Key to the species of the subgenera Prionospio (Prionospio) and P. ( Aquilaspio) from the Levantine coast of Turkey

1. Branchiae pinnate and apinnate (subgenus Prionospio) ............................................................................................. 2

- Branchiae pinnate (subgenus Aquilaspio)..................................................................................................................... 9

2. First and fourth pairs of branchiae pinnate, second and third pairs apinnate .............................................................. 3

- Branchiae arranged otherwise...................................................................................................................................... 6

3. Without dorsal crests..................................................................................................... Prionospio (Prionospio) dubia

- With dorsal crests.......................................................................................................................................................... 4

4. Dorsal crest present only on chaetiger 7, branchiae with sparse pinnules................................................. P. (P.) fallax

- Dorsal crest present on more than one chaetiger ........................................................................................................ 5

5. Two pairs of distinct eyes, dorsal crests present on chaetigers 7–16 ............................................. P. (P.) depauperata

- Two pairs of indistinct eyes, dorsal crests present on chaetigers 6–19 .............................................. P. (P.) steenstrupi

6. First three pairs of branchiae pinnate, last pair apinnate ................................................................ P. (P.) ergeni n. sp.

- Branchiae arranged otherwise ..................................................................................................................................... 7

7. First three pairs of branchiae apinnate, last pair pinnate ...................................................................... P. (P.) caspersi

- First pair of branchiae pinnate, remaining apinnate ................................................................................................... 8

8. Interparapodial pouches first present between chaetigers 2–3 ............................................................ P. (P.) saccifera

- Interparapodial pouches first present between chaetigers 4–5 ................................................................ P. (P.) ehlersi

9. Three pairs of branchiae .................................................................................................................. P. (A.) krusadensis

- Two pairs of branchiae ...................................................................................................................... P. (A.) s exoculata