Systematics and historical biogeography of Crunomys and Maxomys (Muridae: Murinae), with the description of a new species from Sulawesi and new genus-level classification
Crunomys and Maxomys are closely related murine genera from forested regions of Southeast Asia and western portions of the Indo-Australian Archipelago. Previous phylogenetic analyses suggested that a taxonomic reappraisal is necessary for these genera, but limited taxon sampling prevented formal changes. We produced a mitochondrial DNA dataset that includes 376 individuals representing all 22 recognized species and a nuclear dataset comprising thousands of ultraconserved elements missing only 1 recognized species. Our phylogenetic inferences consistently show that Crunomys is nested within Maxomys. We transfer all Maxomys species to the older genus Crunomys to resolve the paraphyly. We also conducted a morphological analysis of species from Sulawesi and describe a new species of Crunomys from the eastern peninsula of the island. We identify 43 geographically defined mitochondrial haplogroups across all species of Crunomys, many of which also are inferred as distinct in a multilocus species delimitation analysis. Historical biogeographic reconstructions consistently inferred multiple dispersal events to and from oceanic islands and among continental shelf islands and mainland Southeast Asia. On both large continental shelf islands like Borneo and large oceanic islands like Sulawesi, in situ divergence produced high levels of diversity.