Polyipnus
Polyipnus is a genus of oceanic ray-finned fish in the family Sternoptychidae. This is the largest genus of the marine hatchetfishes subfamily Sternoptychinae and indeed of the entire Sternoptychidae. It is not quite as apomorphic as their relatives; it may be that the genus is actually a paraphyletic assemblage of less advanced Sternoptychinae and would need to be split.
Fossils of this genus show that they have existed at least since the Early Oligocene, about 30 million years ago.
Species
There are currently 34 recognized species in this genus:Polyipnus aquavitus R. C. Baird, 1971 Polyipnus asper Harold, 1994Polyipnus asteroides L. P. Schultz, 1938Polyipnus bruuni Harold, 1994Polyipnus clarus Harold, 1994 Polyipnus danae Harold, 1990Polyipnus elongatus Borodulina, 1979Polyipnus fraseri Fowler, 1934Polyipnus indicus L. P. Schultz, 1961Polyipnus inermis Borodulina, 1981Polyipnus kiwiensis R. C. Baird, 1971 Polyipnus laruei Vourey, Dupoux & Harold, 2017 Polyipnus laternatus Garman, 1899Polyipnus latirastrus Last & Harold, 1994 Polyipnus limatulus Harold & Wessel, 1998Polyipnus matsubarai L. P. Schultz, 1961Polyipnus meteori Kotthaus, 1967Polyipnus notatus Harold, I. M. Kemp & Shore, 2016 Polyipnus nuttingi C. H. Gilbert, 1905 Polyipnus oluolus R. C. Baird, 1971Polyipnus omphus R. C. Baird, 1971Polyipnus ovatus Harold, 1994Polyipnus parini Borodulina, 1979Polyipnus paxtoni Harold, 1989 Polyipnus polli L. P. Schultz, 1961 Polyipnus ruggeri R. C. Baird, 1971 Polyipnus soelae Harold, 1994 Polyipnus spinifer Borodulina, 1979Polyipnus spinosus Günther, 1887 Polyipnus stereope D. S. Jordan & Starks, 1904Polyipnus surugaensis Aizawa, 1990Polyipnus tridentifer McCulloch, 1914 Polyipnus triphanos L. P. Schultz, 1938 Polyipnus unispinus L. P. Schultz, 1938