Introduction Accessory sex glands (ASGs) are important elements of the male reproductive system which function to enhance the fertility of spermatozoa during reproduction. Certain proteins secreted by the ASG are known to bind to the spermatozoa and affect its function (He et al., 2013). Unlike insects, crustaceans do not possess well developed male accessory sex glands (ASG). Instead, the epithelial lining of the male reproductive tract undergo extensive modifications giving rise to glandular areas which function as accessory sex glands (Malek & Bawab, 1974). Accessory sex glands in male crustaceans chiefly furnish materials necessary for the formation of seminal plasma and are the sites of encapsulation of sperms into spermatophores. The ASG secretory epithelial cells lining the male genital tract functions in the formation of seminal plasma and spermatophore wall material (Adiyodi & Anilkumar, 1988). The presence of male ASG has been reported in many decapod crustaceans such as branchiopods, stomatopods and brachyurans. In some stomatopods and branchiopods, Komai (1920) and Wolfe (1971) have reported the presence of collateral accessory sex glands. Among brachyurans, the presence of ASG has been reported in the land crab Cardisoma carnifex (Kalyanaraman & Chandran, 1982), the ghost crab Ocypode platytarsis (Sukumaran, 1985), estuarine crabs Metopograpsus messor and Sesarma quadratum (Suganthi & Anilkumar, 1998), Chinese mitten crab Eriocheir chinensis (Hou et al., 2010) and the sesarmid crab Parasesarma plicatum (Ganapriya, Suganthi, & Maharajan, 2016). The structure and function of ASG in insects have been studied extensively both under light (Khalifa, 1950; Callahan & Cascio, 1963; Roth, 1967; Odhiambo, 1969a; Louis & Kumar, 1971; Lange & Laughton, 1984) and electron microscope (Beams, Anderson, & Kessel, 1962; Odhiambo, 1969b; De Loof & Lagasse, 1972; Adiyodi & Adiyodi, 1974; Smid & Shoonveld, 1992). Happ (1984) and Gillott (1996) described the structure, development, function and control of secretory activity of male accessory sex glands in insects. Marchini, Brundo, Sottile, and Viscuso (2009) described the structure of male accessory glands of Bolivarius siculus (Orthoptera) and protein analysis of their secretions. Male reproductive system structure and ultrastructure of accessory glands of two species of Reduviid bugs Triatoma sp (Hemiptera) have been described by Freitas, GonÃ§alves, SerrÃ£o, Costa, and Santos–Mallet (2010). Huang, Yu, and Chen (2007) investigated the morphology and ultrastructure of testes and accessory glands along with characterization of their secretions for a braconid species Cotesia vestalis (Hymenoptera) using light and electron microscope. Morphology and histology of male reproductive system and ASG of the bug Spilostethus pandurus (Hemiptera) were described by Elelimy, Ghazawy, Omar, and Meguid (2017).