Several population genetic studies have been conducted on G.
fossarum, but often focused on limited geographical regions
containing only one of the cryptic species and/or were constrained
by the limited availability of highly variable and selectively neutral
markers [13,14,35,38–40]. We here make use of nine recently
developed microsatellite markers [41] to examine the intraspecific
genetic structure within two cryptic species and potential
differences between them. Specifically, we analyse (i) the effect of
geographical distance and drainage boundaries on population
genetic structure, (ii) the presence of distinct genetic clusters within
species, (iii) the effects of recolonization history.