BIOLOGY AND BEHAVIOR OF THE NEOTROPICAL ANT-MIMICKING SPIDER APHANTOCHILUS-ROGERSI (ARANEAE, APHANTOCHILIDAE) - NESTING, MATERNAL-CARE AND ONTOGENY OF ANT-HUNTING TECHNIQUES

Aphantochilus rogersi is an ant-mimicking spider that preys exclusivel y on cephalotine ants. The spiders oviposit in close proximity to nest s of the model ant Zacryptocerus pusillus, and emergent spiderlings te nd to remain in the vicinity of natal egg sacs. Females of A. rogersi actively defend their egg sacs against approaching workers of Z. pusil lus, but the latter may sometimes destroy the eggs. Feeding specializa tion on these ants is confirmed by more than 300 observations of young and adult A. rogersi carrying ant corpses in the held. Although A. ro gersi possesses several behavioural traits which may reduce the risk o f being injured by ants during subjugation, field and laboratory obser vations showed that social defence by Z. pusillus may cause mutilation to the spiders. Tests in captivity revealed an ontogenetic change in the prey-capture techniques employed by A. rogersi. Early-instar spide rlings can apparently only seize the ant's petiole tightly if they are able to approach the ant from the front. As the ant is paralysed, the spiderling positions itself vertically in relation to the substratum. Larger spiders, on the other hand, attack ants most frequently from b ehind, and seem better equipped to seize the ant's petiole firmly with their larger chelicerae. Owing to their greater strength, late-instar spiders are able to Lift the struggling ant aloft. The selection of a suitable oviposition site, the mother's ability to defend herself and the eggs from nearby ants, and the capacity to capture and subdue ant s safely from emergence to maturity, are regarded as crucial traits in herent in the mimetic and feeding specialization by A. rogersi.