Macrostylis, G. O. Sars, 1864

Vey, Aidan & Brix, Saskia, 2009, Macrostylis cerritus sp. nov., a new species of Macrostylidae (Isopoda: Asellota) from the Weddell Sea, Southern Ocean *, Zootaxa 2096 (1), pp. 356-370 : 367

Key to the Southern Ocean species of Macrostylis

1 Pleotelson rounded laterally.......................................................................................................................................... 4

- Pleotelson not rounded laterally ................................................................................................................................... 2

2 Pleotelson laterally straight, with plumose setae ................................................................................. M. hirsuticaudis

- Pleotelson not laterally straight, without plumose setae............................................................................................... 3

3 Cephalon quadrate, pleotelson with lateral indentation............................................................................ M. bifurcatus

- Cephalon triangular, pleotelson slightly produced .................................................................................... M. spiniceps

4 Pereonites 5–7 and pleotelson dorsally setulose.......................................................................................... M. setulosa

- Pereonites 5–7 and pleotelson not dorsally setulose..................................................................................................... 5

5 Pereonite 7 and pleotelson with dorsal spine-like setae ................................................................................... M. sarsi

- Pereonite 7 and pleotelson without dorsal spine-like setae .......................................................................................... 6

6 Pereonites 1–7 subequal, 5–7 with postero-lateral spines .............................................................. M. cerritus sp. nov.

- Anterior pereonites wider than posterior pereonites..................................................................................................... 7

7 Distinct postero-lateral spines on pereonites 4–7, cephalon anterior edge straight............................ M. vinogradovae

- Small postero-lateral spines on pereonites 4–7, cephalon anterior edge slightly rounded .................... M. bipunctatus