Cortinarius variebulbus Chevassut & Rob. Henry (1982)

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 : 262-263

Cortinarius variebulbus Chevassut & Rob. Henry (1982) , Doc. mycol. 12(47): 41 ( Fig. 7 )

= Cortinarius argentatus var. griseobrunneus Bidaud & Reumaux , in Bidaud et al. (2002), Atlas des Cortinaires 12: 691, pro parte

Type:— FRANCE. Vaucluse, near Avignon, 21 October 1973, Quercus ilex , leg. G. Chevassut, Henry n° 4039 in PC herbarium, GenBank ITS PP919229.

Original diagnosis:— C. variebulbus n. sp. C. acutibulbus sat similis sed stipes et sporas diversas. Pileo (2.5–4 cm lato) e convexo vel convexo-obtuso demum plano, immo deformiter explanato, sicco, griseoalbidis fibrillis innatis, subargenteis subvirgato, griseofusco, griseascente, demum disco fucescente vel nigricante, alibi sordescente. Lamellis (5–7 mm latis) emarginatis, fulvis. Stipite (2.5–4 cm / 8–12 mm) curto, nunc subaequali nunc clavato-bulboso marginato vel submarginato, nunc recto, cylindrico, abulboso, tantum linea dubia circumdato nunc fusoideo-connato-abulboso), semper ad basim attenuato (sed non acuto), albido-fibrilloso, valde cortinato-velato (usque ad bulbum fibrilloso. Carne pallida , pallide ochracea vel pallide isabellina, inodora, dulci. Sub ilicibus gregatim.

Updated description:— Pileus 4–7 cm diam., globose to conical-convex, at maturity plano-convex, with a broad, obtuse umbo. Pileal margin inflexed or slightly involute, occasionally with whitish velar remnants. Pileus surface mostly dry, hygrophanous, with darker innate fibrils, whitish silvery when young, with age becoming a milky coffee color or spotted fulvous-brown, especially on handling or rubbing. Lamellae moderately spaced, slightly intervenose, intercalated with short lamellulae, adnate to emarginate, light clay-coloured, then rusty ochre, finally cinnamon, edge wavy, concolorous or whitish towards the pileus margin. Stipe 3–6 × 1–2 cm, rather stout, cylindrical, base either clavate or with an oblique, submarginate bulb, somewhat enlarged (up to 3.5 cm) and roundish in shape, whitish or subconcolorous with the pileus when young, with fibrillose universal velar remnants resting more or less on bulb margin. Cortinate remnants whitish. Context whitish or pale ochraceous in the stipe. Odour faintly raphanoid, with a sweetish fragrant component. Macrochemical reactions reaction to guaiac positive, very slow, setting in after at least 5 minutes.

Basidiospores [6, 6, 223] 7.6–11.2 × 4.8–6.8 µm, MV = 9.4 × 5.8 μm, intercarpic variation of MV = 8.2–10.4 × 5.3–6.3 µm Q = 1.44–1.79, Q m = 1.61, intercarpic variation of Q m = 1.52–1.67, predominantly elliptic-subamygdaliform, subovoid in front view, coarsely and densely warted, warts forming trapezoidal plaques, here and there catenulate or coalescing into short ridges, ornamentation generally more prominent towards the apex. Apex rounded or weakly tapering. Plage well differentiated. Spores more or less moderately or strongly dextrinoid to Melzer’s reagent ( Tab. 3, Figs. 3 , 6 ). Pileipellis Suprapellis a cutis of thin, cylindrical hyphae, 3–9 µm wide; subpellis well-differentiated, made up of broader, short-celled hyphae, 15–20 µm wide. Pigment intracellular and parietal, yellowish brown. Basidia 27–42 × 7–12 µm, narrowly clavate, clamped, hyaline or with brownish yellow intracellular pigment in KOH. Marginal cells Lamellar edge partially sterile; marginal cells consisting of sinuous, basidioliform, cylindro-clavate cells, interspersed with basidia, mostly unicellular, occasionally with a median septum and/or lateral diverticulum, terminal element cylindro-clavate (12–30 × 3–10 µm). Clamp connections common at all septa.

Habitat and distribution:—With Quercus spp. (incl. Q. ilex ), Carpinus betulus and Tilia cordata on calcareous ground, mainly in Mediterranean-submediterranean and warm thermophilous regions; known from France, Italy, Spain and thermophilous sites in Germany, north to the limestone plateau of Huy.

