Gilled boletes are a group of fungi that resemble the well-known pored boletes but the spore-bearing surface is gill-like rather than pored.
The term ‘bolete’ refers in common usage to the pored boletes, and includes the genera Boletus, Leccinum, and Suillus among others. On the underside of the caps of these mushrooms is tissue consisting of soft vertical tubes. The tubes can be separated from the firmer cap flesh above it by wiping it off with a finger. The lower end of the tubes forms a pore surface that makes these mushrooms easy to distinguish from gilled mushrooms.
A smaller group within the order ‘Boletales’ have gill-like structures instead of tubes. The gill-like structure can usually be separated from the firmer cap flesh above it, in the same way that the tubes can be separated in pored boletes.
These gilled boletes have long been considered related to pored boletes because of structural similarities. The spores in some cases are also similar to spores of pored boletes. Molecular studies have so far supported their inclusion in Boletales. Tapinella is one genus which has been separated from the Boletales despite its similarities to Paxillus in particular.(1)
The gilled boletes are not a uniform group. Spore deposit varies from blackish (Chroogomphus, Gomphidius) to whitish (Hygrophoropsis) to shades of brown (Paxillus, Phylloporus). The veil is fibrillose (Chroogomphus), glutinous with a fibrillose inner layer (Gomphidius), or absent (Hygrophoropsis, Paxillus, Phylloporus).
Most amateur mycologists will recognize the genera quite easily without the need of a key to separate them from other gilled mushrooms. Keying them out with a gilled mushroom key is more difficult than learning to recognize them by sight. Gomphidius subroseus, Chroogomphus tomentosus, Hygrophoropsis aurantiaca, and Paxillus involutus are all common distinctive mushrooms. (Chanterelle seekers soon learn to distinguish Chroogomphus tomentosus and Hygrophoropsis aurantiaca which are chanterelle look-alikes.(2) ) The uncommon genus Phylloporus is distinctive as well.
The species within the gilled bolete genera can be more difficult to distinguish.
Gomphidius - slimy, convex cap; whitish flesh; soft, somewhat waxy, decurrent gills that are whitish when young; stem typically whitish in upper part, often yellowish at base, and turning black with handling; veil slimy with inner fibrillose layer; growing on the ground associated with conifers; spore deposit smoky black; spores narrowly elliptical and smooth; pleurocystidia cylindric. See Key to Gomphidiaceae.
Chroogomphus - dry to slimy, convex cap; pink to orange flesh; decurrent gills orange or ochraceous when young; fleshy stem; veil fibrillose; smoky olive to black spore deposit; spores long, elliptic to spindle-shaped, smooth. See Key to Gomphidiaceae.
Hygrophoropsis - orange to brown cap, gills, and stem; cap 1-10 cm, with inrolled margin when young, becoming flat to funnel-shaped, cap surface dry, often felty; gills thin and forked to somewhat vein-like; stem central to off-center; veil absent; spore deposit whitish; spores elliptic, smooth, often dextrinoid.
Paxillus - cap 5-20 cm, convex to depressed, may be viscid when moist (but otherwise dry), margin of cap usually inrolled when young; decurrent gills often veined or poroid near stem, typically yellowish brown to ochraceous brown and often staining darker brown when bruised; stem central to off-center, brownish; veil absent; fruiting on ground or on wood; dark yellow-brown to cocoa-brown spore deposit; spores mostly elliptic, smooth.
a. Spore deposit yellowish brown to rust brown; cap 4-15(20) cm across, dull brown to yellow-brown or reddish brown, staining darker, when young deeply inrolled; fruits under birch in urban settings, less often in forest, summer and fall; common
................................................................................Paxillus involutus
b. Spore deposit darker (vinaceous brown, cinnamon brown, reddish brown, chocolate brown); cap averages larger (5-20 cm across), dingy buff to pale yellowish brown staining darker, when young less deeply inrolled; fruits under aspen, also poplar, birch, oak, sometimes in mixed forest, spring to early fall; rarely identified in the Pacific Northwest
................................................................................Paxillus vernalis
Phylloporus - cap 3-12 cm, convex becoming flat, velvety to subtomentose, dull reddish, reddish brown, or with olivaceous brown hues; gills typically bright yellow to yellow-green, often anastomosed or poroid, separable from cap; stem dry and fleshy; veil absent; spore deposit olivaceous brown; spores spindle-shaped to nearly cylindric, smooth; cheilocystidia and pleurocystidia typically numerous
a. Gills decurrent, may stain blue; cap dull brown, olive-brown, yellow-brown, red-brown, or red; pileipellis stains blue with application of NH4OH (at least in the subspecies that does not stain blue with bruising)
................................................................................Phylloporus rhodoxanthus
b. Gills adnexed to subdecurrent, do not stain blue; cap olive-brown to olive-yellow; pileipellis stains violaceous fuscous, then quickly mahogany-red with application of NH4OH
................................................................................Phylloporus arenicola
Hygrophoropsis aurantiaca (Wulfen ex Fr.) Maire false chanterelle
Paxillus involutus (Batsch) Fr. inrolled pax
Paxillus vernalis Watling spring Paxillus
Phylloporus arenicola A.H. Sm. & Trappe
Phylloporus rhodoxanthus (Schwein.) Bres.
(1) The Eighth Edition of Ainsworth & Bisby’s Dictionary of the Fungi (1995), synonymized Tapinella with Paxillus in Paxillaceae (Boletales). The Ninth Edition (2001) gave the genus independent status in Hygrophoropsidaceae (Boletales). The Tenth Edition (2008) transferred it to Tapinellaceae (Agaricales). For descriptions of Tapinella atrotomentosa ( = Paxillus atrotomentosus) and Tapinella panuoides ( = Paxillus panuoides), see Key to Keys.
(2) Compared with Cantharellus formosus (Pacific golden chanterelle), Chroogomphus tomentosus has a cap that is rounder in outline from above and less wavy from the side, orange flesh, thin gills rather than blunt folds, and blackish spores. Hygrophoropsis aurantiaca has a cap that is not as wavy or frilled as in Cantharellus formosus, cap color that is often browner, thinner more crowded gills (may be blunt when young) that are usually more orange than in C. formosus, and flimsier flesh.
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