Rhachotropis

Lörz, Anne-Nina, 2010, Deep-sea Rhachotropis (Crustacea: Amphipoda: Eusiridae) from New Zealand and the Ross Sea with key to the Pacific, Indian Ocean and Antarctic species, Zootaxa 2482, pp. 22-48 : 46-47

Key to Indo-Pacific and Antarctic species of Rhachotropis

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