Coastal Silver-stiletto vs Common Earthball

Acrosathe annulata compared with Scleroderma citrinum

Taxonomic Classification

Rank	Coastal Silver-stiletto	Common Earthball
Kingdom	Animalia (Animals)	Fungi (Fungi)
Phylum	Arthropoda (Arthropods)	Basidiomycota (Club Fungi)
Class	Insecta (Insects)	Agaricomycetes (Mushrooms)
Order	Diptera (Diptera)	Boletales (Boletales)
Family	Therevidae	Sclerodermataceae
Genus	Acrosathe	Scleroderma
Species	Acrosathe annulata	Scleroderma citrinum

Conservation Status

Coastal Silver-stiletto

LC — Least Concern

Common Earthball

LC — Least Concern

Physical Characteristics

Attribute	Coastal Silver-stiletto	Common Earthball
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.

Common Earthball

Habitat

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

Range

Widely distributed across Asia (Taiwan), Europe (5 countries), North America (United States), and South America (Brazil, Chile).

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.

Common Earthball

<em>Scleroderma citrinum</em>, commonly known as the common earthball or pigskin poison puffball, is a widespread ectomycorrhizal fungus in the family Sclerodermataceae, classified as Least Concern by the IUCN. The species occurs across Asia, Europe, North America, and South America, typically found on forest floors, decomposing wood, and mineral-rich acidic soils in association with hardwood and conifer tree roots. Unlike true puffballs, <em>Scleroderma citrinum</em> is considered poisonous and should not be confused with edible species. Its thick, warty outer skin ranges from yellowish-brown to ochre and encloses a dark purplish-black spore mass that matures over time. The species plays an important ecological role as a mycorrhizal partner, forming mutualistic associations with the roots of oaks, beeches, pines, and other trees, facilitating the uptake of water and nutrients by host plants in exchange for photosynthetically derived carbon. Fruiting bodies typically emerge from late summer through autumn, releasing spores through irregular cracks or a central apical opening when mature. <em>Scleroderma citrinum</em> is a host for the parasitic fungus <em>Pseudoboletus parasiticus</em>, making it ecologically significant within forest fungal communities. Biological traits of this species remain poorly documented in the scientific literature.

Shared Countries

Both species can be found in 4 countries:

🇧🇪 Belgium 🇩🇰 Denmark 🇳🇴 Norway 🇸🇪 Sweden