Key to species of Pontogammarus

1. Uropod 3 endopod reaches half the length of the exopod 1st article ................................................................... 2

- Uropod 3 endopod shorter than half the length of the exopod 1st article .............................................................. 4

2. Dactylus nail of pereopods 5–7 hook-like ...... P. sarsi

- Dactylus nail of pereopods 5–7 straight ..................... 3

3. Mandibular palp very large, plumose D-setae present, last article of antenna 2 bares continuous setal fan ... P. maeoticus

- Mandibular palp normal, D-setae absent, last article of antenna 2 bares several setal clusters ........... P. weidemanni

4. Urosome with dorsal elevations ............................... 5

- Urosome flat .............................................................. 7

5. Dorsal elevations tall, pillar-like ................. P. setosus

- Dorsal elevations low, hump-like .............................. 6

6. Urosomite 1 armed with a crown of spines ................ ...................................................................... P. robustoides

- Urosomite 1 armed with setae only ............ P. aestuarius

7. Uropod 3 exopod 2nd article as long as broad, uropod 2 exopod devoid of spines .................................. P. borceae

- Uropod 3 exopod 2nd article longer than broad, uropod 2 exopod with 1 spine .................................. P. abbreviatus