Niebuhr (ms. Forskål), 1775
Largest of all pterotracheids; reaching a body length of 330 mm (Lalli and Gilmer, 1989). Body basically cylindrical in shape and elongate; the most streamlined in the genus. Visceral nucleus shape narrow and elongate (length ranges from four to seven times width). Eye shape tubular; rectangular in dorsal view, with length averaging 2.2 times retinal width, although (like in Pterotrachea hippocampus) the length to retinal width ratio decreases with age (from about 2.5 in small individuals to 1.9 in large ones).