Considerations on the rare species Phlebopus brasiliensis (Fungi, Basidiomycota, Boletinellaceae) from Atlantic Forest of Northeast Brazil

Phlebopus (Boletales) is a genus of Fungi with species characterized by robust basidiomata with glabrous to tomentose or velvety pileus, a central thick and non-reticulated, non-hollow stipe, and an adnate-depressed hymenophore. Their context is variable in color and unchanging or slowly develops a blue reaction when exposed to air. They also have short subglobose to ellipsoid basidiospores that are smooth and possess clamped hyphae. A recent collection in Brazil turned up the rare Neotropical species P. brasiliensis, which is only known from type materials from the original description, and which is only one of six species present in the country. Here, we validate the identity of this species and insure its separation from similar congeners including P. mexicanus. Phlebopus brasiliensis is characterized by the dry velutinous pileus surface that then becomes finely areolate in older basidiomata and with an olivaceous color; hymenophore with small pores to 0.5 mm wide with a context that is cream-colored then greenish-blue on exposure to air, and the absence of hymenial cystidia. Alternatively, Phlebopus mexicanus has slightly smaller basidiospores (average 6.4 × 5 µm), larger pores (1–2 per mm, each 0.5–1 mm diameter) and granulose-pruinate stipe to base. These differences help confirm the identity of P. brasiliensis and also establish its presence in a new location in Brazil i.e., a conservation zone that differs in disturbance from its type locality.