Summary:
Subgenus Myxacium. Section Defibulati. Cortinarius vanduzerensis is characterized by the dark chestnut cap with a tendency to become corrugated by maturity, pale brown gills at first, and the strikingly violaceous lavender colored slime over much of the stem, (Smith). The name Cortinarius vanduzerensis was widely used for collections of Cortinarius seidliae before the description of the latter. Collections of Cortinarius seidliae have been documented by molecular methods from BC, WA, and OR, whereas Cortinarius vanduzerensis has only been documented by molecular methods from Tillamook County in OR. Spores of C. seidliae are slightly wider at (7.5)8-9 microns and the cap color is given in the description as dirty ochraceous olive brown to brown with a dark brown center. Whether these morphological differences will hold up with further investigation remains to be seen. The description here is derived from the original one for Cortinarius vanduzerensis.

Cap:
4-8cm across, "oval to obtusely conic with the margin appressed at first, expanding to broadly conic"; 'chestnut-black at first, the margin soon chestnut-brown'; slimy, often corrugated at maturity, opaque when moist, (Smith), 4-10cm across, somewhat conic becoming broadly conic or convex; deep chestnut brown to nearly black when young, becoming paler chestnut and finally cinnamon brown when old; very slimy when moist, often wrinkled radially or corrugated when mature, especially toward margin, (Arora)

Flesh:
pallid but soon pale "cinnamon-buff" (moderate orange-yellow); in stem pallid but slowly "cinnamon-buff" at least near base, (Smith), pallid to cinnamon-buff (Arora)

Gills:
adnate, close, only moderately broad, light pinkish yellow when young (in unopened caps), dull cinnamon at maturity, (Smith)

Stem:
10-18cm x 1-2cm, narrowed slightly to the base, light purple to "dark lavender" in upper part, paler over lower third; with a thick slime veil, "at times broken into concentric zones over lower third", (Smith)

Veil:
universal veil slimy violaceous lavender, sheathing at least lower part of stem and sometimes forming concentric zones (Smith)

Odor:
not distinctive, (Smith)

Taste:
not distinctive (Smith)

Microscopic spores:
spores (11)12-14(15) x 7-8(9) microns for Cortinarius vanduzerensis, broadly elliptic to ovate in face view, broadly inequilateral in side view, warty-rugulose, lacking germ pore; basidia 4-spored, broadly clavate, content often in the form of yellow masses or granules in Melzer''s reagent; pleurocystidia none, cheilocystidia 17-26 x 9-15 microns, clavate to clavate-mucronate; clamp connections absent to rare in epicutis of cap, present in hyphae of cortex, (Smith)

Notes:
The type of Cortinarius vanduzerensis was found in the Cascade Head Experimental Forest, Tillamook County, OR (Smith). C. vanduzerensis is currently known with certainty only from the type locality in Tillamook Oregon (Ariyawansa(1)). All three photographs here were taken in Tillamook County, but Cortinarius seidliae likely occurs there too.

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