First person to use this name on MO: Danny Newman
Phaeolus amazonica M. A. De Jesus & Ryvarden nova species
Ad Phaeolus schweinitzii (Fr.) Pat., sed sporae 5-6 × 4-4.3 µm (in P. schweinitzii 6-9 × 4.5-5 µm).
Holotype: Brazil: Roraima state, Maraca Ecological Station, of, 61º 48’ W, – 3º 38’ S, 28 September, 2008, leg Ricardo 4434, in INPA, isotype in O.
Basidiocarps annual, laterally stipitate on the ground from roots (?)stipe lateral, short and stout and tapering towards the base, up to 4 cm long and 2 cm in diam pale yellowish brown; pileus circular to slightly spathulate, up to 6 cm long, 5 cm wide and 1 cm thick, rather soft , pale yellowish brown becoming patch wise brown when the upper hyphae agglutinate by age, but no cuticle as such, slightly tuberculate, glabrous and azonate, pore surface yellowish brown becoming darker where touched and finally light brown when dry, pores thin-walled, round o angular, 2-4 per mm, tubes up 3 mm deep, pale yellowish brown, context fibrous and dense, whitish yellow becoming red with KOH, up to 6 mm thick; tube layer decurrent, distinct from context, greenish to rusty brown, up to 1.5 cm thick.
Hyphal system dimitic; contextual hyphae dark brown to yellowish‑brown in KOH, thin‑ to thick-walled, simple‑septate, 3‑6 μm in diam, skeletal hyphae (?) present, thick-walled and dark brown, apparently without septa.
Cystidia one single seen, 60 × 12 µm pale brown, smooth and clavate.
Basidia 18-20 × 5-7 µm 4‑sterigmate.
Basidiospores 5-6 × 4-4.3 µm, ellipsoid to ovoid, hyaline, smooth, negative in Melzer’s reagent.
Substrata. On the ground (?)
Distribution. Known only from the type locality.
Remarks. Superficially this species looks like an Inonotus species even if the light yellowish context is unusual in the genus. The ascertain its status it was sequenced and even if the sequencing only was partially successful, it was clear that the species do not belong in Hymenochaetaceae. The only alternative is then Phaeolus given the colour, the partly stipitate basidiocarps and the simple septate generative hyphae. Even if the characteristic cystidia seen in P. schweinitzii (the type species) are missing, it seems for the time being better not describe a new genus until more specimens will be found.