Bitter Tooth vs Coastal Silver-stiletto

Hydnellum scabrosum compared with Acrosathe annulata

Key Differences

Bitter Tooth is Near Threatened while Coastal Silver-stiletto is Least Concern.

Taxonomic Classification

Rank	Bitter Tooth	Coastal Silver-stiletto
Kingdom	Fungi (Fungi)	Animalia (Animals)
Phylum	Basidiomycota (Club Fungi)	Arthropoda (Arthropods)
Class	Agaricomycetes (Mushrooms)	Insecta (Insects)
Order	Thelephorales (Thelephorales)	Diptera (Diptera)
Family	Bankeraceae	Therevidae
Genus	Hydnellum	Acrosathe
Species	Hydnellum scabrosum	Acrosathe annulata

Conservation Status

Bitter Tooth

NT — Near Threatened

Coastal Silver-stiletto

LC — Least Concern

Physical Characteristics

Attribute	Bitter Tooth	Coastal Silver-stiletto
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Bitter Tooth

Habitat

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

Range

Distributed across Denmark, Norway, and Sweden. Listed as Near Threatened, this species requires ongoing monitoring to prevent population decline.

Coastal Silver-stiletto

Habitat

Typically found in virtually all terrestrial and freshwater habitats.

Range

Distributed across Belgium, Denmark, Norway, and Sweden.

Bitter Tooth

The Bitter Tooth (Hydnellum scabrosum) is a species in the genus Hydnellum. It is currently classified as Near Threatened on the IUCN Red List. Typically found in forest floors, decomposing wood, and soil ecosystems.

Coastal Silver-stiletto

Coastal silver stiletto (Acrosathe annulata) is a slender robber fly in the family Therevidae, native to northwestern Europe, including the United Kingdom, France, the Netherlands, Belgium, and Scandinavia. Adults are found on coastal sand dunes and sandy heathland, where they perch on bare sand to ambush small flying insects. Stiletto flies in the family Therevidae are characterised by a slender body, long pointed abdomen, and predatory habits; adults prey on a variety of small dipterans and other flying insects during warm, sunny periods. Larvae develop in sandy soil, where they are also predatory, feeding on other invertebrate larvae. Acrosathe annulata is a habitat specialist restricted to open, sandy coastal habitats with sparse vegetation—environments that have declined substantially across northwestern Europe due to dune stabilisation, recreational disturbance, and the cessation of traditional dune management. The IUCN lists it as Least Concern, though regional conservation bodies in the United Kingdom have flagged population declines. It is considered an indicator of high-quality coastal sand dune habitats and is monitored through national invertebrate surveys.