Brown Cup vs Coastal Silver-stiletto

Rutstroemia firma compared with Acrosathe annulata

Taxonomic Classification

Rank	Brown Cup	Coastal Silver-stiletto
Kingdom	Fungi (Fungi)	Animalia (Animals)
Phylum	Ascomycota (Sac Fungi)	Arthropoda (Arthropods)
Class	Leotiomycetes (Leotiomycetes)	Insecta (Insects)
Order	Helotiales (Helotiales)	Diptera (Diptera)
Family	Rutstroemiaceae	Therevidae
Genus	Rutstroemia	Acrosathe
Species	Rutstroemia firma	Acrosathe annulata

Conservation Status

Brown Cup

LC — Least Concern

Coastal Silver-stiletto

LC — Least Concern

Physical Characteristics

Attribute	Brown Cup	Coastal Silver-stiletto
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Brown Cup

Habitat

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

Range

Distributed across Belgium, Brazil, Denmark, Norway, and Sweden.

Coastal Silver-stiletto

Habitat

Typically found in virtually all terrestrial and freshwater habitats.

Range

Distributed across Belgium, Denmark, Norway, and Sweden.

Brown Cup

The Brown Cup (Rutstroemia firma) is a species in the genus Rutstroemia. It is currently classified as Least Concern on the IUCN Red List. Native to Europe and South America, inhabiting ecosystems characteristic of the region.

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.