Lyomyces austro-occidentalis Xue W. Wang & L.W. Zhou, sp. nov.
Index Fungorum number: IF 900292; Mycobank number: MB 900292; Facesoffungi number: FoF 14055; Figs. 1, 2
Etymology – austro-occidentalis (Lat.) referring to the distribution of this species in Southwest China.
Holotype – LWZ 20190816-40a (HMAS).
Diagnosi: – Characterized by annual, resupinate, adnate basidiomes, smooth, white to cream hymenophore, a monomitic hyphae system with encrusted subhymenial hyphae, capitulate cystidia, clavate basidia, and ellipsoid basidiospores.
Basidiomes annual, resupinate, adnate, cracked and brittle when dry, without odour. Hymenophore smooth, white to cream colored. Margin concolorous with or slightly paler than subiculum, abrupt.
Hyphal system monomitic; generative hyphae with clamp connections, hyaline, dichotomous branching, interwoven, thin-walled, 2–3.5 μm in diam, subhymenial hyphae usually with encrustation. Cystidia capitate, ca. 20 × 3 μm. Basidia clavate, 15–20×5–5.5 μm, with four sterigmata ca. 3–4 μm long and a clamp connection at the base; basidioles similar in shape to basidia, but smaller. Basidiospores ellipsoid, with a large oily drop, hyaline, smooth, thin-walled, IKI–, slightly CB+, 4.2–5.2 × 3.1–3.5 μm, L=4.63 μm, W=3.27 μm, Q=1.39–1.44 (60/2).
Material examined – China, Sichuan Province, Leshan, Ebian Yi Autonomous County, Heizhugou National Forest Park, on fallen branch of angiosperm, 16 August 2019, L.W. Zhou, LWZ 20190816-40a (HMAS, holotype), LWZ 20190816-8a (HMAS).
GenBank numbers – LWZ 20190816-8a: LSU=OQ540856; LWZ 20190816-40a: LSU=OQ540857.
Notes – Phylogenetically, Lyomyces austro-occidentalis and L. ochraceoalbus (CLZhao 9819) are nested within a single clade (Fig. 3). Morphologically, L. austro-occidentalis is highly similar to the original description of L. ochraceoalbus in Luo et al. (2021). Therefore, these two names indeed represent the same species. Unfortunately, Luo et al. (2021) did not effectively published the name L. ochraceoalbus according to Art. 40.7 of the International Code of Nomenclature for algae, fungi, and plants (Turland et al. 2018). Here, we redescribed this species as L. austro-occidentalis.
Lyomyces crustosus and L. austro-occidentalis have a close phylogenetic relationship (Fig. 132), and share white to cream colored hymenophoral surface; however, L. crustosus differs in grandinioid to odontioid hymenophore, narrowly ellipsoid to cylindrical, sometimes slightly allantoid, longer basidiospores (5–7 μm in length, Langer 1994). Lyomyces juniperi resembles L. austro-occidentalis by smooth, white to cream hymenophore and ellipsoid basidiospores, but L. juniperi is differentiated by its subulate cystidia and suburniform basidia (Langer 1994).
Figure 1 – Basidiomes of Lyomyces austro-occidentalis (LWZ 20190816-40a, holotype)
Figure 2 – Microscopic structures of Lyomyces austro-occidentalis (LWZ 20190816-40a, holotype). a Basidiospores. b Cystidia. c Basidia and basidioles. d A vertical section of hymenium. Scale bars: 10 μm
Figure 3 – Phylogram generated by the maximum likelihood algorithm based on combined nLSU and ITS sequence data is presented along with the bootstrap values and the Bayesian posterior probabilities above 50% and 0.8, respectively, at the nodes. Type specimens are in bold and the isolates of new species characterized are in blue