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Leccinum longicurvipes (Snell & Smith) comb. prov.*

= Boletus longicurvipes Snell & Smith, 1940

by Michael Kuo


Leccinum longicurvipes is mycorrhizal with oaks in eastern North America. It is a slender and fairly small species with a slimy (when fresh) orange to orange-brown cap, a dull yellowish pore surface, and a whitish stem adorned with fine, pinkish to pinkish brown scabers. A drop of KOH on the cap surface produces a bright red reaction. Under the microscope, Leccinum longicurvipes features a semigelatinized pileipellis disposed as a cutis and large, fusoid-ventricose to fusoid caulocystidia that are hyaline in KOH.

Technical Description:

Ecology: Mycorrhizal with oaks; often found in woods where oak is mixed with Pinus strobus; appearing alone or gregariously in August and September. Analysis of 40 collection records from online herbaria (see Figure 1) reveals only a few records in which oak is actually excluded by the collector's brief notes. One of the records excluding oak is accompanied by a photo that does not match Leccinum longicurvipes; another is accompanied by notes recording a "stipe base soon bright turquoise when cut," which might exclude Leccinum longicurvipes since it is the only recorded instance of bluing flesh for the taxon; the remaining records that exclude oak all describe ecosystems where oak may easily have been present but not noted (under huckleberry bushes in Michigan, in a mixed conifer-hardwood forest in Michigan, under white pine and rhododendron in North Carolina, and under white pine in Massachusetts).

Distribution: Apparently widely distributed east of the Great Plains. Figure 2 represents Leccinum longicurvipes collections in online herbaria. I have examined fresh and dried collections from Missouri.

Macromorphology: Pileus 1.5-8 cm; convex becoming broadly convex; surface viscid, glabrous; often pitted or rugose-reticulate with a reddish brown reticulum; orange when young, fading to dull orangish brown, reddish brown, or yellowish; sometimes with olive hints at maturity; margin often with a tiny sterile extension. Context white or yellowish; unchanging when sliced and exposed to air. Tubes to 2 cm long; pale yellowish, developing greenish hues; pore surface pale yellowish becoming greenish gray, not bruising, depressed at the stipe by maturity; 2 round pores per mm. Stipe 5-10 cm long; 8-15 mm wide at apex; at maturity more or less equal or tapering to apex; often curved; whitish apically, pinkish brown below; finely scabrous with whitish to pinkish, reddish, or reddish brown scabers; basal mycelium whitish to yellowish. Odor and taste not distinctive. Exsiccata with medium brown pilei, dingy brownish yellow pore surfaces (sometimes with olive hints), and fairly bright brownish gold stipe surfaces adorned with brown to reddish brown scabers. Spore print dull olive to light brown. The original description records a "ferruginous-brown" spore print color, but this is an apparent typographical error since the sentence also describes the spores as "dull olive to light brown" under the microscope, with an unspecified mounting medium; when the color reactions to KOH and Melzer's in the 1971 description (which does not specify a print color) are compared, a reasonable interpretation is that the original description inverted the two color descriptions within the sentence.

Chemical reactions: Ammonia negative on context, pinkish red on pileus surface; KOH negative on context, bright red on pileus surface. Iron salts negative on context, according to Smith & Thiers (1971), but this assessment may be based solely on Smith 67602, which might not be Leccinum longicurvipes (see discussion under Figure 1).

Micromorphology: Basidiospores subfusoid; inamyloid; yellowish in KOH; smooth; 13-18 x 4-6.5 µ. Basidia clavate; four-sterigmate; up to 26 x 12 µ. Hymenial cystidia (Figure 3) variously shaped but mostly fusoid-ventricose (often with a long neck); up to 50 x 14 µ; hyaline in KOH; scattered. Pileipellis (Figure 3) a densely interwoven cutis composed of repent and erect elements 4-10 µ wide, somewhat gelatinizing; terminal elements cylindric with rounded apices or occasionally subclavate and inflated slightly, to about 15 µ; hyaline to ochraceous in KOH. Caulocystidia (Figure 3) in bundles with caulobasidia; mostly fusoid-ventricose to fusoid; often with a long, pointed neck; up to 80 x 20 µ or longer; hyaline in KOH.

