Amanita regalis: The Ultimate Mushroom Guide

About The Amanita regalis Mushroom

The Amanita regalis is such a rare mushroom that the German Mycological Society nominated it Mushroom of the Year 2000. This distinction implies that Amanita regalis is also in need of protection.

Indeed, the species occurs only in the natural area of the spruce-fir. It seems to make particular demands from its mycorrhizal partner Picea abis. In new fir woods, the mushroom does not grow. It prefers acid soil in a hilly country.

Amanita regalis is a highly poisonous mushroom. Like the Fly Agaric, this large member of the genus Amanita is also hallucinogenic and can cause sickness and other distressing effects if it is eaten.

Common in Scandinavian countries, it is also found in eastern and northern Europe. In North America, its distribution is restricted to Alaska.

Other names: Royal Fly Agaric, The King of Sweden Amanita.

Amanita regalis Identification

1. Cap

   Initially egg-shaped, becoming convex and eventually flattening out to between 10 and 20cm in diameter, the caps of Amanita regalis are glossy brown; usually retaining irregular, white fragments of the universal veil.

   At maturity, the caps flatten out and occasionally become shallowly concave. Like the closely related Amanita muscaria (Fly Agaric) the Brown Fly Agaric usually retains its warty veil fragments, but in very wet weather the veil fragments can get washed off; this makes misidentification more likely. The volva at the base of the stem is then an important identifying feature.

2. Gills

   White, free, crowded. The gills turn pale yellow as the fruitbody matures.

3. Stem

   10 - 25cm long and 1.5 - 2cm in diameter, the stems of Amanita regalis are white and ragged with a grooved, hanging ring. The swollen base retains the white, sack-like remains of the volva, which eventually fragments into rings of scales around the base of mature specimens.

4. Spores

   White spore print. Broadly ellipsoidal, 8-10 x 6-7μm; inamyloid.

5. Habitat & Ecological role

   Mature Amanita regalis in a conifer forest

   Mycorhizal with conifers, notably spruce as in the case of the mature specimens pictured on the left, and with birches.

6. Season

   August to October in Britain; July to September in Scandinavia.

7. Similar species

   Amanita caesarea (Caesar's Mushroom) is rarely if ever found in northern Europe; its cap is brilliant orange without small veil fragments but with a striated margin, and the stipe is yellow.

   The caps of some examples of Amanita rubescens are glossy brown, but their stems and their cap flesh always turn red when damaged.

Amanita regalis Taxonomy & Etymology

Amanita regalis was first described as Agaricus muscarius β regalis by Elias Magnus Fries in his Systema Mycologicum, published in 1821. In 1887, Pier Andrea Saccardo treated it as a variety of Amanita muscaria. Edmund Michael, in 1903, became the first to consider it a distinct species.

In 1941, Jean-Edouard Gilbert suggested a complete reorganization of the genus Amanita in his world monograph of the genus, and moved it to Amanitaria as A. muscaria var. regalis. In his original (1949) version of Agaricales in Modern Taxonomy, Rolf Singer considered it a subspecies of A. muscaria, but noted that it may be regarded as a separate species; in the fourth edition (1986), he listed it as a distinct species.

A. regalis is classified in a section of Amanita within the genus, a grouping of related Amanitas that have a ring on the stem (or remnants thereof), and a bulb at the base of it.

More recently, a Japanese group studied the biogeography of A. muscaria and related species, and, using molecular phylogenetic analysis, concluded that the taxon should be considered a grouping of A. muscaria, rather than a distinct species. However, as of 2012, both Index Fungorum and MycoBank list the taxon as Amanita regalis.

The species has been called by several vernacular names, including the "Brown fly agaric", the "king of Sweden Amanita", or the king fly agaric. In France it is known as Amanite royale, while in Germany it is Königsfliegenpilz. The specific epithet is derived from the Latin word regalis, meaning "royal". In 2000, it was selected by the German Mycological Society as "Mushroom of the Year".

Amanita regalis Toxicity

Three patients ate different amounts of a common northern mushroom, brown fly agaric, Amanita regalis. All of them believed they had eaten delicious parasol mushrooms, Macrolepiota procera. The symptoms of poisoning began 1-2 hours after ingestion of the mushrooms.

All the patients had marked gastrointestinal symptoms: nausea and heavy vomiting. Two had central nervous system manifestations and cholinergic symptoms: hallucinations, confusion, or loss of consciousness as well as copious salivation, or sweating.

All patients recovered within 4-24 hours without any damage to the liver, kidneys, or central nervous system. It seems that cooking the mushrooms does not completely neutralize the toxic agents of Amanita regalis. The analysis of fried mushrooms shows that it may be possible to identify mushrooms reliably from the remains of a meal.