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The Tanaidacea are ubiquitous and amongst the most abundant taxa in the deep sea. However, their diversity in submarine canyons remains largely unknown. Here, two new species and a new genus of Paratanaoidea are described. Paranarthrura cousteaui sp. nov. is distinguished by the combination of the following characters: post-cheliped sclerites not fused, presence of one seta in the maxilliped endite, one long midventral seta in cheliped, one penicillate seta in the basis of pereopods 4–6, uropod endopod bi-articulated and uropod exopod shorter than endopod article 1. This species was found at the upper reaches of three Portuguese canyons, Cascais, Setúbal and Nazaré Canyons, and the adjacent open slope, between 897 and 1001 m water depths. Tirana vallis gen. et sp. nov. presents a combination of the characters that define the other two genera of Paranarthrurellidae, Paranarthrurella and Armatognathia, but also unique characters within the family: the antenna, cheliped and uropod are more elongate than the rest of the species; the pereopods 4–6 carpus spines reach at least half of the length of the propodus and the propodus of pereopods 4–6 have ramified subdistal spines. This species was found at the middle reaches of Setúbal Canyon (3214–3219 m water depth).
Benthic samples collected along the Brazilian central continental margin from Espírito Santo State to Rio de Janeiro State (19° S to 24° S) during the last 20 years and at depths of 50–2200 m yielded the description of six new species of Typhlotanais in the deep-sea (> 200 m): Typhlotanais andradeorum sp. nov., T. bolarticulus sp. nov., T. ischnochela sp. nov., T. longiseta sp. nov., T. priscilae sp. nov. and T. spinibasis sp. nov. Within these species, we found members of four Typhlotanais morpho-groups as ‘cornutus’ group, ‘greenwichensis’ group, ‘spinicauda’ and ‘trispinosus’ group. Typhlotanais ischnochela sp. nov. exhibited the greatest bathymetric range, occurring from the continental shelf until the lower slope (46–1898.7 m depth). The bathymetric distribution of the other five species of Typhlotanais herein described were restricted to the slope. Tables of diagnostic characters of the Typhlotanais morpho-groups and an identification key to the species of Typhlotanaidae found in Brazil are provided. This work brings the total number of Tanaidacea known for Brazilian coast to 64 species, and the family Typhlotanaidae from Brazil is now represented by 11 species in five known genera.