Bitter Knight vs small tortoiseshell

Tricholoma acerbum compared with Aglais urticae

Key Differences

• Bitter Knight is Endangered while small tortoiseshell is Near Threatened.

Taxonomic Classification

Rank	Bitter Knight	small tortoiseshell
Kingdom	Fungi (Fungi)	Animalia (Animals)
Phylum	Basidiomycota (Club Fungi)	Arthropoda (Arthropods)
Class	Agaricomycetes (Mushrooms)	Insecta (Insects)
Order	Agaricales (Gilled Mushrooms)	Lepidoptera (Butterflies & Moths)
Family	Tricholomataceae	Nymphalidae (Brush-footed Butterflies)
Genus	Tricholoma	Aglais
Species	Tricholoma acerbum	Aglais urticae

Conservation Status

Bitter Knight

EN — Endangered

small tortoiseshell

NT — Near Threatened

Physical Characteristics

Attribute	Bitter Knight	small tortoiseshell
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Bitter Knight

Habitat

Typically found in forest floors, decomposing wood, and soil ecosystems.

Range

Distributed across Belgium, Norway, and Sweden. Currently classified as Endangered on the IUCN Red List, this species faces significant conservation challenges across its range.

small tortoiseshell

Habitat

Typically found in virtually all terrestrial and freshwater habitats.

Range

Found across Europe (41 countries). Listed as Near Threatened, this species requires ongoing monitoring to prevent population decline.

Bitter Knight

The Bitter Knight (Tricholoma acerbum) is a species in the genus Tricholoma. It is currently classified as Endangered on the IUCN Red List. Typically found in forest floors, decomposing wood, and soil ecosystems.

small tortoiseshell

small tortoiseshell (Aglais urticae) is classified as Near Threatened (NT) on the IUCN Red List. Close to qualifying as threatened, with populations that may become vulnerable without conservation action.

Shared Countries

Both species can be found in 3 countries:

🇧🇪 Belgium 🇳🇴 Norway 🇸🇪 Sweden