Three new species of Bryconamericus (Characiformes, Characidae), with keys for species from Ecuador and a discussion on the validity of the genus Knodus

Abstract

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.