Orchestia, Leach, 1814

Momtazi, Farzaneh, Myers, Alan A., Knorrn, Alexander Hans, Moctar, Sidi Mohamed M., Freiwald, André & Sonnewald, Moritz, 2025, Orchestia mauritanica sp. nov. (Amphipoda: Talitridae), a new sand hopper from Mauritania with a Comprehensive Key to the World Species of Orchestia, Zootaxa 5701 (5), pp. 563-572 : 570-571

Key to male Orchestia species of the world

1. Pereopod 7 carpus posterior margin substraight, scarcely concave or evenly convex................................. 4

Pereopod 7 carpus posterior margin markedly irregular and partially concave...................................... 2

2. Pereopod 7 basis flange on posterior margin with concavity............................. O. aestuarensis Wildish, 1987

Pereopod 7 basis flange on posterior margin lacking concavity................................................. 3

3. Gnathopod 2 propodus posterior margin distally straight with distinct proximal shelf.............. O. mauritanica sp. nov.

Gnathopod 2 propodus posterior margin sinuous and lacking distinct proximal shelf.......... O. mediterranea Costa, 1853

4. Uropod 3 ramus subequal in length to peduncle.................................... O. xylino Lowry & Fanini, 2013

Uropod 3 ramus distinctly shorter than peduncle............................................................. 5

5. Pereopod 7 carpus anterior margin strongly crenulate......................................................... 6

Pereopod 7 carpus anterior margin not strongly crenulate...................................................... 7

6. Pereopod 7 carpus pyriform........................................................ O. montagui Audouin, 1826

Pereopod 7 carpus subovoid................................................... O. perezi Myers & Lowry, 2020b

7. Pereopod 7 carpus almost as broad as long................................................................. 8

Pereopod 7 carpus longer than broad...................................................................... 9

8. Pereopod 7 basis posterior margin strongly serrate.......................................................... 10

Pereopod 7 basis posterior margin weakly notched.......................................................... 11

10. Gnathopod 2 propodus almost as broad as long, palm strongly convex................ O. tabladoi Myers & Lowry, 2020b

Gnathopod 2 propodus longer than broad, palm weakly convex..................... O. inequalipes (K.H. Barnard, 1951)

11. Pereopod 7 merus almost parallel-sided...................................... O. forchuensis Myers & Lowry, 2020b

Pereopod 7 merus triangular............................................................................ 12

12. Gnathopod 2 propodus subovoid, palm moderately oblique, convex...................... O. gammarellus ( Pallas, 1766)

Gnathopod 2 propodus pyriform, palm very oblique, straight............................... O. magnifica Vecchi, 1931