Rhachotropis, S. I. Smith, 1883

Bellan-Santini, Denise, 2006, Rhachotropis species (Crustacea: Amphipoda: Eusiridae) of hydrothermal vents and surroundings on the Mid- Atlantic Ridge, Azores Triple Junction zone, Journal of Natural History 40 (23 - 24), pp. 1407-1424 : 1422-1423

Key to Atlantic Rhachotropis

1. Telson entire.................... 2

– Telson cleft or emarginate................ 4

2. Eyes present................ R. integricauda

– Eyes absent..................... 3

3. Pleon, segments 1 and 2 with dorsal tooth only........ R. caeca

– Pleon, segments 1 and 2 with lateral tooth only..... R. flamina n. sp.

4. Rostrum long or medium................. 5

– Rostrum short................... 14

5. Eyes present.................... 6

– Eyes absent.................... 10

6. Telson emarginated.................. 7

– Telson cleft..................... 8

7. Pereon, segment 7 and pleon segments 1-3 with median dorsal tooth. R. proxima

– Pereon, segment 7 and pleon segments 1-3 smooth smooth..... R. glabra

8. Epimeral, plate 3 hardly denticulate.............. 9

– Epimeral, plate 3 not hardly denticulate......... R. inermis

9. Pereon, segments 6-7 with acute dorsal processes....... R. aculeata

– Pereon, segment 6 smooth, segment 7 with a posterodorsal mucronation R. oculata

10. Epimeral, plate 3 hardly denticulate............. 11

– Epimeral, plate 3 weakly denticulate............ 12 11. Pleon, segments 1-2 armed............. R. rostrata

– Pleon, segments 1-2 not armed........... R. pilosa n. sp.

12. Pleon, segment 1 with one dorsal and two lateral teeth..... R. proxima

– Pleon, segment 1 smooth................ 13

13. P7 basis lobate, ‘‘accessory flagellum could not be found’’.... R. faeroensis

– P7 basis not lobate, accessory flagellum present but minute.... R. distincta

14. A1, article 1 with a terminal spine......... R. licornia n. sp.

– A1, article 1 without terminal spine............. 15

15. Eyes present................... 16

– Eyes absent.................... 21

16. Eyes yellowish white............. R. leucophthalma

– Eyes not white................... 17

17. Eyes reduced in size.............. R. lomonosovi

– Eyes large.................... 18

18. Pleon, segment 3, dorsally rounded without tooth....... R. inflate

– Pleon segment 3 with dorsal tooth............. 19

19. Pereon, segments 1-3 ‘‘raised dorsally’’ (Sars dixit)....... R. helleri

– Pereon, segments 1-3 not (raised dorsally)........... 20

20. Urosome, segment 1 smooth............. R. grimaldii

– Urosome, segment 1 with a tooth........... R. macropus

21. P5-7 basis expanded in an acute projection........ R. palporum

– P5-7 basis not expanded in an acute projection......... 22

22. Telson cleft for one-third length.............. 23

– Telson emarginate.................. 24

23. Urosome, segment 1 weakly carinate. Coxa 1 strongly produced.. R. thordisae

– Urosome, segment 1 without carina. Coxa 1 weakly produced.... R. gislii

24. Urosome, segment 1 without tooth.......... R. portoricana

– Urosome, segment 1 with dorsal tooth............ 25

25. Pleon, segments 1-2 weakly tridentate dorsally....... R. thorkelli

– Pleon, segments 1-2 slightly humped with low dorsal tooth..... R. arii