Crustomyces scytinostromoides S.L. Liu & L.W. Zhou, sp. nov.
Index Fungorum number: IF 901046; Mycobank number: MB 901046; Facesoffungi number: FoF 14804; Figs. 1, 2
Etymology – scytinostromoides (Lat.) referring to the similarity to the genus Scytinostroma.
Holobtype – LWZ 20190808-14b (HMAS).
Diagnosis – Differing from C. subabruptus by the dominance of skeletal hyphae in subhymenium and subiculum (Eriksson and Ryvarden 1975; Jülich 1979).
Basidiomes resupinate, effused, adnate, at first ceraceous, with age crustaceous, up to 15 cm long, 5 cm wide, 200 µm thick. Hymenophore smooth with scattered tubercles, whitish to cream when fresh, cream to buff when dry, not cracked. Margin white, thinning out as byssoid, 1 mm wide.
Hyphal system dimitic; generative hyphae with clamp connections, hyaline, thin-walled, 2–3 µm in diam; skeletal hyphae dominant in subhymenium and subiculum, hyaline to yellowish, unbranched, 1.5–2.5 µm in diam; tissues becoming a clay-buff colour in KOH. Gloeocystidia numerous, thin-walled, clavate, sometimes with an apical rounded bulb, 20–30×5–7 µm. Dendrohyphidia numerous, hyaline. Basidia, basidioles and basidiospores not seen.
Material examined – China, Sichuan Province, Ganzi Tibetan Autonomous Prefecture, Jiulong County, Wuxuhai Scenic Spot, on fallen branch of angiosperm, 8 August 2019, L.W. Zhou, LWZ 20190808-14b (HMAS, Holotype), LWZ 20190807-15b (HMAS).
GenBank numbers – LWZ 20190808-14b: ITS=OR557244, LSU=OR527270; LWZ 20190807-15b: ITS=OR557245, LSU=OR527271.
Notes – Crustomyces scytinostromoides has a close phylogenetic relationship with other species of Crustomyces (Fig. 3). Morphologically, C. scytinostromoides has smooth hymenophore, a dimitic hyphal system, and the presence of gloeocystidia, which makes it fit with the concept of Crustomyces. However, the tubercles scattered on smooth hymenophore and the presence of skeletal hyphae in both subhymenium and subiculum make C. scytinostromoides distinct from other species in this genus. Although both specimens of C. scytinostromoides are sterile, the above-mentioned unique morphological characters are acceptable for describing a new species, like previous publications (Tchoumi et al. 2020; Yu et al. 2021).
Figure 1 – Basidiomes of Crustomyces scytinostromoides (LWZ 20190808-14b, holotype). Scale bars: a=1 cm, b=1 mm
Figure 2 – Microscopic structures of Crustomyces scytinostromoides (LWZ 20190808-14b, holotype). a A vertical section of basidiomes. b Hyphae from subiculum. Scale bars: 10 μm
Figure 3 – Phylogeny generated by the maximum likelihood algorithm based on combined ITS and nLSU regions is presented along with the bootstrap values and the Bayesian posterior probabilities above 50% and 0.8, respectively, at the nodes. Holotypes are in bold and the newly generated sequences are in blue. Coniophora olivacea FP-104386 and C. puteana FP-105438 were selected as the outgroup taxa