1. Telson incised or cleft................................................................................................................................................... 3
- Telson entire.................................................................................................................................................................. 2
2. Pereonites laterally smooth, coxa 1 anteroventrally rounded..................................................................... R. glorisae
- Pereonites lateral process, coxa 1 anteroventrally pointed.................................................... R. chathamensis sp. nov.
3. Eyes present.................................................................................................................................................................. 4
- Eyes absent................................................................................................................................................................. 15
4. Pereonites 6 and 7 with dorsal and dorsal lateral teeth............................................................................................... 26
- Pereonites 6 and 7 lacking dorsolateral teeth, urosomite 2 smooth.............................................................................. 5
5. Epimeral plate 3 with middorsal tooth.......................................................................................................................... 6
- Epimeral plate 3 lacking middorsal tooth..................................................................................................................... 7
6. Pereonite 7 with carinae, telson cleft about 10 %................................................................................ R. boreopacifica
- Pereonite 7 smooth or very small carinae, telson cleft about 50 %............................................................. R. macropus
7. Urosomite 1 with tooth................................................................................................................................................. 8
- Urosomite 1 lacking tooth............................................................................................................................................. 9
8. Telson cleft about one third; dorsal protrusion on urosomite 1 not reaching end of urosomite 2............ R. antarctica
- Telson apically notched, about one tenths; dorsal protrusion on urosomite 1 extending length of urosomite 2............ .................................................................................................................................................................... R. barnardi
9. Pereonite 7 with middorsal tooth................................................................................................................................ 10
- Pereonite 7 lacking middorsal tooth........................................................................................................................... 11
10. Pereopods 3 and 4 dactylus long; inner margin uropod 3 setose................................................................... R. oculata
- Pereopod 3 and 4 dactylus short; uropod 3 inner margin spinose................................................................. R. minuta
11. Pleonite 1 and 3 with strong dorsolateral teeth and ridge............................................................................... R. inflata
- Pleonite 1 and 3 lacking strong dorsolateral teeth and ridge...................................................................................... 12
12. Epimeron 1 with carinae or tooth............................................................................................................................... 13
- Epimeron 1 dorsally smooth, lacking teeth or carinae................................................................................................ 14
13. Pereopod 5 and 6 posterior margin of basis double or triple toothed. Antenna 1 shorter than antenna 2...................... ................................................................................................................................................................... R. luculenta
- Pereopod 5 and 6 posterior margin of basis smooth; Antenna 1 same length than antenna 2............ R. schelllenbergi
14. Telson longer than uropod 3: gnathopods 1 and 2 propodi slender............................................................... R. elliotta
- Telson shorter than uropod 3: gnathopods 1 and 2 propodi rounded......................................................... R. conlanae
15. Urosomite 1 with tooth or carinae.............................................................................................................................. 16
- Urosomite 1 lacking tooth or carinae.......................................................................................................................... 20
16. Epimeral plate 3 distinct dorsal tooth......................................................................................................................... 17
- Epimeral plate 3 lacking dorsal tooth......................................................................................................................... 18
17. Dorsolateral teeth present on epimeral plates 1 and 2............................................................................. R. kergueleni
- Epimeral plates laterally smooth................................................................................................................................ 27
18. Telson notch shallow.................................................................................................................................... R. clemens
- Telson deeply cleft...................................................................................................................................................... 19
19. Epimeral plates laterally smooth; no calceoli on antenna............................................................................... R. ludifer
- Epimeral plates with lateral process; calceoli on antenna 1 and antenna 2.............................................. R. calceolate
20. Epimeral plate 3 with tooth......................................................................................................................................... 21
- Epimeral plate 3 lacking dorsal tooth........................................................................................................ R. anoculata
21. Head and pereonites 1–7 smooth............................................................................................................................... 22
- Head and pereonites 1–7 bumpy.................................................................................................................. R. grimaldi
22. Rostrum shorter than head.......................................................................................................................................... 23
- Rostrum long, same length as head........................................................................................................................... 25
23. Epimeral plates 2 and 3 bearing lateral process, telson cleft to at least one-third...................................................... 24
- Epimeral plates 2 and 3 laterally smooth, no distinct processes; telson cleft to less than one-quarter R. rossi sp. nov.
24. Dorsal process of epimeral plate 2 twice as long as process from epimeral plate 1 and 3...................... R. multesimus
- Dorsal process of epimeral plate 2 longer than dorsal process of epimeral plate 1 and 3...................... R. americana
25. Antenna with calceoli; urosomite 1 bearing lateral ridge; uropod 1 outer ramus shorter than inner ramus................... ...................................................................................................................................................................... R. levantis
- Antenna lacking calceoli; urosomite 1 laterally smooth; uropod 1 rami subequal in length...................................... 28
26. Mid-dorsal carinae of epimeron 1 and 2 with double hooks; pereopod 7 basis strongly expanded posteriorly, smooth, rounded...................................................................................................................................................... R. aculeanta
- Mid-dorsal carinae of epimeron 1 and 2 simple; pereopod 7 basis with distinct tooth midposteriorly...... R. gubilata
27. Coxa 1 expanded; pereopod 7 basis strongly notched................................................................. R. abyssalis sp. nov.
- Coxa 1 not expanded; pereopod 7 basis smooth......................................................................................... R. distincta
28. Gnathopod 2 basis expanded; posterolateral corners of epimeral plates 1 and 2 subquadrate...... R. delicata sp. nov.
- Gnathopod 2 basis parallel; posterolateral corners of epimeral plates 1 and 2 broadly rounded................. R. sibogae