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)