Cortinarius fulvescentoideus – Facesoffungi number: FoF 02466

Cortinarius fulvescentoideus Kyto ¨v., Niskanen & Liimat.

Index Fungorum number: IF552368 Facesoffungi number: FoF02466

Etymology: The name refers to affinity to C. fulvescens.

Holotype: K. Liimatainen & T. Niskanen 03-1634 (H).

Pileus 10–25 mm diam., conical to somewhat hemisphaerical, umbonate, later low convex to plane with an umbo or not, up to 1/2 pellucid-striate, surface mat, warm red-brown, hygrophanous. Lamellae adnexed, subdistant, moderately broad to broad, moderately thick, at first light medium brown, becoming rich brown, edges remaining pale for some time, then concolorous. Stipe 40–100 mm long, apex 3–5 mm thick, equal, whitish silky-fibrillose. Universal veil pale pink, very sparse, forming incomplete girdles on the stipe. Basal mycelium white. Context in pileus dark red-brown, in stipe medium yellow-brown. Odour indistinct. Basidia 4-spored, 8–9 x 30–35 um, clavate. Basidiospores 8.2–9.5 x (4.5–)5–5.4 um, Q = 1.64–1.76, ellipsoid to narrowly ellipsoid, finely to moderately verrucose, slightly to somewhat moderately dextrinoid. Lamella trama hyphae moderately to strongly encrusted in MLZ. Pileipellis duplex (in MLZ): Epicutis hyphae 5–12 um wide, smooth to encrusted. Hypoderm distinct, elements up to 28 x 60 um. Trama hyphae 5–13 um wide, encrusted. ITS sequence (holotype) differs from the sister species C. fulvescens and C. tenuifulvescens more than 7 substitutions and indel positions.

Ecology and distribution: In mesic to moist coniferous forests with Picea and Tsuga, often in Sphagnum. Widely distributed and found from Japan, western North America and Europe.

Material examined: FINLAND, Etela ¨-Ha ¨me, Orivesi, Pa ¨ilahti, mesic to moist Picea abies dominated forest with some Pinus sylvestris and hardwood bushes, 26 September 1995, leg. I. Kyto ¨vuori 95-1550 (H). SLOVAKIA, Liptovska ´ kotlina basin, Vaz ˇec, Vaz ˇecke ´ lu ´ky, Picea abies forest, 29 September 2003, leg. K. Liimatainen & T. Niskanen 03-1634, H7018165 (holotype, H;isotype, K), 30 September 2003 leg. K. Liimatainen & T. Niskanen 03-1675, H7018157 (H). Additional specimens: CANADA, British Columbia, cloneSWUBC478, root tip, GenBank no. DQ481834. JAPAN, Yamanashi, Mt. Fuji, Tsuga diversifolia, June 2011, spYM454 root tip, GenBank no. AB848431. U.S.A., Alaska, Bonanza Creek LTER, Site TKN0109, Picea mariana, 2004, clone3199N24.

Notes: Cortinarius fulvescentoideus looks like a slender C. fulvescens and forms a well-supported clade with C. fulvescens and C. tenuifulvescens but strains from two species are partitioned in two highly supported monophyletic subclades that support their delineation. It is morphologically very similar to C. tenuifulvescens and the two species can easily be misidentified. Our data also indicates that they may have somewhat different ecologies; the collections of C. fulvescentoideus are made from mesic to moist coniferous forests, whereas C. tenuifulvescens prefers sandy, well-drained soils, at least in northern Europe. From the other members of the section Fulvescentes C. fulvescentoideus can most easily be distinguished by the spores. The spores of C. fulvescens are narrowly amygdaloid whereas the spores of C. bulliardioides, C. pseudobulliardioides and C. subfloccopus are broader, >5.5 um wide. The spores of C. badiovinaceus are small, ovoidsubglobose.