Hooks: 8-9; anterior teeth: 3-4; posterior teeth: 1.
Maximum adult body length: 6 mm; tail: 49-58 %.
Body slender and transparent; transversal musculature on trunk; head wide; hooks not serrated. Fin bridge absent; one pair of short lateral fins both on trunk and tail; lateral fins fully rayed, rounded. Collarette long and narrow; gut diverticula absent; no eyes. Seminal vesicles conical; position of seminal vesicles: touching both posterior fins and tail fin. Ovaries short. Ova fairly large. Adhesive papillae present; adhesive organs with adhesive appendages absent; apical glands absent.
Distribution: benthic neritic.
Remarks: 5 specimens.were found in Japanese waters, described as Spadella cephaloptera forma angulata and 3 specimens later in coastal waters of Malay raised to species level.
Type locality: Japanese waters