Systematics of an Andean akodontine, Akodon mimus (Cricetidae, Sigmodontinae): insights from molecular markers

ULYSES F.J. PARDIÑAS; JONATHAN GUZMÁN SANDOVAL; CAÑÓN, CAROLA

Postdam

Congreso; 6th International Conference of Rodent Biology and Management & 16th Rodens et Spatium; 2018

University Potsdam

Akodonmimus (Thomas, 1901) is a medium-sized member of the one ofthe most diverse genus of the second largest tribe of sigmodontine rodents,Akodontini. The scarce available data indicate that A. mimus is a monotypic form distributed in Eastern Andean slopesbetween 2000-3700 mfrom southeastern Peru (Puno department) to Central Bolivia (Cochabamba, La Pazand Santa Cruz departments), and  inhabiting primarily elfin forests. Originallydescribed in the genus Oxymycterus,it was later selected as the type species of Microxus, an entity coined by Thomas in 1909, in order to allocateseveral small-bodied long-nosed mostly Andean forms. After the influentialtreatise of Cabrera in 1961, Microxuswas subsumed under Akodon, and neverproperly revisited its generic rank. With the advent of molecular markers insigmodontine systematics, the placement of A.mimus nested in Akodon wascemented on the basis of one specimen from Puno, Peru. However, more recentstudies retrieved an unstable position of A.mimus regarding the remainder species of Akodon or even to close genera such as Castoria, Deltamys and Thaptomys. We examined the phylogeneticposition of A. mimus and also therelationship between Cochabamba and Puno populations referred to the species.Based on four loci and a dense taxonomic approach covering most of theAkodontini, we performed parsimony, maximum likelihood and Bayesian analyses.Our phylogenetic results point to the validity of the genus Microxus or, alternatively, to return toa polytipic Akodon composed byseveral subgenera (i.e., Akodon s.s., Deltamys, Castoria and Microxus).In addition, we detected high levels of genetic divergence between Cochabambaand Puno populations (ca. 10% p distance ? cytochrome b locus), suggesting that they representdifferent species. In this context, Akodonmimus appears as another case of an Andean sigmodontine largely overlookedbut with an unsuspected diversity.