The karyotypes of three rat species from Hainan Island, China, were examined. Niviventer fulvescens (Gray, 1847) had 2n=46 and FN=64, similar to the karyotypes reported for N. fulvescens from Southeast Asia, while Niviventer lotipes () had 2n=52 and FN=66, which is distinct from the known karyotypes of other Niviventer species. Niviventer lotipes was recently considered conspecific with N. tena...