Caloboletus peckii (Frost) Vizzini

Image location: Meadowood Park, Mendham, New Jersey, USA

Notes last updated/edited on 15-Dec-18 This collection was found at the NJMA foray by Ms. Kyoko Okabe. I am leaning toward Caloboletus sp., but Butyriboletus peckii (the current name) is a conceivable possibility as per the information in North America Boletes(2000, as Boletus peckii) and Boletes of Eastern North America (2016), both by Bessette-Roody-Bessette.

Collection Description: Pileus: 4.5-5.7 cm wide, 1.3-1.5 cm thick in the middle when measured from the surface to the juncture with the stipe, pulvinate/cushion-shaped, margin with a narrow band of sterile tissue; surface dry, slightly subtomentose to smooth and glabrous, not staining when rubbed, dull pinkish-red (near oac498 to oac518 to oac539 when fresh), fading somewhat over time post collection, but still retaining the original hue even after drying/preservation; context whitish to pale yellow, soft (with a marshmallow consistency/texture), readily bluing upon exposure to air; odor fungal but with a rancid note; taste bitter. Pore Surface: buff-yellow to dull medium yellow, becoming grayish/dingy yellow (younger fb) to olivaceus-buff post collection (older fb), instantly bluing when bruised and then gradually resolving pale brown; pores circular and minute, 3-4 per mm; tubes 5-7 mm at the widest point (near the stipe), same color as the pores surface, bruising blue when cut Stipe: 6.0-6.7 cm long (measured in sections), 1 cm thick at apex, 1.4-1.8 cm thick at the base, curved and enlarged downward, dry, solid, with a bright lemon yellow apex, dark rose-red to pinkish-red directly below to the middle and brownish (possibly due to handling) in the bottom section, distinctly reticulate from the apex down to the mid-length, at which point the reticulation becomes a network of shallow vertical ridges, quickly transition to a smooth surface toward the bottom section; the reticulation is yellow in the apex and red below, staining bluish and then brownish upon handling; the base section is covered with a whitish coating/bloom; mycelium is possibly white; context is whitish to pale yellow in the upper section (just like in the cap) and readily staining blue upon exposure to air, reddish to deep raspberry red below and dingy yellow in the base. Spore print: a light coating of spores was directly deposited on a glass slide, but its color could not be visualized against a white background; however, the color appears to be olivaceus-brown when the slide is held up against natural light. Spore measurements: [20/1/1], L x W = (9.1-) 9.3-11.2 x (3.3-) 3.5-4.0 μm in lateral (dorsi-ventral) view; L’ x W’ = 10.3 × 3.7 μm; Q = (2.60-) 2.67-2.94 (-3.00); Q’ = 2.82. Not amyloid, not dextrinoid, and light greenish-buff in Melzer’s; equilateral and generally oblong in face-view (dorsal/ventral) and somewhat to subtly inequilateral and approximately oblong in lateral-view, smooth and thin-walled, cylindrical based on the Q-ratio range. Smith and Thiers (1971) list spore lengths reported by Peck as 0.00035-0.00040" (8.9-10.2 μm). After re-examining Peck’s type, they updated the spore measurements to 9-12 (-13) x 3.5-5 μm. Bessette’s NAB gives spore measurements as 10-14 × 3.5 -5 μm. Macrochemical tests: KOH = dingy yellow/mustard yellow on pileipellis, erased bluing then pale orange on cap context; NH3 = dingy yellow/mustard yellow on pileipellis, erased bluing then pale yellow on cap context; FeSO4 = gray to bluish gray on pileipellis, erased bluing then bluish-gray on blotted cap context (difficult to interpret). Habitat: The collector couldn’t remember the particulars of the habitat, but the boletes grew by the stream. I recall that area being surrounded by deciduous trees, including oak and beech.

