Observation 118724: Boletus coccyginus Thiers

When: 2012-12-02

Collection location: Mountain View, California, USA [Click for map]

37.4112° -122.1056°

Who: Len (placeport)

Specimen available

Growing under redwoods, pines and other mixed trees and brush. Bright yellow pores not bluing on handling or cutting. Yellow spore print. Mild pleasant odor.

Proposed Names

2% (3)
Recognized by sight
63% (4)
Eye3 Eyes3
Recognized by sight: Red cap, yellow pores, not bluing (or only very slightly so) very rare.

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
More observations and doubts.
By: Len (placeport)
2012-12-13 13:42:13 PST (-0800)

I didn’t keep the spore print — only have some dried pieces of the mushroom. I do have a high-power scope but may not be able to get spores from the samples.

Another description states that the context of coccyginus may redden:

From http://www.svims.ca/council/Bolete.htm#nB39a:

“39a Cap +/- 5 cm wide, bright red granular, yellow background; not bluing

% Boletus coccyginus

CAP bright rosy red when young, with age granular tomentose cuticle cracking to reveal yellow background; small (3-5 cm wide); flesh pale lemon yellow, not bluing on exposure. TUBES and PORES bright greenish yellow, sometimes slowly turning +/- greenish on cutting; pores large for such a small bolete. STEM pale yellow-buff with a little red at top; not reticulate; 4-7 cm x 0.5-1.0 cm; flesh slowly turning reddish-brown on cutting but not blue. HABITAT soil under conifers. DISTRIBUTION rare, known from only two locations in the Pacific Northwest, described from California. EDIBILITY unknown, but too small to be of much value. MICROSTRUCTURES 11.2-17.6 × 5.3-7 um; pileus cuticle a tangled trichodermium staining dark yellow in KOH, walls asperulate to faintly encrusted."

The cap was “plush-like” in appearance.

The cap diameter was about 5" as you can see from photo 4 next to my knife, which measures 7.1" opened.

The pores developed a greenish hue as they deteriorated.

It also resembles campestris, except for no bluing and too big.

Any more thoughts?

it is unusual, but perhaps NOT coccyginus…
By: Debbie Viess (amanitarita)
2012-12-12 19:43:13 PST (-0800)

whose description in Thiers states that the context is pale yellow and unchanging in color (your mushroom pinks).

the cap should be finely velutinous to pubescent and appear “plush-like.”

IF coccyginus, the spores are highly variable in size and shape: got scope?

Also coccyginus is SMALL (cap 2-4 cm across), in size and color like Boletus campestris except w/out the strong bluing.

How big was this mushroom?

It could be coccyginus, but we’ll need more evidence.

Good call.
By: Len (placeport)
2012-12-12 14:53:41 PST (-0800)

I think Boletus coccyginus was a good call by Noah Siegel. Several folks I had asked could not come up with a strong ID. Thanks!

So what is it?
By: Len (placeport)
2012-12-11 16:03:58 PST (-0800)

Consensus opinions anyone??

Might it be Boletus chrysenteron?
By: Len (placeport)
2012-12-11 10:48:40 PST (-0800)

The flesh of both Boletus chrysenteron and Boletus dryophilus are supposed to turn blue when cut, but the former only slightly. This specimen did not show any obvious bluing but the flesh reddened somewhat when cut.

maybe not…
By: Debbie Viess (amanitarita)
2012-12-09 08:26:56 PST (-0800)

should show some bluing and a red context in the stipe base.

Created: 2012-12-03 00:24:04 PST (-0800)
Last modified: 2012-12-12 19:43:23 PST (-0800)
Viewed: 175 times, last viewed: 2017-10-19 21:18:53 PDT (-0700)
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