new synonymy:
Hyphessobrycon melanopleurus uruguayensis Messner, 1962
is a sr. synonym of
Cyanocharax macropinna Malabarba & Weitzman, 2003

new combination:
Cyanocharax uruguayensis (Messner, 1962)
from Hyphessobrycon

published in:
Malabarba, Weitzman & Litz (2004):
Hyphessobrycon melanopleurus uruguayensis Messner, 1962, an available name and a senior synonym of Cyanocharax macropinna Malabarba & Weitzman, 2003 (Ostariophysi: Characidae).
Neotropical Ichthyology 2 (2): 99-102

abstract (from publication):
Hyphessobrycon melanopleurus uruguayensis, Astyanacinus platensis, and Astyanax stenohalinus, published in a mimeographed paper by Messner in 1962 are considered available names. The subspecific name H. melanopleurus uruguayensis is recognized as a senior synonym of Cyanocharax macropinna Malabarba & Weitzman, 2003, and therefore referred to as Cyanocharax uruguayensis (Messner, 1962), new combination.

remarks:
Despite the fact that Cyanpcharax macropinna now is a junior synonym, following § 67.1.2 of the ICZN, this taxon still is the type species of the genus Cyanocharax. Find more information on the species in its record of Cyanocharax macropinna at PecesCriollos.