Pholiota oblita Niveiro, Popoff & Albertó, 2014

Pholiota oblita Niveiro, Popoff & Albertó View in CoL , sp. nov. ( Figs. 1 View FIGURE 1 , 3A View FIGURE 3 )

= Pholiota digilioi Singer fide Singer (1952: 498), invalid name.

Mycobank # MB 805226

Diagnosis:— Similar to Pholiota flammans and P. subflammans , but with narrower lamellae, elongated cheilocystidia and broader spores.

Type: — ARGENTINA. Salta: Santa Victoria Oeste, Baritú National Park, El Lipeo, trail to Termas del Cayotal (22°25’38.1’’S 64°44’24.7’’W, 1230 m elev.), 21 April 2009, N. Niveiro 976b (Holotype CTES!) GoogleMaps .

Basidiomata gregarious, caespitose, on humus. Pileus 7–30 (40) mm broad, convex to hemispheric, becoming broadly convex, slightly umbonate, surface yellowish brown (M&P 11-G2 to M&P 11-J7), with darker center, to brownish orange (M&P 9-K7), viscid, with small, recurved, fibrillose scales, concolorous with the pileus surface, that eventually “disappear” at maturity, moving in the viscous surface towards the bottom of the gelatinous layer. Margin smooth or appendiculate with veil remnants, not striate. Context fleshy, thin, cream to yellowish color. Odor and taste not tested. Lamellae regular, yellowish, turning chestnut when touched or with age, narrow, to 2.5 mm broad, close, adnate with small tooth, even colorous margin, with lamellulae. Stipe central, 25–42 × 2–4 mm, cylindrical, equal or slightly enlarged at base, yellow (M&P 10-H1) to yellowish brown (M&P 10-J6), with abundant recurved scales from the ring to the base. Annulus ascending, fixed, floccose. Spore print light brown.

Spores 6–7.5 × 3.8–5.5 µm; x = 6.7 × 4.3 µm; Q= 1.18–1.79; Q x = 1.54; n= 75; ovate to ellipsoidal, olive brown, with a small apical germ pore, slightly truncated apex, smooth, slightly thickened wall. Basidia 17–22.5 × 5–7 µm, clavate, 4-spored, hyaline, thin-walled. Pleurocystidia 21.5–50.5 × 5.6–14.8 µm, clavate-mucronate to fusoidventricose, chrysocystidia type, with content amorphous and granular-aggregated forming folded (reticulate) masses. Cheilocystidia 33–47 × 5.5–8.2 µm, cylindrical with rounded apex to slightly capitate, thin-walled, hyaline, with homogeneous content. Hymenophoral trama regular, hyaline hyphae 5–8 µm diam., subhymenium of narrow, hyaline somewhat interwoven gelatinous hyphae. Pileipellis a thick ixocutis (120–150 µm) with cylindrical, pale yellow hyphae, incrusted with brown pigment, 3–6 µm diam., immersed in the gelatinous matrix. Clamp connections present.

Distribution and ecology:— Growing on humus in the Montane Forest of northwest Argentina, from Tucumán (Singer 1952), Salta, and Jujuy Provinces ( Fig. 4 View FIGURE 4 ).

