[Territorial distribution of 2 sympathric species of fleas--parasites of the great gerbil in the Kyzyl-Kum desert].

Fleas of Xenopsylla gerbilli and Xenopsylla hirtipes, parasites of Rhombonus optimus in the Kizil--Kum, have a sympathric distribution. Within a greater part of their common area both species vicariate in landscapes: X. hirtipes occupties more mesophilous parts while X. gerbilli is distributed in all parts where the first species is missing. The distribution of X. hirtipes depends first of all on abiotic environmental factors and that of X. gerbilli--on biotic ones, i. e. on the competition with X. hirtipes. However, under more favourable conditions (northern foothill valleys of the Bukantau ridge) both species occur together in great number.