Key to the species of Scyracepon based on female characters

1 Pereon without middorsal projections ............................................... S. australiana Markham, 2010

- Pereon with middorsal projections...................................................................... ... 2

2 All pereomeres with middorsal projections.............................................. .... S. levis Barnard, 1940

- Less than five pereomeres with middorsal projections...................................................... ... 3

3 Last four pereomeres with middorsal projections ............................................................. 4

- Last two or three pereomeres with middorsal projections ....................................................... 7

4 Middorsal projection of last pereomere elongate, extending to end of pleon ................ S. quadrihamatum Shiino, 1936

- Middorsal projection of pereomeres subequal, not extending beyond first segment of pleon ............................ 5

5 Posterior margin of oostegite 1 smooth.................................................. .. S. polynesiensis n. sp.

- Posterior margin of oostegite 1 bearing projections ........................................................... 6

6 Middorsal projection of pereomere 7 larger than others ............................... S. hawaiiensis Richardson, 1910

- Middorsal projections subequal......................................................... S. pseudoliomerae n. sp.

7 Last three pereomeres with middorsal projections ............................................................. 8

- Last two pereomeres with middorsal projections ............................................................. 9

8 Head bilobate ................................................................... .. S. oceanicum Shiino, 1942

- Head oval ..................................................................... S. tuberculosa Tattersall, 1905

9 Last two pereomeres with small middorsal projections.......................... … S. distincta An, Boyko & Yu, 2012

- Last two pereomeres with prominent middorsal projections ................................................... 10

10 Head markedly bilobate .................................................................. S. biglobosus n. sp.

- Head indistinctly bilobate ....................................................... S. thalamitae (Markham, 1985)