Phaeoclavulina echinoflava P. Zhang & W. H. Liu 2024, sp. nov.

Phaeoclavulina echinoflava P. Zhang & W. H. Liu sp. nov. Fig. 3 Diagnosis. Differs from other Phaeoclavulina species by the bright yellow basidiomata when young, brownish yellow with age. Type. China • Xizang Autonomous Region, Jiangda County, 31 ° 49 ' 39 " N, 98 ° 21 ' 88 " E, 3600 m asl., 29 July 2004, Z. W. Ge 204 (HKAS 45984, holotype). Etymology. echinoflava (Latin), referring to the bright yellow fruiting body and echinulate spores. Basidiomata. Coralloid, 65–75 mm tall, 35–45 mm broad, bright yellow when young [1 A 6–7], yellow to pale brown with age [1 A 3–1 B 3]. Stipe single or falsely fasciculate, 20–30 mm long, yellowish white [1 A 2], smooth, densely white mycelia at the base. Many branches diverge from the stalk, dichotomous to polychotomous, divided three to four times, branches thick and sparse, terminal branches short, in cross-section rounded, bifurcation narrowly V- or U-shaped. Tips of branches concolorous, broom-form or short-digitate by maturity, short and blunt. Context whitish, fleshy. Taste and odor, and macrochemical reactions not recorded. Micromorphology. Context hyphae in parallel arrangement, 5–8 μm wide, cylindric, inflated to 12 μm wide, clamp connections present, ampulliform clamps occasional, thin-walled, smooth, hyaline. Basidia approximately 22–34 × 6–8 µm with four sterigmata 3–5 µm long, hyaline, clavate or subclavate, with clamp connection at base. Cystidia absent. Basidiospores [60 / 2 / 2] (8.0) 9.0–10.5 (11.0) × (3.2) 3.5–4.0 (4.5) μm [Q = 2.39–2.86, Qm = 2.61 ± 0.21] elongate obovoid, slightly thick-walled, ochraceous in KOH, cyanophilic, surface coarse, strongly cyanophilius echinulate, spines 0.8–1.5 μm long, acute; hilar appendage inconspicuous and acuminate. Additional materials examined. • Xizang Autonomous Region, Jiangda County, 3600 m asl., 29 July 2004, Z. W. Ge 212 (HKAS 45992). Habit and distribution. Solitary, growing on the humus layer under shrubland at high altitudes; basidiomata generally occur in summer. Known only from the type locality in China. Comments. The bright yellow fruiting body of P. echinoflava is a distinctive character in Phaeoclavulina. In Phaeoclavulina, P. echinovirens (Corner, K. S. Thind & Dev) Giachini, P. flaccida and P. decurrens (Fr.) Giachini also possess a yellow fruiting body. However, in P. flaccida the fruiting body is beige and the basidia are relatively larger than those of P. echinoflava (38–45 × 5.5–6.5 μm vs. 22–34 × 6–8 μm). Phaeoclavulina decurrens has a ramaroid fruiting body, ochre to buff in color fading to a white stem, and has relatively shorter basidiospores than those of P. echinoflava ((4.2) 4.9 (5.5) × (2.5) 2.9 (3.2) μm vs. (8.0) 9.0–10.5 (11.0) × (3.2) 3.5–4.0 (4.5) μm). P. echinovirens differs from P. echinoflava in having larger basidiomata (7.5–13 × 4.5–7.5 cm) and orange yellow tips. The phylogenetic reconstructions placed P. echinoflava in an isolated position within the Phaeoclavulina clade, which is consistent with the unique fruiting body color of P. echinoflava.