KEY TO FOUR SPECIES OF BOPYRINELLA NIERSTRASZ AND BRENDER À BRANDIS, 1925, BASED ON FEMALES (BOPYRINELLA STRICTICAUDA MONOD, 1933, NOT INCLUDED IN KEY)

1a. Four pairs of pleopods......................... B. thorii (Richardson, 1904)

1b. Five pairs of pleopods............... 2

2a. Maxilliped with setose palp........................ B. nipponica Shiino, 1936

2b. Maxilliped without palp............. 3

3a. Head with frontal lamina, seven pairs of oostegites......... B. albida Shiino, 1958

3b. Head without frontal lamina, five pairs of oostegites.......... B. parameces, n. sp.