Abstract
Two new species of Moenkhausia, one from the rio Tapajós and the other from the rio Xingu basins are described as apparently endemics of the Serra do Cachimbo. Both species, along with M. petymbuaba, share a distinct color pattern composed of large conspicuous dark blotches on the base of the body scales. Moenkhausia chlorophthalma, from rio Treze de Maio, a tributary to rio Curuá (rio Xingu basin), is distinguished by the presence of a proximal well delimited black area on the adipose fin and a green eye in life. Moenkhausia plumbea of the headwaters of tributaries of the rio Braço Norte, rio Tapajós basin is diagnosed by the presence of a dark longitudinal stripe across the eye and six branched pelvic-fin rays (vs. seven). Relationships of the new species with other Moenkhausia are discussed.
Highlights
In the first attempt to group the species of Moenkhausia into subunits, Géry (1977) recognized three assemblages within the genus based on Eigenmann’s (1917: 66-69) key to the species of Moenkhausia: the M. lepidura-group; the M. grandisquamis-group; and the M. chrysargyrea-group
Two undescribed species of Moenkhausia, one from the rio Tapajós and another from the rio Xingu basins were discovered in small creeks located near the headwaters of the rio Curuá, with these portions isolated by large waterfalls from downstream portions of those systems
M. chlorophthalma, M. plumbea, and M. petymbuaba are the only species with a color pattern composed of large dark blotches on the scales of seven to nine dorsalmost longitudinal scale series
Summary
In the first attempt to group the species of Moenkhausia into subunits, Géry (1977) recognized three assemblages within the genus based on Eigenmann’s (1917: 66-69) key to the species of Moenkhausia: the M. lepidura-group (shallow-bodied species with relatively few horizontal scale rows on the body); the M. grandisquamis-group (deepbodied species with relatively few horizontal scale rows); and the M. chrysargyrea-group (deep-bodied species with relatively numerous horizontal scale rows). Two undescribed species of Moenkhausia, one from the rio Tapajós and another from the rio Xingu basins were discovered in small creeks located near the headwaters of the rio Curuá, with these portions isolated by large waterfalls from downstream portions of those systems. We describe both new species, discuss their possible relationships with congeners, and contribute to the understanding of the endemism in the Serra do Cachimbo
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