A new genus and species of fish parasitic cymothoid isopod (Crustacea) from Indian waters, with a key to the branchial-attaching cymothoid genera

Brucethoa bharata gen. et sp. nov. is described from the host fish Glossanodon macrocephalus Bineesh and Endo, 2019 (Argentinidae), at depths of 300–600 metres from the south-west coast of India. This monotypic genus is characterised by a head weakly immersed in pereonite 1, dorsum strongly vaulted, pereonites 6 and 7 with posterolateral margin expanded and coxae not visible in dorsal view, relatively wide pleon, pleonite ventrolateral margins produced with lateral gaps evident, both antennae slender, with antennula slightly longer than antenna, and large pleopod rami that extend laterally well beyond the pleotelson margins. Ovigerous females were found in the branchial cavity of the hosts and have proximally thickened oostegites with the posterior marsupium partly enclosed by two sub-rectangular fleshy lobes. All life stages of the new species are described [including females (ovigerous and non-ovigerous), male, transitional and larvae (premanca and manca)]. The species is currently known only from the type locality and the type host. A revised key to the marine branchial cymothoid genera of the world is provided. Publication LSID: lsid:http://zoobank.org:pub:85E54167-072A-4513-B527-20FFD0F75CCA.