Clitopilus rugosiceps S.P. Jian & Zhu L. Yang
Basidiomata usually clitocyboid, medium- sized to large. Pileus 30–60 mm wide, planoconvex to concave; yellowish gray (2B3) or yellow (4B4–5), occasionally gray (3B2–1); surface usually smooth but sometimes slightly squamulose, slightly viscid when wet; margin slightly incurved to even, usually rugose or undulate; context 3–5 mm thick, whitish (3A1) or chalk white (4A1). Lamellae decurrent, yellowish white (2A2) to slightly yellowish pink (4A2–3), somewhat crowded to crowded, edges entire and concolorous, lamellulae numerous. Stipe 20–25 × 2–8 mm, central to eccentric, usually slim, yellowish white (3A1–2) to grayish white (1B2); surface fibrillose, striate, sometimes pruinose or nonpruinose; the base often slightly inflated with white (1A1) mycelium. Odor unrecorded. Basidiospores 7.5–11(–13) × 5–7 μm, Lm×Wm = 8.73 (± 0.86) × 6.03 (± 0.47) μm, Q = (1.14–)1.17–1.93(–2.10) (Qavg = 1.46 ± 0.17) [68/3/3], hyaline, amygdaliform, limoniform, subfusiform, or sometimes subovoid in profile and face view, angled in polar view with 5–7 obvious longitudinal ridges. Basidia 20–36 × 7–12 μm, clavate, hyaline, 4-spored, rarely 2-spored; sterigmata 2–4 μm long. Lamellar trama more or less regular, composed of 4–8 μm wide, hyaline hyphae; oleiferous hyphae rare; subhymenium consisting of filamentous hyphal segments. Lamella edges fertile. Pleurocystidia and cheilocystidia absent. Pileipellis a cutis composed of more or less radially and compactly arranged, repent, incrusted or smooth, cylindrical hyphae, 3–7 μm wide, with yellowish to yellow intracellular or parietal pigment; subcutis made up of compactly arranged, hyaline, smooth, cylindrical hyphae, 3–7 μm wide; pileal trama composed of subregular, hyaline, filamentous or cylindrical hyphae, 4–10 μm wide. Stipitipellis a cutis composed of compactly arranged, thin-walled, hyaline hyphae, 3–5 μm wide. Caulocystidia absent. Clamp connections absent.
Ecology and distribution: Scattered on soil in coniferous (viz., Pinus yunnanensis) forest, southwest China, Jun to Aug.
Specimens examined: CHINA. YUNNAN PROVINCE: Lushui County, Laowo Village, Ronghua Hamlet, alt. 2100 m, scattered on soil under Pinus yunnanensis, 7 Aug 2011, J. Qin 246 (holotype KUN-HKAS73232). CHINA. YUNNAN PROVINCE: Tengchong County, Guang Pojiao Village, alt. 1900 m, 20 Jun 2009, Y.C. Li 1708 (KUNHKAS59455); Yongping County, alt. 2087 m, 31 Jul 2009, L.P. Tang 1046 (KUN-HKAS57003).
Fig 1. Phylogenetic relationships among representative specimens of Clitopilus, Clitocella, and Clitopilopsis inferred from a multigene (28S, rpb2, tef1, and atp6) data set using both ML and BI methods (only the ML tree is shown). Bootstrap frequencies (>50%) and posterior probabilities (PP > 0.90) are shown on the supported branches. Sequences from type collections are marked, and altitude information of most specimens from KUN-HKAS is shown in the phylogram. New taxa are highlighted in red.