Lyomyces parvus Yurchenko & Langer 2024, sp. nov.
Creators: name: Yurchenko, Eugene
name: Langer, Ewald
name: Riebesehl, Janett
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Corticiales
Hymenochaetales
Lyomyces
Lyomyces parvus

description: Lyomyces parvus Yurchenko & Langer sp. nov.
Figs 8 E, F, 13, 16 G
Type.
Costa Rica • Cartago Province: Orosí, Río Macho, secondary evergreen tropical forest near the Orosí River, 1140 m a. s. l., on dead naked wood, 10 Feb 1989, E. Langer, G. Wagner 97 (holotype: KAS-GEL 1599; isotype: CFMR). GenBank: ITS = PP 471810.
Etymology.
parvus (Lat.) = minute, scanty, due to very thin and small-sized basidiomata.
Description.
Basidiomata effused, 0.1–2 and more cm in extent, 40–70 μm thick, mostly discontinuous, pruinose or farinaceous, in older areas submembranaceous, whitish, subinvisible when dry. Hymenial surface white, without projections. Margin diffuse, indeterminate, up to 0.5 mm wide. Hyphal system monomitic, hyphae clamped at all septa, thin-walled, colourless. Subicular hyphae loosely arranged, 1.5–2.8 μm wide. Subhymenium little differentiated from subiculum; subhymenial hyphae 1.8–3 μm wide. Scattered rosette-like, 2–5 μm in diam., loosely attached crystals present in subiculum, subhymenium, and hymenium. Cystidia smooth or encrusted by crystals, of several types: 1) fusoid to subulate and almost capitulate common, often with slight constrictions, sometimes branched above, 13–31.5 × 2.5–4.5 μm; 2) cylindrical rare, 15–23 × (2.2 –) 2.7–3.3 μm. Basidioles ovoid to short fusoid and subcylindrical, 7.5–17 × 3–5.5 μm. Basidia long-utriform, 23–27 × 3.8–4.5 μm; sterigmata four, 2.5–3 × 1.5 μm. Basidiospores ellipsoid to oblong, (3.7 –) 4–5 (– 5.3) × (2.3 –) 2.5–3.5 μm (in holotype L = 4.6 μm, W = 2.7 μm), Q = (1.4 –) 1.6–1.7 (– 1.8), smooth, thin-walled, colourless, some with a drop inside, Mz –, acyanophilous; apiculus small, short.
Distribution.
The species is so far known from Costa Rica and Ecuador.
Ecology.
The species grows on dead wood in evergreen angiosperm and mixed tropical forests at altitudes of about 1000–2700 m a. s. l.
Additional specimen examined
(paratype). Ecuador • Pichincha Province: Quito City, left slope of the Machángara River canyon, Guápulo Park, 00 ° 11.77 ' S, 078 ° 28.37 ' W, 2660 m a. s. l., small semi-natural forest with Pinus, on a fallen, mostly decorticated branch of Pinus sp., 18 Jul 2019, E. Yurchenko EYu 190718-23 (BLS M-2990). GenBank: ITS = PP 471809; 28 S = PP 471826.
Notes.
The main diagnostic features of this species are very thin, loose basidiomata, hardly visible to the naked eye in a dry state, narrow thin-walled hyphae, presence of subulate and subcapitate cystidia, and ellipsoid, thin-walled basidiospores. The holotype of this species has oblong basidiospores (2.3 –) 2.5–3 μm wide, whereas spores in the paratype are ellipsoid, (2.5 –) 2.8–3.5 μm wide. Other morphological features of both specimens are identical. This species is close to L. crustosus and L. juniperi in the micromorphology of hyphae, hymenial elements, and spores, but has pruinose, discontinuous basidiomata.
description: Published as part of Yurchenko, Eugene, Langer, Ewald & Riebesehl, Janett, 2024, A high species diversity of Lyomyces (Basidiomycota, Hymenochaetales) in Central and South America, revealed after morphological and molecular analysis, pp. 131-169 in MycoKeys 109 on pages 131-169, DOI: 10.3897/mycokeys.109.127606