The Neotropical variegated squirrel, Sciurus variegatoides (Rodentia: Sciuridae) in Nicaragua, with the description of a new subspecies

Abstract

The Neotropical variegated squirrel, Sciurus variegatoides, is represented in Nicaragua by five known subspecies—adolphei, belti, boothiae, dorsalis, and underwoodi. Analyses of morphometrics, color, and color patterns of 394 specimens from throughout the country and all available literature support the retention of these subspecies, but also reveal the presence of a sixth population of these squirrels, which is worthy of description and recognition as a new subspecies. This new subspecies is confined to Isla de Ometepe in Lago de Nicaragua. Variegated squirrels on Ometepe are on average the smallest variegated squirrels in the country in most cranial measures; however, in postorbital breadth, the island population averages larger than the samples from the surrounding mainland. This island population is the smallest and most distinctive of any population of variegated squirrels from throughout the species’ geographic range. The baculum is distinct in size, shape, and angle of the disc. Ometepe variegated squirrels have a distinctive albeit a highly variable color pattern. Although there are some color differences between the populations found on the north island (Volcán Concepción) and the south island (Volcán Maderas), all specimens from Ometepe are regarded as belonging to a single subspecies because there are no discernable differences in cranial measures. Throughout Nicaragua’s Pacific lowland dry tropical forest region, there is no evidence of integration between S. variegatoides dorsalis with S. v. adolphei, the subspecies occurring to the north; between S. v. dorsalis and S. v. underwoodi, the subspecies occurring to the east and northeast; or between S. v. adolphei and S. v. underwoodi in the northwest. The Central Depression region of Nicaragua appears to be a significant geographic barrier to gene flow between taxa. In the Central Highlands, there are regions of intergradation between S. v. belti and S. v. underwoodi and between S. v. belti and S. v. boothiae. The taxa of S. variegatoides found in the country are described and mapped by critically evaluating the historical collecting sites, all published literature, and data presented herein.