Cooperation in the neotropical pseudoscorpion, Paratemnoides nidificator (Balzan, 1888):: feeding and dispersal behavior

Social behavior is rare among arachnids, and permanent-sociality is a strategy documented only in a few spider species. Here we describe the feeding and dispersal behavior of Paratemnoides nidificator, a Neotropical pseudoscorpion presenting non-territorial permanent-sociality. Field and laboratory observations (100 hours and 200 sessions over four years) and manipulative experiments revealed that P. nidificator is a generalist predator that lives in rough bark of trees, in groups of 2 to 175 individuals (42.62 +/- 28.27; N=35 colonies; solitary individuals were never found), including reproductive adults and nymphs. Individuals in groups cooperatively capture prey four times larger than solitary individuals. Adult hunters share food with siblings. Reproduction in natural conditions occurs during the hot/wet season, when food availability is high. Prey diversity and abundance seem to be the main factor limiting reproduction in this species. Phoresy (attachment to a transporter animal) is the basic mode of dispersion in P. nidificator. Grouped individuals use large animals as vectors for dispersal, and once established they use the vector as the first food item of the new colony. However, they can also disperse by colony fission, newly documented herein for this taxon. The elaborate, cooperative behavior in P. nidificator is unique among pseudoscorpions and represents an excellent model for studies on the evolution of sociality in invertebrates.