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A new species of Bryconamericus (Characiformes, Characidae, Stevardiinae) is described from the Pacific coast of northwestern Ecuador, South America. The new species is distinguished from all congeners by the presence in males of bony hooks on the caudal fin rays (vs. absence). The different layers of pigment that constitute the humeral spots have differing degrees of development and structure that are independent of each other. Brown melanophores are distributed in a thin, vertical, superficial layer of the epithelium (layer 1) and in another deeper (layer 2) that overlaps the first and is centered over the lateral–line. B. ecuadorensis has a horizontally oval or elliptical shape layer 2 pigment in the anterior humeral spot (vs. a rectangular or circular layer 2). The new species further differs in having an anterior extension of the caudal peduncle spot (vs. no anterior extension of the caudal peduncle spot) and by having a dark lateral stripe overlaid by the peduncular spot and by the regularly distributed pigmentation on scales on the sides of the body (vs. peduncular spot and other body pigments not superimposed over a dark lateral stripe). Hooks present on all fins of males (vs. hooks present only on anal and pelvic fins of males) distinguishes the new species from B. dahli, the only sympatric congener. Seven other diagnostic characters separating the new taxon from B. dahli are reported. We also include physical, chemical and biological habitat parameters and analyse the impacts from mining on this new species and other organisms present at the type locality.

Bryconamericus caldasi, a new species, is described from the Middle Cauca River drainage, Andean versant of Colombia. The new species is distinguished from all congeners by: the number of predorsal scales (15–17 vs. 9–14); a wide anterior maxilla tooth, at least twice as wide as the posterior tooth, both of which are pentacuspid (vs. maxilla teeth of same size); a dark lateral stripe overlaid by a peduncular spot; and a reticulated pattern on the sides of body (vs. peduncular spot and other body pigments not superimposed over a dark lateral stripe). We found several differences that distinguish the new species from B. caucanus, the only sympatric congener: number of predorsal median scales (15–17 vs. 12–13); convex predorsal profile (vs. oblique); scale size and number of scale rows at caudal–fin base (small scales arranged in two or more rows vs. large scales in just one row); pectoral fins not or just reaching pelvic fin insertions (vs. pectoral fins reaching posterior to pelvic–fin insertions); and dorsal–fin origin position (at vertical through posterior tip of pelvic–fin vs. at a vertical anterior to pelvic–fin tip).

Three new species of characid fishes of the genus Bryconamericus are described from the Pacific coast and Amazon Basin in Ecuador, based on pigmentation and morphometric, meristic and osteological characters. B. bucayensis (n = 48) is distinguished by the number of scales between the lateral line and the pelvic–fin insertions (7–8 vs. 2–7, except B. terrabensis with 7–8 and B. arilepis with 9–10), the number of branched anal–fin rays (33–38 vs. 31 or fewer), the number of anterior anal–fin rays covered by a row of scales at their bases (28–31 vs. 4–26), and its wide anterior maxillary tooth being at least twice the width of the posterior tooth, both of which are pentacuspid (vs. maxillary teeth of same size). B. zamorensis (n = 126) is distinguished from congeners by having five teeth on the maxilla (vs. 1 or 2 teeth on maxilla), except B. rubropictus and B. thomasi, from which it differs in a reticulated pattern over the lateral stripe, generated by the concentration of melanophores, the scale margins, all along the sides of the body, the high number of branched anal–fin rays and vertebras, and the low branched dorsal–fin rays. The dorsal expansion of the rhinosphenoid forms a bony wall between olfactory nerves (vs. dorsal expansion of rhinosphenoid between olfactory nerves absent). Lateral process of palatine surpasses anterolateral margin of ectopterygoid (vs. palatine without lateral processes that laterally surpass the ectopterygoid), and the distal tip of sphenotic spine is laterally wide and undulated (vs. narrow). B. oroensis n. sp. (n = 124) is distinguished by having a dark lateral stripe overlaid with a peduncular spot and a reticulated pattern on the sides of the body (vs. peduncular spot and other body pigments not superimposed over a dark lateral stripe). It has three simple dorsal–fin rays, the first only visible in cleared and stained material and articulated, along with the second simple ray, with the first dorsal pterygiophores. The third simple ray is longer, and articulated with second dorsal pterygiophores (vs. only two simple dorsal–fin rays, both articulated with first dorsal pterygiophores). The anterior frontal is separated and so the fontanel front parietal is continued on the mesethmoids (vs. anterior tips of frontals united, and not separated by mesethmoids). Keys for identification of the species of Bryconamericus known to occur in Ecuador are included and the validity of the genus Knodus (vide Knodus carlosi) is discussed for cis Andean species.

Based on 174 specimens, using morphometric, meristic and osteological characters, we describe a new species: Bryconamericus macarenae from the Güejar River in La Macarena mountain range, Orinoco Basin, Colombia. It differs from congeners in having: an incomplete lateral line (vs. complete lateral line in all except B. delta) and fewer and less conspicuous perforations in the latero-sensorial canal of the extrascapular bone (vs. conspicuous latero-sensorial canal perforation). It has four or fewer unbranched anal-fin rays (vs. five or more unbranched anal-fin rays), a short, thickened extrascapular bone without projections from the posterior margin, or with only a reduced apophysis (vs. extrascapular long, irregular, bony projections on its margins, and with a large undulated apophysis on its posterior margin). It also differs in live coloration. A key of species of Bryconamericus known from the Orinoco Basin and the Catatumbo River is included.

Here we describe for the first time Bryconamericus cinarucoense n. sp. and Bryconamericus singularis n. sp., two new species of Characiformesfrom the Cinaruco River, Orinoco Basin in Venezuela. B. cinarucoense n. sp. is distinguished from all other species of the genus in having: upper jaw extending beyond lower, maxilla short with only one or two teeth, cartilaginous rhinosphenoid extending to anterior part of prevomer, pelvic bone with cartilage along anterior edge, lateral line pores in straight line. B. singularis n. sp. is distinguished from congeners by having top of head flat, dentary with six or seven small unicuspid teeth, a dark lateral band extending from posterior edge of humeral spot to midbase of caudal fin which widens behind dorsal-fin origin, and in having five supraneurals which lack cartilage on the upper and lower extremities. Keys to aid identification of all known Venezuela species are included. Bryconamericus motatanensis is placed in the synonymy of B. alpha. Previous reports of B. breviceps and B. heteresthes from Venezuela are misidentifications, and are here considered as either B. cinarucoense n. sp., or another as yet undescribed species.