Variability in chigger mites of talmiensis species group, genus Neotrombicula Hirst, 1925 (Acari, Trombiculidae) in areas of sympatria on the Western Caucasus

A.A. Stekolnikov

Entomologicheskoe obozrenie, 81(3): 761-777 (2002) (In Russian, English summary).

S U M M A R Y

Variability of morphometric features and host specificity has been studied in three closely related species: Neotrombicula pontica Stekolnikov, 2001, N. sympatrica Stekolnikov, 2001, and N. carpathica Schluger et Vysotzkaya, 1970. Eco-geographical rules has been revealed in N. pontica and N. sympatrica. Scutal width and length, and also relative distance between the base of mastitarsala and base of leg III tarsus (m-t), show strong and significant positive correlations with an altitude above sea level. In N. sympatrica number of idiosomal setae (NDV) is also correlated with an altitude.

N. sympatrica nearly not occured on voles of the subgenus Microtus (Terricola) in localities where sympatria of N. sympatrica and N. pontica been reported. This species parasitizes there only mice of the genus Apodemus. While in other localities, no host specificity of N. sympatrica to Apodemus is found. N. pontica and N. carpathica parasitize the both genera of hosts, but on Microtus these species are some more numerous.

The pattern of distances between samples, constructed by multidimensional scaling, has been considered from the view of probable diagnostic problems in talmiensis group. N. talmiensis is the smallest species in the group. Therefore, the main problem in the systematics of talmiensis group is a distinguishing of small ecogeographical forms of other species from the nominative one. Probable areas of species distribution are described. N. carpathica appear to be southern European species, while N. sympatrica is asiatic one. The Main Caucasus Range is a natural barrier between these species. N. pontica is probably western Caucasian species, inhabiting mountain mesophillous forests and isolated patchs of forest in flood-lands.