Lyophyllum lixivium S. M. Tang & S. H. Li, sp. nov.
Creators: name: Lyu, Tong
name: Tang, Song-Ming
name: He, Jun
name: Wang, Shuai
name: Wu, Xiao-Qu
name: Chen, De-Chao
name: Ao, Cheng-Ce
name: Li, Shu-Hong
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Agaricales
Lyophyllaceae
Lyophyllum
Lyophyllum lixivium

description: Lyophyllum lixivium S. M. Tang & S. H. Li sp. nov. Figs. 2 & 3
MycoBank: MB849904
Etymology: ‘ lixivium ’ refers to the light brown colouration of the pileus.
Holotype: China, Yunanan, Dali City, Cangshan Mountain, 25°41’54” N, 100°2’27.42” E, elev. 2371 m, 11 August 2020, Zhang Zhengquan (HKAS129929, holotype!).
Diagnosis: Lyophyllum lixivium is characterized by having an umbonate pileus and abundant white floccus on the stipe base, stipe, and lamellae becoming dark brown when bruised, broadly globose basidiospores (4.4–6.5 × 3.7–5.8 µm), and presence a fusiform caulocystidia (Figure 2).
Description: Pileus 21–73 mm diam, hemispherical to campanulate when young, becoming umbonate when mature, light brown (5D4–5D6), pileus margin inflexed. Context, 1.6–3.4 mm wide, white, becoming light brown when injured. Lamellae adnate to slightly decurrent, white to creamy, 3.6–5.2 mm wide, with 1–4 unequal lamellulae between two entire, usually discoloring to dark at the edge when touched or injured. Stipe 91–115 × 10–14 mm, greyish yellow (4C4–4C5), cylindrical slightly enlarged towards the base, centrally solid, abundant floccus on the base. Odor and taste not distinctive.
Basidiospores [80/2/2] (3.5–) 4.4–6.5 (–6.7) × (2.9–) 3.7–5.8 (–6.1) µm, av. 5.7 × 4.9 µm, Q = 1.0–1.4, Q m = 1.1 ± 0.09, mostly broadly lacrymoid or amygdaliform with acute apex in side view, ovoid in frontal view, occasionally fusiform, hyaline, thin-walled, always with oil drops. Spore deposit white (1A1). Basidia 26–38 × 7–10 µm, av. 32.1 × 9.4 µm, hyaline, clavate; sterigmata 2.4–4.6 × 1.3–2.5 µm, mostly 4–spored, rarely 2–spored. Hymenophoral trama is regular, hyaline hyphae, thin-walled, 4–15 µm wide. Cheilocystidia 14–36 × 2–6 µm, av. 20.6 × 4.8 µm, clavate. Pleurocystidia 16–33 × 3–5 µm, av. 21.3 × 4.2 µm, clavate. Pileipellis composed of 3.8–9.0 µm wide hyphae, cylindrical hyphae parallel or slightly crossed, smooth. Stipitipellis arranged regular, hyphae parallel, smooth, composed of 7–14 µm wide hyphae. Caulocystidia present on the stipe, 20–40 × 6–8 µm, av. 30.3 × 6.7 µm, fusiform, irregular, with subacute apex, thin-walled. Clamp connections present on the lamellae, pileipellis and stipitipellis.
Habit and habitat: Growing in moss-covered soil under Castanea mollissima.
Distribution: Found only in the type locality in Yunnan province, China.
Additional material examined: China, Yunnan Province, Dali Cangshan Mountain, 11 August 2020, elev. 2371m, S.H. Li 2020081139 (HKAS129930).
Notes: In multi-locus phylogenetic analyses, L. lixivium is related to L. moncalvonum and L. atrofuscum. However, L. moncalvonum originally described from New Zealand, has olivaceous black pileus and globose basidiospores (5.0 ± 0.5 μm; Cooper et al. 2014). Lyophyllum atrofuscum has ellipsoid, subrhomboid, and irregular rhomboid basidiospores (5.5–7 × 3.9–5.0 µm), basidia mostly 2-spored, rarely 4-spored, absent cheilocystidia and caulocystidia on the stipe surface (Wei et al. 2023).
Lyophyllum lixivium is similar to L. bonii, L. fuscobrunneum, L. rhombisporum, and L. solidipes in context, and the stipe becomes black when bruised. The original description of Lyophyllum bonii from the Canary Islands has a paler pileus with no umbo (Consiglio & Contu 2002). According to its original description of Lyophyllum fuscobrunneum, which was described from the Canary Islands, has broadly ellipsoid to ellipsoid basidiospores (5.2–6.7 × 3.7–4.5 µm), relatively large basidia (30–50 × 7–9 µm), and repent to loosely interwoven pileipellis (Dähncke et al. 2011). Lyophyllum rhombisporum has a relatively large basidia (36.5–46.0 × 10.0–11.3 μm) and basidiospores (14.5–17.0 × 10.0–11.5 μm; Wang et al. 2013). Lyophyllum solidipes collected from Hood National Forest of the United States has narrower hyphae of stipitipellis (3–5 μm) and relatively large basidiospores (6.5–8.1 × 3.7–4.7 μm; Clémençon & Smith 1983).
description: Published as part of Lyu, Tong, Tang, Song-Ming, He, Jun, Wang, Shuai, Wu, Xiao-Qu, Chen, De-Chao, Ao, Cheng-Ce & Li, Shu-Hong, 2024, Lyophyllum lixivium (Lyophyllaceae, Agaricales), a new species from Yunnan, China, pp. 50-60 in Phytotaxa 642 (1) on pages 55-57, DOI: 10.11646/phytotaxa.642.1.4, http://zenodo.org/record/13214159