Cortinarius chevassutii Rob. Henry

Fellin, Alessandro, Calledda, Federico, Frøslev, Tobias Guldberg, Armada, François, Stohn, Geert Schmidt, Brandrud, Tor Erik, Dima, Bálint, Valdagni, Alessandro & Bellanger, Jean-Michel, 2024, Cortinarius (Basidiomycota, Cortinariaceae) section Crassispori revisited: resolving the C. chevassutii complex and demystifying C. variebulbus, Phytotaxa 663 (5), pp. 247-266 : 254-258

Cortinarius chevassutii Rob. Henry , in Chevassut & Henry (1982), Doc. mycol. 12(47): 39 ( Fig. 2 )

= Cortinarius subsordescens Rob. Henry (1985) , Bull. Soc. mycol. Fr. 101(1): 27

Type:— FRANCE. Gard-Hérault, Vacquières-Nîmes-Montpellier, October 1978 and October 1979, Quercus ilex , leg. G. Chevassut, holotype Henry n° 70955 in PC herbarium, GenBank ITS MT 934956.

Original diagnosis:— Pileo (4–10 cm lato) convexo dein convexo-plano, demum plano, tum paulum depresso, margine primo sat involuto, nonnumquam infracto-rugoso, fibrilloso griseascenti. Cute innatis fibrillis in reticulo textis, maculis pruinae griseascentis plenis praecipue insigni; colore autem griseo-brunneolo-cinerascenti pallido, dein griseo-fuliginea, demum nigro +/- maculata vel sordescenti. Lamellis (6-8 mm latis) distantibus, sinuato-adnatis vel emarginato-adnatis ex argillaceo-incarnatis mox fulventibus, demum umbrino-fulvis, acie haud integerrimis. Stipite (5-6,5 cm / 10-22 mm) robusto pleno, sat fragili, basi bulboso rotundato marginato, fibrilloso, griseascenti-brunneolo. Carne sordide albida vel isabellina, ad basim tandem quoque brunneo-fuliginea. Sporis ellipsoideo-ovoideo-amygdaliformibus, verruculosis (7,9-8,7/4,3-4,7-5 vel 9,4-10,1/5 μm). Basidiis 4-sp. (33-39/8-8,7 μm). Hyphis fibulatis. Sub Ilicibus sat frequens.

Updated description:— Pileus 3–10 (14) cm diam., initially globose to campanulate-convex, later plano-convex to depressed, with a broad obtuse umbo, margin lobed or notched, often fissured, involute in young specimens, then inflexed to straight. Surface dry, hygrophanous, showing a pattern of greyish brown, radial fibrils, occasionally with an overlay of micaceous, radial striae, ground colour greyish white when young, later light ochraceous or brown, at maturity tending to blacken in radially-arranged areas or striae, with whitish, scattered velar remnants occurring especially towards the centre or at margin. Lamellae adnate to emarginate, sinuous, fairly well-spaced, argillaceous, later dark brown. Edge eroded, wavy-toothed, concolorous with the faces or whitish. Stipe (3)4–7(8) × 1–2 cm, rather stout, cylindric, base weakly to distinctly marginate (rarely bulbous, up to 2–3cm), at times bent downwards, fibrillose, initially white, grey-white or concolorous with the pileus; surface dry, crossed by shiny longitudinal fibrils, lightcoloured when young, but becoming sordid in old age. Velar remnants whitish, more or less restricted to bulb margin, basal mycelium whitish. Context off-white or brownish with red nuances and greyish tinges, more pronounced in stipe base. Odour subraphanoid with fruity notes.

Macrochemical reactions KOH not tested, guaiac negative or weakly positive.

Basidiospores [8, 8, 337] 7.3–9.7 × 4.6–5.6 µm, MV = 8.5 × 5.1 μm, intercarpic variation of MV = 7.9–9.1 × 4.9–5.3 µm, Q = 1.52–1.82, Q m = 1.67, intercarpic variation of Q m = 1.60–1.71, spores yellow-ochre in KOH, mostly elliptic with rounded apex or occasionally slightly tapered, more rarely subamygdaliform or pruniform with a shallow hilar depression. Ornamentation consisting of dense truncate warts, tending to coalesce towards the apex. Plage well-differentiated. Reaction to Melzer’s reagent variable, weakly to moderately dextrinoid in most of the collections analyzed ( Tab. 3, Figs. 3 , 6 ). Pileipellis suprapellis a cutis of subparallel hyphae, 2–7 µm wide, with cylindraceous terminal elements. Pigment brown. Subpellis differentiated, consisting of much broader hyphae, up to 20–25 µm wide; localized presence of yellowish brown intracellular pigment. Basidia 20–35 × 7–9 µm, tetrasporic, cylindro-clavate, hyaline or with greenish-brown intracellular pigment. Marginal cells lamellar edge sterile; hairs measuring 20–40 × 4–6 µm, cylindro-clavate in shape, at times sinuous, either unicellular or two- to three-septate, often with lateral diverticula; terminal element cylindro-clavate (15–20 × 5–7 µm). Clamp connections at all septa.

