Morphometric and Molecular Diversity of the Holarctic Meromyza saltatrix (L., 1761) (Diptera, Chloropidae) in Eurasia

The population diversity of the frit fly Meromyza saltatrix from Poland, Mongolia, and several regions of the Russian Federation was analyzed by morphometric and molecular data on the mtDNA locus COI. Two phenotypes that correspond to two haplogroups (19 haplotypes) were identified by the absence or presence of black setae on the lower surface of the genae. A remarkable clinal variability among populations was demonstrated by the total area and area of the projecting part of the anterior processes of postgonites (APP), which play a critical role in the success of male copulation. Each parameter analyzed divided populations into four groups. Close populations with a natural barrier vary in the total area of the anterior process of the postgonite. We found an increased number of mutations including transversions in frit flies from Mongolia. Populations from Zvenigorod, South Ural Nature Reserve, and Mongolia might be of a later origin. The presence of particular haplogroup in the West European population of M. saltatrix with black setae, which is a unique feature of West European species of Meromyza, and their similarity to the Crimean population by the morphometrics of the APP is an indication of the possible isolation of this population in southern Europe during Quaternary glaciations with subsequent expansion to the northern part of the geographical area.