for distinguishing the individual species. Instead, he focussed on differences in the morphology of the female sexual organs, and revised the number of recognised species from 22 to 6. This included reclassifying the redback and several other species as subspecies of the best-known member of the group, the black widow spider (Latrodectus mactans), found in North America and other regions. He did not consider the subspecies L. h. ancorifer, L. h. aruensis and L. h. indicus distinct enough to warrant recognition. Subsequently, more reliable genetic studies have split the genus into about 30 species, and the redback has no recognised subspecies in modern classifications. Placement A member of the genus Latrodectus in the family Theridiidae, the redback belongs in a clade with the black widow spider, with the katipō as its closest relative. A 2004 molecular study supports the redback's status as a distinct species, as does the unique abdomen-presenting behaviour of the male during mating. The close relationship between the two species is shown when mating: the male redback is able to successfully mate with a female katipō producing hybrid offspring. However, the male katipō is too heavy to mate with the female redback, as it triggers a predatory response in the female when it approaches the web, causing the female to eat it. There is evidence of interbreeding between female katipō and male redbacks in the wild. Description The adult female redback has a body around long, with slender legs, the first pair of which are longer than the rest. The round abdomen is a deep black (occasionally brownish), with a red (sometimes orange) longitudinal stripe on the upper surface and an hourglass-shaped scarlet streak on the underside. Females with incomplete markings or all-black abdomens occasionally occur. The cephalothorax is much smaller than the abdomen, and is black. Redback spiderlings are grey with dark spots, and become darker with each moult. Juvenile females have additional white markings on the abdomen. The bright scarlet red colours may serve as a warning to potential predators. Each spider has a pair of venom glands, one attached to each of its chelicerae with very small fangs. Small compared to the female, the male redback is long and is light brown, with white markings on the upper side of the abdomen and a pale hourglass marking on the underside. Another species in Australia with a similar physique, Steatoda capensis, has been termed the