Rigidotubus tephroleucus J. Song, Y.C. Dai & B.K. Cui, in Song et al., Phytotaxa 333(2): 263 (2018)
Etymology: Tephroleucus (Lat.): referring to the grayish white pore surface.
Diagnosis: Rigidotubus tephroleucus is characterized by resupinate, tough basidiomata, grayish white pore surface, white sterile margin, a monomitic hyphal system with clamped generative hyphae, ovoid to ellipsoid and thin-walled basidiospores, 3.5–4.5 × 2.3–3 μm.
Basidiomata annual, resupinate, adnate, tough, without odor or taste when fresh, up to 20 cm long, 5 cm wide and 3 mm thick at centre. Pore surface grayish white when dry; pores round to angular, 2–4 per mm; dissepiments thin, entire to slightly lacerate; margin sterile, irregular, white, up to 3 mm wide. Subiculum white to buff when dry, membranous, up to 0.5 mm thick. Tubes concolorous with pore surface, tough, up to 2.5 mm long. Hyphal system monomitic; generative hyphae with clamp connections, all hyphae IKI–, CB–; tissues unchanged in KOH. Subiculum Generative hyphae hyaline, thin-walled, frequently branched, interwoven, 1–2 μm in diam. Tubes Generative hyphae hyaline, thin-walled, frequently branched, 0.5–2 μm in diam. Cystidia and cystidioles absent. Basidia clavate, with four sterigmata and a basal clamp connection, 8–12 × 3–5 μm in diam; basidioles dominant, similar in shape to basidia but smaller. Basidiospores ovoid to ellipsoid, thin-walled, hyaline, smooth, IKI–, CB–, 3.5–4.5 × 2.3–3 μm, L = 3.96 μm, W = 2.6 μm, Q = 1.49–1.52 (n=60/2). Rot type A white rot.
Index fungorum number: IF823703
Figure 1. Maximum parsimony (MP) tree of Rigidotubus and related genera based on ITS+28S sequence data. Branches are labeled with bootstrap value (MP/ML) higher than 50%, and posterior probabilities (BI) more than 0.95 respectively. Bold names = New species.
Figure 2. Basidiomata of Rigidotubus tephroleucus. Scale bar = 1.5 cm.
Figure 3. Microscopic structures of Rigidotubus tephroleucus (draw from the holotype). a — Basidiospores. b — Basidia. c — Basidioles. d — Hyphae from trama. e — Hyphae from subiculum. Scale bars: a–e = 10 μm.
Song J., Xing J.-H., Ji X., Sun Y.-F., Cui B.-K., & Dai Y.C.. 2018. Rigidotubus tephroleucus gen. et sp. nov. (Cystostereaceae, Agaricales) evidenced by morphological characters and phylogenetic analyses. Phytotaxa, 333(2), 259. doi:10.11646/phytotaxa.333.2.10