Coastal Silver-stiletto vs Pixie Foam

Acrosathe annulata compared with Stereocaulon pileatum

Key Differences

Coastal Silver-stiletto is Least Concern while Pixie Foam is Critically Endangered.

Taxonomic Classification

Rank	Coastal Silver-stiletto	Pixie Foam
Kingdom	Animalia (動物)	Fungi (菌界)
Phylum	Arthropoda (節足動物)	Ascomycota (子嚢菌門)
Class	Insecta (昆虫)	Lecanoromycetes (チャシブゴケ菌綱)
Order	Diptera (ハエ目)	Lecanorales (チャシブゴケ目)
Family	Therevidae	Stereocaulaceae
Genus	Acrosathe	Stereocaulon
Species	Acrosathe annulata	Stereocaulon pileatum

Conservation Status

Coastal Silver-stiletto

LC — Least Concern

Pixie Foam

CR — Critically Endangered

Physical Characteristics

Attribute	Coastal Silver-stiletto	Pixie Foam
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Coastal Silver-stiletto

Habitat

Typically found in virtually all terrestrial and freshwater habitats.

Range

Distributed across Belgium, Denmark, Norway, and Sweden.

Pixie Foam

Habitat

Native to Europe and North America, inhabiting ecosystems characteristic of the region.

Range

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

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.