Dichomitus squalens

Dichomitus squalens (P. Karst.) D.A. Reid 1965, in Cui, et al., Fungal Diversity 97, 137–392 (2019)

Diagnosis: Fruiting body. — Basidiocarps annual to biennial, pileate, resupinate or effused-reflexed, single to imbricate, without odor or taste when fresh, corky, becoming woody corky upon drying. Pilei irregular, projecting up to 3 cm, 4 cm wide and 15 mm thick at base; resupinate basidiocarps up to 20 cm long, 7 cm wide, and 9 mm thick at center. Pileal surface white to cream when fresh, velutinate, pale yellowish white to yellowish brown upon drying; sterile margin acute or slightly blunt, pale yellow to yellowish brown. Pore surface white to cinnamon when fresh, becoming pale yellowish brown to pale yellowish brown; pores round to angular, 3–5 per mm; dissepiments thin, entire. Subiculum or context white to pale yellow, fibrous to corky, up to 4 mm thick. Tubes concolorous with pore surface or paler, corky when fresh, woody corky when dry, up to 5 mm long. Hyphal system dimitic; generative hyphae bearing clamp connections; skeletal hyphae IKI–, CB+; tissues unchanged in KOH. Generative hyphae infrequent, hyaline, thin-walled, moderately branched, 1.5–4.2 µm in diam; skeletal hyphae dominant, hyaline, thick-walled to subsolid, moderately branched, interwoven, 1.5–6.7 µm in diam. Tubes. — Generative hyphae hyaline, thin-walled, frequently branched, 1.5–3.6 µm in diam; skeletal hyphae dominant, thick-walled to subsolid, abundantly arboriform branched, interwoven, 1.5–5.2 µm in diam. Cystidia or cystidioles absent. Basidia clavate, with four sterigmata and a basal clamp connection, 15–22 9 5.7–8.2 µm; basidioles dominant, in shape similar to basidia, but smaller. Spores. — Basidiospores cylindrical, hyaline, thin-walled, smooth, IKI–, CB–, 8.2–10 9 2.9–3.2 µm, L = 9.17 µm, W = 3.1 µm, Q = 2.96 (n=30/1).

Index Fungorum Number: IF312964

Notes: Macroscopically, Dichomitus squalens can be taken for an Antrodia P. Karst. species, particularly A. serialis (Fr.) Donk, especially when D. squalens is juvenile and whitish. However, the arboriform hyphae and the white rot are the diagnostic of D. squalens.