Unraveling phylogenetic relationships and species boundaries in the arid adapted Gerbillus rodents (Muridae: Gerbillinae) by RAD-seq data

Gerbillus is one of the most speciose genera among rodents, with ca. 51 recognized species. Previous attempts to reconstruct the evolutionary history of Gerbillus mainly relied on the mitochondrial cyt-b marker as a source of phylogenetic information. In this study, we utilize RAD-seq genomic data from 37 specimens representing 11 species to reconstruct the phylogenetic tree for Gerbillus, applying concatenation and coalescence methods. We identified four highly supported clades corresponding to the traditionally recognized subgenera: Dipodillus, Gerbillus, Hendecapleura and Monodia. Only two uncertain branches were detected in the resulting trees, with one leading to diversification of the main lineages in the genus, recognized by quartet sampling analysis as uncertain due to possible introgression. We also examined species boundaries for four pairs of sister taxa, including potentially new species from Morocco, using SNAPP. The results strongly supported a speciation model in which all taxa are treated as separate species. The dating analyses confirmed the Plio-Pleistocene diversification of the genus, with the uncertain branch coinciding with the beginning of aridification of the Sahara at the the Plio-Pleistocene boundary. This study aligns well with the earlier analyses based on the cyt-b marker, reaffirming its suitability as an adequate marker for estimating genetic diversity in Gerbillus.

New data on the recently described Brazilian Cerrado hotspot endemic Cerradomys akroai Bonvicino, Casado et Weksler, 2014 (Rodentia: Cricetidae)

Cerradomys akroai is a recently described rodent species, known from two localities in the Brazilian Cerrado, in southeastern Tocantins state (type locality), and in southwestern Piauí state. Herein we add a third locality recorded from a specimen collected in central Tocantins state, in a “cerrado sensu stricto” habitat. Morphological and molecular analyses confirm the identification. The three localities now known for the species are restricted to northern Cerrado domain, and two are located in sites severely impacted by anthropogenic activities. Current conservation category of Cerradomys akroai is Data Deficient, and additional information on its distribution and biology is required.

Integrative analysis supports a new species of the Oecomys catherinae complex (Rodentia, Cricetidae) from Amazonia

The sigmodontine rodent Oecomys catherinae has been recognized as a species complex that includes five different lineages distributed throughout Brazil south of the Amazon river, named in literature according to their geographic position (central, eastern, northern, western, and westernmost). The western lineage also has been referred as Oecomys aff. catherinae in the literature, because it may represent a distinct species. Herein, we used molecular and morphological data to investigate the possible species distinctiveness within the O. catherinae complex. From molecular analyses, we recovered the western lineage as a monophyletic group with high genetic divergence from the other lineages of the complex. This lineage can be differentiated from other lineages of the O. catherinae complex and other congeners through a combination of mensural and morphological characters that includes: smaller size; posterior margin of nasals usually surpassing the maxillary–frontal suture; supraorbital crest moderately developed, similar to the temporal crest; parietal slightly expanded laterally; subsquamosal fenestra present; alisphenoid strut absent; and anterior cingulum of M1 present. The western lineage occurs in the southern Amazonia, in sympatry with the westernmost lineage and other species of Oecomys. Herein we describe this lineage as a new species, increasing to 19 the number of species within Oecomys.