Cortinarius subsulfurinus Ammirati, Dima, Liimat., Nisikanen & Garnica, Index Fungorum 252: 1 (2015)
Cortinarius subsulfurinus is one of several yellow-green Phlegmaciod species which occur in the Pacific Northwest. It is in section Calochroi. The name refers to it’s close relationship to Cortinarius sulfurinus, a species described from Europe and not known to occur here.
Pileus: 35-90 mm wide, convex to plane or depressed, viscid when wet, yellow-green to olive-brown, margin pale yellow to yellow-green, center darker yellow-brown, reddish-brown or olive, with darker patches of dried gluten visible in fruitbodies of all age. Gills: At first pallid to pale yellow, becoming olive to cinnamon brown. Stipe: 40-90 mm long, 9-20 mm across, pale yellow to pale lemon-yellow, base abruptly bulbous, marginate, mycelium white. Cortina: Pale cream to lemon yellow, most notable when young and on bulb margin. Flesh: Very pale cream to whitish in stipe, occasionally more lemon yellow in surface layers of bulb and cap context. KOH: Brown to reddish brown on cap. Habitat: Mixed conifer forests
The sequenced collections are an exact or very close match to the type collection, as shown by the rough phylogentic tree below. They are also closely related to C.oliveopetasatus (differing by 4 substitutions and one indel in ITS).
The species was not yet described at the time of the 2014 Phlegmacium Type paper (Liimatainen et al 2014) but the analysis of related species shows that C.subsulfurinus would be placed in section Calochroi & Fulvu
When you find an Phlegmaciod Cortinarius with olive-yellow to greenish pileus, Cortinarius subsulfurinus and Cortinarius oliveopetasatus are the most likely candidates. They are closely related species with similar characteristics. Both are viscid, have yellow young gills and patches of gluten. In sequenced collections, we noted that C.oliveopetasatus has more “green” tones – you might call it a “viscid to sticky green mushroom”, while C.subsulfurinus is more yellow, in cap and stipe.
You may also want to consider Cortinarius luteicolor which has similar cap color but different stature. In C.luteicolor, the cap lacks glutinous patches and gills are a more saturated yellow in young specimens. C.luteicolor is in /Laeticolores and the bulb will turn deep purple to burgandy when dried. It may also show different KOH reaction (stipe base pink, and cap redder).
K. Liimatainen et al., “The Largest Type Study of Agaricales Species to Date: Bringing Identification and Nomenclature of Phlegmacium (Cortinarius) into the DNA Era,” Persoonia : Molecular Phylogeny and Evolution of Fungi 33 (2014): 98–140, https://doi.org/10.3767/003158514X684681.
J.F. Ammirati et al., “Cortinarius Subsulfurinus Sp. Nov,” Index Fungorum, no. 551407 (July 31, 2015).
NaCorts: Cortinarius luteicolor