Habitat and distribution:—Mainly with Quercus ilex on calcareous ground, but also with Q. pubescens and Q. cerris , in mediterranean-submediterranean regions. So far known mainly from western-central Mediterranean regions ( France, Italy, Spain), Hungary, and southern temperate outposts in Germany.

Material analysed:— FRANCE. Drôme, Grignan, 10 November 2018, Quercus ilex and Q. pubescens , leg. F. Armada, FA4547; Hérault, Saint-Martin-de-Londres, 30 October 2010, Quercus ilex , leg. F. Richard, FR 10-SML-1; Hérault, Mas-de-Londres, 01 November 2010, Quercus ilex , leg. J.- M. Bellanger, JMB2010110109; Hérault, Bédarieux, Levas, 23 October 2013, leg. G. Turrini, TG2013-163; ibid., TG2013-164; leg. G. Schmidt-Stohn, SSt13-216; ibid., leg. K. Soop, KS-CO2137; Pyrénées-orientales, Pézilla-de-Conflent, 23 November 2011, Quercus ilex , leg. E. Taschen, Pezilla62. HUNGARY. Pest, Gödöllő, Domony valley, 26 October 1994, Quercus spp. , unknown legit, CFP1277a in S herbarium. ITALY. Emilia Romana, Parma, Belvedere fdi Gotra di Albareto, 10 November 2014, Quercus spp. , Ostrya carpinifolia , Corylus avellana , leg. F. Bellù, FB 10-11-2014; Emilia Romana, Parma, Stabielle di Borgo Val di Taro, 26 October 2014, Quercus cerris , leg. F. Bellù, FB 26-10-2014; Emilia Romagna, Bettola, Piacenza, 28 October 2018, loc. “Montosero”, mixed forest with Corylus , Quercus cerris , Q. pubescens and Populus tremula , leg. F. Calledda, n°01992 in TR-gmb herbarium; Liguria, Massaina, La Spezia, 27 October 2022, loc. “Salterana”, Quercus ilex , leg. F. Calledda, n°01994 in TR-gmb herbarium; Lombardy, Cecima, Pavia, 25 October 2009, loc. “Ca del Monte”, forest with Quercus pubescens and Castanea sativa , leg. F. Calledda, n°01991 in TR-gmb herbarium; Marche, Monte Catria, 30 November 2015, leg. E. Ludwig, 2809-II; Toscana, San Giminiano, Siena, 01 November 1995, Quercus ilex , n° 12546 in MCVE herbarium. SPAIN. Castellón, l’Alcalatén, Vistabella del Maestrat, Penyagolosa, Mas de l’Espino , 40°15’37’’ N, 0°20’01’’ W, 05 October 2015, mixed forest of Pinus nigra , P. sylvestris and Quercus ilex , leg. R. Mahiques, MES-4613; Catalonia, Mas de Carcellara , Quercus spp. , 28 October 2005, leg. K. Soop, KS-CO1611.

Comments:—Recognizing a member of the “ Cortinarius chevassutii complex” is not too difficult morphologically, because of the unique set of features that characterize them: the marginate/submarginate basal bulb, the silky white veil, the appearance of the pileus and the small- to medium-sized spores. However, the separation of C. chevassutii sensu stricto from C. pseudobulliardioides (formerly C. chevassutii f. personatus , see below), without molecular tools, remains challenging. Our analysis of numerous confirmed collections of the two species brought to light that spore shape and length/width Q m ratio represent the most and probably only reliable diagnostic characters to tell them apart ( Tab. 3, Fig. 3 ). Indeed, although the length values are not much different between the two species (7.1–9.1 µm vs 7.3–9.7 µm, respectively), we observed that the number of spores reaching a length of 10–11 µm was higher in C. chevassutii . The average Q m ratio is consistently higher in C. chevassutii (av. Q m = 1.67 vs 1.54), which can be observed also in the scatter plot ( Fig. 3 ). We noted that the spores of C. chevassutii are mostly ellipsoid with a rounded apex, whereas those of C. pseudobulliardioides are often subamygdaliform with a tapered apex. However, for a certain, unambiguous distinction of these two species, DNA sequencing may remain necessary. Liimatainen et al. (2020) have obtained, but not included in their phylogeny, an ITS sequence of the holotype of C. subsordescens Rob. Henry , that they listed as a late synonym of C. chevassutii ; this is confirmed here ( Fig. 1 ). Henry (1985) considered C. subsordescens as a species close to C. chevassutii , but he distinguished it from the latter by the amygdaliform spore shape and the more marked degree of blackening. Some mycologists later treated this taxon as a variety of C. chevassutii , while others synonymized the two names (Fernandez-Sasia & Cadiñanos 2000; Bidaud et al. 2002).

