Herpothallon tomentosum L.L. Liu & Lu L. Zhang, sp. nov. Mycobank number: 845791 (Fig. 5)

Type:— CHINA. Fujian Province: Longyan City, Dongxiao National Forest Park, Barbecue field. 450 m elev., 24°58’25.33” N, 117°0’56.67” E, on bark of a tree, 12 July 2022, L.L. Liu, J.X. Xue & L. Wang 20220468 (Holotype in SDNU).

Thallus corticolous, up to 2 cm across, suborbicular to sometimes irregular, not flaking off, loosely to firmly appressed to the substrate, soft, minutely felty, dull, blue green to greenish grey, in section up to 120 µm thick, with few 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 0.9 mm broad, whitish, distinct, byssoid, composed of interwoven and radiating hyphae. Pseudisidia numerous, unbranched, globular, of the same colour as the thallus, soft, felty with many projecting hyphae, 0.06–0.12 mm in diam.. Photobiont trentepohlioid, single or a few cells aggregated; cells yellowish green, 12.5–15 × 5–10 μm. Asci not seen. Pycnidia embedded in the tips of some pseudisidia, opening with a apical pore, pigmentation occasionally extending along the pycnidial wall. Conidia simple, hyaline, short bacilliform, 3–4 × 1–1.5 μm.

Chemistry and spot tests: Thallus and prothallus K−, C−, P−, UV−, I− in medulla. TLC: confluentic acid (major), 2’-O-methylmicrophyllinic acid (minor).

Etymology: The epithet “ tomentosum ” refers to the pseudisidia felty with many projecting hyphae.

Ecology and distribution: The new species was found growing on bark of trees beside a stream of Dongxiao National Forest Park and on bark of trees beside a mountain path of Tianzhu Mountain Forest Park of Fujian Province.

Notes: This species is characterized by the globular pseudisidia each containing a pycnidium, 0.06–0.16 mm in diam., and the presence of confluentic and 2’-O-methylmicrophyllinic acids. Herpothallon tomentosum is most similar to H. cinereum G. Thor (2009: 34) in its minutely felty thallus, the white, byssoid-felty prothallus and the presence of confluentic and 2’-O-methylmicrophyllinic acid in its thallus. However, H. cinereum has a loosely appressed thallus, up to 200 μm thick, and cylindrical pseudisidia up to 0.5 × 0.1 mm, without pycnidia at their tips. Herpothallon tomentosum has the same chemistry as H. confluenticum Aptroot & Lücking (2009: 36); both have pycnidia at the tips of their pseudisidia, but the latter has a rather firm thallus delimited by a dirty whitish prothallus, on a whitish to brownish hypothallus, and cylindrical pseudisidia that are partly cauliflower-like at the tips, up to 0.6 × 0.2 mm (Aptroot et al. 2009). The specimens of H. echinatum that Bungartz et al. collected from Ecuador (2013: 752) also have a non-pigmented thallus, prothallus and hypothallus, globular pseudisidia with pycnidia at the tips, and bacilliform conidia (3–4 × 1–1.5 μm), but they contain psoromic acid (Bungartz et al. 2013). Two other morphologically similar species are H. biacidum and H. subglobosum Pengfei Chen & Lulu Zhang (2022: 07): both have a minutely felty thallus and globular pseudisidia, but differ in chemistry: H. biacidum contains gyrophoric and norstictic acids (Frisch et al. 2010), whereas H. subglobosum contains gyrophoric, lecanoric and umbilicaric acids (Chen et al. 2022).

Phylogenetically, H. tomentosum belongs into a different monophyletic clade from the other species in clade B (Fig. 1), demonstrating that it is a distinct species. As part of our survey, we collected multiple specimens of the new species in two areas. These specimens are similar in morphological and anatomical characters except that some of the specimens lack pycnidia. In our phylogenetic analysis this material appears on the same branch, with a relatively close evolutionary distance, strongly supported (BS=100, PP=1.00).

Additional specimen examined: CHINA. Fujian Province: Longyan City, Dongxiao National Forest Park, Barbecue field. 450 m elev., 24°58’25.33” N, 117°0’56.67” E, on bark of a tree, 12 July 2022, L.L. Liu, J.X. Xue & L. Wang 20220477 (SDNU); Fujian Province: Longyan City, Dongxiao National Forest Park, Bajiao forest to Suoluo group. 558 m elev., 24°58’21.42” N, 117°1’1.71” E, on bark of a tree, 12 July 2022, L.L. Liu, J.X. Xue & L. Wang 20220565, 20220582, 20220587 (SDNU); Fujian Province: Xiamen City, Tianzhu Mountain Forest Park, No. 3 branch road near the air monitoring station. 183 m elev., 24°35’46.33” N, 117°54’31.06” E, on bark of a tree, 11 July 2022, L.L. Liu, J.X. Xue & L. Wang, 20220442, 20220443, 20220462, 20220463 (SDNU).