An integrative approach to the taxonomy of <i>Oxymycterus paramensis</i> (Rodentia, Cricetidae) and related nominal forms

Abstract Oxymycterus includes 17 species of small- to medium-sized sigmodontine rodents. The taxonomy of this genus has been widely studied, but several unresolved issues persist. One example of this is the Paramo Hocicudo, Oxymycterus paramensis, which over its extended latitudinal range has been associated with several nominal forms that have not been evaluated with an integrative approach. Based on phylogenetic analyses of the Cytb gene, qualitative and quantitative morphological characters, and environmental niche modeling, we reexamined the taxonomic status of the nominal forms akodontius, jacentior, and paramensis while considering the recently recognized species O. willkaurco. The phylogenetic reconstruction guided subsequent analysis of morphological variation and the development of the niche models. Considering the results in an integrative framework, we observed congruence among phylogenetic, species distribution models, and environmental niche models (a proxy indicating different environmental preferences), which support the recognition of 2 species within the concept of O. paramensis s.l. At the same time, we did not observe congruent support for this taxonomic hypothesis from morphological evidence, with the absence of diagnostic qualitative or quantitative characters differentiating the 2 taxa. Considering that some lines of evidence suggest the interruption of gene flow, we see more support for recognizing existing names for 2 taxa at the species level: O. paramensis, endemic to Bolivia; and O. akodontius (which has priority over jacentior), distributed from southern Bolivia to northwestern Argentina. However, we recommend more detailed studies to test the taxonomic scenario advanced here.