Tropicoporus nullisetus Xavier de Lima, V.R.T. Oliveira & Gibertoni, sp. nov.

This species is characterized by the pileate basidioma, 4-5 pores/ mm, lack setae, and basidiospores 5-5.5 Μm long.

MYCOBANK NUMBER. — MB 834098.

HOLOTYPE. — Brazil. Alagoas State, Quebrangulo City, REBIO de Pedra Talhada, on dead wood, 9°15’00.7”S, 36°25’38.3”W, 758m, 12.X.2018, V. Xavier de Lima, (URM [URM94073]).

ADDITIONAL SPECIMENS EXAMINED. — Brazil, Alagoas State, Quebrangulo City, REBIO de Pedra Talhada, on dead wood, 09°15’29.0”S, W 36°25’52.0”W, 614 m, 18.VII.2018, V. R. T. Oliveira, (URM [URM 94074]); 09°15’32.6”S, 36°25’12.6”W, 590 m, 02.II.2019, V. R. T. Oliveira, (URM [URM 94075]).

ETYMOLOGY. — From “ nullum ” (Latin) meaning “absent”. Referring to the lack of setae.

HABITAT AND DISTRIBUTION. — Tropical, ombrophilous broadleaf forest.

DESCRIPTION

Basidioma (Fig.8 A-B)perennial,pileate,sessile, broadly attached, solitary to imbricate,applanate to triquetrous in section (Fig.8C), 3.5-10.5 cm wide, 3.5-7.0 cm long, 2.0- 3.5 cm thick at the base, woody hard and light. Pileus surface firstly velutinate, yellowish-brown, but soon forming a hard, darker to black crust of agglutinated hyphae, concentrically sulcated, cracking radially in older parts. Margin obtuse to acute, entire, where tomentum may be persistent, yellowish-brown. Pore surface dark golden brown, glancing, with a sterile zone at the pileus margin, up to 3 mm wide, pores round, (3-)4-5/mm (Fig.8D). Context 0.7-1.2 cm thick at the base, azonate, duplex, with a black line near the pilear surface dividing the upper tomentum, from the lower golden-brown context.Tubes concolorous with the lower context, indistinctly stratified (up to five layers in the holotype), new tubes slightly brighter than older ones, old tubes filled with golden brown mycelia. All structures turning immediately black in KOH 3%, dark reddish when drying out. Hyphal system in the context monomitic, generative hyphae simple and mostly regularly septate, sparingly branched, yellow, golden yellow in water and rusty brown in KOH, mostly thick-walled with wide to narrow lumen, rarely hyaline and thin-walled, 2.5-5.5 Μm in diameter, wall up to 1.5 Μm thick; black line composed by darker, densely agglutinated hyphae. Below the line, hyphae grow downwards until it differentiates +into the tube trama, and above the line, hyphae concolorous or slightly darker, growing upwards composing the tomentum, or agglutinated, forming a dark crust in older parts; tomentum hyphae straight, thick-walled but with a wide lumen, yellow to dark yellow in water, rusty brown in 3% KOH, 2-5 Μm diameter, septate, ends obtuse or clavate, mostly broken. Tube trama dimitic, generative hyphae yellow, thin to slightly thick-walled, 2.5-3 Μm in diameter, skeletal hyphae (Fig. 8E) growing perpendicular to the pilear surface, golden yellow (in water) to brownish-yellow (in 3% KOH), thick-walled with a narrow lumen, wall up to 2 Μm thinning out towards the apex, unbranched, 3.5-4.5 Μm in diameter. Cystidioles frequent, lageniform with a narrow and long or shorter and round apex, or cylindrical with an obtuse or acuminating tip, 14-18 × 5-8 Μm (Fig. 8G). Basidia not observed. Basidiospores ellipsoid with a flattened side, 5-5.5 × 4-4.5 Μm (Q = 1.11-1.37), thick-walled, smooth, pale yellow (in water) and golden yellow to dark rusty brown (in 3% KOH), color variation can be observed in the same basidioma, CB-, IKI- (Fig. 8F, H).

REMARKS

Except for the absence of hymenial setae, this species is morphologically very similar to other neotropical Tropicoporus with pileate basidiomata. However, T. dependens and T. sideroxycola (Vlasák & Y.C. Dai) L.W. Zhou, Y.C. Dai & Vlasák have binding-like hyphae (Zhou et al. 2016); T. guanacastensis has smaller pores (7-8/mm) (Zhou et al. 2016); T. cubensis (Y.C.Dai, Decock & L.W. Zhou) L.W.Zhou & Y.C.Dai have slightly smaller pores (5-6/mm) and basidiospores (4-5 × 3-4 Μm); and T. drechsleri Salvador-Montoya & Popoff seems restricted to Cordia americana (L.) Gottshling & J.E. Mill. (Salvador-Montoya et al. 2018). In the holotype, cystidioles are abundant, but hard to observe in the other analyzed specimens.