Aureoboletus projectellus

What You Should Know

Aureoboletus projectellus is a species of bolete fungus in the family Boletaceae. Found in North America, and recently in Europe, it grows in a mycorrhizal association with pine trees.

The fruit bodies of Aureoboletus projectellus grow singly, scattered, or in groups on the ground in a mycorrhizal association with pine trees. In North America, its range includes eastern Canada (New Brunswick) south to North Carolina and west to Michigan.

Yellow pores age toward brown & bruise lemon yellow. Cap shape often shifts from a hamburger bun to a “cupcake” shape as the tubes extend in maturity. Cap surface often cracks in age. Whitecap flesh often has a rosy tinge & slowly stains yellow-brown. Likes pine. An eastern version of the Admirable Bolete (B. mirabilis).

DNA testing moved this mushroom into the newly erected genus “Aureoboletus” (“Aureo” from the characteristic sunny-yellow pores).

Aureoboletus projectellus Mushroom Identification

1. Ecology

   Mycorrhizal with a variety of pines (species of Pinus, with bundled needles); growing scattered or gregariously; summer and fall; widely distributed in eastern North America from the northeast to the upper Midwest and the southeastern United States, through Texas into Mexico.

2. Cap

   4–14 cm; convex, becoming broadly convex; tacky to sticky; bald; dark brown to dark reddish-brown or purplish-brown; the margin with an overhanging, sterile portion projecting 1–3 mm.

3. Pore Surface

   Pale yellow, becoming olive-yellow and eventually dirty brownish olive; depressed at the stem; not bruising—or, occasionally, bruising blue; 1–2 pores per mm at maturity; tubes to 1.5 cm deep.

4. Stem

   6–17 cm long; 1–3 cm thick; equal, or with a slightly swollen base; shallowly longitudinally ridged at first, becoming widely and prominently ridged or nearly reticulate with maturity; slightly sticky when fresh; pinkish-brown to brown; basal mycelium white and prominent.

5. Flesh

   White to pale yellowish or pinkish in places; not staining on exposure.

6. Chemical Reactions

   Ammonia black on the cap; grayish on flesh. KOH mahogany on the cap; yellowish on flesh. Iron salts gray on the cap; greenish on flesh.

7. Spore Print

   Olive.

8. Microscopic Features

   Spores 19–29 x 6–10 µm; fusiform; smooth; walls 05.–2 µm thick; golden in KOH. Hymenial cystidia 35–70 x 7.5–10 µm; cylindric to fusiform or lageniform; smooth; thin-walled; hyaline to yellow in KOH. Pileipellis a collapsing ixotrichoderm; elements 7.5–12.5 µm wide, smooth or slightly encrusted, hyaline to golden in KOH; terminal cells cylindric with subclavate or slightly irregular apices.

Sources:

Photo 1 - Author: Agnieszka Krawczyk (Creative Commons Attribution-Share Alike 4.0 International)

Photo 2 - Author: dario.z (dario13) (Creative Commons Attribution-Share Alike 3.0 Unported)

Photo 3 - Author: RuslikUA (Creative Commons Attribution-Share Alike 4.0 International)

Photo 4 - Author: Barbara Rybicka (Creative Commons Attribution-Share Alike 4.0 International)