Functional aspects of genital differences inLeucauge argyraandL. mariana(Araneae: Tetragnathidae)

Abstract

Abstract Morphological studies have documented the tendency for male genitalia to diverge rapidly compared to other body parts in many animal groups, including spiders. But documentation of how differences in genital structures of closely related species correlate with differences in the behavior of their genitalia during copulation is rare. This study describes how the genitalia of the spider Leucauge argyra (Walckenaer 1841), a species in which both male and female have unusual derived structures, are used during copulation and compares their sexual behavior with previous descriptions of genital behavior in the congener L. mariana (Taczanowski 1881) and the genital morphology of other Leucauge species. Males of L. argyra have two prominent derived genital structures, both of which interact directly with the female; one of them apparently locks against a modified female structure, while the other is inserted into the female atrium. On the other hand, the most prominent derived female structure does not l...