Brycon

Angulo, Arturo & Gracian-Negrete, Jatziry Marlene, 2013, A new species of Brycon (Characiformes: Characidae) from Nicaragua and Costa Rica, with a key to the lower Mesoamerican species of the genus, Zootaxa 3731 (2), pp. 255-266 : 263-264

Key to species of Brycon from Middle America, adapted from Hildebrand (1938)

1. Scales in lateral line 42 to 61........................................................................... 2

- Scales in lateral line 64 to 84........................................................................... 6

2. Anal fin about equal to length of head, with 24 to 28 total rays.................................................. 3

- Anal fin notably longer than head, with 32 to 38 total rays..................................................... 5

3. Scales in lateral line 43 to 48; 7 or 8 rows of scales between lateral line and origin of dorsal; 3 rows of scales between lateral line and base of ventral; 11 to 14 scales series crossing back between dorsal and adipose; snout projecting very little, with lower jaw reaching outer row of premaxillary teeth (Tuira and Bayano drainages on the Pacific slope and along the Atlantic San Blas coast west to the Rio Cascajal, Panama)............................. B. argenteus Meek & Hildebrand 1913

- Scales in lateral line 48 to 58; 7 to 10 rows of scales between lateral line and origin of dorsal; 3 or 4 rows of scales between lateral line and base of ventral; 15 to 18 scales series crossing back between dorsal and adipose.......................... 4

4. 48 to 55 scales in lateral line; pectoral fins short, failing to reach pelvic fins in small specimens by 2 or 3 rows of scales, about 1.4 in head; snout projecting less strongly, leaving only one row of premaxillary teeth exposed in advance of lower jaw; sides plain silvery (rivers of central Panama: Rio Indio and Rio Cocle del Norte on the Atlantic slope and Rio Cocle del Sur on the Pacific slope).................................................................. B. obscurus Hildebrand 1938

- 53 to 58 scales in lateral line; pectoral fins long, reaching nearly or fully to base of pelvic fins in small specimens, proportionately shorter in adult specimens, about 1.2 in head length; snout strongly projecting, 2 rows of teeth exposed in advance of lower jaw; sides with more or less definite dark cross bars or reticulations formed by black margins on the scales (Chagres system on the Atlantic slope and in the Rio Pacora and adjacent rivers on the Pacific slope, Panama)............................................................................................. B. petrosus Meek & Hildebrand 1913

5. Scales in lateral line 49 to 54; 5 or 6 rows of scales between lateral line and pectoral fin base; 9 to 11 rows of scales between lateral line and dorsal fin base; 5 to 7 rows of scales between lateral line and anal fin base; caudal peduncle large and shallow, its length is 1.78 to 2.35 times its depth (from Wawa basin in northern Nicaragua to Matina basin in southern Costa Rica, Atlantic slope)....................................................................... B. costaricensis n. sp.

- Scales in lateral line 55 to 61; 7 or 8 rows of scales between lateral line and pectoral fin base; 10 to 12 rows of scales between lateral line and dorsal fin base; 7 to 9 rows of scales between lateral line and anal fin base; caudal peduncle short and deep, its length is 1.25 to 1.61 times its depth (from the Grijalva and Usumacinta basins in southern Mexico to the Ulúa and Leán basins in northwestern Honduras, Atlantic slope, and in the Choluteca basin at the Honduran Pacific slope)................................................................................................. B. guatemalensis Regan 1908

6. Mandibula teeth large, usually 8 (rarely 7 or 9) in outer series; premaxillary teeth small, 12 to 14 in outer series (Pacific drainages of Colombia to central Panama).................................................. B. striatulus (Kner 1863)

- Mandibular teeth small, usually more than 10 in outer series; premaxillary teeth larger, 15 or more in outer series........ 7

7. Pectoral short, generally failing to reach base of ventral by 3 to 6 scales, 5.2 to 5.8 in standard length; scales somewhat larger and in more regular series, 66 to 79 between upper angle of gill opening and base of caudal; teeth somewhat larger, 10 to 14 (rarely 16) in outer series on mandible, 12 to 15 on maxillary, and 17 to 20 in outer series on premaxillaries; second suborbital broad, its lower anterior angle less rounded (rivers west of the Panama’s Azuero Peninsula and continuing north until Costa Rica’s Gulf of Nicoya, Pacific slope)................................................ B. behreae Hildebrand 1938

- Pectoral long, frequently reaching nearly or entirely to base of ventral, seldom falling short of this point by more than 2 rows of scales, 4.1 to 5 in standard length; scales rather small and in more or less irregular series, 68 to 83 (usually more than 70) between upper angle of gill opening and base of caudal; teeth rather small, 14 to 20 in outer series on mandible, 10 to 13 on maxillary, and 15 to 18 in outer series on premaxillaries; second suborbital narrow, with rounded lower anterior angle (Rio Chagres and adjacent drainages, Atlantic slope, Panama).................................. B. chagrensis (Kner 1863)