Observation 46788: Rhizopogon Fr. & Nordholm

When: 2010-06-10

Collection location: Sintra, Portugal [Click for map]

Who: zaca

No specimen available

Species Lists


Specimen in which the gleba was liquefied.
Spores and their measures.

Proposed Names

58% (1)
Recognized by sight
-32% (3)
Recognized by sight
80% (3)
Recognized by sight: The thread-like strands on the peridium are called rhizomorphs: root-like forms. The interior is finely loculate (tiny chambered). Need to know more about collection for better suggestion: many Rhizopogon are species specific, found with only a single species of tree or shrub. The gooey section in the bottom photo is an over-ripe specimen, which may be auto-digesting itself. GOOD FIND!

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= Observer’s choice
= Current consensus


Add Comment
By: zaca
2010-06-19 05:40:58 CDT (-0400)

it is a new species, then leave this as Rhizopogon sp .
In fact and speaking of spores dimensions only, although they have the same width as those of R. roseolus are a bit shorter than those of this species. As for the color of the gleba, it may be the result of a process of deliquescense.
I’ll be attentive to new findings. Many thanks, Tuberale.

R. roseolus
By: Daniel B. Wheeler (Tuberale)
2010-06-18 22:01:54 CDT (-0400)

according to Field Guide to North American Truffles, was “… originally described from Europe; the North American version resembles R. vulgaris except it has larger spores and rhizomorphs over all surfaces.” Spores should be “6.5-10 × 3-4 microns, bacilliform, smooth, yellowish singly but brownish in mass.” Your material seems to have smaller mean size spores than R. roseolus. Also, the gleba should be cream with lemon-yellow, not the dark gray or blackish gleba shown in your observation.

I suspect this could be species novum.

Spores measures
By: zaca
2010-06-18 19:12:59 CDT (-0400)

I uploaded an image that includes a photo of the spores as well as their measures which, for convenience, I repeat here:
5.6 [6.8 ; 7] 8.1 × 2.8 [3.5 ; 3.7] 4.4
Q = 1.5 [1.9 ; 2] 2.4 ; N = 106 ; C = 95%
Me = 6.89 × 3.57 ; Qe = 1.95
As far as I can understand the measures now obtained seem to be a point in favour of the species R. roseolus (= R. rubescens). According to the key available in www.natruffling.org this species has larger and wider spores than the others already considered in previous messages: R. luteolus and R. occidentalis, as well as those of the species of the same group, R. ochraceorubens.
Can anyone support this choice?

Re: Fourth photo.
By: zaca
2010-06-15 14:51:12 CDT (-0400)

You are right in both your observations about the fourth photo: (a) The color of rhizomorphs are as you describe; (b) There are some grains of sand. I suppose these are due to runoff of the water in winter time. By the way, the sand that accumulates a bit below that place is very good to colect Cantharellus cibarius. As I told before the place of the Observation is inside a pine forest.
Concerning the species of the pine trees our geographic situation is such that we don’t have Pinus contorta (as far as I known) and our common pine tree is Pinus sylvestris and, in some places, Pinus Pinea.
Thanks to you, the genus of these specimens is already identified and the species maybe one that we have already mention or very close to one of those. Let’s see what microscopy will give me. When I will be able to do it I’ll put here the results.
Thanks again, Tuberale, for your useful comments.

Fourth photo.
By: Daniel B. Wheeler (Tuberale)
2010-06-15 03:58:47 CDT (-0400)

Seems to show rhizomorphs which are staining reddish or orange-red. On same photo, grains of what look like sand still adherring to rhizomorphs. If so, this could be closer to R. occidentalis or R. rubescens; or their associated complexes. Dr. A.H. Smith identified some 150 different species of Rhizopogon, and was considered an expert on the genus (the only one?). He mentioned once he did have the largest identified collection of Rhizopogons in the world. But also mentioned he ALSO had the largest collection of UNidentified Rhizopogons in the world.

The people at Oregon State University’s Forest Sciences Lab have done a lot of revising of Smith and subsequent studies. I think there are about 100 or so currently accepted species. Their key keeps changing, but I think it’s about the only one around.

Most of these species are well beyond my scope of expertise: if it’s not found in sand dunes with Pinus contorta, I’m not real certain what species it is. Out of several hundred collections submitted for identification, I have currently found about 20-30 of the known species, including some which are supposed to be species novum. I’m afraid the subtleties of Rhizopogon identification elude me.

Thanks, Tuberale, you helped a lot.
By: zaca
2010-06-15 02:18:38 CDT (-0400)

I will prepare myself a slide to observe under the microscope, but I’ll keep the address, to use just in case or in future.
In relation to the trees existent at the zone, I really mean Q. suber.

By: Daniel B. Wheeler (Tuberale)
2010-06-14 22:01:59 CDT (-0400)

If you have a dried sample of the material, mail it to: Forestry Sciences Lab -020, Attn: Matt Trappe, 3200 Jefferson Way, Corvallis, OR 97331. Dried material can be identified nearly as easily as fresh. (At least, that’s what they tell me.) Include your notes on where and near what trees and shrubs it was found.

I personally have never found R. luteolus. My inexpertise in this area is profound. I apologize. Always willing to share my lack of knowledge with others.

Oak can form mycorrhizae with Rhizopogon too, although it is rarely searched under. You stated Quercus suber? Not Quercus ruber?

Material with liquified interior are not easy to deal with. Mostly, they are too wet to make good long-term herbaria collections.

I have not seen a Rhizopogon with the particular tint of your observation.

Thanks, parks229 and Tuberale, for your proposals
By: zaca
2010-06-14 12:40:41 CDT (-0400)

Tuberale, can you be a bit more precise about what is needed to go further?
I understood from your comments that the trees and shrubs in the zone may be important. As far as I remember there were no tree in a radius of 4-5 metters. The place is the top of a hill inside a pine tree forest, having a road at one of is sides. Beyond pines (Pinus sylvestris) there were some Quercus suber nearby.
After your comment I looked into my field guide and I found a species whose description seems to match: Rhizopogon luteolus, but there may be others.
I upload another photo with a specimen having the interior more liquefied than those originally presented.

Not Scleroderma.
By: Daniel B. Wheeler (Tuberale)
2010-06-14 11:27:34 CDT (-0400)

Scleroderma means “thick skin,” referring to the peridium. Typically Scleroderma have a peridium at least 1mm thick, and often 1-2cm thick. Scleroderma never have rhizomorphs. Nor do they have a loculate (chambered) gleba (interior).

Created: 2010-06-13 08:13:51 CDT (-0400)
Last modified: 2010-06-20 13:44:38 CDT (-0400)
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