Coastal Silver-stiletto vs Cochran Frog

Acrosathe annulata compared with Nymphargus cochranae

Key Differences

• Coastal Silver-stiletto is Least Concern while Cochran Frog is Vulnerable.

Taxonomic Classification

Rank	Coastal Silver-stiletto	Cochran Frog
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Arthropoda (Arthropods)	Chordata (Chordates)
Class	Insecta (Insects)	Amphibia (Amphibians)
Order	Diptera (Diptera)	Anura (Frogs & Toads)
Family	Therevidae	Centrolenidae
Genus	Acrosathe	Nymphargus
Species	Acrosathe annulata	Nymphargus cochranae

Evolutionary Relationship

Coastal Silver-stiletto and Cochran Frog share a common ancestor at the Kingdom level: Animalia. (Animals)

Conservation Status

Coastal Silver-stiletto

LC — Least Concern

Cochran Frog

VU — Vulnerable

Physical Characteristics

Attribute	Coastal Silver-stiletto	Cochran Frog
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.

Cochran Frog

Habitat

Typically found in freshwater habitats, moist forests, and wetlands.

Range

Found in Colombia. Currently classified as Vulnerable 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.

Cochran Frog

The Cochran frog (Nymphargus cochranae) is a small glass frog in the family Centrolenidae, native to the cloud forests of the western and central Andes in Colombia. Like other centrolenid frogs, it is characterised by semi-transparent or translucent ventral skin through which internal organs — including the heart, liver, and digestive tract — are visible, a feature that gives the family its common name. The species inhabits humid montane rainforest along streams at elevations typically between 1,500 and 2,800 metres, where males call from vegetation overhanging fast-flowing streams to attract females. Eggs are deposited in gelatinous masses on leaves or rocks above the water; upon hatching, tadpoles drop into the stream below and develop in the current-swept environment. Nymphargus cochranae is classified as Vulnerable by the IUCN, primarily due to ongoing deforestation and degradation of cloud forest habitats driven by agricultural expansion, cattle ranching, and coca cultivation across its Colombian Andean range. Glass frogs are additionally sensitive to stream water quality, making them useful bioindicators of watershed health. The species was named in honour of the eminent American herpetologist Doris Mable Cochran of the Smithsonian Institution, who made foundational contributions to Central and South American amphibian taxonomy in the mid-twentieth century. Continued habitat protection and reforestation efforts are critical for its long-term survival.