Meruliopsis crystallina Xue W. Wang & L.W. Zhou, sp. nov.
Index Fungorum number: IF900298; Mycobank number: MB 900298; Facesoffungi number: FoF 14061; Figs. 1, 2
Etymology – crystallina (Lat.) referring to the rhombic crystals in subicular hyphae.
Holotype – LWZ 20190726–28 (HMAS).
Diagnosis – Characterized by white to cream basidiomes, a monomitic hyphal system with strongly rhombic crystallized subicular hyphae, presence of leptocystidia, cylindrical to clavate basidia with numerous oily drops, and ellipsoid basidiospores.
Basidiomes annual, resupinate, effuse, adnate, membranaceous. Pore surface white to cream when dry; pores 4–5 per mm, round; tubes up to 65 μm deep, concolorous with pore surface; dissepiments up to 80 μm thick, entire, with continuous hymenium; margin slightly paler than pore surface, thinning out.
Hyphal system monomitic; generative hyphae simple septate. Subicular hyphae hyaline, thick-walled, strongly dichotomous branched, interwoven, strongly encrusted with rhombic crystals, 3.5–6.5 μm in diam. Tramal hyphae hyaline, slightly thick- to thick-walled, strongly dichotomous branched, interwoven, 3.5–5.5 μm in diam. Leptocystidia cylindrical, hyaline, projecting from hymenium, 25–30 × 4.5–5.5 μm. Basidia cylindrical to clavate, 4-sterigmata, with numerous oily drops, without clamp connection, 15–20 × 4–5 μm; basidioles in shape similar to basidia but slightly smaller. Basidiospores ellipsoid, hyaline, thin-walled, smooth, IKI–, CB + , usually with one or two oily drops, (3.7–)3.8–4.5×(1.9–)2.0–2.3(–2.5) μm, L=4.15 μm, W=2.17 μm, Q =1.90–1.92 (n=120/4).
Material examined – China, Beijing, Yanqing County, Songshan National Forest Park, on fallen trunk of Pinus, 26 July 2019, L.W. Zhou, LWZ 20190726–28 (HMAS, holotype), LWZ 20190726–15 (HMAS), LWZ 20190726–27 (HMAS); ibid., on fallen branch of angiosperm, 26 July 2019, L.W. Zhou, LWZ 20190726–34 (HMAS).
GenBank numbers – LWZ 20190726–15: ITS=OQ540904, LSU=OQ540863; LWZ 20190726–27: ITS=OQ540905, LSU=OQ540864; LWZ 20190726–28: ITS=OQ540906, LSU=OQ540865; LWZ 20190726–34: ITS=OQ540907, LSU=OQ540866.
Notes – Phylogenetically, Meruliopsis crystallina is closely related to M. leptocystidiata (Fig. 3). These two species share white to cream pore surface, strongly encrusted subicular hyphae and the presence of leptocystidia. However, M. leptocystidiata differs by smaller basidiospores (3–4×1.5–2 μm) and the absence of oily drops in basidia (Chen et al. 2020b).
Figure 1 – Basidiomes of Meruliopsis crystallina (LWZ 20190726–28, holotype)
Figure 2 – Microscopic structures of Meruliopsis crystallina (LWZ 20190726–28, holotype). a Basidiospores. b Basidia and basidioles. c Leptocystidia. d Hyphae from subiculum. e Hyphae from trama. Scale bars: a=5 μm, b–e=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