Obesogammarus, Stock, 1974

Copilaș-Ciocianu, Denis & Sidorov, Dmitry, 2022, Taxonomic, ecological and morphological diversity of Ponto-Caspian gammaroidean amphipods: a review, Organisms Diversity & Evolution (New York, N. Y.) 22 (2), pp. 285-315 : 310

Key to species of Obesogammarus

1. Posterior margin of pereopods 3–4 with few sparse setae shorter than the underlying segment ...... O. subnudus

- Posterior margin of pereopods 3–4 with numerous setae as long as/longer than the underlying segment ................. 2

2. Uropod 3 exopod less than twice peduncle length ... 3

- Uropod 3 exopod at least twice as long as peduncle ... 4

3. Posterior margin of basis of pereopods 5–7 with short setae .................................................................. O. olvianus

- Posterior margin of basis of pereopods 5–7 with long setae .................................................................... O. obesus

4. Coxae 1–2 tapering towards distal end, propodus of gnathopod 2 triangular ................................... O. platycheir

- Coxae 1–2 not tapering, propodus of gnathopod 2 roughly rectangular .......................................................... 5

5. Medial surface of pereopod 7 basis without setae ...... ............................................................................ O. crassus

- Medial surface of pereopod 7 basis armed with clusters of setae ............................................................................. 6

6. Posterior margin of pereopod 7 basis sparsely armed with setae .......................................................... O. boeoticus

Posterior margin of pereopod 7 basis densely armed with setae .............................................................. O. acuminatus