No abstract

ABSTRACT

While hypsodonty mostly is associated with medium to large body sizes in sigmodontine rodents, high-crowned molars combined with small bodies rarely are recorded. This latter condition is present in Neomicroxus (Sigmodontinae, incertae sedis), a genus of high-Andean cricetids also characterized by a noticeable set of cranial traits, including enlarged turbinals and rostrum, slanting zygomatic plate, and a marked backward displacement of the vertical ramus of the dentary, linked with an enlargement of the basicranial region. These morphological features, combined with the isolated position of this lineage in molecular-based phylogenies, indicate that Neomicroxus should be situated in a new tribe. We name and describe this Páramo novelty monotypic clade here. As a working hypothesis, the hypsodonty displayed by this group is considered an evolutionary response to continued volcanic ash falls that characterized the region during the Neogene. A reappraisal of tribe recognition within the two cricetid largest subfamilies, arvicolines and sigmodontines, is made, coupled with a discussion about the role of morphological convergence in “long-nose” cricetids.

The monotypic rodent Mindomys Weksler, Percequillo & Voss, 2006 (Cricetidae, Sigmodontinae) is one of the rarest members of the speciose tribe Oryzomyini. As this species is restricted to the Chocó forests of the western Andean slope in northern Ecuador, our knowledge is based on a few specimens collected decades ago. Here we add the first data on some aspects of external anatomy (cheiridia examined in fresh, ears, rhinarium), genital anatomy (penis), soft anatomy (palate, stomach, caecum) and postcranial skeleton retrieved from a full adult male, recently trapped in Reserva Drácula, Carchi, Ecuador. Several features of this specimen, paradoxically the first to be added to Ecuadorian mammal collections, reinforce the view that Mindomys is an arboreal sigmodontine.

We provide insights into the diversity of small non-volant mammals (SNVMs) in the Reserva Geobotánica Pululahua, a peri-urban natural area of Quito, Pichincha province, Ecuador. Based on Sherman-like traps and pitfall traps, we recorded 21 species of SNVMs. They represent 40% of the total species reported for the entire province, and include six species that are endemic to the northwestern slope of the Ecuadorian Andes. Despite its proximity to the city of Quito (less than 5 km), Pululahua seems to have an average richness compared with other similar localities in the Ecuadorian Andes. Our results are a baseline for future conservation plans for SNVMs.

Neomicroxus, a recently named genus, comprises small-bodied cricetid rodents patchily distributed in high-Andean ranges from Ecuador to Venezuela. Currently, two species of Neomicroxus are recognized, N. bogotensis, endemic to the Cordillera Oriental in Colombia and Cordillera de Mérida and Páramo de Tamá in Venezuela, and N. latebricola that occurs northern Andes of Ecuador. The genus is among the most poorly understood Neotropical rodents and to date no formal assessment about its alpha taxonomy was conducted. Based on DNA evidence of the first portion of the mitochondrial cytochrome b gene (cytb) and the first exon of the interphotoreceptor retinoid binding protein (IRBP), as well as craniodental measurements,we explored the divergence degree, genetic structure and phyletic relationships of the two species currently allocated under Neomicroxus. Our analyses support the monophyly of the genus as well as its uncertain tribal affiliation. Neomicroxus was retrieved as structured in two main branches, in agreement with the traditional recognition of two species. The populations referred to N. bogotensis exhibit deep divergence values (> 6 %) pointing to the existence of undescribed species under its concept. In contrast, populations of N. latebricola show a shallow genetic structure although implying recognizable geographical breaks. A moderate degree of genetic and morphological differentiation supports a new subspecies for the western populations of N. latebricola. Our contribution is the first attempt to better understanding the alpha taxonomy of Neomicroxus, highlighting the importance of the geographic complexity as a barrier to the genetic flow in N. bogotensis and the significance of the subspecies concept to formalize the geographic variation recovered in N. latebricola. Neomicroxus, un género recientemente nominado, agrupa roedores cricétidos de pequeño tamaño distribuidos en zonas altas de los Andes, desde Ecuador hasta Venezuela. Actualmente, se reconocen dos especies,

The subtropical forests of the Pacific slope of Ecuador lie within a region of wide biodiversity due to the biogeographic influence of Chocó. However, the diversity of small non-volant mammals in these forests is poorly understood. We conducted surveys at seven localities in 2020 and 2021 in Lita, northwestern Imbabura province, Ecuador. Sampling was done on an altitudinal range of 1,314–1,812 m. We used a combination of techniques (Sherman, Tomahawk, and pitfall traps) to capture non-volant small mammals. Our accumulated trapping effort was 2,724 trap/nights. We recorded 180 individuals of 23 species, of which rodents were the most diverse with 17 species, representing 73.9% of the composition. The record of Pattonimus musseri Brito et al. (2020) stands out, representing both latitudinal and elevational altitudinal range extensions. Finally, our results indicate that Lita is a natural area with a high concentration of non-volant mammals in the northwestern Ecuadorian subtropics.