Gammarus fossarum
Gammarus fossarum is a species complex of freshwater amphipod crustacean native to Europe. They are abundant members of the macroinvertebrate community, and also used as model organisms for ecotoxicology. Description Gammarus fossarum go through nine or ten moults of their exoskeleton before reaching sexual maturity; weighing just 0.1 mg at birth, by adulthood they have a wet weight of 5 to 7 mg. Adult G. fossarum are between 4.5 and 10 mm in length, and weigh up to 41 (females) to 61 (males) mg wet weight. Distribution Gammarus fossarum are widely distributed throughout central and southeastern Europe. They are found in France, Italy, Germany, Switzerland, Austria, Slovenia, Serbia, the Netherlands, Belgium, Hungary, Croatia, Albania, Bulgaria, and Bosnia and Herzegovina. It was previously thought to be a single species based on morphological characteristics, however genetic and genomic research has revealed additional diversity within G. fossarum. Mitochondrial DNA showed that there were three distinct clades in central Europe, subsequently called types A, B, and C. More recent population genetic analyses on amphipods from across the entire distribution range of G. fossarum have revealed that it is in fact a species complex of at least 80 cryptic species. Thesee analyses found at least