A first species-wide phylogenetic analysis of small mammals from Costa Rica using mitochondrial cytochrome b

Abstract

Within the Mesoamerican biodiversity hotspot, Costa Rica shows high species richness, due to its biogeographical, tectonic and climatic history. Small mammals (i.e. species of less than 500 grams) are a very diverse group in Costa Rica with about 52 native species. This high diversity, recent records of new species and molecular studies detecting cryptic genetic diversity highlight this group and this region as an important target for the DNA barcoding approach. Here we used 131 tissue samples across multiple localities in Costa Rica and sequenced the complete mitochondrial cytochrome b (1140 bp). These samples represented 17 recognized species (including Didelphis marsupialis, which is technically not a small mammal) and two taxa of uncertain status. The new sequence data were supplemented with previously published data from INSDC. Our phylogenetic analyses are consistent with and extend upon recent revisions in Heteromys, Peromyscus and Reithrodontomys and suggest possible new cryptic forms within what are currently named Melanomys chrysomelas, Nyctomys sumichrasti and Proechimys semispinosus. The previously named “Heteromys sp” is indeed likely a new species requiring a full taxonomic description. Our results suggest the continuity of previously described species at our newly described localities in Costa Rica reinforcing recent taxonomic surveys and field guides for the small mammals of Costa Rica. To confirm the presence of cryptic species and major genetic forms in Heteromys, Peromyscus, Reithrodontomys, Melanomys, Nyctomys and Proechimys there needs to be greater sampling, additional genetic markers, morphometrics and other studies. Scotinomys also shows interesting phylogenetic subdivision, requiring further investigation.