MYLIOBATIFORMES, Compagno, 1973

Ota, Renata Rúbia, Deprá, Gabriel de Carvalho, Graça, Weferson Júnio da & Pavanelli, Carla Simone, 2018, Peixes da planície de inundação do alto rio Paraná e áreas adjacentes: revised, annotated and updated, Neotropical Ichthyology 16 (2), pp. 1-111 : 10-15

Key for genera of fish from the upper rio Paraná basin, between the mouth of the rio Paranapanema and the Itaipu Reservoir, mainly focusing at its floodplain

1. Five pairs of gill openings in ventral region of head, not covered by opercle; dorsal region of tail with pointed, strong stingers ( MYLIOBATIFORMES )........................ ....................................... Potamotrygon (Potamotrygonidae)

1’. One single or a pair of gill openings; caudal peduncle lacking stingers ................................................................... 2

2. Both eyes on same side of head, in adults ( PLEURONECTIFORMES ) ............................................. ..................................................... Catathyridium (Achiridae )

2’. Eyes bilaterally situated in head .................................... 3

3. One single, small gill opening, behind head, in midventral region; body snake-shaped ( SYNBRANCHIFORMES ). ............................................... Synbranchus (Synbranchidae)

3’. One pair of gill openings; body not snake-shaped ........ 4

4. Anterior portion of dorsal and anal fins with one or more spines ......................................................................... 5

4’. Spine occasionally present on dorsal fin, always absent on anal fin.......................................................................... 19

5. Two pairs of maxillary barbels; pelvic fin in abdominal position, without spine ( CYPRINIFORMES ) ................. ........................................................... Cyprinus (Cyprinidae)

5’. Maxillary barbels absent; pelvic fin in thoracic position, usually below pectoral fin, with spine................................. 6

6. Nostril with two openings; lateral line with one sinuous branch, from above gill opening to end of caudal fin (Incertae sedis).............................. Plagioscion (Sciaenidae)

6’. Nostril with one opening; lateral line interrupted (with one superior branch, anterior, and another median branch, posterior), or occasionally continuous in some specimens of Cichla (in which case the two branches meet at right angles) ( CICHLIFORMES ) .............................................. 7

7. Teeth bicuspid; dark-brown blotch present on posterodorsal margin of opercle ..................................................... 8

7’. Teeth conical; dark-brown blotch absent on posterodorsal margin of opercle ..................................................... 9

8. Inferior branch of first gill arch with more than 20 long, thin gill rakers ................................ Oreochromis (Cichlidae )

8’. Inferior branch of first gill arch with up to 15 short, thick gill rakers ................................... Coptodon (Cichlidae)

9. Superior branch of first gill arch with a well-developed lobe.................................................................................... 10

9’. Superior branch of first gill arch without a lobe .......... 13

10. Dark-brown blotch present on flank ........................... 11

10’. Dark-brown blotch absent on flank ........................... 12

11. Dorsal fin with 15 to 18 spines... Geophagus (Cichlidae )

11’. Dorsal fin with 12 to 14 spines ................................... ............................................... Gymnogeophagus (Cichlidae)

12. Three or four dark-brown longitudinal and conspicuous stripes present on lower half of flank; dark-brown suborbital stripe present, from inferior margin of orbit to contact of subopercle and interopercle .............................. ..................................................... Apistogramma (Cichlidae ) 12’. Dark-brown longitudinal stripes absent on flank; suborbital stripe absent (a dark-brown suborbital stripe is present in juveniles, but it extends only from ventral margin of orbit to preopercle) ........ Satanoperca (Cichlidae )

13. First gill arch with more than 70 long, thin gill rakers (almost as long as gill filaments) ....................................... ............................................. Chaetobranchopsis (Cichlidae)

13’. First gill arch with less than 40 short, thick gill rakers................................................................................. 14

14. Notch between dorsal-fin spines and soft rays present .................................................................. Cichla (Cichlidae)

14’. Notch between dorsal-fin spines and soft rays absent .... 15

15. Body elongated, greatest depth contained 2.8 to 5.0 times in standard lengh .................... Crenicichla (Cichlidae)

15’. Body deep, greatest depth contained 1.7 to 2.5 times in standard lengh ............................................................... 16

16. Dorsal fin with 19 to 21 soft rays and anal fin with 15 to 17 soft rays; more than 20 circumpeduncular scale rows................................................... Astronotus (Cichlidae)

