vs Coastal Silver-stiletto

Chrysococcus bisetus compared with Acrosathe annulata

Key Differences

is Not Evaluated while Coastal Silver-stiletto is Least Concern.

Taxonomic Classification

Rank		Coastal Silver-stiletto
Kingdom	Chromista (Chromista)	Animalia (Animals)
Phylum	Ochrophyta (Ochrophyta)	Arthropoda (Arthropods)
Class	Chrysophyceae (Chrysophyceae)	Insecta (Insects)
Order	Chromulinales (Chromulinales)	Diptera (Diptera)
Family	Dinobryaceae	Therevidae
Genus	Chrysococcus	Acrosathe
Species	Chrysococcus bisetus	Acrosathe annulata

Conservation Status

NE — Not Evaluated

Coastal Silver-stiletto

LC — Least Concern

Physical Characteristics

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

Habitat & Geographic Range

Habitat

Native to Europe, inhabiting ecosystems characteristic of the region.

Range

Distributed across Norway and Sweden.

Coastal Silver-stiletto

Habitat

Typically found in virtually all terrestrial and freshwater habitats.

Range

Distributed across Belgium, Denmark, Norway, and Sweden.

Chrysococcus bisetus is a species of unicellular chrysophyte microalga in the genus Chrysococcus, class Chrysophyceae, order Chromulinales. The genus Chrysococcus is characterized by cells enclosed within a lorica — a secreted outer case or vesicle — through which flagella protrude, a structure that distinguishes it from many other chrysophytes. The epithet bisetus, meaning two-bristled, describes a diagnostic feature of the lorica, which bears two bristle-like projections used for species identification. Chrysococcus species inhabit freshwater and brackish environments, typically occurring in cool, nutrient-poor to moderately enriched lakes, ponds, and slow-flowing water bodies. C. bisetus has been recorded from Norwegian and Swedish waters, consistent with the historical focus of chrysophyte research in Scandinavian freshwater habitats, and also from Brazilian waters, suggesting a broader distribution. Chrysophytes including Chrysococcus species are important components of oligotrophic lake phytoplankton, where they contribute to primary production and serve as food for zooplankton. The golden-brown coloration of Chrysococcus arises from chlorophylls a and c together with fucoxanthin, pigments shared with other heterokonts. Unlike diatoms, chrysophytes produce chrysolaminarin as their storage carbohydrate rather than starch. C. bisetus has not been assessed under IUCN criteria and is listed as Not Evaluated. As with most freshwater microalgae, global population size and distribution are poorly characterized, limiting meaningful conservation assessment.

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.