Hooks: 6-7; anterior teeth: 4-6; posterior teeth: 10-12.
Maximum adult body length: 9 mm; tail: 26-31 %.
Body slender; transversal musculature absent; head narrow; hooks serrated, both in juveniles and in adults. Fin bridge absent. Anterior fins of medium length, fully rayed, rounded; posterior fins of medium length, partially rayed, rounded. Collarette absent; gut diverticula present. Small eyes with T-shaped pigment spot. Seminal vesicles with knob and trunk. Seminal vesicles with appendages; position of seminal vesicles: touching posterior fins and well separated from tail fin. Ovaries medium length, to region of ventral ganglion; ova small. Adhesive papillae and adhesive organs absent. Apical glands absent.
Distribution: epipelagic; North Pacific, transitional waters.
Remarks: seminal vesicles with one appendage on the knob.
Type locality: North Pacific transitional waters.