First record of parthenogenesis in the invasive amphipod Talitroides topitotum

Parthenogenesis has been recorded in many invertebrate taxa, including the Crustacea. However, there is only strong evidence for this mode of reproduction for one species of Amphipoda, the marine Crassicorophium bonellii. Here, we present evidence for parthenogenesis in a Brazilian population of a euterrestrial, synanthropic amphipod species, Talitroides topitotum. The absence of males is not ubiquitous but is commonly noted in geographic records of this species. This is the first experimental study to test for and find parthenogenesis in an all-female T. topitotum population. Females collected from Southern Brazil were used to establish a parental generation in the laboratory (two ovigerous and three non-ovigerous separately, each in its own terrarium). Individuals were screened twice a week for the presence of offspring. Female #1 produced offspring through to the F4 generation. From this lab study, we conclude that T. topitotum can reproduce without males through a mechanism of asexual reproduction, namely, parthenogenesis. This trait may facilitate its establishment in new environments even when introduced in low numbers. These findings provide a basis for future studies aimed at understanding reproductive patterns and comparing them with those of sexually reproducing populations.