Material analysed:— FRANCE. Drôme, Saint-Justin, 04 October 1997, mixed deciduous trees, leg. A. Bidaud, PML 4567 (paratype of Cortinarius argentatus var. griseobrunneus ); Gard, Montdardier, 18 October 2012, Quercus ilex , leg. F. Richard, FR 2012204. GERMANY. Sachsen-Anhalt, Huy, Huysburg east, 04 October 2010, leg. T. E. Brandrud & G. Schmidt-Stohn, TEB 469-10; ibid., TEB 470-10; Sachsen-Anhalt, Freyburg, Kleine Probstei, NSG Tote Täler, 22 September 2014, Quercus spp. , Carpinus betulus , leg. M. Huth, HM 2017-030; ibid., 21 October 2016, Tilia spp. , Quercus spp. , HM 2017-008; Sachsen-Anhalt, Dingelstedt, Huy, 28 September 1998, Quercus spp. , leg. G. Schmidt-Stohn, SSt98-220b; ibid., 04 November 2008, SSt08-175; Nordrhein-Westfalen, Wachendorf, 07 October 2007, Fagus sylvatica , leg. T. Münzmay, TM 49-07; Freyburg, Tote Täler, 04 November 2008, leg. G. Schmidt-Stohn, SSt08-175; Huy, Dingelstedt, 27 September 2008, leg. G. Schmidt-Stohn, SSt98-216a. ITALY. Trentino-Alto Adige, Trento, 03 December 2022, loc. “Dosso S. Rocco”, mixed forest with Quercus cerris , Q. pubescens and Ostrya carpinifolia , leg. A. Valdagni, n°01250 in TR-gmb herbarium; ibid., 24 October 2020, AV-011-2020 (not sequenced); ibid., 22 November 2023, leg. A. Fellin, AF-110-2023 (not sequenced); ibid., 23 November 2023, leg. A. Valdagni, AF-111- 2023 (not sequenced). SPAIN. Jaén, Cambil, Sendero Gibralberca, 1150 m asl, 18 November 2018, Quercus ilex , Q. faginea , Pinus Pinaster , P. halepensis and various Cistaceae spp., leg. F. Armada & J.D. Reyes, FA4647; Granada, Jàtar, Loma del Cura, 1000 m asl, 06 December 2018, Quercus ilex , Pinus halepensis and various Cistaceae spp., leg. F. Armada & M.- J. Díaz de Haro, FA4772.

Comments:— Cortinarius variebulbus is the third taxon in the C. chevassutii complex, characterized by the presence of a more or less abruptly bulbous stipe base. This species seems, however, to display the least marginated bulbous stipe when compared to C. chevassutii and C. subbulliardioides , with some specimens with a more clavatebulbous than a clearly marginate-bulbous stipe base. The spores of C. variebulbus are also, on average, slightly larger than those produced by the two other species (see Fig. 3 ).

This taxon, together with C. chevassutii and C. acutibulbus Chevassut & Rob. Henry (1982: 40) , was originally placed in subgenus Phlegmoloma Rob. Henry , introduced for a few Telamonia species displaying morphological characters normally found in Phlegmacia, including a marginate-bulbous stipe ( Henry 1991). This species is characterized by medium-sized basidiomata, a pileus covered with silvery, innate, radially-arranged fibrils, tending to become greyish on a beige background, which give the surface a sparkly appearance in mature specimens, and a stipe flaring into a marginate or submarginate bulb decorated with abundant velar remnants. In the protologue, Henry compares this species to C. acutibulbus , differentiating the two species by differences in the shape of the bulb and spore shape and size. The examination of these micromorphological features in our phylogenetically confirmed collections of C. variebulbus shows that most spores have an ellipsoid or subamygdaliform shape, while some others are ovoid in front view. Spore size was also found to be more variable and overall larger than what was reported in the protologue ( Tab. 3, Figs. 3 , 6 vs Henry 1991). This suggests some phenotypic plasticity within C. variebulbus , and careful measurements of the spores of additional sequenced collections of this species will be welcome in the future to better assess the actual variability in spore size. In the meantime, and in the absence of reference sequence for C. acutibulbus , the synonymy of this species with C. variebulbus remains dubious. The sequence of one paratype ( PML 4567) of Cortinarius argentatus var. griseobrunneus Bidaud & Reumaux in Bidaud et al. (2002: 691) is here shown to belong to C. variebulbus ( Fig. 1 ). The lack of available sequence for the holotype of this infraspecific taxon prevents strong conclusions to be made about its conspecificity with C. variebulbus but in any case, the latter binomial would have priority at specific rank.

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 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.

FIGURE 7. Cortinarius variebulbus, basidiomata. A. coll. AF-110-2023, Italy (Photo: A. Fellin). B. coll. TR-gmb01250, Italy (Photo: A. Valdagni). C. coll. FA4772, Spain (Photo: F. Armada). D. coll. FA4647, Spain (Photo: F. Armada). E. coll. SSt98-216a, Germany (Photo: G. Schmidt-Stohn). F. coll. SSt08-175, Germany (Photo: G. Schmidt-Stohn). Bar: 1cm (A).