Taxonomic Revision of Endemic Rodents

Abstract

Rodents of the family Muridae represent the most species-rich mammalian family globally, yet their systematics in high-endemism regions -- particularly tropical archipelagos, isolated mountain ranges, and continental islands -- remain poorly resolved due to the combination of morphological conservatism, complex geographic variation, and historical undersampling of remote populations. This study presents a comprehensive integrative taxonomic revision of endemic murids from four high-endemism regions: the Philippine archipelago, the Sulawesi region (Indonesia), the Ethiopian Highlands, and the Iberian Peninsula, incorporating whole-genome low-coverage sequencing (2-4x) of 1,247 specimens from 247 localities, geometric morphometric analysis of 384 museum crania, and ecological niche modelling for 84 taxa. The integrative analysis recognised 47 species as valid (of 64 names currently in use at the study sites), synonymised 18 nominal species, described 12 species as new to science, and elevated 18 previously synonymised taxa to species rank based on molecular phylogenetic divergence (p-distance > 5% COI, reciprocal monophyly), morphometric distinctiveness (Procrustes distance significantly outside intraspecific range), and ecological niche differentiation (no overlap in 95% niche hypervolumes). Seven of the 12 new species occur within existing protected areas; five do not, representing immediate conservation priorities. IUCN Red List assessments are provided for all 47 valid species, with 28 (59.6%) assessed as threatened (VU/EN/CR) under the revised taxonomy. These revisions substantially alter the conservation status landscape for endemic rodents in these four regions.