16’. Dorsal fin with 8 to 15 soft rays and anal fin with 8 to 10 soft rays; up to 16 circumpeduncular scale rows ......... 17

17. Two scale rows on cheek; three or four dark-brown longitudinal stripes on lower half of flank ......................... ............................................................ Laetacara (Cichlidae)

17’. More than two scale rows on cheek; dark-brown longitudinal stripes absent on flank................................... 18

18. Interradial membranes of dorsal and anal fins with scales ............................................... Cichlasoma (Cichlidae)

18’. Interradial membranes of dorsal and anal fins without scales .................................................. Aequidens (Cichlidae)

19. Body knife-shaped; anal fin with more than 100 rays; dorsal and pelvic fins absent ( GYMNOTIFORMES ) .... 20

19’. Body not knife-shaped; anal fin with up to 62 rays; dorsal and pelvic fins present............................................ 27

20. Caudal fin present ....................................................... 21

20’. Caudal fin absent ....................................................... 22

21. Snout prolonged into a thin, long and tubular rostrum ... ..................................... Sternarchorhynchus (Apteronotidae)

21’. Snout, when prolonged into a rostrum, not tubular .... ................................................. Apteronotus (Apteronotidae)

22. Mouth superior; dentary prognathous, longer than premaxilla ...................................... Gymnotus (Gymnotidae )

22’. Mouth terminal; dentary slightly shorter than premaxilla, or both dentary and premaxilla of same size......................... 23

23. Snout long and tubular ................................................ 24

23’. Snout short, not tubular ............................................. 25

24. Body pale yellow with dark-brown transverse stripes; anal fin hyaline and all anal-fin rays unbranched............... .......................... Gymnorhamphichthys (Rhamphichthyidae)

24’. Body brown with dark-brown vermiculate pattern, including anal fin; most anal-fin rays branched ................. ..................................... Rhamphichthys (Rhamphichthyidae)

25. Anterior nostril on superior lip..................................... ....................................... Brachyhypopomus (Hypopomidae)

25’. Anterior nostril on dorsal region of snout.................. 26

26. Orbital margin free, eye not covered by skin and surrounded by groove; most of anal-fin rays unbranched.. ................................................. Sternopygus (Sternopygidae)

26’. Orbital margin covered by skin, continuous with skin of head; most of anal-fin rays branched............................. ............................................... Eigenmannia (Sternopygidae)

27. Top of head flat and covered by scales ( CYPRINODONTIFORMES ) ....................................... 28

27’. Top of head not flat and without scales ..................... 32

28. Adult males without gonopodium; dorsal fin much closer to caudal fin than to vertical through half of body .. ..................................................... Melanorivulus (Rivulidae)

28’. Adult males with gonopodium; dorsal fin on vertical through half of body or slightly posterior to it.................. 29

29. Dark-brown blotches on lower half of flank ............... ................................................... Phallotorynus (Poeciliidae)

29’. Dark-brown blotches absent or, when present, on midline of flank ................................................................. 30

30. Body with dark-grey reticulate coloration pattern, except on ventral region; dorsal fin with dark-brown blotch...................................... Pamphorichthys (Poeciliidae)

30’. Body entirely with dark-grey reticulate coloration pattern; dorsal fin hyaline.................................................. 31

31. Males and females with dark-brown, vertically elongated, blotch on flank, below dorsal fin; adult males with long gonopodium, its length contained 2.6 to 3.1 times in standard lengh ................. Phalloceros (Poeciliidae)

31’. Males irregularly multicolored, and females without dark-brown blotch on flank; adult males with short gonopodium, its length contained 3.2 to 3.6 times in standard lengh ..................................... Poecilia (Poeciliidae)

32. Body naked or covered by plates ( SILURIFORMES ) ......................................................... 33

32’. Body covered by scales ............................................. 84

33. Body entirely naked, without plates............................ 34

33’. Body partially or entirely covered by plates (even when visible only on snout, such as in Scoloplax )............ 64

34. Opercle with spines..................................................... 35

34’. Opercle without spines .............................................. 36

35. Mouth inferior; nasal barbel absent ............................. ......................................... Paravandellia (Trichomycteridae)

35’. Mouth terminal; nasal barbel present ......................... ....................................... Trichomycterus (Trichomycteridae)

