Collection_#: OMS 300102
Collector: Joseph D. Cohen (Joe Cohen)
Habitat: Mixed forest, largely hardwood, largely riparian
Substrate: Soil
Nearest_Tree: hardwood, possibly Fraxinus latifolia (Oregon Ash), see photos of branch, bark of nearest tree; also nearby but not as close: Alnus (Alder)
Habit: few
Taste: indistinct, slightly sweet
Odor: indistinct
Spore measurements:
(6.7) 7 – 8 (8.8) × (4.4) 4.6 – 5.6 (5.8) µm
Q = (1.3) 1.4 – 1.6 (1.7) ; N = 20
Me = 7.6 × 5.2 µm ; Qe = 1.5
Piximètre 5.9 R 1532 : le 1/07/2018 à 07:41:50.7726508

Other: Chemical: context negative in KOH, NaOH, FeSO4; cap surface negative or darker in KOH, NaOH, negative in FeSO4

Tube layer: 3.5-4.5mm thick


slight older basidiocarps
includes branch of nearest tree
bark of nearest tree
arrows show nearest tree, mushrooms
MO 321297 OMS 300102 tubes (1).jpg
tube layer
MO 321297 OMS 300102 spores unmounted.jpg
MO 321297 OMS 300102 spores Melzers.jpg

Proposed Names

56% (1)
Recognized by sight
57% (2)
Recognized by sight: Growing with ash, veiny pores, sideways cap
Used references: North American Boletes easily rules out the other candidates below

Please login to propose your own names and vote on existing names.

= Observer’s choice
= Current consensus


Add Comment
BLAST of Obs 146484
By: Joseph D. Cohen (Joe Cohen)
2018-07-02 13:49:14 UTC (+0000)

Note that while the sequence of Observation 146484 is a 99-100% match to 3 B. meruliodes Genbank sequences, it’s also a 90-91% match to 2 other sequences (from Florida).
Will the real B. merulioides please stand up? Probably not until there’s a type sequence.

Spore data
By: I. G. Safonov (IGSafonov)
2018-07-01 18:33:08 UTC (+0000)

Joe, your measurements (importantly obtained from a spore print) are significantly different than those reported for B. merulioidies. The spores are clearly shorter and narrower. These data suggest, as I already suspected, your mushroom is a different taxon.
If this critter is endemic to the PNW/West Coast and the tree-aphid-mushroom relationship checks out, the question still remains as to why there have been so few sightings so far and why they are restricted to a narrow geographic area.

How did it get here?
By: Joseph D. Cohen (Joe Cohen)
2018-07-01 17:55:05 UTC (+0000)

Great question by Igor: (How did this taxon arrive at this narrow geographic range?) I won’t speculate. But I do note that the question remains regardless whether this and the other far western observations/collections id’d as B. merulioides are actually that species.
Also good point about possible human introduction. One should not assume that the possible tree associate is Fraxinus latifolia (Oregon Ash); I’m very weak on tree identification and I consulted only a western guidebook. It could be an imported eastern Ash (or something else entirely).
I’m tied up for about 10 days, but will then try to have a closer look at the tree, especially to see if I can find aphids.

microscopy failure
By: Joseph D. Cohen (Joe Cohen)
2018-07-01 17:41:25 UTC (+0000)

Due to my technique, age/condition of this collection, and/or inherent nature of the taxon, I could not decent microscopy of the tubes — just an undifferentiated gelatinous mess.

Spores — from a deposit – are slightly smaller than Smith’s description (7.6 × 5.2 µm vs 7-10 × 6-7.5µm), but otherwise consistent with it: shape, color, dextrinoid, smooth, lack of apical pore, slightly thick wall.

Great discussion, indeed!
By: I. G. Safonov (IGSafonov)
2018-07-01 00:36:43 UTC (+0000)

I’ve been giving this and the related observations some thought. Let’s suppose for a moment that 321297 et al. from OR are indeed B. merruliodies. The biggest question I have is how this species wound up naturally on the other side of the Rockies considering that (1) it’s not some ubiquitous and unfastidious saprobe, 2) there is no overlap in bolete flora between the two coasts and 3) the natural range of B. merrulioides from east to west pretty much coincides that of the eastern ash species as per its MO observations. Even if one considers this unique tree-fungus-insect relationship to be more wide-spread and more commonplace – allowing it to occur naturally in a disjunct fashion and to possibly involve additional species of ash and aphid – it’s is not going to be easy to explain in light of only three reports so far, all originating from a narrow geographic range in the PNW) on one hand, and the substantial distribution of F. latifolia stretching from northern WA down to the middle of CA on the other… unless this MO-documented occurrence is an isolated and unnatural introduction perhaps related to some kind of human activity.
Joe, thank you for all your additional research and comments here (I kept checking the obsie repeatedly while writing this comment). One would think that raw Irish potatoes would taste just like raw Idaho potatoes. :-) The pleasant taste of your Oregon Ash bolete perhaps suggests it’s not B. merulioides (wishful thinking, right?). Re the dry vs viscid cap, it could well be a weather dependent feature. As to the additional locus/loci for sequencing, I would go with a protein-coding gene that offers the possibility of a best possible genetic bar code. Maybe RPB-1 or RPB-2?
This discussion reminds to get a bona fide collection of B. merrulioides before our eastern ash trees get completely destroyed by the emerald ash borer. I surmise that with the ultimate extinction of the American ash species, merrulioides may disappear, too, or will at least become very rare.

