Boletales » Boletaceae » Brasilioporus

Brasilioporus olivaceoflavidus

Brasilioporus olivaceoflavidus A.C. Magnago 2022, in Magnago, et al., Mycologia 114, 607-625 (2022)

Etymology: olivaceoflavidus (Latin), referring to the olive-green vesture over a yellowish ground on the pileus.

Diagnosis: Differs from Brasilioporus simoniarum by the olive-green pileus fibrils and squamules over a yellowish ground Pileus 1055 mm broad, initially parabolic and velutinous to slightly tomentose, with age convex to plano-convex and matted fibrillose to fibrillose- squamulose; fibrils and squamules dark olive-green (OAC 859), more concentrated centrally, over a yellowish (OAC 849, OAC 856) ground, blackening with age, dry; margin straight. Hymenophore adnexed to adnate, slightly depressed around the stipe, initially off-white (OAC 816), pinkish (OAC 668) with age; tubes 49 mm long centrally; pores 11.5 mm wide, angular, pale white (OAC 816), upon pressure staining orangish red (OAC 712) then slowly to black (OAC 908). Stipe 2041 × 49 mm, central, subequal, grayish brown (OAC 736), lighter near the tubes, subglabrous to velutinous. Context whitish (OAC 816), becoming pinkish orange (OAC 795) then blackening when exposed, especially in the stipe. Odor and taste not obtained. 10% NH4OH negative on all surfaces.

Basidiospores 912 × 45 μm (Qm = 2.18, n = 40, s = 9), subcylindrical to fusoid, hyaline, inamyloid, thin-walled, smooth under light and scanning electron microscopes, pinkish brown in fresh deposit. Basidia 2835 × 810 μm, clavate, hyaline to fuscous, 4-sterigmate; sterigmata 45 μm long. Pleurocystidia 3366 × 811 μm, ampulliform to ventricose-rostrate, hyaline or with fuscous yellow contents, inamyloid. Cheilocystidia 2243 × 46 μm, narrowly clavate to cylindrical, hyaline, inamyloid. Hymenophoral trama boletoid; mediostratum hyphae 46 μm wide, light yellow, inamyloid; oleiferous hyphae present; lateral stratum hyphae 1216 μm wide, divergent, not gelatinized. Pileipellis a trichodermial palisade; individual hyphae with discontinuous spiral incrustations most evident in young basidiomata; terminal cells 1122 μm wide, light brown, dextrinoid, with rounded apex. Pileus trama interwoven; individual hyphae 412 μm wide, hyaline to light yellow. Stipitipellis trichodermial; hyphae similar to those of the pileipellis but with reduced incrustations; terminal cells 39 μm wide. Stipe trama longitudinally parallel; individual hyphae 49 μm wide, hyaline. Clamp connections absent on hyphae of all tissues.

Index Fungorum NumberIF836726

Notes: Brasilioporus olivaceoflavidus is similar to the Amazonian Austroboletus olivaceus in the small basidiomata, olivaceous pileus, black-bruising hymenophore, and gray stipe but differs from it by the yellowish pileus ground color and lack of a bulbous stipe base. The basidiospores of A. olivaceus are also faintly roughened and considerably larger (1116 × 56 vs. 912 × 45 μm) (Singer et al. 1983). Brasilioporus olivaceoflavidus also resembles two bolete species described from Dicymbe forests of Guyana (Henkel 1999). The first of these, Brasilioporus rufonigricans, is differentiated from B. olivaceoflavidus by larger basidiomata with a pileus 40120 mm wide and a stipe 60100 × 1020 mm, gray to grayish black, subreticulate, and smooth at the apex. The basidiospores of B. rufonigricans are also larger (1215.2 × 3.64.8 μm) with a higher Qm (3.1) than those of B. olivaceoflavidus, and the pileipellis hyphae lack spiral encrustations. The second species, Nevesoporus exiguus, although strikingly similar in stature and overall coloration to B. olivaceoflavidus, differs by the lack of a reddish phase in the bruising reaction, instead going straight to black, and phylloporoid tube trama. Both B. rufonigricans and N. exiguus are also heterospecific with B. olivaceoflavidus from a molecular standpoint. Two other neotropical bolete species described in Singer et al. (1983) with pinkish to reddish brown basidiospores share the reddish to blackish bruising reaction seen in B. olivaceoflavidus: the Central American Tylopilus sanctarosae Sing. and the Amazonian Tylopilus acutosquamosus Sing. Both of these have much larger pilei (50120 mm wide) than B. olivaceoflavidus. Tylopilus sanctarosae also differs by the blackish pileus with grayish ground, hymenophore and context that bruise grayish pink to slowly blacking,versiform cheilocystidia, and smooth pileipellis terminal elements. Tylopilus acutosquamosus also differs from B. olivaceoflavidus by the grayish to black pileus, reticulated stipe, and fusoid pleurocystidia (Singer et al. 1983).  Among Malaysian species of Boletus subg. Tylopilus described by Corner (1972), B. olivaceoflavidus keys toGroup 6” (144) based on the blackish bruising reaction but differs from species of this group, Boletus nigropurpureus Corner, B. alboater Schwein., and B. holophaeus Corner, because of their much larger basidiomata (40200 mm pileal width) and lack of pigmented pleurocystidia, among other features. Three other Malaysian species of Boletus subg. Tylopilus are habitually diminutive (Boletus nanus Massee, B. psittacinus Corner, B. coccineinanus Corner), with a pileus width between 5 and 25 mm. Among these, B. psittacinus is most similar to B. olivaceoflavidus in pileus size and coloration but has golden pruinose tube edges and a longer stipe (3060 mm). All three of these taxa differ from B. olivaceoflavidus by the lack of a reddish to blackish bruising reaction and the presence of a villose stipe base with prominent yellow or white mycelial strands, as well as other morphological features. Among Congolian boletes described by Heinemann (1954), none combine the characters of small size and reddish to blackish bruising reaction.



Figure 1. Brasilioporus olivaceoflavidus. AH. ACM 1298, holotype. I. ACM 1310. A. Basidiospores. B. Basidia. C. Pleurocystidia. D. Cheilocystidia. E. Pileipellis terminal elements. FI. Basidiomata. Bars: AD =10 μm; E = 25 μm; FI = 10 mm.


Corner E.J.H. (1972). Boletus in Malaysia. Singapore, Singapore: Government Printer. p. 263.

Heinemann, P. (1954). Flore iconographique des champignons du Congo. Fascicle 3. Boletineae. Brussels, Germany: Le Jardin botanique de lEtat. p 5178.

Henkel T.W. (1999). New taxa and distribution records for Tylopilus from Dicymbe forests of Guyana. Mycologia 91, 655665.

Magnago, A. C., & Alves-Silva, G., & Henkel, T. W., & da Silveira, R. M. B. (2022). New genera, species, and combinations of Boletaceae from Brazil and Guyana. Mycologia 114, 607-625.

Singer, R., & Araujo, I., & Ivory, M.H. (1983). The ectotrophically mycorrhizal fungi of the neotropical lowlands, especially central Amazonia. Beihefte zur Nova Hedwigia. 77,1352.


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