Key to eastern and southern African species of the genus Marcusenius (the river system and country name where the holotype was collected is given for each species in brackets)

1a Dorsal fin rays 26–28; anal fin rays 32–33; vertebrae 45–46 (Cuanza River system, Angola)....... Marcusenius angolensis

1b Dorsal fin rays 20–26; anal fin rays 26–31; vertebrae 41–44.................................................... 2

2a Teeth on both jaws bicuspid; dark brown uniform bar on the body between origins of dorsal and anal fins; total vertebrae 42 (Ruvuma River system, Mozambique).................................................. Marcusenius livingstonii

2b Teeth on both jaws unicuspid, conical; dark brown bar between origins of dorsal and anal fins absent................... 3

3a Lateral scale series 69–73............................................................................... 4

3b Lateral scale series 52–66............................................................................... 6

4a Dorsal fin rays 22–25; anal fin rays 28–31; gill rakers on inner side of first gill arch 17 (Limpopo River system, South Africa)............................................................................ Marcusenius krameri sp. nov.

4b Dorsal fin rays 20–23; anal fin rays 26–28; gill rakers on inner side of first gill arch 13–15........................... 5

5a Circumpeduncular scales 19; caudal peduncle depth 8.4–10.2% SL; gill rakers on inner side of first gill arch 15; vertebrae 44 (Mhlatuze River, South Africa)............................................. Marcusenius caudisquamatus sp. nov.

5b Circumpeduncular scales 16–17; caudal peduncle depth 6.10–8.3% SL; gill rakers on inner side of first gill arch 13–14; verte- brae 42–43 ( Pongola River system, South Africa)......................................... Marcusenius pongolensis

6a Gill rakers on inner side of first gill arch 18–19; Circumpeduncular scales 14–18................................... 7

6b Gill rakers on inner side of first gill arch 13–17; Circumpeduncular scales 12–16................................... 8

7a Vertebrae 41 (Tana River, Kenya)......................................................... Marcusenius devosi

7b Vertebrae 43–44 (Lower Zambezi River system, Mozambique).......................... Marcusenius macrolepidotus

8a Preanal distance 56.6–59.2% SL; gill rakers on inner side of first gill arch 13 (Ruvuma River system, Mozambique).......................................................................................... Marcusenius lucombesi

8b Preanal distance 59.3–65.9% SL; gill rakers on inner side of first gill arch 15–17................................... 9

9a Vertebrae 45–46; gill rakers on inner side of first gill arch 15–17 (rarely 17); gill rakers on outer side of first gill arch 9 (Cunene River, Angolan/Namibian border).......................................... Marcusenius multisquamatus

9b Vertebrae 43–44; gill rakers on inner side of first gill arch 17; gill rakers on outer side of first gill arch 10 (Upper Zambezi River system, Namibia)............................................................. Marcusenius altisambesi