A single specimen growing on the raised sandy bank of Coopers Road, ~200 ft to the north of intersection with the Red Trail. Young oaks, oak saplings, and mature pitch pines seen at the collection site, but I believe the bolete is mycorrhizal with the oaks. This is the same spot, give or take a few yards, where obs 245956 was collected. Given the strong morphological semblance adjusted for age, I am almost certain it’s the same species.
Morphological Description: The convex-pulvinate medium brown to yellow-brown cap is 4.5 cm wide and 1.5 cm thick in the middle; the cap margin is wavy and devoid of a sterile tissue overhang; the cap flesh is yellowish-cream, slowly staining faintly blue when exposed to air in the middle of the cap and at the cap-stipe juncture, but not above the tubes.
The pores are mustard-yellow to greenish-yellow, 1-1.5 mm wide, angular, somewhat compound, with some reddish-brown natural stains; the yellowish-green tubes are 1.3-1.5 cm deep and not staining blue.
The stipe is 4.5 cm long, gently tapering downwards to a pointy tip, 1.3 cm wide at the apex and 0.8 cm wide near the base; the stipe surface is yellow in the apex, covered with a coating of reddish-cinnamon scruffy dots/pruina below, ridged in the apex and coarsely reticulated below down to about the middle and more or less smooth below and down toward the base; the stipe flesh is generally concolorous with that of the cap, but with deep yellow areas below the stipe surface and in the base, not staining blue.
The basal mycelim is both white and yellow (see pix).
The spore print is yellowish olive-brown when fresh, pale grayish-olive at low humidity.
Macrochemical Tests: KOH = mahogany/brown on the cap pellicle; amber brown on cap flesh. NH4OH = green flash under the reagent drop and green halo (due to vapors), resolving brown; yellow-brown to olivaceous-brown under the drop with pinkish ring around it and a malachite-green halo on cap flesh(see pic).
Spore Data & Discussion: Mounted in Melzer’s and measured only in the profile (dorsi-ventral) view; [20/1/1], L x W = (10.5-) 11.6~14.6 × 4.2~4.7 (-4.9) μm, L’ x W’ = 12.9 × 4.5 μm; Q = (2.37-) 2.48~3.2 (-3.32), Q’ = 2.87, cylindric to elongate based on the Q values; dingy yellow to greenish-yellow and persistently dextrinoid in the posterior half, the dextrinoid reaction varies from a light pinkish hue to a pronounced medium brownish-red infusion; moderately ventricose and spindle-shaped and sometimes constricted in the anterior end in the area of the suprahilar plage in the face (dorsal/ventral) view; inequilateral, subfusiform to fusiform and somewhat ventricose, with a well-defined suprahilar plage in the profile view.
For their own collections of illudens, Smith & Thiers (The Boletes of MI) report spores of 10-14 × 4-5 μm that are “…bluish gray slowly becoming brownish in Melzer’s (fleeting amyloid), rarely slightly dextrinoid…”. I didn’t notice any fleeting amyloid reaction in 293363 probably because (1) I was not looking for it and/or (2) because by the time I finally looked at the spores at x1000, the reaction could have already run its course. Smith & Thiers’ examination of the spores from Peck’s illudens type is reported as 11-13 × 4-4.5 μm, “in Melzer’s merely slightly tan…”. The dextrinoid property of spores of any intensity is absent in their collections of spacideus/spadiceus var. gracilis, subtomentosus/subtomentosus var. perplexus and tenax. I don’t know what to make of the dextrinoid spores of 293363 in the context of its tentative identification as illudens – based on the macromorphological traits of this collection and matching them to the literature descriptions of this taxon – but other existing collections of this entity, e.g., obs 245956, obs 249274 and obs 249357 should perhaps be examined for repeatability this interesting property.


Right half of fb tested with ammonia (middle) and KOH (to the right)
Dextrinoid spores
Smallest spore (lower left corner) & 2nd to largest spore (below “10 tick”)

Proposed Names

29% (1)
Used references: Obs 245956 collected in the same spot
Based on chemical features: Staining of cap and cap context with KOH and NH3

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= Observer’s choice
= Current consensus


Add Comment
Observation updated
By: I. G. Safonov (IGSafonov)
2017-10-30 19:20:35 CDT (-0400)

Spore measurements & pix posted and notes updated/edited.