Inocybe vaurasii Esteve-Rav., E. Larss. & Pancorbo, sp. nov. Figs. 2–3

MykoBank no.: MB843429

Etymology:—dedicated to Jukka Vauras from Finland for his valuable contributions to the study of the genus Inocybe.

Diagnosis:— Inocybe vaurasii has similar morphological characters and habitat to I. xanthomelas, such as its slender habit, pale colouration, asteriform spores and preference for Fagaceae forests on limestone soils; the two clearly differ in their ITS data sequences, as well as in the combination in I. vaurasii of the more ochre-orange colours of the pileus, larger pleurocystidia (av. 68 × 17.5 µm vs. 54.5 × 15.8 µm), and spores with more prominent knobs (2.2–3.3 vs. 1.2– 2.4 µm in height); in BLAST the closest ITS sequences are that of I. phaeocystidiosa (87.5 %), as well as I. blandula (86.8 %) and I. alpinomarginata (86.0 %).

Holotype:— FRANCE. Nouvelle-Aquitaine: Pyrénées-Atlantiques, Osse-en-Aspe. Forêt d’Issaux, under Corylus avellana in a Fagus sylvatica forest, 43.00222, -0.70667, 917 m asl., 9 October 2016. F. Pancorbo, AH 47714!, GenBank: ITS ON263162, LSU ON276736, isotypes in FP16100904!, GB!

Description

Basidiomata agaricoid and stipitate. Pileus 20–45 mm diam., not hygrophanous, at first hemispherical to conic-convex, then plano-convex, umbo usually distinctive, broadly conical or shallow, rarely absent; margin slightly incurved when young, finally straight, regular to wavy in old and expanded specimens, sometimes crenulated by remnants of veil; velipellis poorly developed, visible on the umbo in young specimens, arachnoid, whitish, but ephemeral in washed or aged collections; colour uniformly orange-brown when young (Mu 10YR 7/6), becoming ochraceous to chamois towards the margin with age (Mu 5YR 8/8, 2.5GY 8/4); surface dry, smooth, radially fibrose, occasionally subrimose in mature specimens, sometimes showing the presence of remnants of a cobwebby whitish veil. Lamellae crowded [L = 42–56; l = (0)–1(–2)], free to hardly adnexed, subventricose, initially whitish, then pale grey (Psathyrella -like), later pale-ochraceous to clay-brown, finally tobacco-brown; edge whitish or paler, entire to finely fimbriate. Stipe 28–74 × 4–7 mm, fibrose, frequently sinuose and slender, cylindrical, abruptly bulbous towards the base (6–13 mm diam.); colour white when young, darkening with age, finally dark greyish to black; surface densely pruinose along its entire length. Cortina not observed. Context fibrose, whitish when young, turning dark grey to blackish with age or desiccation. Odour not distinctive, taste not significant. Average IS=810.

Basidiospores star-shaped (Inocybe asterospora -like), ochraceous, provided with numerous knobs (8–11), 2.2–3.3 µm high, subisodiametric, (8.6–)9.1– 10.8 –12.4(–14.2) × (6.8–)7.7– 8.9 –10.2(–11.8) µm. Q = (1–)1.02– 1.2 –1.39(–1.57) (307 spores from 3 collections). Basidia hyaline, claviform, mostly 4-spored, (21.9–)25.5– 28.6 –32(–32.6) × (9.7–)11.2– 12.9 –14.6(–16.8) µm (44 basidia from 1 collection). Gill edge nearly homogeneous and sterile. Cheilocystidia (34.6–)44.6– 67.1 –97.7(–108.4) × (13.8–)14.6– 17 –20.5(–21.7) µm (112 cystidia from 3 collections), very abundant, hyaline or showing a ochraceous intracellular pigment, crystalliferous at apex, mostly lageniform, sometimes shortly pedicellate, with very pale yellow reaction to ammonia; paracystidia clavate, hyalin. Pleurocystidia numerous, similar to cheilocystidia, (44.1–)52.6– 67.9 –83.7(–94.8) × (13.7–)15.5– 17.7 –20.3(–22.2) µm, Q = (2.46–)2.96– 3.8 –5.22(– 6.08) (134 cystidia from 3 collections), hyaline or showing a ochraceous intracellular pigment, medium to thick-walled (0.56–)0.83– 1.3 –1.95(–2.03) µm. Stipitipellis a cutis of parallel hyphae of 2.8–4.8 µm wide. Caulocystidia abundant, lageniform to subcylindrical (30.6–)40.2– 66.8 –86.9(–107.9) × (9.8–)10.5– 14.1 –17.5(–18.2) µm. Q = (1.87–)2.85– 4.8 –7.11(–7.95) (Holotype), present from the apical part to the base of the stipe in tufts, mixed with numerous hyaline piriform to clavate paracaulocystidia, thick-walled. Clamps present.

Habitat & Distribution:— Inocybe vaurasii is a species with a preference for continental forests of Fagaceae, especially Fagus sylvatica in Europe, but also found associated with Quercus robur in Sweden; it does not seem to show a marked edaphic preference for soil ph, although most of the studied collections come from calcareous soils or at least more nutrient rich soils. Based on the collections studied and data obtained from GenBank, its distribution area extends throughout humid continental Europe (Germany, Denmark, France, Italy, Spain and Sweden), but it is also known to exist in northern Iran, as shown by GB reference FR852271, which corresponds to the Fagaceae forests of the Hyrcanian Forests (Bahram et al. 2012). Some citations refer to I. xanthomelas or I. cf. asterospora, due to their morphological similarity (see Table 1).

Additional collections examined of Inocybe vaurasii:— DENMARK. Jylland; Midtjylland, Barrit, Staksrode skov, Fagus forest on clay and sandy soil, 20 September 2017, E. Larsson EL310-17 (GB-0207631!) (duplicate in AH 56215), GenBank: ITS-LSU ON 227440.— FRANCE. Nouvelle-Aquitaine: Pyrénées-Atlantiques, Osse-en-Aspe. Forêt d’Issaux, under Corylus avellana in a Fagus sylvatica and Abies alba forest, 43.00167, -0.70806, 924 m asl., 11 October 2016, F. Pancorbo, AH 48140!, duplicate in FP16101106!, TUR-A!, GenBank: ITS-LSU ON 259048; ibidem, on muddy ground under Fagus sylvatica, 43.00120, -0.70898, 933 m asl., 13 October 2018, F. Pancorbo, AH 48238!, duplicate in FP18101307!, GenBank: ITS-LSU ON 259049.— SWEDEN. Skåne: Sjöbo, Lövestad, Lövestads åsar, in Fagus forest, 18 September 1981, Leif & Anita Stridvall, LAS81/325 (GB-0064778!); Skåne: Brunnby, Kockenhus, in deciduous forest, 20 July 2004, K. Bergelin (GB-0179884!), GenBank: ITS-LSU ON 227442; Skåne: Andrarum, Christinehofs slottspark, under Quercus robur, 21 September 2005, E. Larsson EL143-05 (GB-0207629!), GenBank: ITS-LSU AM882722; Västergötland: Göteborg, Botaniska trädgården, Vitsippsdalen, deciduous forest, 16 September 2006, M. Ryberg (GB-0129258!), GenBank: ITS-LSU ON 227441; ibidem, under Fagus and Quercus, 8 September 2011, E. Larsson EL226-11 (GB-0207630!), GenBank: ITS-LSU ON 227443; Halland, Hasslöv, Osbäcks bokskog, 16 September 2009, S. Jacobsson SJ09-028 (GB!).