Alpha-taxonomy in the cricetid rodent Neomicroxus (Sigmodontinae, incertae sedis), a first assessment

Carola Cañón, Jenny Curay, Jorge Brito, Javier Colmenares, Ulyses Pardiñas




Neomicroxus, a genus recently named, 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 from the Cordillera Oriental in Colombia and Cordillera de Mérida and Páramo de Tamá in Venezuela, and N. latebricola that occurs northern Andes of Ecuador.  This 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 (cyt-b) 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 supported the monophyly of the genus as well as their uncertain tribal affiliation.  Neomicroxus was retrieved as structured in two main branches, in agreement with the traditional recognition of two species as the main content.  The populations referred to N. bogotensis exhibit deep divergence values (> 6%) pointing to the existence of undescribed species under its concept.  On the contrary, 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

Discussion and conclusions

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.

Palabras clave

Andes; Colombia; Ecuador, Microxus, Neomicroxus bogotensis, Neomicroxus latebricola.

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