Description of Bradyetes paramatthei sp. nov. (Copepoda: Calanoida), a new aetideid species from the deep Pacific Ocean with notes on the genus Bradyetes

A new and rare aetideid species of the benthopelagic genus Bradyetes Farran, 1905 is described from female specimens collected near the seafloor from the abyss of the Pacific, Atlantic and Southern Oceans between 2000 and 2014. The new species, Bradyetes paramatthei sp. nov., is described from the Kurile-Kamchatka Trench (Pacific Ocean) and is additionally reported from the Angola and Guinea basins and from the Meteor Seamount of the Atlantic Ocean. Bradyetes paramatthei sp. nov. is related to the species B. matthei Johannessen, 1976, but differs in the shape of the prosome posterior corners, which are oval-rounded, and in the proximal segment of the antennal exopod, which is supplied with one seta. These two species are shown to constitute a separate species group within the genus Bradyetes. The other species group contains the remaining congeners including Bradyetes inermis Farran, 1905, for which morphological variability is discussed. Specimens of this species show diverse morphology and comprise 3 morphotypes distinguished by the P1, with a developed or absent lateral lobe, the P1 basal medial seta, which is either nude or supplied with setules, and by the different number of setae of the maxillule praecoxal arthrite.