36. Adipose fin absent ....................................................... 37

36’. Adipose fin present .................................................... 39

37. Head strongly depressed; opercular opening in ventral position; caudal peduncle keeled in dorsal region ............. ....................................................... Amaralia (Aspredinidae)

37’. Head not depressed; opercular opening in lateral position; caudal peduncle rounded dorsally...................... 38

38. Dorsal and pectoral fins without spines ....................... ............................................................ Cetopsis (Cetopsidae)

38’. Dorsal and pectoral fins with strong spines ................ ....................................... Trachelyopterus (Auchenipteridae)

39. Eye covered by head skin, orbit without free margin. 40

39’. Eye not covered by head skin, orbit with free margin.... 45

40. One pair of barbels, most of times encapsulated ......... ............................................... Ageneiosus (Auchenipteridae )

40’. More than one pair of barbels, not encapsulated ....... 41

41. Eyes laterally on head (visible in ventral view); adipose fin very small, much shorter than head ............... 42

41’. Eyes dorsally on head (not visible in ventral view); adipose fin large, as long as or longer than head .............. 44

42. Posterior nare anteromedial to eye; anal-fin base about twice as long as head........ Auchenipterus (Auchenipteridae)

42’. Posterior nares between eyes; anal-fin base about as long as long as head or shorter.......................................... 43

43. Caudal fin bifurcate; anal-fin base about as long as dorsal-fin base ................................. Tatia (Auchenipteridae)

43’. Caudal fin truncate or slightly rounded; anal-fin base more than three times as long as dorsal-fin base................ ..................................... Parauchenipterus (Auchenipteridae )

44. Adipose fin fused to caudal fin; caudal fin rounded..... ................................................. Heptapterus (Heptapteridae)

44’. Adipose fin not fused to caudal fin; caudal fin bifurcate .......................................... Phenacorhamdia (Heptapteridae )

45. Nasal-barbel present.................................................... 46

45’. Nasal-barbel absent.................................................... 47

46. Dorsal fin with seven (I,6) and anal fin with 29 or 30 rays; caudal fin bifurcated.................. Ictalurus (Ictaluridae )

46’. Dorsal fin with 61-79 and anal fin with 45-60 rays; caudal fin rounded................................... Clarias (Clariidae)

47. Body with dark-brown transverse bars, from dorsal to ventral region, occasionally visible only on distal portion of caudal fin....................................................................... 48

47’. Body without dark-brown transverse bars (only darkbrown blotches on dorsal region, not extending ventrally, in Imparfinis )..................................................................... 50

48. Lateral line incompletely pored; caudal fin emarginate (caudal-fin lobes rounded, with no projecting tips); tip of tubular anterior nostril reaching past border of upper lip ..... ......................................... Microglanis (Pseudopimelodidae)

48’. Lateral line completely pored; caudal fin bifurcate (caudal-fin lobes slightly pointed); tip of tubular anterior nostril distant from border of upper lip............................. 49

49. Dark-brown transverse bar on caudal-fin lobes united with dark-brown transverse bar on posterior portion of caudal peduncle; dorsal and lateral surfaces of head grey, with light-beige blotch on cheek........................................ ....................................... Rhyacoglanis (Pseudopimelodidae)

49’. Dark-brown transverse bar on caudal-fin lobes not united with dark-brown transverse bar on posterior portion of caudal peduncle; dorsal and lateral surfaces of head completely grey ........ Pseudopimelodus (Pseudopimelodidae )

50. Anal fin long, with 55 to 62 rays.................................. .............................................. Hypophthalmus (Pimelodidae)

50’. Anal fin short, with up to 25 rays............................... 51

51. Barbels flattened.................... Pinirampus (Pimelodidae )

51’. Barbels round............................................................. 52

52. Premaxilla much longer than dentary, its dentigerous plate entirely exposed, even with closed mouth ................ .......................................................... Sorubim (Pimelodidae)

52’. Premaxilla slightly shorter, or of same size, or slighlty longer than dentary, with its dentigerous plate entirely hidden with closed mouth ................................................. 53

53. Lips thick, dorsal and ventral portions folded outwards. ................................................. Iheringichthys (Pimelodidae)

53’. Lips thin, not folded................................................... 54

54. Premaxilla slightly shorter than dentary ...................... .................................................. Hemisorubim (Pimelodidae )

