Key to species of Rhachotropis from Japanese and adjacent waters

1 Head with dorsal protrusion ...................................................................................................... 2

—— Head dorsally smooth ................................................................................................................ 3

2 Pereopods 5 and 6 basis produced posteriorly .......................................................... R. aculeata

—— Pereopods 5 and 6 basis not produced posteriorly .................................................... R. marinae

3 Pereonite 7 with middorsal tooth .............................................................................................. 4

—— Pereonite 7 dorsally smooth ...................................................................................................... 6

4 Pleonite 3 and urosomite 1 with middorsal tooth .................................................... R. macropus

—— Pleonite 3 and urosomite 1 without middorsal tooth ................................................................. 5

5 Pereopod 5 basis not produced posteriorly. Pereopod 6 basis oval ................................ R. oculata

—— Pereopod 5 basis strongly produced posteriorly. Pereopod 6 basis triangular ........................................................................................................................ R. reiwa

6 Urosomite 1 with dorsal tooth ................................................................................................... 7

—— Urosomite 1 dorsally smooth .................................................................................................... 8

7 Pereonites dorsally smooth. Telson cleft for 5% of its length ................................... R. distincta

—— Pereonites with dorsal protrusion. Telson cleft for 10% of its length ................................ R. saskia

8 Eyes small, not pigmented. Telson elongate, length 3.8 times width ............................................................................................................................ R. natator

—— Eyes large, pigmented. Telson not elongate, length shorter than 2 times width ................................................................................................................................ 9

9 Pereopods 5–7 basis produced posteriorly ...................................................... R. lowryi sp. nov.

—— Pereopods 5–7 basis not produced posteriorly ............................................................. R. inflata