Pholiota subcaespitosa E.J. Tian sp. nov.
Index Fungorum number: IF 559945; Mycobank number: MB 559945; Facesoffungi number: FoF 12907; Figs. 1, 2
Etymology – Based on the similarity to Pholiota caespitosa.
Holotype – HMJAU37330.
Diagnosis – Differs from other Pholiota species by the pileus with umbonate or depressed disc, slim stipe, brownish to brown fibrillose scales on the surface of pileus and stipe, small basidiospores, pleurocystidia as chrysocystidia, cheilocystidia mainly with two shapes: fusoid-ventricose and cylindric with subcapitate, the former small and rare with short cells chained at base, the latter often flexuous and at times with branches. Pileus 18–35 mm broad, convex, becoming plane, with obtuse umbo or slightly depressed on the disc in age, with a waved margin at maturity, yellowish white (4A2), fading to near whitish toward margin, light brown (5D4) on the disc, slightly viscid when wet, decorated with brownish fibrillose scales appressed and often not apparent in age. Lamellae adnate to sinuate-uncinate or with a decurrent tooth, light brown to brown, narrow, close, edges even. Stipe 40–70 mm long, 2–5 mm thick, equal, solid becoming stuffed to hollow, dingy pallid, becoming light brownish below, naked above, elsewhere with dingy brown fibrils or scales. Veil fibrillose, leaving an evanescent ring zone.
Spore deposit brown. Basidiospores 5–7 × 3.2–4 μm (Q =1.5–2), in face view elliptic, oblong to subovate, in side view slightly inequilateral, wall smooth and thick, germ pore distinct, sometimes making the spore apex somewhat truncate, rust brown (6E8) to light brown (6D8) in KOH, slightly paler in Melzer’s reagent. Basidia 20–24 × 5.5–6.5 μm, 4-spored, clavate, hyaline in KOH. Pleurocystidia as chrysocystidia, 30–42 ×8–9.5 μm, subfusoid, fusoid-ventricose to clavate-mucronate, with thin and smooth wall, hyaline to yellow brown in KOH, content showing a refractive amorphous inclusion as revived in KOH. Cheilocystidia 20–67 × 5–8 μm, cylindric with subcapitate apex, often flexuous, at times with branches, or fusoid-ventricose, some ventricose with 2–3 short cells chained at base, wall thin, rare slightly thick, hyaline in KOH, rarely yellowish, content homogeneous. Gill trama parallel, hyphae 3–24 μm diam, thin-walled, hyaline to yellowish brown in KOH. Pileus hyphae 2–8.6 μm in diam, yellowish to yellowish brown in KOH, wall thin, with spiral incrustations. Context hyphae 3–10 μm in diam, thin-walled, hyaline in KOH. Clamps regularly present.
Habitat – Caespitose on hardwood stumps in autumn.
Materials examined – China, Jilin Province, Changchun, Saman huanle Valley, Jingyuetan National Forest Park, 10 September 2016, Guangcheng Cao, HMJAU37330 (holotype); ibid., 1 September 2012, Enjing Tian, HMJAU37368.
GenBank numbers – HMJAU37330: ITS = OP244888, LSU = OP223415; HMJAU37368: ITS = OP244889, LSU=OP223416.
Notes – Pholiota subcaespitosa is similar to P. caespitosa in shape, germ pore and size of basidiospores, the pleurocystidia, and caespitose growth (Smith and Hesler 1968). However, the latter lack cylindric cheilocystidia. In the phylogram (Fig. 3), P. subcaespitosa clustered together with P. caespitosa and P. gummosa. Pholiota gummosa has the similar cylindric cheilocystidia with P. subcaespitosa, but the former can be easily distinguished by its absence of pleurocystidia (Smith and Hesler 1968).
Figure 1 – Basidiomes of Pholiota subcaespitosa (HMJAU37330, holotype). Photo by G. Cao
Figure 2 –Pholiota subcaespitosa. A Cheilocystidia. B Basidia. C Basidiospores. D Pleurocystidia. Scale bars: A–D=10 μm. Drawings by E. Tian
Figure 3 – BI phylogram of Pholiota based on data set (ITS+28S). PPs>0.95 and bootstrap values>70% are shown. The new species in this study are in bold and blue. The tree is rooted with the two species of Stropharia