THE NEOTROPICAL VARIEGATED SQUIRREL, SCIURUS VARIEGATOIDES (RODENTIA: SCIURIDAE) IN NICARAGUA, WITH THE DESCRIPTION OF A NEW SUBSPECIES HUGH H. GENOWAYS AND ROBERT M. TIMM ABSTRACT The Neotropical variegated squirrel, Sciurus variegatoides, is represented in Nica- ragua 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 aver- age 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 subspe- cies 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 re- gions 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. Key words: biodiversity, biogeography, Central America, color pattern variation, geographic variation, Mammalia, morphology, Neotropics, subspecies novum, taxonomy INTRODUCTION The Neotropical variegated squirrel Sciurus well as premontane and montane forests, but it favors variegatoides Ogilby, 1839 (Rodentia: Sciuridae) is second-growth, disturbed, and heterogeneous habitats the largest and most widely distributed of the squirrels where it tends to nest in the largest trees available. found in Central America. Variegated squirrels occur from southwestern Chiapas through central Panama This is often the most conspicuous squirrel in and range in elevation from sea level to 2,600 m; much of the Central American forests. Because of its however, they are most abundant at elevations below size and at times abundance, variegated squirrels play 1,500 m. Sciurus variegatoides occupies a wide array important ecological roles in Neotropical ecosystems as of habitats, including lowland dry and wet forests, as they feeds on seeds, fruits, fungi, insects, and smaller 479 480 SPECIAL PUBLICATIONS, MUSEUM OF TEXAS TECH UNIVERSITY vertebrates. It can be the principal handler of seeds, of distributions and status of several of the taxa are now especially as seed predators of palms, but can also possible. In the absence of genetic information for increase seed dispersal and germination by caching. these subspecies, and given localities of intergradation This species can be quite abundant locally, especially between them as documented below, S. variegatoides is in agricultural situations. It can do considerable dam- treated as a single, widespread, variable species herein. age feeding on developing bananas (Musa, Musaceae), coconuts (Cocos nucifera, Arecaceae), coffee beans In a recent review of the squirrels of Nicaragua, (Coffea sp., Rubiaceae), cacao pods (Theobroma cacao, Medina-Fitoria et al. (2018) reported range extensions Malvaceae), papaya (Carica papaya, Caricaceae), and for southern flying squirrels (Glaucomy volans) and other crops. pygmy squirrels (Microsciurus alfari) and reviewed the then known distributions of these and S. granaten- Sciurus variegatoides is one of the most vari- sis, S. richmondi, and S. variegatoides. They provide able species of all mammals with respect to color; descriptions and a useful key to the species of sciurids hence the English common name, variegated squirrel, in the country, their conservation status, and color im- is especially appropriate. Fifteen subspecies, based ages of each. In their report on the variegated squirrels primarily on color, currently are recognized (Harris found on Isla de Ometepe, they provided two images of 1937; McPherson 1971; Hall 1981), acknowledging free-ranging animals demonstrating some of the color the considerable geographic variation within the spe- variation found in the island population and stated that cies, yet little systematic or ecological information is these squirrels were of uncertain taxonomic status. available for most populations (Best 1995). The spe- cies ranges in pelage color from nearly black to steely Between February 1964 and the spring of 1968, gray, or grizzled gray, to reds, and to having a broad, several field parties from University of Kansas led by black dorsum with white, red, bright orange, or light J. Knox Jones, Jr. and James Dale Smith, collected orange sides and ventrum (Harris 1937; Reid 2009; mammals and their ectoparasites throughout Nicaragua. Thorington et al. 2012). Herein, these collections are reported along with other specimens housed in museums to re-examine the sys- As currently defined, this broadly distributed and tematic status of several populations of S. variegatoides highly variable squirrel has continued to be recognized focusing on the taxa found in Nicaragua. One goal is as a single species, although there is considerable to build a better understanding of the geographic varia- size and color variation among subspecies. Interest- tion in this species and to re-evaluate the diversity that ingly, there appears to be little, and in some cases no, is currently recognized. The field parties from Kansas introgression in color morphs between several of the were the first to collect mammal specimens at several subspecies; although between some, there is a narrow localities on Isla de Ometepe, the large volcanic island zone of introgression. There has been no revisionary in Lago de Nicaragua. The tree squirrels on Ometepe work since Harris’s classic review of the species (Harris represent a previously unrecognized taxon, which is 1937). A considerable number of specimens have be- described below as part of this species complex. come available since Harris’s work and a re-assessment METHODS AND MATERIALS A total of 394 specimens of Sciurus variegatoi- to the nearest 0.1 mm as defined by Hall (1981) and des from throughout Nicaragua comprise the basis of include the following: greatest length of skull (GLS), this report, with additional specimens examined from condylobasal length (CBL), zygomatic breadth (ZB), throughout the species’ range and a review of the pub- interorbital breadth (IOB), postorbital breadth (POB), lished literature to assess distributions, morphology, mastoid breadth (MB), length of nasals (LN), length of and color variation. All measurements in the accounts palatal bridge (PB), and length of maxillary toothrow that follow are in millimeters and weights are given in (LTR). External measurements and reproductive data grams (g) or kilograms (kg). Cranial measurements are those recorded on specimen labels by the collector. were taken by Genoways with digital calipers accurate GENOWAYS AND TIMM—SCIURUS VARIEGATOIDES IN NICARAGUA 481 Statistical analyses were performed using Minitab Harris’s (1937) color terminology was followed (Minitab, Inc., State College, Pennsylvania, USA). in describing the coloration of these squirrels to provide There is no secondary sexual dimorphism in size in the user with a standard, uniform set of descriptors for these squirrels and given the small sample sizes, as- the various colors and because Harris did an outstand- sessment of sexual dimorphism was not feasible; thus ing job of elucidating the patterns present. measurements of males and females were pooled in analyses of variation among groups. A number of prin- Specimens reported in the systematics accounts cipal component analyses were undertaken using either below are housed in the following museums: American individual localities or small geographic areas as units Museum of Natural History, New York (AMNH); Brit- beginning with 27 operational groupings. Individuals ish Museum (Natural History) London, UK [BM(NH)]; deemed intergrades as judged by external color charac- Muséum national d′Histoire naturelle, Paris, France teristics were not included in morphometric analyses. (MNHN); Museum of Texas Tech University, Lubbock Based on these results, six groups that represent taxo- (TTU); University of Kansas Museum of Natural His- nomic and geographic units were formed for the final tory, Lawrence (KU); and National Museum of Natural principal components analysis. Discriminant function History,