Etmopterus benchleyi n. sp., a new lanternshark (Squaliformes: Etmopteridae) from the central eastern Pacific Ocean

A new species of lanternshark, Etmopterus benchleyi n. sp., is described from eight specimens collected off the Pacific coast of Central America at depths ranging between 836 and 1443 meters. The new species is placed in the Etmopterus spinax clade by a lack of flank markings and the moderately short, slender, hook-like, conical dermal denticles distributed over the body. It can be distinguished from its closest congeners based on a combination of coloration, proportional body measurements, meristic counts, arrangement of dermal denticles, and size at maturity. The dorsal fins of the new species are either similar in size or the second dorsal fin is slightly larger than the first vs. the second dorsal fin distinctly larger than the first in E. granulosus, E. princeps, and E. litvinovi. The pre-oral length is shorter in the new species (6.9–9.0% TL) than in its closest congeners, E. granulosus (7.9-11.3% TL) and E. princeps (9-10% TL). The tooth count in the lower jaw is higher in E. benchleyi (30–36) than in E. granulosus (28), but lower than in E. litvinovi (40–50) and E. princeps (40–50). Photophores in E. benchleyi are sparse compared to other etmopterids and difficult to identify due to its uniform black color. This new species is also distinct from other members of the E. spinax clade in having dense concentrations of dermal denticles closely surrounding the eyes and gill openings. E. benchleyi is the only Etmopterus species presently known from the Pacific coast of Central America.