Hemileccinum duriusculum Mei-Xiang Li, Zhu L. Yang & G. Wu, sp. nov.
Index Fungorum number: IF 901102; Mycobank number: MB 901102; Facesoffungi number: FoF 14841; Figs. 1, 2, 3
Etymology – The epithet ‘duriusculum’ refers to the wrinkled pileus.
Holotype – HKAS 125907.
Basidiomes stipitate-pileate, medium-sized to large. Pileus up to 9 cm in diam, convex to plano-convex, surface glabrous, but some areas often covered with inconspicuous subtomentose or pulverulent squamules, often strong rugose, light brown to brown (5D5, 6D5–6E5), sometimes much paler with light red tinge, margin and surface ridges lighter in color, dry; context yellowish white to pale yellow (1A2–1A3), unchanging when bruised, ca. 10–15 mm thick. Hymenophoral tubes concolorous with pores, pale yellow (3A3) to grayish yellow (4B4), unchanging when bruised; pores polygonal to roundish, 1.5–2 per mm, tubes ca. 13 mm long, unchanging when bruised. Stipe 10–13 × 1.2–2.1 cm, subcylindrical, clavate, slightly bulbous at the base, upper part light yellow (4A5), lower part reddish to grayish reddish (5C4–8C5); surface covered with finely granular yellowish to brownish yellowish scales; context of stipe cream to pale yellow, unchanging when bruised; basal mycelium cream.
Basidia 24–35×8–12 µm, clavate, thin-walled, 4-spored; sterigmata 4–6 µm long, colorless in KOH. Basidiospores [40/2/2] 12–15×4–6 µm [Q =(2.5–) 2.6–2.8 (–3), Qm = 2.74 ± 0.17], subfusiform in side view with slight suprahilar depression, subfusoid in ventral view, yellowish to brownish in KOH, smooth under light microscopy, but ornamented with irregularly warts under SEM. Hymenophoral trama nearly phylloporoid type with hyphae of the lateral strata touching or almost touching each other with hyphae diverging from the central strand to the subhymenium; hyphae subcylindrical to cylindrical, 5–13 µm wide. Cheilocystidia 25–49×10–14 µm, lanceolate to clavate or ventricose, thin-walled, colorless in KOH. Pleurocystidia 33–43×8–10 µm, ventricose-subfusiform, with long beak, thin-walled. Pileipellis a subepithelium 110–130 µm thick, composed of moniliform hyphal segments 5–30 µm wide, thin-walled, colorless in KOH, with narrowly cylindrical to shortly cystidioid terminal cells 6–23×4–20 µm. Pileal trama composed of interwoven hyphae 4–24 µm wide. Stipitipellis ca. 130 µm thick, hymeniform, with narrowly or broadly clavate terminal cells 11–25×7–12 µm. Caulobasidia abundant, 16–32×9–12 µm, thin-walled. Stipe trama composed of parallel hyphae 4–10 µm wide. Clamp connections absent in all tissues.
Habitat and distribution – Scattered on soil in subtropical forests dominated by Fagaceae (Quercus spp., Castanopsis spp. and Lithocarpus spp.). Currently known from eastern, central and northeastern China.
Material examined – China, Zhejiang Province, Huzhou, Anji County, 1400 m elev., 21 September 2021, Yan-Jia Hao 2527 (HKAS 125907, holotype; EFHAAU2843, isotype). Henan Province, Nanyang, Neixiang County, 600 m elev., 31 July 2010, Xiao-Fei Shi 416 (HKAS76664). Liaoning Province, Anshan, 1980 m elev., 14 August 2015, Jing Li 251 (HKAS91279).
GenBank numbers – HKAS 125907: LSU = OQ600185, TEF1-α = OQ718485, RPB1 = OQ750573; HKAS76664: LSU = OQ600186, TEF1-α = OQ718484, RPB1 = OQ750572, RPB2 = OQ718482; HKAS91279: LSU = OQ600187, TEF1-α = OQ718483, RPB1=OQ750573, RPB2=OQ718481.
Notes – Hemileccinum duriusculum is characterized by the yellowish brown to brown wrinkled pileus, context and hymenophore unchanging in color when cut, scaly stipe surface and a subepitheliod pileipellis. Phylogenetically, Hemileccinum rugosum is closely related to H. duriusculum (Fig. 4). However, H. rugosum differs from H. duriusculum in its narrower basidiospores (10–12×4–5 µm) and the lighter color (light orange to reddish orange) of the pileus (Wu et al. 2016a). Morphologically, Hemileccinum hortonii originally described from Illinois, USA is somewhat similar to H. duriusculum, but differs from the latter by its narrower basidiospores (12–15×3.5–4.5 µm, Smith and Thiers 1971).
Figure 1 – Basidiomes of Hemileccinum duriusculum. a–c EFHAAU2843 (holotype). d HKAS76664. e, f HKAS91279. Scale bars: 2 cm
Figure 2 – Microscopic features of Hemileccinum duriusculum (EFHAAU2843, holotype). a Basidiospores. b Hymenium and subhymenium. c Cheilocystidia. d Pleurocystidia. e Pileipellis. f Stipitipellis. Scale bars: 10 µm
Figure 3 – The basidiospores under SEM of Hemileccinum duriusculum (EFHAAU2843, holotype)
Figure 4 – The phylogenetic analysis of Hemileccinum based on nrLSU, TEF1, RPB1 and RPB2 sequences using maximum likelihood method. The new species was labelled in red. Bootstrap values (≥50) were shown on the branches