Phanerochaete hainanensis S.H. He & Y.C. Dai, sp. nov.
Index Fungorum number: IF 837508; MycoBank number: MB 837508; Facesoffungi number: FoF 09974; Fig. 1
Etymology – The specific epithet “hainanensis” refers to the Hainan Province, southern tropical China where the type was collected.
Holotype – BJFC 022063
Fruiting body – Basidiomata annual, resupinate, broadly effused, closely adnate, inseparable from substrate, coriaceous to soft corky, first as small patches, later confluent up to 20 µm long, 8 cm wide. Hymenophore smooth, pale orange (5A3), light orange [5A (4–5)] to greyish orange [5B (3–6)], darkening in KOH, uncracked; margin thinning out, distinct, lighter than hymenophore surface, white (5A1) to orange white [5A2], up to 0.2 cm wide. Context greyish orange, up to 500 µm thick.
Microscopic structures – Hyphal system monomitic; all hyphae without clamp connections. Subiculum thin; hyphae colorless, distinctly thick-walled with a wide lumen, smooth, rarely branched, moderately septate, interwoven, 4–9 µm in diam. Subhymenium thickening; hyphae colorless, thin-walled, smooth, vertically arranged, more or less agglutinated, 3–7 µm in diam. Cystidia subulate to subcylindrical, slight tapered toward the apex, sometimes with one or two secondary simple septa, colorless, slightly thick-walled or thin-walled at the tip part, smooth, projecting above the hymenium, with a basal simple septum, 35–70×3–7 µm. Basidia clavate, colorless, thin-walled, with a basal simple septum and four sterigmata, 16–25×4–5.5 µm; basidioles numerous, similar to basidia but smaller. Basidiospores ellipsoid, colorless, thin-walled, smooth, neither dextrinoid nor amyloid in Melzer’s agent, acyanophilous in cotton blue, (4.3–) 4.5–5 (–5.3)×2.2–2.8 (–3) µm, L=4.9 µm, W=2.5 µm, Q=1.96 (n=30/1).
Material examined – CHINA, Hainan Province, Lingshui County, Diaoluoshan Nature Reserve, on fallen angiosperm trunk, 17 March 2016, He 3562 (BJFC 022063, holotype). Guangxi Autonomous Region, Shangsi County, Shiwandashan Forest Park, on fallen angiosperm trunk, 26 July 2012, He20120726-1 (BJFC 014522), BJM (isotype).
GenBank numbers – ITS=MT235692, LSU=MT248179.
Notes – Phanerochaete hainanensis is characterized by the large basidiomata with pale orange hymenophore, thickened subhymenium with a compact texture, smooth leptocystida and small basidiospores (Fig. 1). The new species is similar to P. argillacea in that it shares the compact texture and similar size of leptocystidia and basidiospores but differs in having lighter hymenophore darkening in KOH (Wu 1998). Phanerochaete hainanensis is somewhat similar to P. metuloidea and P. sordida in that they share the thick and tough basidiomata, which, however, differs in having encrusted cystidia and a well-developed subiculum (Burdsall 1985; Xu et al. 2020). In the phylogenetic tree, P. hainanensis forms a distinct lineage and is not closely related to other species of Phanerochaete s.s. (Fig. 2).
Figure 1 – Phanerochaete hainanensis (BJFC 022063, holotype). a Basidiospores. b Basidia and basidiole. c Cystidia. d Hyphae from subiculum
Figure 2 – Phylogenetic tree obtained from maximum parsimony analysis of a concatenated ITS and nrLSU sequence data of Phanerochaete s.s. Branches are labelled with parsimony bootstrap values equal to or greater than 50% (front), likelihood bootstrap values equal to or greater than 50% (middle) and Bayesian posterior probabilities equal to or greater than 0.95 (back). The new species is in bold