Was the San Quintín kangaroo rat really rediscovered?

Abstract

The San Quintín kangaroo rat ( Dipodomys gravipes Huey, 1925) is one of the three kangaroo rats in northwestern Baja California and the largest of them in most body dimensions. After a dramatic population decline in the 1980s, it was declared as potentially extinct in the wild by Mexican law. In 2017, the species was claimed to be rediscovered, but critical data supporting the species recognition were not provided. The question remained: Was the San Quintín kangaroo rat really rediscovered? We analyzed individuals identified by us as D. gravipes to validate our identification. We compared cranial morphometric and mitochondrial data of on-purpose collected specimens with those of historic specimens and with those of sympatric kangaroo rats in Baja California, particularly the Dulzura kangaroo rat ( Dipodomys simulans (Merriam, 1904)). Cranial morphometry and body dimensions of current specimens are indistinguishable from those of historic D. gravipes, while being different from D. simulans in most dimensions. External measurements such as cranial traits adequately distinguish both species. The mitochondrial analysis revealed strong support for the species grouping of sequences of our specimens and DNA sequences of D. gravipes from the GenBank repository. This study comprises a morphometric and molecular confirmation of the presence of the species after >25 years of failures to find it.