Pronotum relatively flat, frontal margin
of pronotum slightly projecting as obtuse triangle; median carina completed, lateral carinae parallel on prozona, the prozona nearly square; humeri forming an obtuse triangle, with a pair of abbreviated carinaes between humeri.
fluviatilis: (A) individuals with the carapace tending toward a square shape, its surface flattened and irregular, the branchial region flattened or concave, and the lateral margins sharp, provided with 2 (rarely 3) notches; the frontal margin is visible in dorsal view; the lower orbital margin has distinct granules; (B) individuals with the carapace more orbicular in shape, its surface less irregular, the branchial region clearly convex, and the lateral margins rounded and smooth, devoid of teeth; the frontal margin not visible in dorsal view; the lower orbital margin with smaller granules.
However, during the preliminary examination of the material deposited at MZUESC, some extreme morphological variations among the specimens were observed, especially in the lateral margin of the carapace, the frontal margin, and the orbits.
fluviatilis collected in the study area: form A--characterized by the frontal margin of the carapace bordered by conspicuous granules, the anterolateral margin provided with developed teeth plus granules, and the posterolateral margin provided with granulation similar to that found on the front (Figs.
7A, B, 8): The frontal margin is bordered by a series of conspicuous granules.
The carapace near the front is densely punctuated; the gastric elevations are pronounced; the frontal margin and the upper, lateral, and inferior margins of the orbits are finely granulated.
The species of Uroleucon have a frontal margin and a frontal medial tubercle varying in shape; the following terms are used to describe the frontal margin: (1) V-shaped if it is deep with a small frontal medial tubercle that does not alter the profile of the frons; (2) subrectangular, if it is well-defined though not very deep and the frontal medial tubercle is low; and (3) sinuate, if the frontal margin is not very deep and the frontal medial tubercle is almost as high as the frontal lateral ones delimiting the margin.
Head dark brown, like coxae, and darker than trochanters; frontal margin subrectangular; dorsal setae 58-70 [micro]m, 1.
Head brown to dark brown, near black in more pigmented specimens, darker than trochanters; frontal margin V shaped; dorsal setae 30-65(70) [micro]m, 1.
Head brown, darker than trochanters; frontal margin subrectangular; dorsal setae 45-55(58) [micro]m, 1.