Additional specimens examined (paratypes):— ARGENTINA, Salta: Santa Victoria Oeste, El Nogalar de los Toldos Natural Reserve, trail to Santa Victoria (22°16’46.6’’S 64°42’35.0’’W, 1677 m elev.), 25 April 2012, N. Niveiro 2590 ( BAFC!), GoogleMaps 2596 ( LIL!), GoogleMaps 2598 ( CTES!), GoogleMaps E. Albertó 2707 ( CTES!) GoogleMaps . Jujuy: Ledesma, Calilegua National Park, Bosque del Cielo trail (23°40’87.6’’S 64°54’08.4’’W, 1695 m elev.), 27 April 2012, N. Niveiro 2622, 2625 ( CTES!) . Tucumán: Santa Rosa, ad terram in silvis subtropicali vel Montana sub Phoebe, Eugenia, alno, etc ., 17 Dec. 1950, leg. R. Singer T 1058 ( LIL!). Ib. “quebradita” near the Tafí del Valle , alt. 2350 m, 11 Jan. 1950, leg. R. Singer 846a ( LIL!). Ib. Rio de los Sosas, ad terram arenosam supra radices arboris dicotyledoneae ad ripam fluminis , alt. 950 m, 26 Feb. 1952, leg. R. Singer T 1907 ( LIL!). Ib. Anta Muerta, Sierra de San Javier, ad terram humosam (nunquam ad ligna), fasciculariter crescents in silva montano-subtropicali , 3 Nov. 1949, leg. R. Singer T 757 ( LIL!). Ib. Parque Aconquija, Sierra de San Javier , ad terram vel ad lignum submersum putridis simun in humo silvestri in silva montano-subtropicali, 17 July 1949, leg. R. Singer T 601 (LIL!). Ib. Anta Muerta, Sierra de San Javier , ad humum lignosum in cave trunci in silva montano-subtropicali, 19 Dec. 1949, leg. R. Singer T 794 ( LIL!). Ib. Sierra de San Javier, Ciudad Universitaria , in subtropical forest (upper level) on a dead dicot trunk together with Pleurotus ostreatus , 12 May 1957, leg. R. Singer T 3097 ( LIL!) .

Remarks: —This species was originally described by Singer as P. digilioi Singer , based on material collected in Tucumán Province (Singer 1952: 496). It was not considered a validly published species because no Latin diagnosis was included and no type material was designated ( McNeill et al. 2012). Although Singer (1952: 496) mentioned that he would formally describe it in the future, he never did publish it. No other description was published after that, and no further record of this species was found ( Mueller & Wu 1997). For this reason we have named this species with the epithet oblita , which means “forgotten” in Latin.

Pholiota oblita is characterized by its narrow lamellae, large cheilocystidia and slightly broad spores. It belongs to the subgenus Pholiota , section Adiposae , stirps Subflammans because it has yellowish basidiomata covered by conspicuous scales, at first flocose-squarrose, erect, separable scales, that eventually “disappear” at maturity moving towards the bottom of the gelatinous layer ( Singer 1986: 580, Smith & Hesler 1968: 166).

Other species from stirps Subflamans related to P. oblita include P. flammans (Batsch) P. Kumm. , known from the Northern Hemisphere, and P. subflammans (Speg.) Sacc. , from the South American Andino-Patagonic forest. Both species differ from P. oblita by their smaller spores: 4–5 × 2.5–3 µm in P. flammans ( Smith & Hesler 1968: 167) and 5–6.3 × 3–3.4 µm in P. subflammans ( Spegazzini 1887a, 1887b, Horak 1967: 358); less elongated cheilocystidia, 18–20 × 3 µm in P. flammans ( Smith & Hesler 1968: 167) , 17–22 × 6–8.2 µm in P. subflammans (Singer 1952: 497) ; and wider lamellae, which are moderately broad to broad in both species ( Smith & Hesler 1968: 167, Singer 1952: 499). Moreover, P. flammans differs from the other species in its more robust basidiomata, with larger pileus and wider stipe ( Smith & Hesler 1968: 167). Both species were found in colder zones than P. oblita ( Smith & Hesler 1968: 167, Singer 1952: 499).

Singer (1952: 498) described slightly shorter spores (5–8.8 × 3.5–4.8 µm) for Pholiota digilioi than the present description, but the remaining morphometric characteristics (basidia, chrysocystidia, cheilocystidia) are identical in both descriptions.

Moreover, when Singer (1952: 497) analyzed the Spegazzini type material from Tierra del Fuego and topotype material collected by himself of P. subflammans , he described similar spores (5.5–7 × 3.7–4.2 µm) to P. digilioi , differing from the observations made by Spegazzini (1887a, 1887b) and Horak (1967). However, upon reanalyzing the materials examined by Singer (1952: 497), we observed that P. subflammans has slightly narrower spores and shorter cheilocystidia ( Fig. 2 View FIGURE 2 ).

According to the characters mentioned above (and outstanding in the key and Table 1 View TABLE 1 ) we propose P. oblita (= P. digilioi ss. Singer 1952) as a new species, similar to P. flammans and P. subflammans (= P. baeosperma ), being, so far, an endemic species from the southern Yungas Forest.