Inocybe lucida Esteve-Rav., Pancorbo & E. Larss., sp. nov.

Index Fungorum number: IF 844183; MycoBank number: MB 844183; Facesoffungi number: FoF 14221; Fig. 1

Etymology – from latin “lucidum”, referring to the shiny and smooth appearance of the pileus.

Diagnosis – Inocybe lucida is close in morphological characters and habitat to I. oblectabilis and I. avellaneorosea. It differs from both by the greater average length of the pleurocystidia (Lm=57.3 µm) and the smaller spores (Spavg=8.3×6.3 µm), provided with 11–14 nodules of nonuniform height and width (from 1 to 1.8 µm). Similar to I. oblectabilis in the greasy appearance of the pileus in humid environment and the pale pinkish tones of the stipe, characters that separate both at first sight from I. avellaneorosea. In ITS sequence the similarity is 92% from I. oblectabilis and 89.5% from I. avellaneorosea.

Macromorphology – Basidiomata agaricoid and stipitate. Pileus (12–)15–35(–45) mm, at first conical-campanulate, then convex to plano-convex, with distinct obtuse umbo when expanded, hygrophanous in wet weather; margin straight, regular to wavy or cracked with age, fissurate at times; velipellis absent or very fleeting, observed only in a few very young specimens; colour initially uniformly brownish to chestnut brown (Mu 7.5YR 5/6-8, 4/6 to Mu 5YR 4/4-6) when wet, paling to brown ochraceous to tawny (Mu 10YR 5/6-8, 6/6-8) when dehydrating, especially from the umbo towards the margin; surface radially fibrous, smooth, shiny, often with a greasy aspect in wet condition, sometimes sticky and adhering earth particles, at first with uniform appearance, then becoming subrimose or distinctly rimose towards the margin. Lamellae crowded (L=52–60; l=1), free to almost free, ventricose, initially white, becoming ochraceous or yellow ochraceous, then pale brown, finally tobacco brown; edge concolourous to slightly paler in adult specimens, finely crenulate. Stipe 25–50(−60)×3–7 mm, straight or sometimes sinuose or curved towards the base, abruptly bulbous, bulb clearly marginate, 7–10 mm broad; colour initially very pale pinkish or pinkish grey (Mu 5YR 7/3-4), especially in the upper half of the stipe, soon fading with age, especially in the lower half, and practically whitish to ochraceous with, sometimes, a pinkish reflection (in AH 51880 the pinkish shade being absent); surface densely pruinose over the entire length. Cortina absent. Context fibrose, dirty whitish at the pileus, at the stipe sometimes with a faint pinkish reflection or white along the entire length, including the bulb. Smell not significant when cut, taste not recorded. Colour of exsiccatum brown at the pileus, somewhat paler at the stipe (tawny to light ochraceous), not blackening.

Micromorpholology – Spores (6.5–)7.1–8.3–10(–11.5)× ­­(5.0)5.3–6.3–7.5(–8.3) µm, Q=(1.02–)1.16–1.3–1.51(–1.63) (n=257 from 5 coll.), mostly subisodiametric to sometimes subheterodiametric, distinctly nodulose under the optical microscope, provided with 11–17 distinct knobs variable in height (0.9–1.8 µm high), yellowish, apicula distinct. Basidia (22.8–)23.2–25.9–28.3(–29.3)×(8–)8.3–9.6–10.7(–11.1) µm; Q=(2.17–)2.35–2.7–3.04(–3.12), 4-spored, rarely 2-spored, clavate. Pleurocystidia abundant, (37.3–)48.4–57. 3–67.2(–70)×(11.6–)12.6–15.7–20.5(–23.8) µm, Q=(2.36–)2.71–3.6–4.76(–5.29), (n=132 from 5 coll.), fusiform to rarely lageniform, hyaline, base attenuate even pedicellate, weakly crystalline apex, walls (0.7–)0.85–1.6–2.58(–2.75) µm thick, slightly thicker at the apex, hyaline to hardly yellowish in 10% NH4OH. Lamella edge practically sterile, composed by numerous protruding hyaline cheilocystidia mixed with abundant mostly hyaline, clavate, paracystidia. Cheilocystidia numerous, (30.5–)36–47.8–59.7(–65)×(11–)12.2–15.3–20(–21.9) µm, Q = (1.87–)2.29–3.1–4.07(–4.36), somewhat shorter and wider than pleurocystidia. Hymenophoral trama regular to subregular, consisting of parallel hyphae, 3.3–7.3 μm wide, cylindrical to subfusiform in shape, often constricted at the septa, hyaline. Subhymenium poorly developed, consisting of 2–3 layers of small, subisodiametric, irregular cells, (5.8–)6.7–8.2–9.8(–10.7) μm diam. Pileipellis a cutis consisting of parallel cylindrical cells, 4.8–9.4 µm wide, somewhat constricted at the septa, with finely encrusting yellowish pigment, mixed with oleiferous, aseptate, flexuous hyphae of variable width, with yellowish ochraceous content; subcutis with wider and paler elements. Stipitipellis a cutis of parallel hyphae (2.8–)3.5–4.5–5.6(–5.8) µm, mixed with some oleiferous hyphae, bearing numerous caulocystidia along the entire length of the stipe, (33–)36.5–58.1–86.8(–93.5) × (6.8–)11–15–19.1(–22.3) µm, Q=(2.13–)2.39–3.9–5.94(–7.07) (n=102 from 5 coll.), lageniform, fusiform, mixed with numerous clavate to subglobose hyaline paracaulocystidia. Clamp connections abundant.

Habitat – In mediterranean and warm continental forests in Europe, on acid or decalcified soils under Quercus (Q. ilex subsp. ilex, Q. ilex subsp. rotundifolia, Q. suber, Q. pyrenaica and Q. humilis).

