Structure and function of the female reproductive system in three species of goblin spiders (Arachnida: Araneae: Oonopidae)

Because of their reproductive biology, spiders are extremely promising subjects for testing hypotheses on sexual selection. Further, their genital morphology provides useful characteristics for taxonomy. However, the structure and functional morphology of the genitalia of members of most spider groups are poorly known. This is especially true for members of the Haplogynae. In this article, the female genitalia of three oonopid species are described, using light and scanning electron microscopy. The male palps are also briefly described. The female genitalia of all these three species do not correspond to the description of haplogyne genital systems given in the literature. Receptacula are lacking in the genitalia of Opopaea deserticola and Zyngoonops sp. Sperm are present in the uterus internus of members of these two species, indicating that fertilization occurs there or in the ovary. Females of Zyngoonops sp. have a pouch that possibly holds appendages on the male endites during copulation. Modifications on the endites might allow males to exert copulatory courtship. A secretory sac was found inside the receptaculum of Gamasomorpha lutzi. Previous studies on oonopids with the same type of genitalia showed that the sac contains sperm and that it can be discarded during copulation. Spermatozoa were also found inside the uterus internus of members of G. lutzi. A sclerite in the uterus wall of females of all three species might serve to lock the uterus during copulation in order to prevent sperm from getting into it, as suggested for a variety of other oonopids. The male palps of O. deserticola and Zyngoonops sp. are simple. Furrows on the emboli of G. lutzi suggest that males use the palps as copulatory courtship devices. The present study reveals the complex genital morphology of three species belonging to the little known spider family Oonopidae, and provides new insights into the function of their genitalia in the context of sexual selection.