Observation 209030: Suillus granulatus group

When: 2015-07-05

Collection location: Lake John, Pennsylvania, USA [Click for map]

Who: Dave W (Dave W)

No specimen available

Under white pine.

Proposed Names

61% (3)
Recognized by sight
-2% (2)
Recognized by sight: The North American “S. granulatus” is S. weaverae
Used references: Nguyen, N., Vellinga, E. C., Bruns, T. D., & Kennedy, P. (2016). Phylogenetic assessment of global Suillus ITS sequences supports morphologically defined species and reveals synonymous and undescribed taxa. Mycologia, 16-106.
86% (1)
Eye3 Eyes3
Recognized by sight
Used references: See comments.

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
Yes, Dave,
By: I. G. Safonov (IGSafonov)
2016-12-23 13:22:09 PST (-0800)

you are correct and my Fuscoboletinus comment is rather weak. Still, aside from the spore print color, there is a bigger problem in the form of a “fibrillose to cottony” partial veil present in MGW-1086.

According to what I read…
By: Dave W (Dave W)
2016-12-23 12:54:03 PST (-0800)

(see link in previous comment), the original placement of weaverae in Fuscoboletinus was based on spore-print color.

By: I. G. Safonov (IGSafonov)
2016-12-23 12:47:55 PST (-0800)

Sorry to cut into your discussion, gents…
It is interesting that A.H. Smith and his colleagues (R.L. Shaffer and H.D. Thiers) never considered the possibility of synonymy of S. weaverae and the American “S. granulatus” on account of the two being different morphologically to the extent that the former was originally placed into Fuscoboletinus. The same goes for S. lactifluus even though its morphological affinity to “S. granulatus” is implicitly mentioned in The Boletes of Michigan. Furthermore, Smith & Thiers (1971) report S. lactifluus growing under P. strobus, a soft pine, whereas all the collections of Nguyen et al. are associated with P. resinosa, a hard pine. If S. lactifluus is indeed exclusively a hard-pine associate, collections by Smith & Thiers may represent S. granulatus in the sense of American authors.

The original descriptions of S. weaverae can be found at:

http://www.mykoweb.com/... (scroll down to PAGE 88)

For some reason, Nguyen et al. don’t directly address the identity problem existing with the two S. weaverae vouchers, both collected by Margaret G. Weaver (hence the species epithet). Voucher MGW-1992 from year 1969, used in the original phylogenetic treatment of the genus Suillus by Kretzer et al. {Mycologia 88(5): 776-785 1996}, may not not be the same species as the holotype MGW-1086 from year 1964 (= MICH343243 in Nguyen et al.), as the two entities don’t clade together.

By: Django Grootmyers (heelsplitter)
2016-12-23 11:50:21 PST (-0800)

Nguyen et al. mention that the holotype of S. weaverae was infected with a Hypomyces species but they don’t mention anything about a veil.

The following link…
By: Dave W (Dave W)
2016-12-23 11:27:03 PST (-0800)

is a description of S. weaverae (as understood previous to the possible merger with S. granulatus).
There is mention of a veil sheathing the lower stipe in young specimens. This does not jive with my concept of granulatus. However, it’s possible that what had originally been called weaverae is an atypical form of what has generally been called granulatus.

By: Django Grootmyers (heelsplitter)
2016-12-23 10:51:52 PST (-0800)

I proposed the ID before seeing that the North American “S. Lactifluus” specimens in the cladogram were S. granulatus and probably introduced from Europe. The true S. granulatus is mycorrhizal with hard pines though, so this is most likely either S. weaverae or something else. I don’t really know all that much about Suillus though and I’m not sure how to differentiate Nguyen’s concepts of S. weaverae and S. granulatus other than ecology.

The name Suillus weaverae…
By: Dave W (Dave W)
2016-12-23 09:38:00 PST (-0800)

is proposed as a replacement for the NA S. granulatus. But according to information recently gleaned from a discussion, the original description of S. weaverae does not appear to fit this species. Moreover, the molecular data appears to be anything but conclusive.

I think it’s best to continue to call this NA entity “granulatus” until a new name has been properly reviewed/established. Recall a few years ago how the NA Morchella “esculenta” went from esculentoides to califiornicus to americana.

Created: 2015-07-05 19:43:35 PDT (-0700)
Last modified: 2017-12-01 10:33:37 PST (-0800)
Viewed: 145 times, last viewed: 2018-04-04 15:57:29 PDT (-0700)
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