Crab Brittlegill

Description

The crab brittlegill is a russula with a cap 5–10 cm across whose colour is variable: purple, wine-red, pink, brown-red, yellow or greenish, depending on the tree under which it grows. The gills are cream and turn brown when touched, the stem reddish or white with a red tinge. The most reliable feature is the smell of older specimens, resembling herring or cooked crustaceans.

It grows from August to the end of November in coniferous, deciduous and mixed forests and in parks, singly or in groups.

Red forms can be confused with the mildly poisonous sickener, green ones with other green russulas, and green gilled mushrooms in general with the death cap. Do not collect mushrooms you have doubts about.

Identification features

Cap

Diameter 5–10 cm (descriptions also give 5–20 cm); hemispherical when young, then flat, depressed in the centre. Colour variable, depending on the associated tree: in coniferous forests purple, under oaks pink or brown-red, under birches yellow to yellow-green; most often purple to wine-red, also greenish, darker towards the centre. Surface first slimy, then dry and suede-like, with fine grooves near the margin.

Hymenophore (underside of the cap)

Gills creamy white in young specimens, then yellowish-cream, turn brown when pressed; narrowly spaced. Attachment to the stem — no data.

Stem

Height 4–8 cm (descriptions also give 4–12 cm), thickness 15–30 mm. Smooth or slightly wrinkled, red or white with a red tinge, turns brown when damaged. Ring and volva absent.

Flesh

Creamy, in places brown-yellow. Taste somewhat acrid when young, later almost imperceptible (according to some descriptions mild, gills mild to somewhat bitter). The smell of the mature fruiting body resembles herring, and according to some descriptions cooked crabs or shrimps (trimethylamine); it intensifies with age. With FeSO4 dark green. Do not taste the flesh of unknown mushrooms.

Spore print and spores

Spore print ochre (creamy yellow). Spores 8–11 × 7.5–8.5 µm or 8.8–9.9 × 6.7–7.8 µm (descriptions give different ranges), oval, with spines about 1 µm.

Habitat and distribution

Ecology. Terrestrial mycorrhizal fungus; grows singly or in groups in deciduous, coniferous and mixed forests and in parks; according to some descriptions it prefers Douglas fir, less often pine and larch, and occurs under beeches and oaks.

Distribution. Temperate zone of the Northern Hemisphere, up to the Arctic Circle, south to Costa Rica. For Poland — no details. Not legally protected in Poland.

Fruiting. From August to the end of November (in North America July–October in the east, October–January in the west).

What can it be confused with?

• Russula emetica (the sickener; Polish: gołąbek wymiotny) — Red forms; the sickener always has a white stem and white gills and an acrid taste, without a smell of herring.
• Russula aeruginea (the grass-green russula) — Green forms of the crab brittlegill always smell of crustaceans; the grass-green russula does not.
• Russula olivacea — Cap more velvety.
• Russula graveolens, R. clavipes and others from section Xerampelinae — Most similar russulas do not have a seafood smell; details — no data.

Never rely on a single feature. If you are not sure — do not pick it; show the mushroom to a qualified mushroom expert.

Interesting facts

• The epithet xerampelina comes from Greek and means "the colour of dried vine leaves".
• The characteristic seafood smell (trimethylamine) gave it the English names "crab brittlegill" and "shrimp mushroom".
• It gives its name to the section Xerampelinae, a group of closely related russulas.
• It is most likely a complex of at least three species.