Distribution – found in mediterranean Europe, known from France, Spain and Slovenia.

Material examined – France, Corsica, Ghisonaccia, Domaine de Pinia, 42.012777, 9.459444, 4–12 msl, in acidic sandy soil of mixed mediterranean forest [Quercus suber, Q. humilis (= Q. pubescens), Cistus sp., Pinus pinaster, Arbutus unedo], 6 November 2019, A. Altés, G. Moreno, F. Pancorbo, F. Esteve-Raventós, E. Larsson, P.A. Moreau & N. Suberbielle, (AH 51854). Idem, (AH 51866). Corte, Domaine Saint Jean (San Giovanni), 42.295277, 9.172222, 400 msl, in acidic soil in mixed forest [Quercus suber, Q. humilis (=Q. pubescens), Cistus sp., Pinus pinaster, Arbutus unedo], 7 November 2019, A. Altés, G. Moreno, F. Pancorbo, F. Esteve-Raventós, E. Larssson, P.A. Moreau & N. Suberbielle, (AH 51880). Ibidem, (AH 50881). Ibidem, (EL 351-19, GB). Ibidem, 8 November 2019, A. Altés, G. Moreno, F. Pancorbo & F. Esteve-Raventós, (AH 51895). Spain, Andalucía, Cádiz, road from Los Barrios to Facinas (CA-221), Puerto de Ojén, 220 msl, in acidic soil of cork oak wood (Quercus suber), 20 December 1993, A. Ortega, (GDA 31866; AH 46863). Andalucía, Cádiz, Tarifa, Parque Natural del Estrecho, Sierra de la Plata, Monte Silla del Papa, 36.126732, -5.763624, 360 msl, in acidic cork oak wood (Quercus suber), 18 May 2016, F. Sánchez, (FP16051801, AH 50982). Andalucía, Córdoba, road of Las Ermitas, El Bañuelo, 37.934166, -4.848611, 516 msl, in acidic mixed cork oak and holm oak wood (Quercus suber and Q. ilex subsp. rotundifolia), 13 December 2005, G. Moreno, J. Llistosella, P. Pérez-Daniels & F. Esteve-Raventós, (AH 36259). Castilla-León, Avila, Candeleda, Fuente del Roble, 40.172425, -5.234914, 594 msl, in acidic soil in oak wood (Quercus pyrenaica), 1 May 2011, M.A. Ribes, (AH 50955, holotype), (FP11050102 isotype). Cataluña (Catalonia), Barcelona, road from Vallgorguina to Collsacreu (C-61), in acidic soil of holm oak wood (Quercus ilex subsp. ilex), 15 October 1991, G. Moreno & F. Esteve-Raventós, (AH 25011). La Rioja, Ocón, Santa Lucía, 42.301666, -2.263333, 800 msl, in decalcified sandy soil of holm oak wood (Quercus ilex subsp. rotundifolia), 15 June 2008, A. Caballero, (AC3858, AH 36385). Pais Vasco (Euskadi), Vizcaya (Bizkaia), Musques (Muskiz), La Campa Auzoa, 43.321388, -3.133333, 70 msl, under oaks (Quercus robur), 1 June 2013, R. Fernández-Sasia, (RFS 130601-02, AH 40423).

GenBank numbers – ITS-LSU: (AH 51854, ON994209; AH 51866, ON994215; AH 51880, ON994204; AH 50881, ON994208; EL 351-19, OP002056; AH 50955, ON994205; AH 36385, ON994206; AH 40423, ON994207), ITS: (AH 36259, ON994214; AH 25011, ON994210)

Notes – Inocybe lucida is similar to I. oblectabilis in their macroscopic characters viz, a slender habit, colours of the pileus and stipe with a marked hygrophaneity, being the pileus very smooth and acquiring in wet weather a shiny and glossy appearance. However, the two species differ markedly in the spore size (clearly smaller in I. lucida), in the appearance of the knobs (higher in I. lucida), and also in the much larger cystidia in I. lucida, with a clear tendency to be narrowly fusiform and pedicellate (Fig. 1). Although the spores are similar in ornamentation (Fig. 2), I. lucida can be distinguished from I. avellaneorosea by the longer cystidia, differently coloured stipe and the shiny and very smooth appearance of the pileus in wet weather. According to the data from the numerous collections studied, it seems to behave as a southern species on the European continent, with a marked preference for acid soils, fruiting in mediterranean and subcontinental Quercus sp. (Fagaceae) forests, both evergreen (Q. ilex, Q. suber) and deciduous (Q. faginea, Q. pyrenaica, Q. robur) (Figs. 2, 3).

Figure 1 – Inocybe lucida (AH 50955, holotype). a Basidiomata in situ. b Basidiospores mounting in NH4OH. c Pleurocystidia. d Cheilocystidia. e Caulocystidia at the base of stipe. Scale bar: a=20 mm, b=10 μm, c–e=50 μm

Figure 2 – SEM spores of Inocybe oblectabilis epitype: a Basidiomata. b Basidiospores. Inocybe avellaneorosea holotype: c Basidiomata. d Basidiospores. Inocybe lucida holotype: e Basidiomata. f Basidiospores. Scale bar: b, d, f=2 μm

Figure 3 – Most probable tree inferred by Bayesian inference in species of Inocybe oblectabilis group based on ITS and LSU sequences. Posterior probability from Bayesian analysis/Bootstrap-ML values are shown at the branches. Thick branches indicate nodes with phylogenetic support in both analysis (posterior probability≥0.95 and bootstrap values≥95%). The tree is rooted with Pseudosperma spurium (AM882784). The country of origin of each collection is abbreviated by ISO codes, with the species types marked in bold