Histopathology associated with haptor attachment of the ectoparasitic monogenean Neobenedenia sp. (Capsalidae) to barramundi, Lates calcarifer (Bloch)

[Extract] Capsalid monogeneans are harmful ectoparasites of ornamental and farmed fishes in tropical/subtropical marine environments (Thoney & Hargis 1991; Hirazawa et al. 2011; Whittington 2012). Neobenedenia spp. have low host specificity, a direct life cycle, high fecundity and robust eggs, which contribute to their ability to inflict mass mortalities in aquaculture (Ogawa et al. 1995; Deveney, Chisholm & Whittington 2001; Rückert, Palm & Klimpel 2008; Whittington 2012).\ud \ud Neobenedenia spp. attach to external surfaces of their host using two attachment organs located anteriorly and one larger posterior attachment organ called the haptor. The haptor is believed to act as the principal anchoring organ of the parasite to the host (Whittington 2012). This organ has chitinous structures that provide mechanical attachment including paired anterior hamuli, accessory sclerites, posterior hamuli and peripheral hooklets (Whittington & Horton 1996). A marginal valve on the haptor allows the organ to create suction on the host. The anterior attachment organs lack accessory chitinous structures and are located directly above the pharynx, which is used to graze on epidermal and mucous cells of the fish (Whittington 2012)