Genital morphology of Nephila edulis: implications for sperm competition in spiders

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Abstract
The genital morphology of the female is assumed to control the pattern of sperm priority. Spiders are divided roughly along phylogenetic lines into haplogyne and entelegyne types, the principal difference being in female genital morphology (cul-de-sac and conduit types of spermathecae). Nephila edulis is an entelegyne spider and we studied the genital morphology of both sexes by means of scanning electron microscopy and semithin sectioning. In the female, the copulatory ducts leading to the spermatheca were much longer and more differentiated than the fertilization duct. We question the common assumption that possession of genitalia of the conduit type with separate copulatory and fertilization ducts will automatically lead to first-male sperm priority because in our typical entelegyne species, the copulatory ducts were similar in arrangement to the combined copulatory/fertilization ducts in genitalia of the typical cul-de-sac type.