Herpothallon glaucescens L.L. Liu & Lu L. Zhang, 2023

Liu, Linlin, Zuo, Qijia, Xue, Junxia, Ren, Zhaojie & Zhang, Lulu, 2023, Three new species of Herpothallon (Lichenized Ascomycota) from Southern China, Phytotaxa 597 (4), pp. 287-296 : 289-291

Herpothallon glaucescens L.L. Liu & Lu L. Zhang , sp. nov. Mycobank number: 843998 ( Fig. 2 )

Type:— CHINA. Zhejiang Province: Lishui City, Jingning County, Baiyun Protection Station . 1131.3 m elev., 27°72′57.76″ N, 119°64′12.09″ E, on bark of Cunninghamia R. Br. , 2 December 2020, C.G. Zhao & Lu L. Zhang 20211617 (Holotype in SDNU).

Thallus corticolous, up to 3 cm across, suborbicular, sometimes flaking off, loosely to firmly appressed to the substrate, felty to byssoid, dull, white in the center, whitish grey to greyish green along the margin, in section up to 200 µm thick, with abundant calcium oxalate crystals throughout the thallus (insoluble in KOH, dissolving and recrystallizing as colourless, needle-shaped crystals in 10% H 2 SO 4), with 1–2 µm wide hyphae. Hypothallus whitish, byssoid, composed of 1–2 µm wide hyphae.Prothallus up to 2 mm broad, whitish, indistinct, byssoid, composed of interwoven and radiating hyphae. Pseudisidia numerous, sparse to dense, dispersed or 2–3 in coralloid aggregations, often branched, swollen, subglobose to ±vermiform, rounded at the top, of the same colour as the thallus, compact with few projecting hyphae, 0.15–0.18 mm in diam., or 0.22–0.3 × 0.11–0.18 mm. Photobiont trentepohlioid, single or a few cells aggregated; cells yellowish, 10–12.5 × 7–8 μm. Asci and pycnidia not seen.

Chemistry and spot tests: Thallus and prothallus K−, C−, P+ bright yellow, UV−, I+ blue in medulla. TLC: psoromic acid (major), 2’-O-demethylpsoromic acid (minor).

Etymology: The epithet “ glaucescens ” refers to the whitish grey colour of the thallus and the pseudisidia.

Ecology and distribution: The new species was found growing on bark of Cunninghamia R. Br. at the Baiyun Protection Station in the Zhejiang Province and the bark of other trees in the Daming Mountain National Nature Reserve of the Guangxi Zhuang Autonomous Region.

Note: This species is characterized by a thallus with swollen, compact, subglobose to ±vermiform, often branched pseudisidia, with few projecting hyphae, and the presence of psoromic and 2’-O-demethylpsoromic acids. Although H. globosum G. Thor (2009: 42) also has globose pseudisidia and contains psoromic acid, it lacks calcium oxalate crystals, has a red hypothallus and prothallus, the upper parts of its pseudisidia are dark red and often with black spots ( Aptroot et al. 2009). Herpothallon biacidum Frisch, Elix & G. Thor (2010: 286) possesses a loosely attached thallus with abundant calcium oxalate crystals, globular to short cylindrical pseudisidia, up to 0.30 × 0.12 mm, in small coralloid aggregations, but it has a brown to blackish brown hypothallus and produces gyrophoric and norstictic acids (Frisch et al. 2010). Herpothallon coralloides Jagadeesh (2014: 40) is also similar to H. glaucescens because of its firmly to loosely appressed thallus and white prothallus, cylindrical pseudisidia that are simple to irregularly branched and coralloid, but the pseudisidia of H. coralloides are much larger, up to 1.0 × 0.1 mm. The two species also differ in chemistry, H. coralloides containing confluentic and norstictic acids ( Jagadeesh Ram 2014).

Phylogenetically, H. glaucescens is the sister taxon to H. echinatum ( Fig. 1 ), they are similar in containing psoromic acid as a major secondary metabolite, but H. echinatum has a much softer thallus, often seemingly farinose due to loose soredioid fragments, and its pseudisidia are cylindrical, more elongated, up to 0.5 × 0.1 mm, and are mostly unbranched, felty with projecting hyphae.

Additional specimen examined: CHINA. Guangxi Province: Nanning City, Wuming County, Daming Mountain National Nature Reserve, 592.0 m elev., 23°30′12.336″ N, 108°26′08.231′′ E, on bark of a tree, 30 December 2020, X. Zhang et al. 20211618 ( SDNU) .

Figures

FIGURE 1. Phylogenetic tree constructed from Maximum Likelihood analysis of Herpothallon species, based on the mtSSU dataset. Maximum likelihood (ML) bootstrap value ≥ 70, and Bayesian posterior probabilities (PP) value ≥ 0.95 are shown above the branches. Bootstrap values are shown in the order of ML, PP in the tree. Newly described species are marked in bold. Scale = 0.02 substitution per site.

FIGURE 2. Herpothallon glaucescens (holotype, SDNU 20211617). A. Thallus and prothallus. Scale = 2 mm. B. Pseudisidia. Scale = 600 µm.