A new deep-water scavenger species in the genus Caeconyx (Crustacea, Amphipoda, Lysianassoidea, Uristidae) from the Porcupine Abyssal Plain.

Caeconyx papso sp. nov. within the family Uristidae is described from the Porcupine Abyssal Plain, Northeast Atlantic Ocean. The new species differs from the only other member of the genus, Caeconyx caeculus, in possessing a triangular, sub-acute eye lobe, a convex and broadly rounded posterodistal margin of epimeron 1, and propodi of pereopods 3 and 4 that are not slender or elongate. Molecular sequence data for COI, H3, 16S, and 28S genes are provided for C. papso sp. nov. Phylogenetic analyses were conducted using this sequence data to assess the relationships between the new species, other members of the family Uristidae, and morphologically allied taxa within the family Tryphosidae. The new species is fully illustrated, and a key to species within Caeconyx is presented.