Common Fat-tailed Mouse Opossum vs Elm Leech

Thylamys pusillus compared with Hypsizygus ulmarius

Key Differences

• Common Fat-tailed Mouse Opossum is Least Concern while Elm Leech is Critically Endangered.

Taxonomic Classification

Rank	Common Fat-tailed Mouse Opossum	Elm Leech
Kingdom	Animalia (Animals)	Fungi (Fungi)
Phylum	Chordata (Chordates)	Basidiomycota (Club Fungi)
Class	Mammalia (Mammals)	Agaricomycetes (Mushrooms)
Order	Didelphimorphia (Didelphimorphia)	Agaricales (Gilled Mushrooms)
Family	Didelphidae	Lyophyllaceae
Genus	Thylamys	Hypsizygus
Species	Thylamys pusillus	Hypsizygus ulmarius

Conservation Status

Common Fat-tailed Mouse Opossum

LC — Least Concern

Elm Leech

CR — Critically Endangered

Physical Characteristics

Attribute	Common Fat-tailed Mouse Opossum	Elm Leech
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Common Fat-tailed Mouse Opossum

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Elm Leech

Habitat

Inhabits tropical and subtropical moist broadleaf forests within the Indomalayan biogeographic realm.

Range

Widely distributed across Asia (Taiwan), Europe (4 countries), and North America (United States). Currently classified as Critically Endangered on the IUCN Red List, this species faces significant conservation challenges across its range.

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.