Behavioral mimicry in Myrmarachne species (Araneae, Salticidae) from North Queensland, Australia

Abstract

Batesian ant mimics - such as salticids belonging to the genus Myrmarachne - resemble their models to deceive potential predators, sometimes including the ants themselves. Myrmarachne species in addition to being striking visual mimics of ants also wave their first pair of legs in the air, much like the antennal movement of ants. Whether this leg movement is part of Myrmarachne species' mimicry is debated. In this study the leg I movement of four Myrmarachne species was investigated, with particular attention given to the frequency and amplitude of the leg waving. Correlations between the leg waving and other behaviors of Myrmarachne species were also looked at. There were interspecific differences in leg I movements, and the leg I waving also depended on other behaviors such as ''bobbing'' the opisthosoma. Thus the leg I movement of Myrmarachne species is behavioral mimicry of the antennal movement of ants, in other words increasing the spiders' resemblance to the ants to avoid predation. This ''antennal illusion'' displays characteristics of a plastic trait which has evolved under selection pressure.