54’. Premaxilla slighlty longer than dentary, or of same size .................................................................................... 55

55. Dark-brown blotches on dorsal region of body present ......................................... Imparfinis (Heptapteridae )

55’. Dark-brown blotches on dorsal region of body absent ................................................................................ 56

56. First dorsal and pectoral-fin rays hardened on its base, but not pungent ................................................................. 57

56’. First dorsal and pectoral-fin rays developed into pungent spines................................................................... 60

57. Posterior nostril much closer to orbit than to anterior nostril ................................ Cetopsorhamdia (Heptapteridae)

57’. Posterior nostril equidistant or much closer to anterior nostril than to orbit............................................................ 58

58. First dorsal-fin ray much longer than the others; pectoral fin with 14 or 15 rays................... Megalonema (Pimelodidae)

58’. Dorsal-fin rays approximately of same size; pectoral fin with up to 10 rays ......................................................... 59

59. Head long, 2.4 to 3.2 times in standard length; tooth plate present on vomer ....... Steindachneridion (Pimelodidae)

59’. Head short, 4.1 to 4.2 times in standard length; tooth plate absent on vomer ................... Rhamdia (Heptapteridae )

60. Orbit small, its diameter contained 9.0 to 11.0 times in head length........................................................................ 61

60’. Orbit large, its diameter contained 3.0 to 6.5 times in head length........................................................................ 62

61. Orbital diameter contained 1.5 to 2.5 times in interorbital distance.......... Pseudoplatystoma (Pimelodidae)

61’. Orbital diameter 3.5 to 4.5 times in interorbital distance ............................................ Zungaro (Pimelodidae)

62. Dark-brown longitudinal stripe present on flank; supraoccipital process uniformly narrow........................... .................................................. Pimelodella (Heptapteridae)

62’. Dark-brown longitudinal stripe absent, or, when present, alternating with light-beige stripes (only in P. ornatus ); supraoccipital process wider basally, narrowing towards tip......................................................................... 63

63. Supraoccipital process reaching nuchal plate; branched dorsal-fin rays of different size, first approximately twice as long as last ................................ Pimelodus (Pimelodidae)

63’. Supraoccipital process not reaching nuchal plate; branched dorsal-fin rays of approximately same size, except the last................................ Rhamdia (Heptapteridae )

64. Bony plates hardly visible on body sides, but well developed on snout ..................... Scoloplax (Scoloplacidae)

64’. Bony plates fully developed on body sides, absent or less developed on snout .................................................... 65

65. One series of plates along lateral line, each one with a posteriad spine-shaped process ......................................... 66 65’. More than one series of plates on flank, without a spine-shaped process......................................................... 70

66. Barbels branched; mental barbels united by membrane at their bases; coracoid process not covered by skin ........ 67

66’. Barbels unbranched; mental barbels not united by membrane at their bases; coracoid process covered by skin..... 68

67. Opercle and preopercle not covered by skin; orbit large, its diameter contained 2.5 to 3.1 times in head length; maxillary-barbel not reaching pectoral-fin base ....... ....................................................... Trachydoras (Doradidae)

67’. Opercle and preopercle covered by skin; orbit small, its diameter contained 3.6 to 4.9 times in head length; maxillary-barbel reaching or surpassing pectoral-fin base ... .......................................................... Ossancora (Doradidae)

68. Lateral plates very elongated vertically, almost meeting dorsal and adipose fins ...... Platydoras (Doradidae)

68’. Lateral plates slightly elongated vertically, distant from dorsal and adipose fins ............................................. 69

69. Dorsal and ventral region of caudal peduncle covered by plates ......................................... Rhinodoras (Doradidae)

69’. Dorsal and ventral region of caudal peduncle without plates ............................................... Pterodoras (Doradidae)

70. Two series of deep plates on flank; mouth terminal or subterminal........................................................................ 71

70’. Several longitudinal series of plates on flank; mouth inferior, sucker-shaped ...................................................... 74

71. Coracoid bones, between pectoral fins, covered by skin; orbit small, its diameter contained more than 9.0 times in head length ................. Callichthys (Callichthyidae)

71’. Coracoid bones exposed; orbit large, its diameter contained less than 7.5 times in head length..................... 72

