1. Maxilliped palp 4 -articulate, article 4 rudimentary; palp reaching well beyond tip of inner plate. Gnathopod 1 propodus broader than long.................................................. 2
- Maxilliped palp 3 -articulate, reaching only to tip of inner plate. Gnathopod 1 propodus subequal in length and breadth, or slightly longer than broad...................................... 3
2. Eyes present ................................................................................................. N. amblyops
- Eyes absent ....................................................................................................... N. abyssi
3. Gnathopod 1 propodus palm smooth and striated, not denticulate............................... 4
- Gnathopod 1 propodus palm distinctly denticulate ..................................... N. chevreuxi
4. Uropod 3 rami subequal. Telson entire ............................................................. N. ruffoi
- Uropod 3 rami distinctly unequal. Telson slightly emarginate ............. N. quadrimanus