Pleonexes, Spence Bate, 1857

Souza-Filho, Jesser F. & Andrade, Luiz F., 2022, A new species of Pleonexes Spence Bate, 1857 (Amphipoda: Senticaudata: Ampithoidae) from the São Pedro and São Paulo Archipelago, Equatorial Atlantic, Brazil, with comments on the genus, Zootaxa 5209 (2), pp. 199-210 : 208-209

Identification key to Pleonexes species in the world

1 Male gnathopod 2 palm incised, with thumb-like process..................................................... 2

- Male gnathopod 2 palm not incised....................................................................... 4

2 Telson with subacute apex...................................... Pleonexes divisura ( Shoemaker, 1933) comb. nov.

- Telson with truncate apex.............................................................................. 3

3 Male gnathopod 2 basis not setose, uropod 2 peduncle with minute distoventral process..... Pleonexes kava ( Myers, 1985)

- Male gnathopod 2 basis heavily setose, uropod 2 peduncle without distoventral process... Pleonexes parakava ( Peart, 2007) 4 Male gnathopod 2 palm not defined...................................................................... 5

- Male gnathopod 2 palm well defined by distinct angle or process............................................... 9

5 Telson with truncate apex.............................................................................. 6

- Telson with subacute apex.............................................................................. 7

6 Mandible palp long................................................ Pleonexes navosa ( Myers, 1985) status nov.

- Mandible palp very short................. Pleonexes suapensis ( Correia, Guedes-Silva & Souza-Filho, 2016) comb. nov.

7 Telson cusps very large................................................... Pleonexes poipu (J.L. Barnard, 1970)

- Telson cusps small.................................................................................... 8

8 Antenna 1 subequal in length to antenna 2.................................. Pleonexes kaneohe (J.L. Barnard, 1970)

- Antenna 1 shorter than antenna 2, reaching distal end of peduncle........................... Pleonexes lowry sp. nov.

9 Telson cusps very large............................................................................... 10

- Telson cusps small................................................................................... 11

10 Male gnathopod 2 propodus subrectangular.............................. Pleonexes gammaroides Spence Bate, 1856

- Male gnathopod 2 propodus suboval........................................... Pleonexes helleri ( Karaman, 1975)

11 Gnathopod 2 palm excavated........................................... .. Pleonexes maxillissius ( Ledoyer, 1984)

- Gnathopod 2 palm not excavated....................................................................... 12

12 Gnathopod 2 propodus suboval......................................................................... 13

- Gnathopod 2 propodus subrectangular................................................................... 14

13 Coxa 1 anteroventral corner slightly produced, antenna 1 densely setose....... Pleonexes auriculata ( Rabindranath, 1972)

- Coxa 1 anteroventral corner produced, antenna 1 poorly setose........................ Pleonexes rotunda ( Peart, 2007)

14 Gnathopod 2 palm convex, palmar corner rounded............................. Pleonexes kulafi (J.L. Barnard, 1970)

- Gnathopod 2 palm almost straight, palmar corner square............................ Pleonexes meganae ( Peart, 2007)