72. Maxillary barbel short, not reaching pectoral-fin base; dorsal-fin spine approximately the same size as its first unbranched ray.......................... Corydoras (Callichthyidae)

72’. Maxillary barbel long, surpassing gill opening; dorsal-fin spine short, smaller than half of its first unbranched ray ................................................................. 73

73. Caudal fin bifurcated; dark-brown spots absent over body; maxillary barbel not reaching pelvic-fin base.......... ............................................. Hoplosternum (Callichthyidae)

73’. Caudal fin emarginated; dark-brown spots present all over body; maxillary barbel surpassing end of pelvic fin .. ....................................... Lepthoplosternum (Callichthyidae)

74. Caudal peduncle very depressed (dorsoventrally compressed) ...................................................................... 75

74’. Caudal peduncle deeper than broad (laterolaterally compressed) ...................................................................... 78

75. Snout very long, prolonged into rostrum; dorsal-fin origin much posterior to vertical through pelvic-fin origin ...................................................... Farlowella (Loricariidae)

75’. Snout short, not prolonged into rostrum; dorsal-fin origin anterior to slightly posterior to vertical through pelvic-fin origin................................................................. 76

76. Inferior lip with several filaments; premaxillary teeth at least twice as large as dentary teeth ............................... ......................................................... Loricaria (Loricariidae) 76’. Inferior lip without filaments; premaxillary and dentary teeth of approximately same size ......................... 77

77. Inferior lip cushioned, with few papillae; dentary with 10 to 20 teeth......................... Loricariichthys (Loricariidae )

77’. Inferior lip not cushioned, with several papillae; dentary with 5 to 8 teeth............ Rineloricaria (Loricariidae)

78. Dorsal-fin with I,7-9 rays ............................................ 79

78’. Dorsal fin with I,10-15 rays ....................................... 83

79. Adipose fin absent ....................................................... 80

79’. Adipose fin present .................................................... 82

80. Gill opening much larger than orbital diameter; least distance between posterior nostrils much larger than orbital diameter; large body size, reaching 440.0 mm standard lengh .............................. Rhinelepis (Loricariidae)

80’. Gill opening approximately same size of orbital diameter; least distance between posterior nostrils smaller or equal to orbital diameter; small body size, reaching up to 40.0 mm standard lengh................................................ 81

81. Caudal-fin lobes simetrically colored; both with an oblique dark-brown band ..................................................... ............................................. Curculionichthys (Loricariidae)

81’. Caudal-fin lobes asimetrically colored; dorsal caudalfin lobe overall clearer than ventral, both without oblique bands .......................................... Otothyropsis (Loricariidae)

82. Tentacles present on snout; interopercular region mobile, with long and strong spines .................. Ancistrus (Loricariidae)

82’. Tentacles absent; interopercular region slightly mobile, without spines ............... Hypostomus (Loricariidae)

83. Ground color of body pale yellow with brown blotches. ............................................... Megalancistrus (Loricariidae )

83’. Ground color of body black with white spots and vermiculate pattern.............. Pterygoplichthys (Loricariidae)

84. Lateral line canal system absent on body ( CLUPEIFORMES ).................. Platanichthys (Clupeidae)

84’. Lateral line canal system present on body ( CHARACIFORMES ).................................................... 85

85. Premaxilla, maxilla and dentary entirely without teeth ........................................................................................... 86

85’. Premaxilla, maxilla or dentary at least partially with teeth .................................................................... 87

86. Palate with two parallel grooves, forming three longitudinal folds; dark-brown longitudinal band on flank from vertical through dorsal-fin base to end of caudal peduncle, or restricted to caudal peduncle ......................... .................................................. Cyphocharax (Curimatidae)

86’. Palate with irregular glomerular projections; dark-brown longitudinal band on flank from opercle to caudal-fin base .................... Steindachnerina (Curimatidae)

87. Dentary without teeth, at least in its anterior edge...... 88

87’. Dentary with teeth, even anteriorly ........................... 90

88. Dentary with rounded edge, in ventral view................ ................................................... Hemiodus (Hemiodontidae)

88’. Dentary with straight edge, in ventral view............... 89

89. Dentary without lateral teeth...... Apareiodon (Parodontidae)

89’. Dentary with one to four lateral teeth (visualized in opened mouth) ................................ Parodon (Parodontidae ) 90. Teeth depressible, small and numerous, implanted in lips .................................. Prochilodus (Prochilodontidae )

