Infection prevalence and pathology of the cymothoid parasite Olencira praegustator in Atlantic menhaden

Abstract

Cymothoidae (Crustacea, Isopoda) is a family of obligate ectoparasites that infect boney and cartilaginous fishes in aquatic environments worldwide, excluding the Arctic (Smit et al., 2014). Most cymothoids are found in shallow tropical waters, and the central Indo-Pacific supports the highest cymothoid diversity, with 79 of the estimated 365 species worldwide (Smit et al., 2014). While 310 species representing 32 genera of Cymothoidae are found on or in marine fishes, several genera have adapted to freshwater systems, notably within the Amazon Basin and Rift Valley Lakes in eastern Africa (Hata et al., 2017; Smit et al., 2014). As true ectoparasites, cymothoids attach exteriorly to the scales of fish, burrow inside hosts' body cavities, or infest the buccal and branchial cavities, where they consume host tissue and blood (Sikkel & Welicky, 2019; Smit et al., 2014). Although many species are relative generalists able to infect multiple species (Bruce, 1986; Smit et al., 2014), others have been documented on only a single fish species. For instance, Anilocra chaetodontis Bunkley Williams & Williams 1981 can infect four species in the genus Chaetodon (Welicky et al., 2017), but Mothocya bermudensis Bruce, 1986 is highly host specific and has only been reported from one species, the common halfbeak (Hyporhamphus unifasciatus ranzani 1841)