Li-Song Wang et al. 18-60317; Luquan Co., Mt. Jiaozi Snow, 4000 m elev., 26°05'N, 102°51'E, on moss over rock, 2016, Li-Song Wang et al. 16-54907; Lijiang Co., Mt. Laojunshan, 4036 m elev., 26°37'N, 99°44'E, on rock, 2017, Li-Song Wang et al. 17-55591. Xizang Province: Linzhou Co., Mt. Qiala, 4830 m elev., 30°06'N, 91°16'E, on the meadow, 2016, Li-Song Wang et al. 16-53527; Zuogong Co., on the way from Rumei to Zuogong, 4968 m elev., 29°43'N, 98°01'E, on the meadow, 2016, Li-Song Wang et al. 16-52925, 16-53079, on the meadow, 2016, Li-Song Wang et al. 16-52931.

Figures

Figure 4. Maximum Likelihood phylogeny of the genus Rhizoplaca and related genera of Lecanoraceae, based on combined nrITS, nrLSU, RPB 1, RPB 2 and mtSSU. ML bootstrap value ≥ 70 % and posterior probabilities ≥ 0.95 from the Bayesian analysis are given adjacent to nodes.

Figure 5. Lecanora chondroderma (A, B KUN-L 18 - 60317): A habit B apothecial anatomy (LCB) and ascospores (water). Squamarina kansuensis (C-G KUN-L 18 - 59601): C habit D apothecial anatomy (LCB) E ascus and ascospores (LCB) F apical structure of ascus (Lugol's) G section of thallus (LCB). S. oleosa (H, I KUN-L 09 - 30043): H habit I ascus and ascospores (water). Scale bars: 100 μm (B - apothecia, D); 5 μm (B - ascospores, F); 10 μm (E); 20 μm (G); 25 μm (I).