90’. Teeth well developed, not depressible, implanted in dentary, premaxilla and occasionally in maxilla............... 91

91. Adipose fin absent ....................................................... 92

91’. Adipose fin present .................................................... 95

92. Teeth in palate and lateral line absent; dark-brown blotch on dorsal fin present, occupying almost the entire fin ................................ Pyrrhulina (Lebiasinidae)

92’. Teeth in palate and lateral line present; dark-brown blotch on dorsal fin absent ................................................ 93

93. Dorsal profile of head straight; pectoral, pelvic and anal fins with dark-brown stripes; dark-brown rounded blotch present on posterodorsal region of caudal peduncle .............. ........................................................... Hoplias (Erythrinidae )

93’. Dorsal profile of head convex; pectoral, pelvic and anal fins without dark-brown stripes; dark-brown blotch absent on caudal peduncle ................................................ 94

94. Dark-brown rounded blotch on opercle; caudal fin evenly darkened .................... Hoplerythrinus (Erythrinidae)

94’. Dark-brown rounded blotch, when present, on humeral region; caudal fin with dark-brown spots ............ ....................................................... Erythrinus (Erythrinidae )

95. Abdomen keeled.......................................................... 96

95’. Abdomen rounded.................................................... 102

96. Abdominal keel without spines................................... 97

96’. Abdominal keel with spines....................................... 98

97. Mouth very large, with well developed canine teeth; lateral line with 142 to 145 pored scales............................ .................................................. Rhaphiodon (Cynodontidae)

97’. Mouth and teeth small; lateral line with 33 to 37 pored scales......................................... Triportheus (Triportheidae)

98. Teeth tricuspid (lateral cusps very small, most of times immersed in gum), arranged in a single row both in premaxilla and in dentary........ Serrasalmus (Serrasalmidae)

98’. Teeth not tricuspid, arranged in two rows both in premaxilla and in dentary (the second dentary row represented by one minute conical teeth, next to the symphysis) ........................................................................ 99

99. Adipose fin longer than deep ....... Metynnis (Serrasalmidae)

99’. Adipose fin as long as deep...................................... 100

100. Dorsal fin with 24 to 27 rays Myloplus (Serrasalmidae )

100’. Dorsal fin with 14 to 16 rays ................................. 101

101. Adipose fin with rays ........ Colossoma (Serrasalmidae)

101’. Adipose fin without rays........................................ .................................................. Piaractus (Serrasalmidae )

102. Teeth mammiliform, arranged outside mouth and turned forward, in adults ................. Roeboides (Characidae)

102’. Teeth not mammiliform, arranged inside mouth ... 103

103. Spinoid scales on body........ Galeocharax (Characidae )

103’. Cycloid scales on body .......................................... 104

104. Palate with teeth...................................................... 105

104’. Palate without teeth absent .................................... 106

105. Teeth conical and/or tricuspid in both premaxilla and dentary; gill rakers almost as long as gill filaments and close to each other, without spines ........... Oligosarcus (Characidae) 105’. Teeth conical and canine in both premaxilla and dentary; gill rakers short and spaced apart, with spines..... ..................................... Acestrorhyncus ( Acestrorhynchidae )

106. One teeth row in premaxilla.................................... 107

106’. Two or three teeth rows in premaxilla ................... 116

107. Pectoral fin with three unbranched rays..................... .................................................. Characidium (Crenuchidae)

107’. Pectoral fin with one unbranched rays................... 108

108. Pseudotympanum absent......................................... 109

108’. Pseudotympanum present ...................................... 113

109. Lateral line incomplete; anal-fin origin on vertical through dorsal-fin base or slightly posterior to dorsal fin; small size, reaching 60.0 mm standard lengh ....................... .................................................... Aphyocharax (Characidae)

109’. Lateral line complete; anal-fin origin much posterior to end of dorsal fin; large size, reaching 500.0 mm standard lengh ....................................................... 110

110. Caudal-fin lobes covered by small scales; dark-grey blotch present on dorsal fin ................................................ ..................................................... Leporellus (Anostomidae)

110’. Caudal-fin lobes naked, with scales covering only the base of its rays; dark-grey blotch absent on dorsal fin.................................................................. 111

