Humidicutis roseorubra Reschke & C. W. Fisch. 2021, sp. nov.

Humidicutis roseorubra Reschke & C.W. Fisch., sp. nov. Figs. 4–6

Mykobank MB838254

Diagnosis: —Differs from other species of Humidicutis by the combination of conical, rose red basidiocarps, basidia with long sterigmata and ellipsoid to ovoid basidiospores.

Etymology: —rosa (Latin) = rose, ruber (Latin) = red, referring to the colour of the basidiocarps.

Type: — PANAMA. Chiriquí Province: near Cerro Punta, Entre Ríos, Montaña Azul, montane forest dominated by Quercus spp., 2300 m a.s.l., N 08°53’42.8’’ W 82°34’58.7’’, 21 June 2017, J. Rodríguez KaiR621 (holotype UCH9223, isotype M-0312081)!

Basidiocarps mycenoid. Pileus 2.2–4.8 cm diam., conical to convex with acute umbo or pronounced papilla, margin straight and uneven, red (10 B 7, 11 A 6–7, 11 B 7–8), rose (11 A 5) to greyish rose (12 B 5–6), pileal surface glabrous, but innately fibrillose and with fine, protruding fibrils if seen through a lens, translucently striate up to 1/3 of the radius, hygrophanous reaction not recorded. Lamellae adnate to emarginate, often with inconspicuous decurrent tooth, ventricose, medium spaced, white, with rather even and concolourous edge. Stipe 6.5–12.0 × 0.3–0.4 cm, cylindrical, flexuous, cartilagineous, hollow, rose (11 A 3, 12 A 3–4) at the tip, pinkish white (11 A 2), pale red (9 A 3, 10 A 3), pastel red (7 A 5, 8 A 4–5), orange red (8 A 6), reddish orange (7 A 5) to light orange (6 A 5) towards the base, glabrous, polished. Basal mycelium white, rather inconspicuous to distinctly tomentose, with numerous short rhizomorphs. Odour indistinct, taste not tested.

Basidiospores 6.5–7.5–8.5 × 4.5–5.0–5.5 µm, Q = 1.35–1.52–1.70 (n = 81 of 2 specimens), ellipsoid, ovoid to somewhat subcylindrical, sometimes slightly constricted, smooth, hyaline, thin-walled, inamyloid. Basidia (33–)36–45 × 5.0–7.5 µm, clavate, hyaline, thin-walled, 4-spored, with a toruloid clamp connection at the base, sterigmata mostly up to 11.0 µm long, rarely up to 17.5 µm. Hymenial cystidia absent. Lamellar trama subregular, formed by inflated to fusiform cells, (23–)30–150 × 10.0–25 µm. Pileipellis a slightly gelatinized cutis composed of somewhat interwoven hyphae, consisting of cylindrical cells, 35–100 × 2.5–9.5 µm. Subpellis not developed. Pileitrama composed of wide inflated to fusiform cells, 25–95 × (6.5–)10.0–30(–34) µm. Stipe surface composed of narrow, cylindrical cells, 100– 260 × 3.0–4.0 µm. Pigment not located. Clamp connections present in the hymenium, absent elsewhere.

Habitat: — Basidiocarps found solitary or scattered in a small group on soil in a Quercus -dominated montane forest at about 2300 m a.s.l. in Chiriquí, Panama.

Notes: — Humidicutis roseorubra is relatively close to H. brunneovinacea R. Garibay-Orijel in Yuan et al. (2020: s.p.), with a p-distance of 6% in the ITS. This species differs from H. roseorubra by darker pilei with brownish tones, somewhat broader ellipsoid basidiospores, and rare presence of clamp connections at the base of basidia. Humidicutis dictiocephala A. Barili et al. in Crous et al. (2017: 333), described from Ecuador, lacks pinkish tones in the pileus and has pale orange lamellae. Further, probably similar species exist (Cantrell et al. 2001; Lodge et al. 2013), however, they have not yet been described.

Additional specimen examined:— PANAMA. Chiriquí Province: near Cerro Punta, Entre Ríos, Montaña Azul, montane forest dominated by Quercus spp., 2300 m a.s.l., N 08°53’42.8‘‘ W 82°34‘58.7‘‘, 21 June 2017, K. Reschke, M. Cuevas, T. Hofmann, B. Wergen, C. Fischer, E. Heinemann, J. Rodríguez KaiR622 (M-0312082)!