Morphological and morphometrical analyses of three cryptic species of Tatera Lataste, 1882 (Rodentia : Muridae) from West Africa

Three chromosomally well-differentiated but morphologically similar species of the Gerbilline rodent genus Tatera occur in West Africa, namely T.gambiana, T. guineae and T. kempi. In order to find reliable diagnostic characters, morphological and morphometrical analyses were performed on samples of these three species from Mali, the only country where they are known to occur sympatrically. Body measurement comparisons show that T guineae has a longer tail and hindfoot, and T gambiana a shorter car, relative to the two other species. Skull measurements are less variable between species as only a larger upper tooth row characterizes T kempi, and a shorter tympanic bulla length T guineae. Conversely, geographically distant samples of T kempi from Mali and Chad differ mainly for skull measurements. There is a wide overlap between the ranges of values recorded in the three species. Principal Component and Discriminant Analyses of skull measurements highlight the distinctiveness of T guineae. whose sample is clearly separated from those of T. kempi and T. gambiana. All these results validate the status of morphologically cryptic species for T. kempi and T. gambiana, long treated as synonymous. Tatera guineae is the most differentiated, but the diagnosis of an individual specimen may prove difficult due to the observed interspecific overlap in all the characters considered.