When: 2017-08-22

Collection location: Tsukuba, Ibaragi, Japan [Click for map]

Who: lxjfx

Specimen available

Growing under hardwoods

Cap flesh stains blue slightly when cut; pores blueing when injured; flesh at stipe apex reddening when cut; basal tomentum white; pileipellis trichoderm; spores brown, smooth, hyaline, (8.506-)9.12-10.46(-11.514) x (3.418-)3.68-4.2(-4.358) µm, Q:2.13-2.84, N:20

Species Lists


Pileipellis (1 div = 2.59μm)
Spores (1 div = 1μm)

Proposed Names

30% (2)
Recognized by sight
Used references:
- Šutara, J. O. S. E. F. “Xerocomus sl in the light of the present state of knowledge.” Czech Mycol 60.1 (2008): 29-62. http://www.natur.cuni.cz/~botanika/cvsm/CM60104F.pdf
Based on microscopic features:
- Pileipellis is composed of trichoderm
4% (2)
Recognized by sight: Reddish stem, slight blue staining
56% (1)
Used references: “Hourangia, a new genus of Boletaceae to accommodate Xerocomus cheoi and its allied species”: Zhu, Wu, Zhao, Halling & Yang, Mycol. Progr. 14(37): 5 (2015)
Based on chemical features: BLASTn results of the TEF-1-alpha sequence

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

= Observer’s choice
= Current consensus


Add Comment
Good info, lxjfx
By: I. G. Safonov (IGSafonov)
2018-01-21 17:49:30 PST (-0800)

It’s all coming together nicely, but we are still lacking a name for your collection. :-)

By: lxjfx
2018-01-21 17:23:53 PST (-0800)


LSU sequences of specimen listed above are 96% match to HKAS 68178.
They are also morphologically similar to MO287702.

“black spots” Discolorations
By: lxjfx
2018-01-21 06:32:46 PST (-0800)

I could not observe.

By: I. G. Safonov (IGSafonov)
2018-01-20 08:18:51 PST (-0800)

Yep, the black spots give it away. I didn’t see these when I searched for nigromaculatus pix a couple of days ago online. Perhaps I didn’t scroll down far enough. There were many photos of these xerocomoid boletes claimed to be the species, but none had the spots.
Did yours have the discolorations? By the way, your spore measurements are very close to those of Hongo.

By: lxjfx
2018-01-20 02:54:45 PST (-0800)
By: lxjfx
2018-01-19 05:06:14 PST (-0800)


The names listed above are species of Xerocomus with records discovered in Japan by 2007.

I see
By: lxjfx
2018-01-18 23:24:27 PST (-0800)

Thanks for the detailed information, IGSafonov!

By: I. G. Safonov (IGSafonov)
2018-01-18 22:48:55 PST (-0800)

The species epithet means “black-spotted”, referring to the “the blackish staining of cap and stem”.1 Hongo’s original morphological description on page 170 in Ref. 1 is in Latin! I also found a description of X. nigromaculatus in French accompanied by a good picture that appears to be in line with the description.2 It doesn’t look like your mushrooom at all.
There is a single LSU accession of nigromaculatus in GenBank, KX575653, suitable for inferring basic phylogeny at the genus level. I don’t know if this voucher was properly identified, but it definitely clades in Xerocomus. Your mushroom is likely to belong in Hourangia based on both the marco-morphology and molecular data.

1 http://www.jjbotany.com/pdf/JJB_041_165_172.pdf
2 http://www.mycodb.fr/...

Xerocomus in Japan
By: lxjfx
2018-01-18 21:20:00 PST (-0800)

Xerocomus nigromaculatus is popular in Japan and is similar to this specimen.


According to the reference, “Xerocomus nigromaculatus (Hongo 1966) is similar to H. cheoi. However, X. nigromaculatus differs from H. cheoi by the blackish staining of the pileus and the stipe.”1.
However, both species have the feature of reddening to blackening flesh, I think that it is not evident to make them different species only by the feature.

1 “Hourangia, a new genus of Boletaceae to accommodate Xerocomus cheoi and its allied species”: Zhu, Wu, Zhao, Halling & Yang, Mycol. Progr. 14(37): 5 (2015)

You are welcome, lxjfx
By: I. G. Safonov (IGSafonov)
2018-01-18 17:06:53 PST (-0800)

Do you think your mushroom has a name? Could it have already been published as a Xerocomus? Are there any modern field guides featuring the Boletales of Japan? If not, you are probably staring a new taxon because Hourangia is a small genus and your collection is not any of the known taxa. Do a bit more microscopy, sequence a couple of additional loci, and you can publish a paper. :-)
You have probably seen my analysis of obs 288004, which is definitely a member of Lanmaoa, probably L. angustispora. I have the LSU of obs 242876 match that of 288004, so the two are likely conspecific. So far this locus did a good job resolving taxa in Lanmaoa.
More data will be posted soon – stay tuned. :-)

Thanks IGSafonov,
By: lxjfx
2018-01-18 15:51:37 PST (-0800)

The characteristic that the stipe becoming brownish after reddening (image 775872) also supports that this specimen belongs to the genus Hourangia.

DNA sequencing discussion and results
By: I. G. Safonov (IGSafonov)
2018-01-17 22:37:54 PST (-0800)

> A clean and contiguous TEF-1-alpha sequence of 671 bps was obtained from this material and posted to this observation. There are no ambiguous characters.
> A BLASTn search gave multiple Hourangia sp. accessions as top hits in the 88-95% similarity range (all listed as Xerocomus, but a search of species names in Index Fungorum led to a Hourangia paper). The top hit is a yet unidentified Hourangia sp. voucher HKAS-68178, followed by Hourangia macrocarpa at ~94%.
> Hourangia is a really neat genus in the subfamily Xerocomoideae. Phylogenetically, it’s “sandwiched” between Phylloporus and Xerocomus being more closely related to the former genus. Indeed, morphologically some of its species with their wide-pored and decurrent tubes look a bit like hybrids of a gilled bolete and a xerocomus. “Hourangia” means “thick hymenium” in Chinese (see the ref. listed in name proposal), referring a diagnostic morphological trait of the tubes being 3–5 times thicker than the pileal context.

Another possibility
By: I. G. Safonov (IGSafonov)
2017-08-23 10:15:50 PDT (-0700)

is Xerocomellus – e.g., Xe. communis.

Interesting species, lxjfx
By: I. G. Safonov (IGSafonov)
2017-08-23 10:03:06 PDT (-0700)

You could try matching it to Xerocomus from China in the following relevant paper (downloadable pdf): https://www.researchgate.net/...
It has both pix and descriptions of many Xerocomus species.