DNA Sequencing Results (last updated on 20-Dec-18): > A clean and contiguous nrLSU sequence of 1443 bps was obtained from this voucher. There is a single ambiguous character, a “Y”, corresponding to either “C” or “T”. A BLASTn search of the first 961 characters (to the LR5 primer) did not return any matching or very close hits. When the search results were sorted by % identity, there was no clear indication of this sequence clading in Caloboletus. However, a phylogram built in GenBank from representative well-identified accession associated with a number of genera of yelllow- or red-pored bluing boletes from this hit list gave a clear indication of the association with Caloboletus. Since B. peckii was not on this hit list, I aligned the sole published nrLSU sequence of the alleged collection of peckii (accession JQ326999) with that of MO246697 separately. JQ32699 is only 649 nucleotides long, and it overlays with the 270—>918 bp fragment of my sequence. Even though there are no gaps, the two sequences are 23 bases off, corresponding to only 96.0% similarity. Obviously these two entities are not conspecific. > A clean and contiguous 913 bp TEF-1-alpha sequence was also obtained from this voucher. There are 6 ambiguous characters: two “Y” (C/T) and four “R” (A/G). Four of these (2 x “R” & 2 x “Y”) are present in the 610 bps region circumscribed by the EF1-983F and EF1-1567R primers. Other than the few ambiguities present here, this sequence is a perfect match to the corresponding regions in those of obs 286214 (my other NJ collection) and Robert G.‘s obs 283600 from CT, making these three collections conspecific. These three sequences finally published in GenBank on 10-Dec-18 (MH318614, MH337297, and MH347321). The only previously published TEF-1 accession of the alleged collection of peckii (JQ327026) is 1117 bps long. Its alignment with MH318614 (this obsie) revealed that common overlap is only 621 bps long. There are a total of 58 mismatching positions, corresponding to the very low similarity of 91%. A BLASTn search of a 610 bps sequence fragment (the region between & including the EF1-983F and EF1-1567R primers) produced a hit list from which a phylogram was built in GenBank to probe the phylogenetic relationships. It’s been annotated for clarity and uploaded to this post.

Discussion: > Once a common taxon, nowadays Boletus peckii Frost in Peck is an infrequently encountered North American bolete.^{[#fn1 1]} Interestingly, the aforementioned field guides by Bessette et al. draw a morphological parallel with Baorangia bicolor, the only significant difference between the two being the reticulation usually seen in peckii and its unpalatable taste. > In 2014, B. peckii, along with a number of other bolete taxa from Boletus sect. Calopodes Fr. emend. Lannoy & Estadès, was transferred by A. Vizzini into Caloboletus Vizzini gen. nov.^{[#fn2 2]} Morphologically, it differs from the typical members of Caloboletus (now delimited by a number published molecular studies) by the color of its cap; however, its inherently bitter taste is one of key defining traits of this genus. > In 2015, Zhao et al. transferred C. peckii into Butyriboletus D. Arora & J.L. Frank based on the phylogenetic analysis of the aforementioned alleged peckii collection, known as “voucher 3959”.^{[#fn3 3]} According to N. Siegel (see his comment below) and Reference #1, voucher 3959 – collected by R. Petersen in Tennessee in 1963 – could very well be a misidentified collection of Boletus speciosus or perhaps another member of North American Butyriboletus. > In terms of gross morphology, MO246697 is a very good match to the original description of B. peckii.^{[#fn4 4]} The bitter taste, the yellow pore surface bruising blue, the reticulated stipe, and the bluing of the flesh all point to Caloboletus as the likely generic placement for MO246697. Furthermore, the nrLSU and TEF-1 sequences of MO246697 do not match the corresponding molecular data of Petersen’s peckii voucher. The well-document record of MO246697 and the apparent absence of any pictures and/or a description of voucher 3959, further make the identity of Petersen’s collection of peckii questionable. Phylogenetically, MO246697 shows a strong affinity to Caloboletus. Analysis of the TEF-1 sequence in GenBank/BLASTn is attached to this post. The two plausible conclusions drawn from this discussion are that MO246697 is Boletus peckii and that Vizzini was right in making peckii a member of Caloboletus based on the morphology alone. References: ^{[#fn1 1]} http://iucn.ekoo.se/iucn/species_view/223743/ ^{[#fn2 2]} http://www.indexfungorum.org/... ^{[#fn3 3]} https://www.researchgate.net/... ^{[#fn4 4]} https://www.biodiversitylibrary.org/...

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