Brazilian ichthyologists Leandro Sousa, André Netto-Ferreira and José Birindelli have described two new species of Moenkhausia tetra from the Amazon River drainage in northern Brazil in the latest issue of the journal Neotropical Ichthyology.
Moenkhausia chlorophthalma (pictured above) is known from the Xingu River drainage and is distinguished from congeners in having a combination of: large dark blotches on the anterior to central portions of the scales forming the seven dorsal-most longitudinal series, absence of a conspicuous midlateral dark stripe, a proximal, well-delimited black area on the adipose fin, seven longitudinal rows of large dark blotches, 25–28 lateral line scales, four scales between the lateral line and the dorsal-fin origin, seven branched pelvic-fin rays, and 7–12 scales covering the anal-fin base.
This species is named after the iridescent green eyes in the live fish (Greek chloros=green and ophthalmos=eye).
Moenkhausia plumbea (above) is distinguished from congeners in having a combination of: large dark blotches on the anterior to the central portions of each scale along the seven dorsal-most longitudinal series, a dark longitudinal stripe along the eye, absence of a conspicuous midlateral dark stripe, eight or nine longitudinal rows of large dark blotches, 33–36 lateral line scales, five scales between lateral line and dorsal fin), (usually) six branched pelvic-fin rays, and 4–9 scales covering the anal-fin base.
This species is known from the Tapajós River drainage and is named after its dark midlateral stripe (Latin plumbum=lead).
For more information, see the paper: Sousa, LM, AL Netto-Ferreira and JLO Birindelli (2010) Two new species of Moenkhausia Eigenmann (Characiformes: Characidae) from Serra do Cachimbo, ParaÌ, Northern Brazil. Neotropical Ichthyology 8, pp. 255–264.