Q L / W

length (L) × width length (L) × width

Q L/W total; 95 %

(W) (W)

species Voucher N variation; 95 % variation

total (µm); MV MV MV

(µm); MV

XC2013-176 8.1 –9.1 –10.2 × 8.3– 9.1 –9.9 × 1.45– 1.58 – 1.44– 1.58 –

34

(isotype) 5.3– 5.8 –6.1 5.4– 5.8 –6.2 1.74 1.72

6.8 –8.2– 10.2 × 7.1 –8.2– 9.1 × 1.30– 1.54 – 1.40– 1.54–

Total 449

4.7 –5.3– 6.1 4.8 –5.3– 5.8 1.74 1.74

Cortinarius 7.7– 8.2 –9.1 × 7.4– 8.2 –9.0 × 1.45– 1.55 – 1.41– 1.55 – AF-110-2023 25

variebulbus 5.0– 5.3 –5.7 4.9– 5.3 –5.7 1.72 1.69 9.4– 10.1 –11.0 × 9.3– 10.1 –10.9 × 1.50– 1.62 – 1.52– 1.62 –

FA4647 35

5.7– 6.3 –6.9 5.7– 6.3 –6.9 1.77 1.72

7.6– 8.8 –10.6 × 7.4– 8.8 –10.2 × 1.47– 1.65 – 1.47– 1.65 –

TR-gmb01250 70

4.6– 5.3 –6.3 4.5– 5.3 –6.1 1.87 1.82

9.1– 9.9 –11.0 × 9.1– 9.9 –10.7 × 1.46– 1.62 – 1.48– 1.62 –

FA4772 31

5.7– 6.1 –6.7 5.7– 6.1 –6.5 1.78 1.76

8.6– 9.0 –10.0 × 8.2– 9.0 –9.8 × 1.40– 1.52 – 1.38– 1.52 –

FR2012204 30

5.4– 6.0 –6.3 5.6– 6.0 –6.4 1.72 1.66

9.6– 10.4 –12.0 × 9.4– 10.4 –11.4 × 1.52– 1.67 – 1.53– 1.67 –

PML4567 32

5.9– 6.3 –7.3 5.7– 6.3 –6.9 1.82 1.81

7.6– 9.4 –12.0 × 7.6– 9.4 –11.2 × 1.40– 1.61 – 1.44– 1.61–

Total 223

4.6– 5.8 –7.3 4.8– 5.8 –6.8 1.87 1.79

Figures

FIGURE 1. ITS phylogeny of section Crassispori. Newly generated sequences are highlighted in Bold. Branch support is indicated as SH-aLRT/%BPP values (cf. Materials & Methods), with thickened branches highlighting significant support of both metrics (≥ 0.82/95). The three species treated in the Taxonomy section are highlighted in grey boxes. * This holotype collection has been erroneously identified as n°5357 in Bidaud et al. (2002, p. 691), but the material corresponds to that of PML5356, described in the same publication (A. Bidaud, pers. com.).

FIGURE 2. Cortinarius chevassutii, basidiomata. A. coll. TR-gmb01992, Italy (Photo: F. Calledda), B. coll. TG2010-035b, Italy (Photo: G. Turrini), C. coll. FA4547, France (Photo: F. Armada), D. coll. TG2013-164c, France (Photo: G. Turrini), E. coll. TR-gmb01994, Italy (Photo: F. Calledda), F. coll. TR-gmb01991, Italy (Photo: F. Calledda).

FIGURE 3. Spore size of Cortinarius chevassutii, C. pseudobulliardioides and C. variebulbus. The lines are drawn on the basis of scatter diagrams and contain 95 % of the spore measurements of each species, as reported in Table 3. X/Y axis: length/width of spores (μm).

FIGURE 6. Basidiospores of Cortinarius chevassutii, Cortinarius pseudobulliardioides and Cortinarius variebulbus. (Photos G. Boerio). A. Cortinarius chevassutii, coll. TR-gmb01992; B. Cortinarius pseudobulliardioides, coll., TR-gmb01993. C. Cortinarius pseudobulliardioides, coll. TR-gmb01999. D. Cortinarius variebulbus, coll. TR-gmb01250.