Macrobrachium

Valencia, Diego M. & Campos, Martha R., 2007, Freshwater prawns of the genus Macrobrachium Bate, 1868 (Crustacea: Decapoda: Palaemonidae) of Colombia, Zootaxa 1456, pp. 1-44 : 3-4

Key to species of Macrobrachium from Colombia

1. Second pair of pereopods different in shape ( Fig. 7 C, D)........................................................................... 2

— Second pair of pereopods similar in shape ( Fig. 6 C, D).............................................................................. 6

2. Larger second pereopod with carpus shorter than merus ( Fig. 7 C)............................................................ 3

— Larger second pereopod with carpus as long as or longer than merus ( Fig. 9 C)......................................... 4

3. External surface of palm of large chela of second pair of pereopods with rectangular space densely pubes- cent ( Fig. 11 C) ........................................................................................................................... M. hancocki

— External surface of palm of large chela of second pair of pereopods without densely pubescent rectangular space ( Fig. 7 C) ....................................................................................................................... M. crenulatum

4. Ventral margin row of palm of larger second pereopod with smaller spines on the base of finger ( Fig. 8 C)...................................................................................................................................................................... 5

— Ventral margin row of palm of larger second pereopod with smaller spines on midpalm length ( Fig. 9 C).. .................................................................................................................................................. M. faustinum

5. Palm of larger second pereopod swollen with ventral margin strongly convex with external and internal surfaces of palm thickly pubescent ( Fig. 14 C) ............................................................................ M. olfersii

— Palm of larger second pereopod compressed with ventral margin straight or nearly convex with external and internal surfaces of palm less pubescent ( Fig. 8 C) ................................................................ M. digueti

6. Second pair of pereopods with merus longer than palm ( Fig. 2 C).............................................................. 7

— Second pair of pereopods with merus shorter than palm ( Fig. 3 C)........................................................... 10

7. Rostrum as long as or longer than scaphocerite ( Fig. 15 A, 2 A)................................................................. 8

— Rostrum shorter than scaphocerite ( Fig. 16 A) ............................................................................. M. praecox

8. Merus shorter than carpus ( Fig. 2 C)........................................................................................................... 9

— Merus same length as carpus ( Fig. 18 C)........................................................................................ M. reyesi

9. Upper margin of rostrum convex on orbital region ( Fig. 2 A) ............................................. M. amazonicum

— Upper margin of rostrum straight on orbital region ( Fig. 15 A) ............................................ M. panamense

10. Second pair of pereopods with carpus shorter than merus ( Fig. 3 C)......................................................... 11

— Second pair of pereopods with carpus longer than merus ( Fig. 1 C).......................................................... 12

11. Fingers of second pair of pereopods longer than palm ( Fig. 5 C). .............................................. M. carcinus

— Fingers of second pair of pereopods as long as or shorter than palm ( Fig. 3 C) .................. M. americanum

12. Fingers of second pair of pereopods thickly pubescent ( Fig. 1 C).............................................................. 13

— Fingers of second pair of pereopods slightly pubescent or without pubescence ( Fig. 4 C)...................... 15

13. Fingers of second pair of pereopods less than half of palm length ( Fig. 17 C) ........................ M. rathbunae

— Fingers of second pair of pereopods more than half of palm length ( Fig. 1 C).......................................... 14

14. Carpus of second pair of pereopods less than 10 times as long as wide ( Fig. 1 C)................ M. acanthurus

— Carpus of second pair of pereopods more than 10 times as long as wide ( Fig. 20 B)................ M. tenellum

15. Cutting edge of fingers of second pair of pereopods with row of small teeth of similar size from base to midportion or beyond ( Fig. 12 C)............................................................................................................... 16

— Cutting edge of fingers of second pair of pereopods without row of teeth of similar size ( Fig. 4 C)....... 17

16. Palm of second pair of pereopods less than 4.5 times as long as wide ( Fig. 21 C)............ M. transandicum

— Palm of second pair of pereopods more than 4.5 times as long as wide ( Fig. 12 C) ............ M. heterochirus

17. Palm of second pair of pereopods more than 9 times as long as wide ( Fig. 10 C) ...................... M. ferreirai

— Palm of second pair of pereopods less than 7 times as long as wide ( Fig. 4 C) ….................................... 18

18. Carapace without spinules on anterolateral surface ( Fig. 6 A) ...................................................... M. cortezi

— Carapace with spinules on anterolateral surface ( Fig. 4 A)........................................................................ 19

19. Palm of second pair of pereopods strongly swollen, less than 3 times as long as high and with spines of different size on internal margin ( Fig. 13 C, D) ......................................................................... M. nattereri

— Palm of second pair of pereopods subcylindrical, more than 3 times as long as high and with spines of similar size on internal margin ( Fig. 4 C, D) ............................................................................ M brasiliense