Description of two new species of Hyalella (amphipoda: Hyalellidae) from eastern North America with a revised key to North American members of the genus

Since the 1990s, it has been presumed that different populations/size classes of the freshwater amphipod Hyalella azteca(Saussure, 1858) were different species, and a multitude of genetic evidence was later produced to confirm that it is in fact a cryptic species complex. However, no new species of Hyalellahave been described from the eastern United States or Canada since then. Herein we describe two new species, Hyalella( Hyalella) spinicaudaand Hyalella( Hyalella) wellborni, collected from Illinois, Indiana, Michigan, Wisconsin, and Texas, USA, and Ontario, Canada, based on morphological characters but informed by genetic analyses. In addition, we provide an updated key to the described species of Hyalellain North America and the Caribbean.