B. merulioides taste
By: Joseph D. Cohen (Joe Cohen)
2018-06-30 23:55:22 UTC (+0000)

Per Smith: “taste of raw Irish potatoes”; per Miller & Miller: “acidic, unpleasant”.

For me, the tase was sweetish, mild, more like Boletus s.s.; no acidity, not unpleasant. I don’t know how that compares to raw Irish potatoes.

Smith’s description is var. opacus
By: Joseph D. Cohen (Joe Cohen)
2018-06-30 23:35:22 UTC (+0000)

Smith’s description of Boletinellus merulioides in The Boletes of Michigan is of var. opacus Peck, which is dry. The type specimen of B. merulliodes was viscid (per Smith; my Latin is almost nonexistent).

Thanks for the research & suggestion
By: Joseph D. Cohen (Joe Cohen)
2018-06-30 22:50:22 UTC (+0000)

!. Thank you both for your helpful contributions to this interesting discussion.

2. There’s a description of Boletinellus glandulosus (I just added the name to MO) in Peck’s 1909 protolog: It includes:

The dense blackish dots on the tube walls appear at first sight like glands and suggest the specific name. They furnish a singular character which belongs to no other known species of the genus and serves as a ready mark of distinction for this species.

3. MyCoPortal has an Idaho specimen with the name B. merulioides. Not where I’d expect this species to turn up.

4. This collection is about 4 miles (as the pollen flies) from Clackamette Park, where Observation 146484 was collected.

5. Which region(s) — in addition to ITS — would you suggest sequencing?

Re B. merulioides proposal
By: I. G. Safonov (IGSafonov)
2018-06-30 18:50:32 UTC (+0000)

Current literature on B. merulioides suggests it’s a denizen of eastern NA. Reports from Asia are probably erroneous (likely a different species), but this needs to be confirmed. As merulioides is in a mutualistic relationship with the leafcurl ash aphid, a number of intriguing questions need to be answered about this association to consider the possibility of the eastern Ash Bolete occurring in the Pacific North West with endemic species of aphids/ash trees. Here is some useful info on the woolly ash aphid from Oregon State University:
At this time, in addition to this post, there are only two more MO observations of Boletinellus in the PNW: obs 146484 and obs 243037, both also from Oregon! The former was sequenced and its ITS found to match those of several B. merulioides vouchers deposited in GenBank. As ITS is prone to give “false positives”, especially with recently diverged taxa, this needs to be followed up by at least another locus for comparison.

Of the other 3 candidates suggested
By: Leah Bendlin (Leah Bendlin)
2018-06-30 18:14:43 UTC (+0000)

…Gyrodon (Boletinellus) proximus: known only from Florida, pileus dark brown to purplish brown

G. rompelii: Texas south into Mexico and South America. Pinkish red zone near base of stipe, becoming rusty in ages, is distinctive.

Boletinellus glandulosus I cannot find info for, other than that the name exists.

For G. merulioides, characteristics include fruiting under ash, pileus yellowish brown to reddish brown, bruising dull yellow brown. The distribution doesn’t include this far west in North American Boletes (“from eastern Canada south to Alabama, west to Wisconsin, and Mexico”) but I have seen this pop up in the Facebook PNW forum a few times, with ash, and David Arora confirmed it’s also in the PNW.

By: I. G. Safonov (IGSafonov)
2018-06-30 16:26:41 UTC (+0000)

I see you added more pix and notes — good documentation. A cross-sectional photo would be useful, too.
I was about to say that the compound leaves in your pix remind me of the northeastern species of ash, and now looks like your were able to ID the tree to a certainty before I started going over a list of ash tree species in Wikipedia. Is there a parasitic aphid munching on the roots of the Oregon Ash, with which this Boletinellus sp. is associated?
As far as the literature is concerned, it appears Boletinellus has not been comprehensively studied, though Watling transferred 3 species into it in 1997:
I would also add this Index Fungorum link that shows all currently recognized species of Boletinellus: Not sure if this link would work, but the species list therein can be obtained from the general search page of IF.
Looks like there are three described species found in the USA in addition to merrulioides: glandulosus, proximus, rompelii.

Nearest tree
By: Joseph D. Cohen (Joe Cohen)
2018-06-30 15:53:28 UTC (+0000)

Possibly Fraxinus latifolia (Oregon Ash). See Pojar & MacKinnon, Revised Plants of the Pacific Northwest Coast, p. 50 (1994, 2004 printing)

Recommended articles
By: Joseph D. Cohen (Joe Cohen)
2018-06-30 12:04:36 UTC (+0000)

Thanks again.
Another question: Can you recommend any articles which would be useful for identification purposes, other than than the ones I added here?

No problem, Joe
By: I. G. Safonov (IGSafonov)
2018-06-30 05:08:22 UTC (+0000)

Don’t know what species this could be.
It would be helpful to know habitat details, including nearby trees, though it’s not necessarily mycorrhizal. As you know, the eastern Ash Bolete prefers to get its sugar from an insect.

Thanks for Boletinellus suggestion
By: Joseph D. Cohen (Joe Cohen)
2018-06-30 04:39:44 UTC (+0000)

Thanks for the suggestion.
I didn’t have time /equipment to collect this today, but will try to do so tomorrow.
- Joe

Created: 2018-06-30 03:59:36 UTC (+0000)
Last modified: 2018-07-02 13:49:14 UTC (+0000)
Viewed: 258 times, last viewed: 2019-08-13 18:56:29 UTC (+0000)
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