Elasmopus

Souza-Filho, Jesser F. & Senna, André R., 2009, Two new species of the genus Elasmopus Costa, 1853 (Amphipoda: Gammaridea: Maeridae) from off the Northeast Brazilian Coast, Zootaxa 2301, pp. 55-68 : 66-67

Key to species of the genus Elasmopus recorded from Brazilian waters (only males)

1. Epimeron 3 produced in a sharp spine; basis of pereopod 5 with posterior margin concave ..................................... 2

- Epimeron 3 not produced, sometimes with short denticles; basis of pereopod 5 with posterior margin not concave 3

2. Gnathopod 2, propodus without a row of tubercles and perpendicular rows of long setae on inner face, palm acute, shorter than posterior margin of propodus, palmar corner defined by 2 spines .............. Elasmopus karamani sp. nov.

- Gnathopod 2, propodus with a row of tubercles and perpendicular rows of long setae on inner face, palm extremely acute, longer than posterior margin of propodus, not defined by spines or stout setae ..... Elasmopus lejeunei sp. nov.

3. Dactyli of pereopod 5–7, anterior margin with 3–4 denticles ...................... Elasmopus spinidactylus Chevreux, 1908

- Dactyli of pereopod 5–7, anterior margin smooth ....................................................................................................... 4

4. Gnathopod 2, palm with 3 spines (one defining palmar corner) and not densely setose ............................................... .................................................................................................................................. Elasmopus aff. rapax Costa, 1853

- Gnathopod 2, palm without spines and densely setose................................................................................................ 5

5. Gnathopod 2 with a well developed process near hinge of dactylus with 6–8 robust setae; pereopod 6, posterior mar- gin of basis not castelloserrate ............................................................................. Elasmopus brasiliensis (Dana, 1853)

- Gnathopod 2 without processes near hinge of dactylus; pereopod 6 with posterior margin of basis castelloserrate .... ............................................................................................................................. Elasmopus pectenicrus (Bate, 1862)