(modified after Kornicker 1969, 1975 and 1995)
1 Carapace longer than 2.50 mm........................................................................... 2
- Carapace shorter than 2.50 mm........................................................................... 3
2 Carapace with abundant short setules with parallel sides and pointed or digitated tips........................... S. octo
- Carapace without short setules with parallel-sides and pointed or digitated tips............................. S. menziesi
3 Carapace longer than 1.4 mm............................................................................ 4
- Carapace shorter than 1.3 mm........................................................................... 12
4 Carapace with series of lateral ridges and nodes..................................................... S. antarctica
- Carapace without lateral ridges and nodes.................................................................. 5
5 Carapace with numerous pits............................................................................ 6
- Carapace without pits.................................................................................. 8
6 Postero-dorsal bulge on carapace densely covered with spines................................... S. dietkeyseri, n. sp.
- Postero-dorsal bulge on carapace covered with setules or scattered spines and setules................................ 7
7 Carapace longer than 2.0 mm, 4 + 5 segments of 5 th limb with 4-5 setae, 7 th limb with 2 + 2 distal setae.............. S. mastix
- Carapace shorter than 2.0 mm, 4 + 5 segments of 5 th limb with 6 setae, 7 th limb with 3 + 3 distal setae............. S. sandersi
8 Carapace equal or longer than 2.0 mm..................................................................... 9
- Carapace shorter than 2.0 mm........................................................................... 10
9 Postero-dorsal bulge of carapace with ridge-like hirsute ventral margin, 1 st endopodite segment of second antenna of female with 2 setae................................................................................... S. bisetula
- Postero-dorsal bulge of carapace without ridge-like hirsute ventral margin, 1 st endopodite segment of second antenna of female with 3 setae..................................................................................... S. torus
10 Carapace longer than 1.7 mm and with abundant setae on lateral surface......................................... 11
- Carapace shorter than 1.6 mm and with sparse satae on lateral surface........................................ S. trox
11 Y-Sclerite without ventral branch..................................................................... S. rex
- Y-Sclerite with ventral branch................................................................... S. variabilis
12 Caudal process projecting posteriorly and valves with indistinct radial riblets................................ S. sandix
- Caudal process projecting posteriorly and valves without radial riblets........................................... 13
13 Lateral eyes absent.............................................................................. S. syrinx
- Lateral eyes present................................................................................... 14
14 First antenna without ventral spines on 2 nd and 4 th segments............................................... S. illex
- First antenna with ventral spines on 2 nd and 4 th segments.................................................. S. crux