Observation 120075: Rhizopogon Fr. & Nordholm
When: 2012-11-19
Herbarium specimen reported

Notes: Phil (gunchky) sent me this collection for further study. I have received the dried sporocarp, found under Pinus resinosa (Red pine), and taken further photos. The original collection was sent with cotton padding, which I could not completely remove. Any white threads still adherring to the dried collection should be easy to discount.

As dried, sporocarp is slightly larger than a Jefferson Nickel (21.2mm diameter). I would estimate size at 25mm x 18mm. Peridium has dried to mostly black with dark brown highlights, knobbly, no indications of the rhizomorphs present on the fresh specimen (see MO obs. 117317). Gleba sepia to light brown with olivaceous highlights, but also with black to brownish-black areas; loculate, locules less than .2mm across, scattered. As fresh, gleba included areas of white, off-white, olive, olive-yellow, light brown and red.

Gleba does not appear to have any gel or gel-like material in it. But the only Rhizopogon I can find reference to with Pinus resinosa was Rhizopogon olivaceoniger, which was renamed by Trappe in 1975 to Alpoa o. I have found many collections of Alpova diplophloeus, and have also collected Pachyphloeus. This collection as dried does not seem to match any of those.

Species Lists

Images

293690
Dried gleba mostly light brown, sepia, dark brown to black. Minutely loculate. Locules about 0.02.-0.04mm diameter.
293691
Peridium of dried sporocarp mostly black or dark brown, with light brown highlights. Some white cotton threads still attached.
293692
This close-up shows darkest colors of gleba, plus a feature not seen in the other half: rows of tissue.

Proposed Names

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Used references: NATS Field Guide To Selected North American Truffles and Truffle-like Fungi.

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Comments

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Phil replied
By: Daniel B. Wheeler (Tuberale)
2012-12-16 13:53:42 PST (-0800)

the peridium was dry as found. The gleba was moist, but not tacky or soggy. He also noted the taste was bitter.

From Key to Spores of the Genera of Hypogeous Fungi of North Temperate Forests
By: Daniel B. Wheeler (Tuberale)
2012-12-15 21:14:32 PST (-0800)

by Castllano, Trappe, Maser & Maser, c. 1989, Mad River Press, Inc.

“Gleba: Solid, gelatinous, often sticky to the touch, the spores being borne in a gelatinous matrix that fills the chambers walled off by meandering veins. This is the primary difference of Alpova from Rhizopogon, which has chambers that are empty or at times filled with spore powder but not a gelatinous matrix.”

Trappe transferred several species of Rhizopogon into Alpova in 1975 (Trappe, J.M. A revision of the genus Alpova with notes on Rhizopogon ad the Melanogastraceae. Nova Hedwigia Beih. 51:279-309; 175a.) Among those transferred to Alpova was Rhizopogon olivaceoniger, originally described from Nova Scotia under Red pine (Pinus resinosa).

This obs. does not look to have any gel in any chambers, but does contain locules, which are small chambers related to both Alpova and Rhizopogon. As this obs. does not have any gel mentioned in the original notes on the collection, it should be considered Rhizopogon.

Created: 2012-12-15 13:16:45 PST (-0800)
Last modified: 2012-12-15 13:18:16 PST (-0800)
Viewed: 52 times, last viewed: 2016-04-28 16:56:31 PDT (-0700)
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