Collared Worm Salamander vs Common Fat-tailed Mouse Opossum

Oedipina collaris compared with Thylamys pusillus

Key Differences

• Collared Worm Salamander is Data Deficient while Common Fat-tailed Mouse Opossum is Least Concern.

Taxonomic Classification

Rank	Collared Worm Salamander	Common Fat-tailed Mouse Opossum
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Chordata (Chordates)	Chordata (Chordates)
Class	Amphibia (Amphibians)	Mammalia (Mammals)
Order	Caudata (Caudata)	Didelphimorphia (Didelphimorphia)
Family	Plethodontidae	Didelphidae
Genus	Oedipina	Thylamys
Species	Oedipina collaris	Thylamys pusillus

Evolutionary Relationship

Collared Worm Salamander and Common Fat-tailed Mouse Opossum share a common ancestor at the Phylum level: Chordata. (Chordates)

Conservation Status

Collared Worm Salamander

DD — Data Deficient

Common Fat-tailed Mouse Opossum

LC — Least Concern

Physical Characteristics

Attribute	Collared Worm Salamander	Common Fat-tailed Mouse Opossum
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Collared Worm Salamander

Habitat

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

Common Fat-tailed Mouse Opossum

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Collared Worm Salamander

The Collared Worm Salamander, known scientifically as <em>Oedipina collaris</em>, is a slender, elongated salamander belonging to the family Plethodontidae, the lungless salamanders. <em>Oedipina collaris</em> is characterised by its worm-like body form, extremely elongated trunk with many vertebrae, short limbs, and a long tail — morphological features that adapt the species for a burrowing or semi-fossorial lifestyle. As a plethodontid salamander, <em>Oedipina collaris</em> lacks lungs and respires entirely through its moist skin, making it highly dependent on humid environments. The species inhabits freshwater habitats, moist forests, and wetlands. Detailed biological traits including typical lifespan, body length, and weight are poorly documented for this species in available literature. The Collared Worm Salamander is currently assessed as Data Deficient on the IUCN Red List, indicating that insufficient information is available to determine its conservation status accurately, and further research on the species' distribution and population trends is required.

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.