Aquatic Invasions (2012) Volume 7, Issue 3: 337–346 doi: http://dx.doi.org/10.3391/ai.2012.7.3.005 Open Access © 2012 The Author(s). Journal compilation © 2012 REABIC Research Article Cryptic invasion of Baltic lowlands by freshwater amphipod of Pontic origin Michal Grabowski*, Tomasz Rewicz, Karolina Bacela-Spychalska, Alicja Konopacka, Tomasz Mamos and Krzysztof Jazdzewski Laboratory of Biogeography & Invertebrate Ecology, Department of Invertebrate Zoology & Hydrobiology, University of Lodz, Banacha 12/16, 90-237 Łódź, Poland E-mail:
[email protected] (MG),
[email protected] (TR),
[email protected] (KBS),
[email protected] (AK),
[email protected] (TM),
[email protected] (KJ) *Corresponding author Received: 15 September 2011 / Accepted: 16 November 2011 / Published online: 25 November 2011 Abstract Gammarus varsoviensis is morphologically close to G. lacustris, with which it is often misidentified. Geographic range of G. varsoviensis includes Germany, Poland, Lithuania, Latvia, Belarus and Ukraine. Such a distribution pattern led us to the assumption that the species might have originated in the Black Sea drainage area. From there, as early as the nineteenth century, it could possibly have migrated to the Baltic basin through the Pripyat-Bug canal. Thus, the goals of this study are: (1) to indicate the level of genetic divergence of G. varsoviensis from the morphologically closest species – G. lacustris and (2) to investigate the possibility of the Pontic origin of G. varsoviensis and its range expansion across the Black Sea/Baltic Sea watershed to Central Europe through the artificial canal network. Altogether 128 partial 16S rDNA sequences of Gammarus varsoviensis from 19 localities were gained.