Thomasomys ucucha

Discovering the Enigmatic Thomasomys ucucha

Thomasomys ucucha, a rodent species found in Ecuador’s high-altitude forests and grasslands, is a fascinating creature that has captured the attention of scientists for over a century. Imagine stumbling upon a tiny, dark-furred mouse with large, broad incisors—this is Thomasomys ucucha, a unique species that has been around since 1903 but only formally described in 2003.

The Name Game

Thomasomys ucucha’s name tells a story. The genus Thomasomys honors Oldfield Thomas, an English zoologist who made significant contributions to mammalogy. Meanwhile, the Quechua word ‘mouse’ is embedded in its species name, reflecting the indigenous heritage of Ecuador.

A Physical Description

This medium-sized rodent has a dark brown upper part and grey underparts, with long mystacial vibrissae (whiskers) and sparse dark hairs on the ears. Its digits and metapodials are covered in dark hairs, while the ungual tufts have gray hairs. Females possess six mammae, and their measurements vary: head and body length 94-119 mm, tail length 122-151 mm, hindfoot length 26-30 mm, ear length 17-20 mm, and weight 24-46 g.

Skull Structure

The front part of the skull is short and broad with poorly developed notches. The zygomatic arches are rounded and spread widely, while the braincase is robust. The incisive foramina are short and don’t reach near the first molars. The palate is short and lacks ridges or grooves, with simple palatal pits at the back. The mesopterygoid fossa has a broad roof with small sphenopalatine vacuities. An alisphenoid strut separates two foramina at the base of the skull.

Teeth and More

The large upper incisors are orthodontic and heavily pigmented with orange, while the molars have distinct cuspules but less developed accessory ridges compared to T. hylophilus. The third upper molar is reduced relative to the second in Thomasomys ucucha, with lower molars being generally similar but sometimes having undivided anteroconids and unreduced third molars.

Penis Structure

The glans penis of T. ucucha is small and covered with penile spines, except for an area near the tip. This unique feature adds to its complexity as a species.

Habitat and Distribution

Thomasomys ucucha thrives in the high-altitude forests and grasslands of Ecuador’s Cordillera Oriental, specifically between 3,380-3,720 meters above sea level. It has been found in various habitats including páramo and subalpine rainforest. This species is part of a group of muroid rodents that includes several other Thomasomys species.

Conservation Status

The conservation status of T. ucucha is ‘vulnerable’ due to its highly localized distribution and potential habitat destruction for agricultural purposes, but it occurs near or in protected areas. This makes the preservation of its habitat crucial for the survival of this unique species.

Thomasomys ucucha, a tiny yet complex creature, is a testament to the biodiversity of Ecuador’s high-altitude ecosystems. Its unique features and habitat make it a valuable subject for scientific study and conservation efforts. As we continue to explore and understand these small mammals, we uncover not just new species but also the intricate web of life that sustains our planet.