Alder leaf beetle vs Common Oak Fern

Agelastica alni compared with Gymnocarpium dryopteris

Key Differences

• Alder leaf beetle is Least Concern while Common Oak Fern is Critically Endangered.

Taxonomic Classification

Rank	Alder leaf beetle	Common Oak Fern
Kingdom	Animalia (Animals)	Plantae (Plants)
Phylum	Arthropoda (Arthropods)	Tracheophyta
Class	Insecta (Insects)	Polypodiopsida (Polypodiopsida)
Order	Coleoptera (Beetles)	Polypodiales (Polypodiales)
Family	Chrysomelidae	Cystopteridaceae
Genus	Agelastica	Gymnocarpium
Species	Agelastica alni	Gymnocarpium dryopteris

Conservation Status

Alder leaf beetle

LC — Least Concern

Common Oak Fern

CR — Critically Endangered

Physical Characteristics

Attribute	Alder leaf beetle	Common Oak Fern
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Alder leaf beetle

Habitat

Typically found in virtually all terrestrial and freshwater habitats.

Range

Distributed across Belgium, Denmark, Norway, Sweden, and United States.

Common Oak Fern

Habitat

Found across multiple habitat types including temperate broadleaf and mixed forests, temperate coniferous forests, and boreal forests and taiga, among 4 distinct biome types within the Palearctic biogeographic realm. Populations are also found in montane and highland environments at higher elevations.

Range

Found across Europe (6 countries) and North America (Canada, United States). Currently classified as Critically Endangered on the IUCN Red List, this species faces significant conservation challenges across its range.

Alder leaf beetle

The Alder leaf beetle (Agelastica alni) is a species in the genus Agelastica. It is currently classified as Least Concern on the IUCN Red List. Typically found in virtually all terrestrial and freshwater habitats.

Common Oak Fern

<em>Gymnocarpium dryopteris</em>, the common oak fern, is a delicate terrestrial fern in the family Cystopteridaceae (or Woodsiaceae, depending on classification). Despite its common name, the species is not specifically associated with oak trees; rather, it typically grows in cool, moist, shaded environments including boreal and mixed forests, rocky woodland slopes, stream banks, and shaded cliff faces. <em>Gymnocarpium dryopteris</em> spreads by rhizomes and forms low, spreading colonies with characteristic triangular, three-pinnate fronds that emerge from a slender creeping rootstock. Its geographic range spans Europe and North America, with populations in cool temperate and boreal zones. The species is currently assessed as Critically Endangered in certain regional assessments, suggesting that particular populations face severe decline, likely due to habitat loss, forest fragmentation, and altered hydrology, even if the species retains a broader global range. Biological traits such as lifespan, body size, and diet remain poorly documented at a standardized population level. <em>Gymnocarpium dryopteris</em> is a characteristic indicator of undisturbed cool woodland habitats and is valued for both its ecological role in forest understoreys and its aesthetic appeal.

Shared Countries

Both species can be found in 5 countries:

🇧🇪 Belgium 🇩🇰 Denmark 🇳🇴 Norway 🇸🇪 Sweden 🇺🇸 United States