Fibroporia gossypium (Speg.)

1. Fibroporia gossypium (Speg.) Parmasto, Conspectus Systematis Corticiacearum (Tartu): 207 (1968). Figs. 2 View Figure 2 a-c; 9a

Basidiomata resupinate, seasonal, white to cream, in age or drying becoming sordid cream, adnate to effuse, soft when young turning wax-resinous and brittle when old, growing as radial meshes, up to 1 mm thick. Margin white, rhizomorphic to fimbriate, sterile, up to 1 mm of extension. Subiculum cottony, white, less than 1 mm thick. Tubes sordid cream to whitish cream, less than 1 mm deep. Hymenial surface poroid. Pores easily to hardly seen to the naked eye, circular to angular, decurrent in some parts, (3–)5–7 per mm. Dissepiments dentate to lacerated, pubescent. Hyphal system dimitic. Generative hyphae frequent in the trama of young parts and scarce in old parts, with unilateral clamps, thin-walled, hyaline, 2–3.5(–4) μm diam. Skeletal hyphae abundant in the subiculum, thick-walled to almost solid, sparingly branching, 3–4 μm diam. Cystidia absent. Cystidioles scarce to frequent, fusiform, hyaline, thin-walled. Basidia not found. Basidiospores frequent, slightly thick-walled, hyaline, cylindrical to oblong-ellipsoid in frontal view and allantoid to slightly obovoid in lateral view, (4.3–)4.5–5.7(–5.9) × 2–2.4(–2.5) μm, Lm × Wm = 5 × 2.3 μm; Q = 2–2.5(–2.6); Qm = 2.2 (n = 32/1).

Material examined: Juquitiba, São Paulo Green Belt Biosphere Reserve, Trilha da Onça Parda , 13.VII.2022, F . Pagin et al. FP 528, ( SP 528856 ) .

X ylophagous on gymnosperm wood and rarely on angiosperm wood, the species causes brown rot ( Ryvarden & Gilbertson 1993; Ryvarden 2016).

This species has a circumpolar distribution into the coniferous forests of Europe, warm parts of temperate zone, Argentina, Brazil, North America and Asia ( Rick 1960; Lombard 1990; Ryvarden & Gilbertson 1993; Spirin 2007; Yuan & Dai 2008). Previously recorded from the Brazilian Atlantic Forest of the state of Rio Grande do Sul ( Rick 1960). This is the second record from Brazil and the first record from the Southeast of Brazil.

The type locality of F. gossypium is La Plata, Buenos Aires, Argentina ( Spegazzini 1899, as Poria gossypium Speg. ).

Fibroporia gossypium can be recognized in the field by its resupinate, seasonal, soft to wax-resinous, white to sordid cream basidiomata, rhizomorphic to fimbriate margin, cottony subiculum, as well as by its circular to angular pores. In addition, the dimitic hyphal system composed of clamped generative hyphae and of skeletal hyphae plus the cylindrical to broadlyellipsoid, slightly thick-walled, (4.3–)4.5–5.7(–5.9) × 2–2.4(–2.5) μm, basidiospores are diagnostic.

Fibroporia vaillantii (DC.) Parmasto is a morphologically similar species, but differs by a softer, not wax-resinous to brittle basidiomata, as well as by larger, 5–7 × 3–4 μm, basidiospores ( Ryvarden & Gilbertson 1993). Antrodia porothelioides (Cke) Ryvarden , another morphologically similar species, differs by host preference (angiosperms wood), has slightly smaller pores and slightly longer basidiospores ( Ryvarden & Gilbertson 1993; Ryvarden 2015).

Fibroporia gossypium was first described from La Plata ( Argentina, South Hemisphere) and later identified from countries of the Northern Hemisphere ( Spegazzini 1899; Ryvarden & Gilbertson 1993); molecular metadata show conspecificity between specimens from both Hemispheres (Rajchenberg et al. 2006). Fibroporia gossypium presents an antitropical distribution with conifers being its main hosts in the Northern Hemisphere and with Nothofagus spp. being its main hosts in Patagonia ( Argentina, South Hemisphere), where Fibroporia vaillantii colonizes conifers ( Rajchenberg 2022).

Our record is the second for Fibroporia gossypium in Brazil, the first one was made by Rick (1960) from an unidentified host at Rio Grande do Sul, and this species was classified as native ( Rick 1960; Maia & Carvalho 2010), agreeing with its antitropical distribution. In our fungal inventory, F. gossypium was recorded in a site near to the Tropic of Capricorn, deviating from its typical distribution. This suggests that F. gossypium is an opportunistic and rare species in this region where it is associated with coniferous hosts; in this case sampled from a dead stump of Pinus sp. The morphologically similar Fibroporia vaillantii had never been recorded in Brazil, and Antrodia porothelioides was recorded only once by Rick (1960) in Rio Grande do Sul, though with differences in morphology and substrate preference when compared to Fibroporia gossypium .