Niebuhr (ms. Forskål), 1775
Body elongate, with prominent tail. Caudal tail filament present, but usually broken off during net capture. Ventrolateral folds of cutis present on the trunk, extending posteriorly to near the anterior end of fin. Tentacles lacking in males and females. No permanent posterior egg string in females. Pyriform visceral nucleus ranges in shape from squat to narrow and elongate. Eyes range in shape from rectangular to triangular, depending upon the width of the retinal base (Bonnevie, 1920). Morphometric analyses of the eyes (see Pterotrachea hippocampus 2 for orientation of measurements) and the visceral nucleus by Seapy (1985) revealed species-specific patterns, which are included below. Central tooth of radula with a broad rectangular basal plate; more similar to the basal plate in atlantids than in carinarids. The genus differs conspicuously from all other heteropods insofar as it bears two rows of additional palatine teeth on the roof of the buccal cavity (MacDonald, 1871).
Pterotrachea coronata
Pterotrachea scutata
Pterotrachea hippocampus