Contributions to Zoology, 67 (4) 237-256 (1998)G. A. Bishop; R. M. Feldmann; F. Vega: The Dakoticancridae (Decapoda, Brachyura) from the Late Cretaceous of North America and Mexico

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Reproductive Structures

The genital structures of Dakoticancer overanus lie on the coxae of the pereiopods (Figs 1.4, 1.5); the oviduct perforations on the coxa of the third pereiopod and the seminal ducts on the coxa of the fifth pereiopods (Bishop 1984b). The oviduct perforations are small oval openings near the posterior-proximal corner of the coxa, just in from the articulator with the sternum. The orifice is nearly surrounded by a raised rim separating abundant setal pits on the outside from smooth exoskeleton on the inside. A specimen approximately 15.63 mm wide has oviduct perforations 0.15 mm in diameter. The seminal duct is small and usually not visible, normally being pressed against the second somite of the abdomen. Only when the coxa is flexed is the seminal duct visible.

Bishop and Sturgeon (in preparation) have demonstrated that the gonopores of Avitelmessus grapsoideus are carried on the coxae of pereiopod 3 (oviducts) or pereiopod 5 (seminal duct). The oviduct perforations are small openings situated near the posterior articulation of the coxal articulation with the sternum and the seminal duct openings are found on the proximal side of the coxal articulation, often hidden if p3 is in a relaxed position.