Biogeographical links between steppe insects in the Monegros region (Aragón, NE Spain), the eastern Mediterranean, and central Asia

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Abstract
Sixty‐two species of insects in thirty‐six families and nine orders, plus one species of Acari, were found to have disjunct distributions, or to belong to species groups with disjunct distributions, between the steppe areas in the central Monegros region (NE Spain) and the steppes in the eastern Mediterranean or central Asia. The accumulation of examples of a wide range of taxonomic groups, and the phyletic links of apparent endemic species of the central Ebro valley with eastern species, are considered to support the pre‐Pleistocene origin of their relict distributions, associated with the persistence of steppe habitats over gypsiferous soils in the area since the Late Tertiary. The case of disjunct distributions of phytophages and their parasitoids on plants with disjunct distributions themselves, such asKrascheninnikovia ceratoides(L.) Gueldenst. (Chenopodiaceae) or theJuniperus thuriferaL. −J. excelsaBieb. complex (Cupressaceae), would seem to provide strong evidence supporting the continuity of their presence in the central Ebro valley through the Quaternary.