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Comparative Cytogenetics. 2007. 1(1): 3-16.

A karyosystematic investigation of a group of sibling species related to Stictotarsus griseostriatus (De Geer) (Coleoptera: Dytiscidae)

Dutton L.A., Angus R.B.

Abstract. A karyological investigation has been carried out on material of the Stictotarsus griseostriatus-group of species from 19 localities in Europe and AsiaMinor. Seven karyotypically distinct species have been recognised: S. griseostriatus De Geer from the Baltic coast of Sweden, S. multilineatus Falkenström from inland Sweden and Scotland, and five new species: S. alpestris sp. n. from the central andeastern Alps, S. inexpectatus sp. n. from the western Alps, S. ibericus sp. n. from theIberian Peninsula and western Alps, S. creticus sp. n. from Crete and S. riberae sp. n.from Bulgaria and Turkey. Chromosome numbers range from 2n = 60 + X0 (male), XX (female) (S. griseostriatus) to 2n = 52 + X0 (male), XX (female) (S. ibericus, S. creticus). In addition, S.ibericus shows a fusion-fission polymorphism between two pairs of autosomes. It isconsidered that the differences between the karyotypes are such that any hybridswould be sterile. Aedeagi and parameres are illustrated, but it is considered that themorphological distinctions between the species are virtually non-existent. Thedistributions of the species are discussed and the complexities arising from range-changes resulting from Pleistocene climatic fluctuations are noted.