Amanita rubrovolvata

Description

Commonly known as the Red Volva Amanita, Yunnan Red, or Yellow Slender Caesar, Amanita rubrovolvata is a fascinating mushroom with vibrant colors and a mysterious nature.

🌟 Appearance

Amanita rubrovolvata features a reddish-orange cap up to 6.5 cm (2+1/2 inches) wide, fading to yellow at the edges and often covered in powdery volva remnants. The cream-colored stem can reach up to 10 cm (4 inches) tall, with a ring near the top and a bulbous base covered in bright orange patches. Its white gills are crowded and free from the stem, giving this mushroom a distinctive, striking look.

🌍 Distribution & Habitat

This species is widely found in eastern Asia—including Japan, China, South Korea, and as far south as the Malay Peninsula. It grows on the forest floor, forming mycorrhizal relationships with trees. Originally discovered in Japanese beech forests, it has also been found near oaks, rhododendrons, and in plantations of Castanopsis indica in the Himalayas. These partnerships help both the fungus and the trees thrive, with the fungus aiding the trees in nutrient absorption.

📜 History & Classification

Amanita rubrovolvata was first described in 1939 by Japanese mycologist Sanshi Imai. It belongs to the subgenus Amanita of the genus Amanita and shares close relations with other well-known species like A. muscaria.

The name comes from the Latin words "ruber" (red) and "volvatus" (closely sheathed), referring to the red volva at the base of the stem.

🧬 Toxicity & Psychoactivity

The psychoactivity of Amanita rubrovolvata has not been clearly established, and its edibility remains uncertain. Some studies suggest it may cause neurological symptoms in animals, including changes in blood glucose and enzyme levels, but its effects on humans are not well-documented. Given its potential toxicity, it's recommended to avoid consumption, and it is not considered a psychoactive mushroom like Amanita muscaria.

Mushroom Identification

🍄 Cap

• Size: 2.0–12 cm (13⁄16–4+3⁄4 in) wide

• Shape: Convex to flattened, sometimes with a small raised bump (umbo)

• Color: Deep red to reddish-orange in the center, fading to yellowish-orange at the edges

• Texture: Covered in red, orange, or yellow powdery to granular remnants of the volva

• Margin: Grooved, extending 30-60% of the cap’s radius, with no veil remnants

🌿 Gills

• Color: White to yellow, free from attachment to the stem

• Arrangement: Crowded, with shorter, truncated gills (lamellulae)

• Size: 3–6 mm (1/8–1/4 in) broad

🦵 Stem

• Size: 5–22 cm (2–8+3⁄4 in) long, 0.5–3 cm (1/4–1+1/8 in) thick

• Shape: Cylindrical, slightly thicker at the top, narrowing upward

• Color: Creamy above the ring, cream to yellow below

• Base: Roughly spherical bulb (1–2 cm wide) covered in red, orange, or yellow remnants of the volva

• Ring: Membranous, white on top with a yellowish tint underneath and a red-orange edge

🎨 Volva

• Color: Red to orange powdery remnants at the base

• Structure: Membranous sac (saccate), persisting at the base of the stem

🦠 Spores

• Spore Print: White to cream

• Shape & Size: Spherical to subglobose, 7.5–10.0 × 6.5–9.0 µm

• Special Trait: Inamyloid, meaning they do not react to iodine

❓ Other Notes

• Odor/Taste: Not recorded for this species

• Clamps: Present at the bases of the basidia

Look-Alikes

1️⃣ Amanita frostiana

Primarily occurs in eastern North America. It features short grooves at the edge of its yellowish-orange cap, which sets it apart. Additionally, its spores are slightly larger, and it has a yellow volva, unlike the red volva characteristic of A. rubrovolvata. Moreover, A. frostiana contains clamps at the bases of its basidia, a feature not found in A. rubrovolvata.

Photo sources:

Photo 1 - Author: Atsushi Nakajima (CC BY 4.0)

Photo 2 - Author: Jie-Hao Ou (CC BY 4.0)

Photo 3 - Author: Cynthia Su (CC BY 4.0)

Photo 4 - Author: Mikel Duffy (CC BY 4.0)

Photo 5 - Author: Atsushi Nakajima (CC BY 4.0)