Cave ground-beetle vs Common Fat-tailed Mouse Opossum

Trechus montanheirorum compared with Thylamys pusillus

Key Differences

• Cave ground-beetle is Critically Endangered while Common Fat-tailed Mouse Opossum is Least Concern.

Taxonomic Classification

Rank	Cave ground-beetle	Common Fat-tailed Mouse Opossum
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Arthropoda (Arthropods)	Chordata (Chordates)
Class	Insecta (Insects)	Mammalia (Mammals)
Order	Coleoptera (Beetles)	Didelphimorphia (Didelphimorphia)
Family	Carabidae	Didelphidae
Genus	Trechus	Thylamys
Species	Trechus montanheirorum	Thylamys pusillus

Evolutionary Relationship

Cave ground-beetle and Common Fat-tailed Mouse Opossum share a common ancestor at the Kingdom level: Animalia. (Animals)

Conservation Status

Cave ground-beetle

CR — Critically Endangered

Common Fat-tailed Mouse Opossum

LC — Least Concern

Physical Characteristics

Attribute	Cave ground-beetle	Common Fat-tailed Mouse Opossum
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Cave ground-beetle

Habitat

Inhabits temperate broadleaf and mixed forests and Mediterranean forests and woodlands within the Palearctic biogeographic realm. Populations are also found in montane and highland environments at higher elevations.

Range

Found in Portugal. Currently classified as Critically Endangered on the IUCN Red List, this species faces significant conservation challenges across its range.

Common Fat-tailed Mouse Opossum

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Cave ground-beetle

The Cave ground-beetle (Trechus montanheirorum) is a species in the genus Trechus. It is currently classified as Critically Endangered on the IUCN Red List. Inhabits temperate broadleaf and mixed forests and Mediterranean forests and woodlands within the Palearctic biogeographic realm. Populations are also found in montane and highland environments at higher elevations.

Common Fat-tailed Mouse Opossum

The Common Fat-tailed Mouse Opossum (<em>Thylamys pusillus</em>) is a small marsupial belonging to the genus Thylamys within the family Didelphidae. Like other members of its genus, this species typically stores fat in its tail, which becomes swollen during periods of food abundance and is metabolised during leaner times, a physiological adaptation that provides energy reserves. <em>Thylamys pusillus</em> is generally found in diverse terrestrial and aquatic ecosystems, often in dry woodlands, scrublands, and grassland habitats of South America. The species is assessed as Least Concern on the IUCN Red List, indicating it is not currently considered at risk of extinction. Detailed geographic range data are not available in the current record, but members of this genus are typically distributed across parts of Argentina, Bolivia, Paraguay, and Uruguay. Biological traits including average lifespan, body dimensions, and specific dietary composition remain poorly documented in the scientific literature, though Thylamys species are generally considered omnivorous, often consuming insects, small vertebrates, and plant material.