Polyporales » Polyporaceae » Sparsitubus

Sparsitubus nelumbiformis

Sparsitubus nelumbiformis L.W. Hsu & J.D. Zhao 1980, in Cui, et al., Fungal Diversity 97, 137392 (2019)

Diagnosis: Basidiocarps annual to biennial, effused-reflexed to pileate, hard corky when dry. Pilei irregular, projecting up to 1.5 cm, 3 cm wide and 2 cm thick at base. Pileal surface dark vinaceous gray, indistinctly concentrically zonate, glabrous. Sterile margin wide, cream, distinctly paler than other part, acute, wavy and curved down when dry, even to incised. Pore surface ash-gray brown when dry; margin distinct, cream, up to 4 mm wide; pores developed by the development of an apical pore which isolated and separated each other by a distinct distance, circular, 24 per mm; dissepiments thin, entire; hymenophores among tubes pale gray, subtomentose. Context pinkish buff, hard corky to woody hard when dry, up to 10 mm thick, concentrically zonate; a distinct black zone present between two layers of context when biennial; a distinct black cuticle present on the pileal surface. Tubes mouse gray, hard corky when dry, up to 1 mm long. Hyphal system dimitic; generative hyphae mostly bearing clamp connections, sometimes with simple septa; skeletal hyphae dextrinoid, CB+; contextual tissues unchanged in KOH; tubes and upper surface darkening in KOH. Generative hyphae hyaline, thin-walled, occasionally bearing clamp connections, very rarely with simple septa, rarely branched, 23 µm in diam; skeletal hyphae hyaline to yellowish brown, thick-walled, flexuous, interwoven, 2.53.7 µm in diam. Generative hyphae in upper cuticle mostly with simple septa; skeletals in upper cuticle golden yellow, thick-walled with a distinct lumen, flexuous, strongly gelatinized, 2.54 µm in diam. Generative hyphae hyaline, thin-walled, occasionally bearing clamp connections, unbranched, 1.52.5 µm in diam; skeletal hyphae hyaline to yellowish brown, thick-walled with a narrow lumen, skeletal part subparallel along the tubes, 23 µm in diam. Cystidia and cystidioles absent. Basidia barrel-shaped, with four sterigmata and a basal clamp connection, 1517 × 6.57.5 µm; basidioles in shape similar to basidia, but slightly smaller. Basidiospores broadly ellipsoid to subglobose, yellowish, fairly thick- to thick-walled, asperulate, mostly collapsed when mature, IKI, CB+ , (4.2– )4.55.5(–6) × (3.7–)44.5(–5) µm, L = 5 µm, W = 4.2 µm, Q = 1.151.27 (n = 60/2).

Index Fungorum NumberIF113107

Notes: Sparsitubus nelumbiformis was originally described from subtropical China (Xu & Zhao 1980). The basidiospores of this species in the original description was mentioned as hyaline, 5.56.2 × 4.55 µm, but after reexamined its type specimen and more recently collections, we found its basidiospores are thick-walled, yellowish, 4.55.5 × 44.5 µm, which are distinctly smaller than its original description. Sparsitubus nelumbiformis has very unique characters: tubes separated from each other, a dimitic hyphal structure with strongly dextrinoid and cyanophilous skeletal hyphae, basidiospores yellowish, thick-walled, asperulate and cyanophilous. Sparsitubus nelumbiformis, Cryptoporus volvatus, and Ganoderma species share similar hyphal structure, especially they all have cyanophilous skeletal hyphae, and cyanophilous basidiospores. However, macroscopically, S. nelumbiformis has well-developed tubes, while Ganoderma and Cryptoporus have tubes separated only by thin wall context. In addition, basidiospores of S. nelumbiformis are thin, single-walled and asperulate, while basidiospores are either thick-walled in C. volvatus or double-walled in Ganoderma species (Dai et al. 2007).