111. Teeth cuspidated in both premaxilla and dentary, in adults; teeth aligned to form an arch.................................. ...................................................... Schizodon (Anostomidae )

111’. Teeth incisiform in both premaxilla and dentary, in adults; teeth not aligned, formig a stair pattern when seen in ventral view................................................................. 112

112. Premaxilla and dentary with three teeth .................... .............................................. Megaleporinus (Anostomidae)

112’. Premaxilla with three or four, and dentary with four teeth, or, when premaxilla and dentary with three teeth, flank with dark-brown longitunal stripes (in L. amblyrhynchus )............................ Leporinus (Anostomidae )

113. Dentary teeth with three central cusps of the similar size, forming a somewhat straight edge .......................... 114

113’. Dentary teeth cusps gradually decreasing in size from central cusp, or central cusp much longer than lateral cusps.................................................................. 115

114. Lateral line complete; premaxilla with five or six teeth; anal fin of mature males with hooks ........................ ...................................................... Serrapinnus (Characidae )

114’. Lateral line incomplete; premaxilla with eight to 11 teeth; anal fin of mature males without hooks ................... ............................................... Aphyocheirodon (Characidae )

115. Lateral line complete; anal fin of mature males without bony hooks and caudal peduncle without arching ..................................................... Odontostilbe (Characidae)

115’. Lateral line incomplete; anal fin of mature males with bony hooks and caudal peduncle arched ventrally .... ...................................................... Serrapinnus (Characidae)

116. Maxilla with 11 to 33 teeth ..................................... 117

116’. Maxilla without teeth, or with up to 5 teeth........... 118

117. Premaxilla with three teeth rows; body scales without black spots............................................ Brycon (Characidae) 117’. Premaxilla with two teeth rows; body scales with black spots......................................... Salminus (Characidae )

118. Predorsal region very convex; anal fin with 39 or more rays................................. Psellogrammus (Characidae )

118’. Predorsal region straight or slightly convex; anal fin with up to 35 rays............................................................ 119

119. Premaxilla projecting much more anteriorly than dentary; premaxilla with three rows of heavy teeth ...... Piabina

119’. Premaxilla and dentary aligned; premaxilla with two teeth rows (even when outer row is not aligned, a third row is never present) ............................................120

120. Lateral line complete ............................................121

120’. Lateral line incomplete........................................126

121. Inner row of premaxilla with five teeth.................122

121’. Inner row of premaxilla with four teeth...............123

122. Caudal-fin lobes covered by small scales ............... ................................................. Moenkhausia (Characidae)

122’. Caudal-fin lobes without scales, except on its base ........................................................ Astyanax (Characidae)

123. Humeral blotch absent; anal-fin origin slightly posterior to dorsal-fin origin ......... Planaltina (Characidae )

123’. Humeral blotch present, sometimes inconspicuous; anal-fin origin on vertical through end of dorsal-fin base.... 124

124. Caudal-fin lobes covered by small scales ............... .......................................................... Knodus (Characidae)

124’. Caudal-fin lobes without scales, except on the base.....125

125. Mouth terminal; greatest body depth contained 4.0 to 4.2 times in standard lengh; middle portion of dorsal and anal fins not dusky; distal portion of caudal-fin lobes hyaline ........................................ Piabarchus (Characidae)

125’. Any feature other than the combination of characters above (mouth subterminal or terminal; greatest body depth contained 2.7 to 4.2 times in standard lengh; middle portion of dorsal and anal fins dusky or not; distal portion of caudal-fin lobes dusky or hyaline) ................. ............................................. Bryconamericus (Characidae)

126. Dark-brown blotch on caudal-fin base occupying its whole depth; or distal portion of caudal-fin lobes black.... ................................................. Moenkhausia (Characidae)

126’. Dark-brown blotch on caudal-fin base absent; or, when present, not occupying its whole depth, and distal portion of caudal-fin lobes hyaline ...............................127

127. Black blotch present on dorsal fin, or 7 or 8 scales in transverse series above lateral line ............................. ............................................ Hyphessobrycon (Characidae )

127’. Black blotch absent on dorsal fin, and transverse series of scales with 5 or 6 above lateral line ...............128

128. Inner row of premaxilla with three or four teeth..... ........................................................ Diapoma (Characidae)

128’. Inner row of premaxilla with five teeth ................. ............................................... Hemigrammus (Characidae)