ИСТИНА

Gerbils belonging to Meriones meridianus species complex are widely distributed across the arid zone of Eurasia. High among-population morphological variability and lack of data on affiliated taxa of uncertain status (such as M. dahli and M. chengi) warrant revision of M. meridianus sensu lato. We examined geographical variation of midday gerbil based on craniometric data and compared it to the pattern of mtDNA variation as revealed in recent publications. 635 skulls of M. meridianus from Russia, Kazakhstan, Uzbekistan, Turkmenistan, Tajikistan, Mongolia, China and 30 skulls of M. dahli were examined. Model-based clustering analysis, as implemented in Mclust, was used to identify the number and content of morphological clusters. The pattern of craniometric variation perfectly agrees with the one suggested by mtDNA. Three clearly defined morphological groups corresponding to mtDNA clades are evident. We believe that these three taxa (M. meridianus, M. penicilliger, M. psammophilus) should be elevated to full species rank. M. psammophilus occurs in the Mongolian part of the range except for the western Mongolian Dzhungaria which inhabited by M. meridianus. The range of the latter extends westwards to NW Kazakhstan and Kalmykia. M. penicilliger occupies the southern part of the range from Tian Shan to Turkmenistan. M. chengi is most probably a synonym to M. psammophilus. M. dahli is craniometrically rather close to M. meridianus and, hence its species status appears questionable.