Rhodocollybia tablensis J.L. Mata & Halling

Reschke, Kai, Lotz-Winter, Hermine, Fischer, Christian W., Hofmann, Tina A. & Piepenbring, Meike, 2021, New and interesting species of Agaricomycetes from Panama, Phytotaxa 529 (1), pp. 1-26 : 17-18

Rhodocollybia tablensis J.L. Mata & Halling in Mata et al. (2004: 349), Figs. 13d, e, 14

Description: —Basidiocarps collybioid. Pileus 4.0–15.0 cm diam., campanulate to convex-umbonate when young, broadly convex or almost plane with a low, broad umbo when older, margin initially slightly incurved, becoming straight and sometimes uplifted, even to wavy, surface initially somewhat fibrillose, later glabrous, centre greyish orange (6B4–6) to brownish orange (6C5–8, 7C5) in young basidiocarps, fading to brownish orange (6C5), hygrophanous. Lamellae free, extremely crowded, white to pale yellow (4A3), with minutely fimbriate edges and minutely pruinose sides. Stipe 7.0–15.0 × 0.8–1.0 cm, cylindrical to slightly broadening towards the base, sometimes tapering at the very base to slightly rooting, stuffed to hollow, tough, often slightly contorted, white, sometimes with brown spots (7E7), surface fibrillose and somewhat longitudinally ridged. Basal mycelium white, sometimes with rather thick and long rhizomorphs. Spore print yellowish white (4A2). Odour indistinct to pleasant, taste not tested.

Basidiospores 5.0–5.6–6.5 × 3.5–3.8–4.0 µm, Q = 1.33–1.50–1.75 (n = 44 spores of 2 specimens), broadly ellipsoid to obovoid, smooth, hyaline, predominantly thin-walled and inamyloid, some thick-walled and dextrinoid. Basidia 22–30 × 5.0–10.0 µm, clavate to subclavate, 4-spored. Lamellar edge sterile. Cheilocystidia 20–35 × 5.0–8.0 µm, clavate, fusiform, utriform to cylindrical, thin-walled. Pleurocystidia abundant in young, scarce in old basidiocarps, 30–75 × 8.0–15.0 µm, broadly cylindrical to slightly capitate, with several constrictions or a short blunt rostrum, very thin-walled, easily collapsing. Pileipellis a cutis composed of slightly interwoven and gelatinized hyphae, with erect and/or flexous terminal cells and cylindrical or narrowly utriform outgrowths, with incrusting pigment. Stipe surface composed of parallel hyphae with incrusting pigment. Caulocystidia scattered to fasciculate, abundant in young specimens, 20–65 × 4.0–10.0 µm, cylindrical, clavate to subclavate, often furcate or diverticulate. Hyphae with refractive content present in the pileipellis and trama. Clamp connections abundant in all parts of the basidiocarp.

Habitat: —Gregarious on soil in leaf litter of Alnus acuminata and Quercus spp. in montane forests in Chiriquí Province, Panama.

Notes: — Rhodocollybia tablensis was described by Mata et al. (2004) from two specimens from a montane Quercus -dominated forest at approx. 1700 m a.s.l. in the Talamanca Mountain range of Costa Rica. Four specimens were collected in Panama in similar habitats at 1700 to 2400 m a.s.l., approx. 15–30 km from the type location. The ITS sequences derived from these specimens have a p-distance of approx. 0.5% to the sequence of the paratype specimen of R. tablensis (Acc. AF505755 ). While the specimens from Panama were generally rather similar to the original description, some characters were deviating from it. Mature, expanded basidiocarps of the specimen KaiR438 reached a pileus size of 15 cm diam., whereas those of the type specimens where rather small, with pileus sizes of 0.6–3.2 cm diam. A spore print, which could be obtained for PAN238, was yellowish white in contrast to the white spore print reported in the original description. In addition, some basidiospores of the specimens from Panama are thick-walled and dextrinoid. This is remarkable, because R. tablensis was supposed to be one of two neotropical species, which do not present this typical characteristic of the genus Rhodocollybia according to observations published by Mata et al. (2004). In addition to these deviations, the caulocystidia of the specimens from Panama were more variable in shape than reported in the original description.

Specimens examined: — PANAMA. Chiriquí Province: near Cerro Punta, Las Nubes, Sendero Cascada , montane cloud forest dominated by Alnus acuminata , on soil, 2240 m a.s.l., N 08°53’40.2’’ W 82°37’0.8’’, 12 July 2015, H. Lotz-Winter, T. Hofmann, O. Koukol, P. Zehnalek PAN238 (M-0312089) !; ibid., 2190 m a.s.l., N 08°53’39.8’’ W 82°36’57.6’’, 11 June 2017, K. Reschke & J. Rodríguez KaiR483 ( UCH 11753, M-0312087) !; ibid., 2230 m a.s.l., N 08°53’48.0’’ W 82°37’05.7’’, 11 June 2017, K. Reschke & J. Rodríguez KaiR484 ( UCH 11754, M-0312088)!; near Alto Boquete, Pipeline Trail, montane forest in a ravine, on soil, 1750 m a.s.l., N 08° 49’ 42.9” W 82°29’ 30.09”, 2 June 2017, K. Reschke, M. Cuevas KaiR343 ( UCH 11750, M-0312086) !.