A new genus of Tanaidacea (Peracarida, Typhlotanaidae) from the Atlantic slope

Abstract

Two new species of deep-sea Tanaidacea (Aremus islandica n. sp. and A. brasilica n. sp.) were collected in the SW and N Atlantic during the scientific cruises organized within the HABITATS and IceAGE (Icelandic Animals Genetic and Ecology) initiatives in 2009 and 2011, respectively. Both species fit well to the current definition of Typhlotanaidae, but differ from the other members of the family by the striking feature of absence of the pleopods (one pair of pinnate setae on each pleonite ventrally), therefore they were accommodated to the newly erected genus – Aremus n. gen.; the new genus lacks the prickly tubercles on the carpus of pereopods 4–6, although it has three distinct serrated spines that makes it similar to four typhlotanaid genera, namely: Meromonakantha, Paratyphlotanais, Hamatipeda and Obesutanais. However, the morphology of the body does not correspond to the typical Meromonakantha neither to short body of Obesutanais. Furthermore Paratyphlotanais and Hamatipeda differ from the new genus on the spines form, in which the first one has long serrated spines and the second has hook-like spines. Both new species can be distinguished by (1) length of the ventrodistal seta on cheliped carpus, (2) length of dorsodistal seta on carpus of pereopods 1–3 and (3) length of the uropodal endopod. The systematics of the typhlotanaids without prickly tubercles on the pereopods 4–6 is briefly discussed.