Amanita hygroscopica

Amanita hygroscopia (/æməˈnaɪtə /ha͡ɪɡɹəskˈo͡ʊpi͡ə), also known as the pink-gilled destroying angel is a deadly poisonous fungus, one of many in the genus Amanita.

Taxonomy
The species was first described by William Chambers Coker in 1917.

Description
The cap is 2.5 cm wide and hemispheric. The gills are adnate, crowded, medium broad, entire, white, unchanging.

The stem is about 30 × 5–8 mm, narrowing upward, smooth, glabrous, white, unchanging when bruised. The ring is fixed 10 mm from the top of the stem, very short, skirt-like, grooved by the gills above, white, persistent. The bulb is ovoid, white, 20 × 15 mm. The volva is neither appressed nor widely spreading, the edge is either 3-lobed or ragged. The mushroom is odorless and tasteless.

Similar species
A. hygroscopia resembles several edible species, most notably Agaricus campestris.

Toxicity
The principal toxic constituent is α-Amanitin, an elective inhibitor of RNA polymerase II and III, which causes liver and kidney failure. 15% of those poisoned will die within 10 days and those who survive are at risk of lifelong, permanent liver damage.

There is no antidote for amanitin poisoning; treatment is mainly supportive (gastric lavage, activated carbon, and fluid resuscitation). In severe cases the only effective treatment may be a liver transplant.

Amatoxins, the class of toxins found in these mushrooms, are thermostable: they resist changes due to heat, so their toxic effects are not reduced by cooking.