1. Epimeron 3, posteroventral corner rounded............................................................................................................... 2
- Epimeron 3, posteroventral corner angled.................................................................................................................. 7
2. Telson entire .......................................................................................................................................... S. integricauda
- Telson cleft.................................................................................................................................................................. 3
3. Gnathopod 2 palm large................................................................................................................................ S. peartae
- Gnathopod 2 palm small............................................................................................................................................. 4
4. Mandibular palp article 2 with D2-setae..................................................................................................................... 5
- Mandibular palp article 2 without D2-setae............................................................................................................... 6
5. Mandibular palp article 3 with D3-setae; uropod 2 without robust setae on rami.................................. S. californica
- Mandibular palp article 3 without D3-setae; uropod 2 with robust setae on at least one ramus.............. S. cantractia
6. Gnathopod 2 palm convex; pereopod 6 coxa slightly lobate posteriorly................................................. S. robertsoni
- Gnathopod 2 palm concave; pereopod 6 coxa not lobate posteriorly....................................................... S. antarctica
7. Gnathopod 2 palm large............................................................................................................................... S. murrayi
- Gnathopod 2 palm small............................................................................................................................................. 8
8. Pereopod 7, basis posteroventral lobe extending beyond ischium............................................................................. 9
- Pereopod 7, basis posteroventral lobe not extending beyond ischium..................................................................... 10
9. Maxilliped palp article 2 broad; pereopod 6 coxa strongly lobate posteriorly............................................ S. hispana
- Maxilliped palp article 2 slender; pereopod 6 coxa slightly lobate posteriorly........................................... S. rodondo
10. Pereopod 6 coxa strongly lobate posteriorly............................................................................................................. 11
- Pereopod 6 coxa slightly lobate posteriorly.............................................................................................................. 13
11. Mandible palp article 2 broadened distally.................................................................................................. S. ledoyeri
- Mandible palp article 2 slender................................................................................................................................. 12
12. Mandible palp articles 2 and 3 with D-setae; telson longer than broad.................................................... S. inverarae
- Mandible palp articles 2 and 3 without D-setae; telson about as long as broad.............................................. S. ruffoi
13. Maxilliped palp article 2 slender (length about 2.4 x breadth); telson moderately cleft (about 38%).......... S. moorei
- Maxilliped palp article 2 broad (length about 1.8 x breadth); telson deeply cleft (about 67%)..................... S. abyssi