Molecular Data: One partial sequence has been deposited in GenBank: AF139685 (partial 28S large subunit ribosomal RNA, deposited by Binder & Besl without a voucher or herbarium citation), aligned by Binder & Besl (2000), Binder & Hibbet (2004) and by den Bakker & Noordeloos (2005). The Binder & Hibbett and den Bakker & Noordeloos alignments are similar (though not identical), placing AF139685 in a clade with DNA from specimens identified as Leccinum subglabripes and Leccinum rubropunctum.


Leccinum longicurvipes

Leccinum longicurvipes

Leccinum longicurvipes

Leccinum longicurvipes
Figure 1

Leccinum longicurvipes
Figure 2

Leccinum longicurvipes
Figure 3

Leccinum subglabripes
Boletus longicurvipes
AHS 10320
Courtsey of the University of Michigan Press and Herbarium


The description of the caulocystidia above is, to my knowledge, the first for this taxon; it is based on ASM 10042 and ANM 446 in EIU. Snell & Smith (1940) did not describe caulocystidia in the original account; Smith & Thiers (1971) did not include a description of caulocystidia, despite patiently recording the data for the type collection of Boletus rubropunctus (caulocystidia primarily clavate) in the course of an argument against synonymy for the two taxa. The European treatment of Leccinum by den Bakker & Noordeloos (2005) found shape and pigmentation of caulocystidia to have some predictive value in limited taxonomic areas.

My hypothesis is that Leccinum longicurvipes is morphologically distinct from Leccinum rubropunctum, which I have treated as an "uncertain" taxon because it is poorly documented. Molecular results (Binder & Hibbett, 2004; den Bakker & Noordeloos, 2005) ostensibly support my hypothesis, but should be discounted. See my treatment of Leccinum rubropunctum for a full discussion of these issues.

References and Material Studied:

Collections Examined: MISSOURI: Kuo 09240500 (Stoddard County), A. S. Methven 10042 (Wayne County; EIU). NORTH CAROLINA: A. N. Miller 446 (Macon County; EIU).

Collection Notes Examined: H. E. Bigelow 15796 (Massachusetts, 1969; NY); 17818 (Massachusetts, 1978; NY); A. H. Smith 10133 (Tennessee, 1938; MICH), 10507 (Tennessee, 1938; MICH), 67602 (Michigan, 1963; MICH), 81618 (Michigan, 1972; MICH), 81810 (Michigan, 1972; MICH), and 86227 (Michigan, 1975; MICH).

Online Herbarium Records Examined: NY: 15; MICH: 23; OSU: 0; TENN: 1; BPI: 1.

Field Guides and Online Treatments: Smith, Smith & Weber, 1981; Weber & Smith, 1985; Phillips, 1991/2005; Bessette, Roody & Bessette, 2000; Roody, 2003; Phillips, 2007.

Technical References: Snell & Smith (in Snell, Smith & Thiers), 1940; Coker & Beers, 1943 (data not included above; treated as a synonym of Boletus rubropunctus), Singer, 1947 (data not included above; treated as a synonym of Leccinum rubropunctum); Snell & Dick, 1970 (data not included above; treated as a synonym of Leccinum rubropunctum); Smith & Thiers, 1971; Both, 1993; Binder & Hibbett, 2004; den Bakker & Noordeloos, 2005. Full citations for these works can be found here.

* Note: This is not a sanctioned publication, and Leccinum longicurvipes is not an officially accepted combination. Singer placed this taxon in synonymy with Leccinum rubropunctum, but since my hypothesis is that the taxa are distinct his synonymy reference can obviously not be cited as a combination into Leccinum.

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Kuo, M. (2007, March). Leccinum longicurvipes. Retrieved from the MushroomExpert.Com Web site:

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