INTRODUCTION:

The Lesser Golden-bellied, Nephelomys nimbosus, is endemic to Ecuador and restricted only to the forests of the eastern slope of the Andes. This species is known from four localities along the upper reaches of the Napo River (Baeza, Chaco-river Oyacachi) and the headwaters of the Pastaza River (San Antonio and San Francisco).

METHODS:

The taxonomic identity of an individual Oryzomys sp ., collected on July 6, 2003, in Tapichalaca province of Zamora Chinchipe southeastern Ecuador, was reviewed in detail, the review determined that correspond to Nephelomys nimbosus.

RESULTS:

The specimen of N. nimbosus (adult female) has the following characteristics: dark reddish-brown fur, hair cover between 11 to 13 mm in length; whitish-gray with yellowish hues on the venter. The skull has a thin, delicate-looking face; supraorbital ridges undeveloped; mesopterigoidea pit rectangular with corners rounded on the leading edge; the incisive foramen is shorter and wider in the middle; mandible with small mental foramen; short and rounded sigmoid notch.

DISCUSSION AND CONCLUSIONS:

This record extends the geographic range of the species to the southeast of Ecuador by about 350 km, and adds a fifth locality. Percequillo (2015) mentions that N. nimbosus is parapatric with N. auriventer, and replaces it in higher altitudes above 2,000 m. However a review of specimens revealed a specimen of N. auriventer collected at 2,950 m, indicating that these two species may be sympatric in part of their ranges. However no information was available where the two species have been collected from the same locality.