Multilocus Phylogeny of Asiatic Striped Squirrels (Sciuridae, <i>Tamiops</i> ) Reveals Their Evolutionary Relationships and Species Limits

The genus <i>Tamiops</i>, classified within the family Sciuridae and the subfamily Callosciurinae, is distributed across East and Southeast Asia. The taxonomic classification of <i>Tamiops</i> has historically been contentious, with species diversity often underestimated due to reliance on pelage color variations for species descriptions, which are thought to reflect seasonal changes. To clarify the internal phylogenetic relationships and taxonomic status of the <i>Tamiops</i> species, we conducted morphological analyses and constructed multi-locus phylogenetic trees using a large DNA dataset that encompassed one mitochondrial locus (Cyt-b) and three nuclear loci (IRBP, PRKCI, RAG1), as well as 20 complete mitochondrial genomes. We identified seven well-supported monophyletic clades of <i>Tamiops</i> based nuclear data evidence. The K2P genetic distances among the seven lineages of <i>Tamiops</i> varied from 0.095 to 0.204. Consequently, we elevated one subspecies<i>-</i> <i>T</i>. <i>maritimus hainanus</i> <i>-</i>to full species status, having diverged from its common ancestor approximately 6.01 million years ago. Ultimately, we recognized a total of seven valid species within the genus <i>Tamiops</i>, which include <i>T</i>. <i>swinhoei</i>, <i>T</i>. <i>maritimus</i>, <i>T</i>. <i>hainanus</i>, <i>T</i>. <i>barbei</i>, <i>T</i>. <i>roldolphii</i>, <i>T</i>. <i>minshanica</i>, and <i>T</i>. <i>mcclellandii</i>. Divergence time estimation suggested that <i>Tamiops</i> began to diversify approximately 13.3 million years ago (Mya). Our findings provide insights into the evolutionary relationships and previously overlooked species diversity within the genus <i>Tamiops</i>.