The male reproductive system in the Crustacea comprises testis and vas deferens and placed dorsally or dorsolaterally with respect to the underlying

Sexual Biology and Reproduction in Crustaceans.

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hepatopancreas (Mauchline, 1980). The testis is either fused or partially joined at the anterior end. In the red claw crayfish Cherax quadricarinatus, the testes are paired structures all along their complete length (Lopez Greco et al., 2007). On the other hand, in another crayfish, Astacus leptodactylus, the testis has two anterior lobes and only one posterior lobule, suggesting variability in testes morphology within the same group of crustacean (Erkan et al., 2009). Each genital duct consists of collecting tubules within the testis, the vas deferens, a dilated region called seminal vesicle, and finally the ejaculatory duct.

In most of the brachyuran crabs, the paired genital system consists of the testis, vas deferens, and the ejaculatory duct opening into the penis. The reproductive system, especially the vas deferens, fills much of the body cavity in the adult males. In the swimming crab, Portunus sanguinolentus, the paired testes are medially interconnected by a commissure, giving the testes, the shape of “H” (Fig. 11.1). The testes are a pair of convoluted tubular organs with many lobes. The testes lie dorsal to the hepatopancreas. The vas deferens arises from the posterior end of the testis (see Fig. 11.1). The male reproductive tract is divided into the proximal, mid, and distal vas deferens. The vas deferens ends with the penile papilla on the medial surface of the coxa of the last periopod (Ryan, 1967). The bilateral male reproductive system in the form of “H,” located in the cephalothoracic cavity seems to be a general feature among brachyuran crabs. In Callinectes danae, the paired testes are joined to each other by a transverse commissure near the vas deferens (Zara et al., 2012).

The male genital system opens to the exterior through simple gonopores, elevated genital papillae (in some cases) or elaborates copulatory structures that are used as a taxonomic character (Wilson, 2009). In addition, several accessory sex

Male reproductive system in brachyuran crab Portunus sanguinolentus

FIGURE 11.1 Male reproductive system in brachyuran crab Portunus sanguinolentus. T, testis; T.C., testicular commissure; A.V.D., anterior vas deferens; M.V.D., mid vas deferens; P.V.D., posterior vas deferens; E.D., ejaculatory duct; P, penis; P.L., first pleopod. Adapted from Ryan, E.P., 1967. Structure and function of the reproductive system of the crab Portunus sanguinolentus (Herbst) (Brachyura: Portunidae). II. The female system. Proc. Symp. Crustacea 2, 522-544.

glands are also reported to be part of the male reproductive system. Their secretions have obvious functions, such as sperm nutrition, sperm activation, spermato- phore dehiscence, and other physiological functions in modifying the behavior of the females after mating (see chapter: Accessory Reproductive Glands).

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