Rickenella fibula (Bull.) Raithelh., Metrodiana

Funez, Luís Adriano, Monteiro, Marcela, Costa-Rezende, Diogo Henrique, Alves-Silva, Genivaldo & Drechsler-Santos, Elisandro Ricardo, 2023, Rickenella fibuLA (Repetobasidiaceae: Basidiomycota): a tiny species with large distribution also occurs in Brazil, Iheringia, Série Botânica (e 2023008) 78, pp. 1-10 : 4-6

Rickenella fibula (Bull.) Raithelh., Metrodiana 4: 67.1973.

( Figs. 2-3 )

Macroscopic characters: Basidiomata small, omphalinoid. Pileus 3–4 mm diameter, hemispheric at first, becoming convex to nearly plane with a shallow central depression and slightly wavy margin in age; surface dry to hygrophanous, glabrous to the naked eye and finely pubescent under a lens, yellowish orange to orange, deep orange to brownish at the central depression. Lamellae 18–20, decurrent to deeply decurrent, furcate or transvenose, white to yellowish white, up to 2 mm wide; lamellulae 1–2 of different lengths between the two complete lamellae, edge entire, concolorous, intervenose, not to occasionally forked. Stipe central, 12–15 × 0.2–0.5 mm, cylindrical to subcylindrical, often curved, equal or slightly tapered downwards and upwards, cartilaginous, solid, white to yellowish white, somewhat translucent; surface covered with finely pubescent; basal mycelia white. Odor and taste not distinctive. Microscopic characters: Basidiospores (4.8–)5.0–6.7 × (1.6–)2.0–2.8(– 3.0) μm, Q = (1.43–)1.51–1.82(–2.0), Qm = 2.3 ± 0.7, ellipsoid, thin-walled, hyaline, smooth, inamyloid. Basidia 14.5–20 × 3.6–4.3 μm, clavate, 4-spored, thin-walled; sterigmata 3.6–4 μm, often clamp connections at the base of the basidia. Pleurocystidia 36.5–51.1 × 5.2–8.4 μm, narrowly lageniform to subcapitate, often with subcapitate apex, hyaline, thin-walled, inamyloid. Cheilocystidia similar to pleurocystidia in shape and size. Lamella trama regular to subregular, hyphae 8.5–17.7 μm wide, cylindrical or subfusoid, thin-walled, hyaline, inamyloid. Pileus trama subregular, hyphae 3–12 μm wide, thin-walled, hyaline, inamyloid. Pileipellis as a cutis with scattered pileocystidia, hyphae 3–12 μm wide, cylindrical or subfusoid, thin-walled, hyaline. Pileocystidia similar to pleurocystidia in shape and size. Stipitipellis a cutis with scattered caulocystidia, hyphae 3–11 μm wide, with cylindrical elements, hyaline, thin-walled. Caulocystidia similar to pleurocystidia in shape and size. Clamp connections present.

Specimens examined: BRAZIL, SANTA CATARINA, Grão Pará, Serra do Corvo Branco , 17.III.2020, L.A. Funez & W.I. Ribeiro-Nardes 8951 ( FLOR); Urubici, Parque Nacional de São Joaquim , 01. V.2019, D.H. Costa-Rezende, L.A. Funez & M. Monteiro 584 ( FLOR); Estrada geral da Santa Bárbara , 02. V.2019, L.A. Funez, M. Monteiro & D.H. Costa-Rezende 8948 ( FLOR); 8949 ( FLOR) ; 19.IX.2019, L.A. Funez, W.I. Ribeiro-Nardes & M. Comin 9097 ( FLOR) ; 26.III.2019, L.A. Funez, T. Kossmann, D.H. Costa-Rezende & D.K.S Guimarães 9155 ( FLOR) ; 30.I.2020, L.A. Funez, W.I. Ribeiro-Nardes & M. Comin 9422 ( FLOR); 28°9’38’’S, 49°37’5’’W, 21. V.2019, F. Bittencourt, L.A. Funez & D.H. Costa-Rezende 1278 ( FLOR) .

Figures

Figure 2. Macroscopic characters of Rickenella fibula. A. Detail of the pileus; B. Detail of the stipe, showing the decurrent lamellae; C. Hymenophore, showing the lamellae and lamellulae.

Figure 3. Microscopic characters of Rickenella fibula. A. Pleurocystidia; B. Basidiospores attached to the basidia; C. Basidia.