Cortinarius oulankaensis is an agaric fungus in the family Cortinariaceae, first described in 2013. The fungus features a grey-brown to dark brown cap measuring 4âÂÂ10 centimetres across, pale grey-brown gills that darken with maturity, and a club-shaped stipe with whitish fibres that turn brown over time. It grows in late September in coniferous forests on lime-rich soils primarily in northern Europe, particularly in Finland's Oulanka National Park and near Steinkjer, Norway, though environmental DNA evidence suggests it may also occur in British Columbia, Canada.
Cortinarius oulankaënsis was formally described in 2013 after combined morphological and DNA (ITS + rpb2) analyses showed it to be distinct from related brown Cortinarius species. The species epithet honours its type locality in Oulanka National Park, Kuusamo, Finland. The holotype (Niskanen et al. 05âÂÂ169) was collected on 19 September 2005 in a spruce (Picea abies)âÂÂdominated, baseâÂÂrich woodland; material is preserved at the herbarium of the University of Helsinki (H).
The cap (pileus) measures 4âÂÂ10 cm across, beginning hemispherical before flattening into a broad dome often marked by a shallow central bump (umbo). Its surface is clothed in fine, whitish fibres (fibrillose) when young and appears greyâÂÂbrown with pale whitish fibrils at the margin; it becomes uniformly dark brown and then fades to yellowish brown as it dries (hygrophanous). The gills are mediumâÂÂspaced to rather distant, with a slight notch where they meet the stipe (emarginate); initially pale greyâÂÂbrown, they deepen to dark brown with maturity. The stipe is 5.5âÂÂ10 cm tall and 0.9âÂÂ1.3 cm thick at the apex (1.5âÂÂ2.5 cm at the base), nearly cylindrical to clubâÂÂshaped, and initially covered in whitish fibres that soon turn brown. Remnants of the universal veil form a thin, greyish sheath low on the stipe. The flesh is pale greyâÂÂbrown above, turning chocolate brown at the base; it bears no distinctive odour.
Under the microscope, the spores measure 9.3âÂÂ11.1 by 6.1âÂÂ6.8 üm (on average 9.9âÂÂ10.6 by 6.3âÂÂ6.6 üm) and are narrowly ellipsoid to slightly almondâÂÂshaped (amygdaloid). They are densely ornamented with coarse warts (verrucose) and stain reddishâÂÂbrown in Melzer's reagent (a dextrinoid reaction, indicating a particular sporeâÂÂwall chemistry). The gill tissue is made up of smooth to finely roughened hyphae, while the cap cuticle (pileipellis) consists of thinâÂÂwalled hyphae bearing zebraâÂÂstriped pigment encrustations. A layer of slightly larger cells (hypoderm) lies beneath, and clamp connections (bridgeâÂÂlike hyphal structures) occur throughout.
This species fruits in late September in mesic to moist coniferous forests on calcareous (limeâÂÂrich) soils, typically under spruce with occasional pine and birch. Although it can be locally abundantâÂÂespecially in Oulanka National Park (Finland) and near Steinkjer (Norway)âÂÂit is rare overall and confined to the hemiboreal and boreal vegetation zones of northern Europe. An environmental DNA sequence matching C. oulankaënsis has also been recovered from ectomycorrhizal roots in British Columbia, Canada, suggesting a widerâÂÂbut as yet poorly documentedâÂÂdistribution. In the 2019 Finnish red list, C. oulankaensis is considered a vulnerable species, unchanged from its 2010 classification.