Pre-copulatory guarding of penultimate females by male crab spiders, Misumenoides formosipes

Abstract

Abstract. Previous studies have identified a first mate sperm priority pattern for spider species belonging to the Entelegynae, which are characterized in part by complex female genitalia. First mate sperm priority leads to the hypothesis that unmated females should be a particularly valuable resource from a male perspective and therefore pre-copulatory guarding of immature females is expected. Laboratory experiments with an entelegyne species, Misumenoides formosipes, supported the prediction that males would cohabit with penultimate females longer than with either adult-virgin or once-mated females, and field distributions of males corroborated these results. Males took up residence under inflorescences occupied by penultimate females and fought with introduced intruder males. In staged fights differences of 10% or greater in cephalothorax width of opponents influenced fight outcome, whereas body length and weight had no effect. Fights often resulted in leg autotomization and were sometimes lethal. The loss of a raptorial foreleg significantly reduced subsequent fighting success.