Map of the Pacific Ocean showing the locations and depths of collection of the four fish species described in this study. (a) Pseudoliparis swirei (n = 18), Mariana Trench, 7,626 m, no. 200133; scale bar, 1 cm. (b) Notoliparis kermadecensis (n = 7), Kermadec Trench, 7,515 m, no. 100171; scale bar, 1 cm. (c) Coryphaenoides yaquinae (n = 4), abyssal plain, 5,255 m, no. 200152; scale bar, 5 cm. (d) Careproctus melanurus (n = 11), continental slope, representative image; scale bar, 1 cm.