Two new tanaidaceans (Crustacea: Peracarida) from Portuguese submarine canyons (NE Atlantic, West Iberian Margin)

Abstract

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).

Leviapseudes tethys (Tanaidacea: Apseudidae), a new species from a submarine canyon of the French Mediterranean Sea, with remarks and a diagnosis for the genus

“…The biodiversity of Tanaidacea in submarine canyons is largely understudied; however, the recent works available included the discovery of new taxa that provided significant information for the understanding of the systematics of the group. For instance, Sganga & Roccatagliata (2016) described Deidamiapseudes, a genus of an uncertain position between the Apseudidae and Metapseudidae Lang, 1970, andGarcía-Herrero et al (2021)…”

“…Studies have shown that tanaidaceans are among the dominant taxa in benthic macrofaunal assemblages in submarine canyons (e.g., Cunha et al 2011;Gunton et al 2015); however, to date only two studies make species-level references to Tanaidacea: García-Herrero et al (2021) covering three canyons in the Portuguese margin, and Sganga & Roccagliata (2016) in Mar de Plata Canyon (SW Atlantic). Although Lacaze-Duthiers Canyon is one of the most studied canyons in the Mediterranean Sea (e.g., Got & Stanley 1974;Vénec-Peyré 1990;Fabri et al 2014;Meistertzheim et al 2016), our knowledge of the soft-bottom macrofauna community composition is scarce.…”