Descriptions of Three Newly Discovered Abyssal Snailfishes (Liparidae) from the Eastern Pacific Ocean

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Three species of snailfishes (family Liparidae) are described from single collections based on morphological and genetic evidence, from the eastern abyssal Pacific, depths 3,268–4,119 m. Careproctus colliculi, new species, the Bumpy Snailfish, can be identified by its pink color in life, 22 pectoral-fin rays (uppermost rays long), round head, eight caudal rays, large eye, and well-developed pterygiophores that form a large suction disk. Careproctus yanceyi, new species, the Dark Snailfish, bears a moderate ventral suction disk (<3% standard length), single nostrils, six branchiostegal rays, and is distinct from other eastern Pacific deepwater snailfishes in having a fully black body with a rounded head and horizontal mouth. Additional defining characters include a small gill opening located entirely above the pectoral fin, two pectoral radials, and 22 pectoral-fin rays. Paraliparis em, new species, the Sleek Snailfish, is distinguished from other snailfishes by its long, black, laterally compressed body, absence of a suction disk, prominently angled jaw, single pectoral-fin radial, anteriorly positioned anus, and five branchiostegal rays. Each of these three taxa has a distinct mitochondrial cytochrome c oxidase subunit I (COI) sequence compared to all other sequenced snailfishes. Genetically, Paraliparis em, new species, is most similar to P. wolffi from the Crozet Basin in the Indian Ocean, as well as bearing similarity to the northeastern Pacific snailfishes P. megalopus and P. ulochir, together known as Paraliparis Clade I. Careproctus yanceyi, new species, shows little similarity in COI sequences to other taxa and perhaps represents a distinct clade in the family. The COI sequence of Careproctus colliculi, new species, fits in the Osteocareprocta clade, most similar to Careproctus continentalis, C. discoveryae, C. longipectoralis, and Osteodiscus cascadiae. Paraliparis em, new species, and Careproctus yanceyi, new species, show significant morphological and genetic divergence from one another, despite both being black snailfishes collected on the same submersible dive. These findings reveal cryptic diversity in deep-sea snailfishes and highlight the necessity of combined imaging, morphological, and genetic approaches to studying fish biodiversity. These three newly discovered species begin to fill an important sampling gap for the family Liparidae and demonstrate the importance of snailfishes in communities of the abyssal seafloor.

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