Key to the species of the genus Arcturina .

This key is based only on females of the species. Hence, it does not include A. cylindralis Pillai, 1963, which was described based on sub-adult male specimens (see Remarks in Bamber 2008).

1. Pereonite 5 with lateral projection; head with strong medial projection.................. A. plumbiformis Nunomura, 2008

- Pereonite 5 with no lateral projection; head with small or no medial projection.....................................2

2. Antennular article 2 and 3 with serrate margin....................................... A. rhomboidalis Koehler, 1911

- Antennular article 2 and 3 without serrate margin............................................................ 3

3. Pereonite 4 strongly convex in lateral view.............................................. A. scutula Kensley, 1975

- Pereonite 4 smoothly curved or straight in lateral view........................................................4

4. Pereonite 4 widest anteriorly; dorsal ridges anteriorly divergent, absent from head........... A. hexagonalis Barnard, 1925

- Pereonite 4 widest anterior one-third part; dorsal ridges extending on to head......................................5

5. Body size <3 mm; pereonites 5–7 without dorsal ridges................................... A. psittacus Bamber, 2008

- Body size> 3.5 mm; pereonites 5–7 with dorsal ridges........................................................6

6. Body with dorsal ridges converging on pereonite 3 and anterior of pereonite 4; head with no medial projection; pereopods 5–7 basis and ischium with no serrations................................................ A. triangularis Barnard, 1957

- Body with dorsal ridges not converging on pereonite 3 and anterior of pereonite 4, instead remaining more or less parallel; head with small medial projection; pereopods 5–7 basis and ischium with serrations................. A. serrulatus sp. nov.