Monotypic status of the South American relictual marsupial Dromiciops gliroides (Microbiotheria)

The long-recognized monotypic status of the relictual marsupial genus Dromiciops was recently challenged by a controversial reanalysis of previously published mtDNA data that were combined with a new morphological study to conclude that the genus contains 3 species: D. bozinovici, D. mondaca, and D. gliroides. We present here new phylogenetic and coalescent species delimitation analyses to test the multispecific status of Dromiciops relative to the proposed 3 new species. Our molecular analysis is based on partial sequences of 4 nuclear (RAG1, ApoB, vWF, and IRBP) and 2 mitochondrial (12S RNA and Cytb) genes. Genetic distances showed low differentiation among the proposed Dromiciops species, consistent with typical levels of intraspecific variation. Phylogenetic analyses yielded only moderate support for monophyly of D. bozinovici, while depicting polyphyly in D. gliroides and D. mondaca. Species delimitation analyses did not recover the proposed 3-species scenario, and the taxonomic index of congruence among these methods (C-tax = 0.5-1.0) supported monotypic status for Dromiciops. Taking into consideration all the genetic analyses and previously reported morphological analyses, we conclude that all Dromiciops lineages belong to a single species.