Tapinella panuoides
Description
Tapinella panuoides is a fungus species in the genus Tapinella. This inconspicuous wood rotter is characterized by a dull ochre-brown, often shallowly-lobed cap, wavy intervenose gills, and a conifer fruiting habit. Because of its nondescript appearance, it is sometimes confused with several other gilled, shelf fungi.
Despite its pleasant taste, the species is poisonous.
Common names: Fan Pax, Stalkless Paxillus, Oyster Rollrim.
Mushroom Identification
Ecology
Saprobic; growing alone or gregariously on woodland conifer wood and lumber; summer and fall (also overwinter in warmer climates); widely distributed in North America.
Cap
3-8 cm; fan- or shell-shaped; planoconvex; dry; finely velvety when young, but sometimes becoming bald with age; tan, yellow-brown, or orangish brown; the margin inrolled at first, often with a somewhat scalloped appearance.
Gills
Close; dull orangish to yellowish; frequently forked, cross-veined, crimped, or corrugated, especially near the base.
Stem
Absent, or present only as a small lateral extension.
Flesh
Whitish or dirty yellowish; not changing when sliced.
Odor and Taste
Not distinctive.
Spore Print
Yellowish-brown or brownish.
Microscopic Features
Spores 3.5-5 x 2.5-4 µ; ellipsoid; smooth; hyaline and uniguttulate in KOH; frequently dextrinoid. Hymenial cystidia not found. Pileipellis a cutis of hyaline-in-KOH elements 2.5-5 µ wide.
Look-Alikes
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Can be distinguished by a hardwood habit, apricot-orange, pubescent cap, straight, not wavy gills, and skunk odor.
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Has a dull-brown, similarly-shaped cap but has gills with serrulate edges and an unpleasant taste.
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Distinguished by a more centrally attached stipe and distinctly forked, bright-orange gills.
Tapinella corrugata (Paxillus corrugatus)
Is similar to this species. The gills often differ in color but the potential exists for confusion.
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Has brownish gills that darken when bruised.
Medicinal Properties
Free-radical scavenging activity/neuroprotective effects
Two p-terphenyl compounds, identified as leucomentin-4 and leucomentin-2 were isolated from methanolic extract of the fruit body of Paxillus panuoides.
These compounds strongly inhibited lipid peroxidation in rat liver microsomes with IC50 values of 0.10 and 0.06 µg/ml, respectively (Yun et al., 2000). It was later suggested the neuroprotective effect that the leucomentins have is due to their ability to chelate iron (when present with DNA and H2O2), thus inhibiting iron-mediated oxidative damage to DNA (Lee et al., 2003).
Hemagglutination activity
Purified lectins from T. panuoides extracts were able to hemagglutinate human red cells, with an anti-A specificity. The reaction of anti-A agglutinin was strongly inhibited by N-acetyl-D-galactosamine (Furukawa et al., 1995).
Antitumor activity
Several of the p-terphenyl ortho-quinones described above were found to be active in assays against tumor cell cultures (Cali et al., 2004).
History
Originally described in 1818 by Swedish mycologist Elias Magnus Fries, who gave it the binomial scientific name Agaricus panuoides, the Oyster Rollrim was transferred to the genus Tapinella in 1931 by the French mycologist Édouard-Jean Gilbert (1888 - 1954).
Synonyms of Tapinella panuoides include Agaricus panuoides Fr., Paxillus panuoides (Fr.) Fr., Paxillus fagi Berk. & Broome, Paxillus panuoides var. fagi (Berk. & Broome) Cooke, Paxillus panuoides var. ionipes Quél., and Paxillus panuoides var. rubrosquamulosus Svrcek & Kubicka.
Tapinella as a mushroom genus was established in 1931 by the French mycologist Édouard-Jean Gilbert (1888 - 1954). Tapinella comes from Tapis, meaning a carpet.
The specific epithet panuoides means 'similar to a Panus species', and Panus means a swelling or tumor.
Photo sources:
Photo 1 - Author: Ron Pastorino (Ronpast) (CC BY-SA 3.0)
Photo 2 - Author: Strobilomyces (CC BY-SA 3.0)
Photo 3 - Author: Richard Kneal (bloodworm) (CC BY-SA 3.0)
Photo 4 - Author: Richard Kneal (bloodworm) (CC BY-SA 3.0)
