Observation 217160: Caloboletus Vizzini

A single fruiting body growing in grass in a small stand of beech trees close to edge of woods and next to the trich of obs 217153.
Description: The cap is glabrous, grayish-tan, reminiscent of B. pallidus.
The cap margin has a narrow band of sterile tissue. The pore surface is pale yellow, bluing when injured. The stipe is of raspberry rose (#B3446C) to raspberry (#872657) color, has a mostly smooth or slightly ribbed texture here and there, with a fine reticulation and vertical ridging at the apex and just below (see the pix). The exposed context shows a remarkable staining action consisting of blue, yellow and reddish-brown (see the pic). The taste is bitter, but not as harsh as the bitter bolete, and slightly astringent. Chemical tests were not performed.

Molecular Data Discussion: A clean and contiguous 1443 bps nrLSU sequence has been obtained for this material. The identity of the 124th nucleotide is ambiguous and is represented by “N”. A GenBank BLAST search of sequence fragment 1—>972 returned the following relevant results (sorted by identity):
Caloboletus radicans #KJ184557 = 98.9% similar
Caloboletus rubripes #KF030280 (Western USA) = 98.9% similar
Caloboletus polygonius #KU317763 (Greece) = 98.8% similar
Caloboletus panniformis #KJ605674 (China) = 98.6% similar
Caloboletus panniformis #KJ184555 (China) = 98.6% similar
Caloboletus rubripes #KT968656 (Western USA) = 98.6% similar
Caloboletus calopus # KF030279 (Western USA) = 98.5% similar
Caloboletus inedulis # KF030281 (Eastern USA) = 97.8% similar

Molecular sequencing of the nrLSU locus supports the original identification made from gross morphology as Caloboletus. Genetically, the closest USA relative at this time is Caloboletus rubripes. However, this bolete looks sufficiently different from any other member of Caloboletus found in northeastern North America (C. firmus, C. inedulis and C. roseipes), and the molecular data is in agreement with gross morphology. Also, there are no perfect matches recovered from a GenBank search of nrLSU sequences. Taken together, the evidence suggests an undescribed/new taxon from North America.

Species Lists


Proposed Names

86% (1)
Recognized by sight
Based on chemical features: A nrLSU sequence of this material aligned well with a bunch of Caloboletus spp. The closest NA relative is C. rubripes. There were no perfect matches in GenBank, suggesting this is a new North American taxon.

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= Observer’s choice
= Current consensus


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