The dusky antechinus (Antechinus swainsonii), also known as Swainson's antechinus or the dusky marsupial mouse, is a species of small marsupial carnivore, a member of the family Dasyuridae. It is found in Australia.
The dusky antechinus is the largest antechinus. The largest and darkest fur Dusky Antechinus occur in higher altitudes.[5] It can be distinguished from its relatives by its much darker fur, which is also apparent in the pale form.[5] It is mostly nocturnal but has suggested to be partly active during the day.[5] It mostly eats invertebrates, although it will occasionally devour small lizards and skinks.[5] Like all antechinuses, the dusky antechinus has a short and vigorous mating season (which occurs during winter), after which nearly all of the males die. However, compared to the other antechinus species whose male individuals are almost invariably semelparous and females usually so, iteroparity is more commonly seen in the present species (perhaps due to its comparatively large size). The dusky antechinus is also known for being unusually vocal for an antechinus, and has been observed hissing and chattering.[3]