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Source: ITIS_080509
Family: Acrididae
Sandbar Grasshopper
[Melanoplus fluviatilis Bruner, 1897, more ]
Structurally the same as M. foedus with practically identical reproductive structures and external morphology, but colored differently, with the dorsum of the pronotum usually plain (lacking pale lateral stripes) and with the overall coloring more dull (less shiny). North from Oklahoma the dark postocular bar (behind the eyes on head and upper sides of pronotum) is usually strongly developed and typically nearly black. Hind femur barred dark above, internally, and often on the outer face; usually reddish ventrally and on the inner side. Hind tibiae varied in color (buff, yellowish, green, blue, red, purple, etc.), often within the same population, rarely even with right and left hind tibiae of different colors.
Where they occur together, M. foedus (almost) always has pink to red hind tibiae; the outer face of the hind femur is usually plain or nearly so (most often yellowish) with the ventral side and the inner face usually yellowish; has pale stripes laterally on the dorsum of the pronotum; dark postoccular bars are usually poorly developed or even absent and never dark; and favors more oppen sandy grassland habitats. M. foedus is more similar in coloring to M. packardii, than to M. fluviatilis, but is usually more yellowish or orangey in hue with less developed dark markings than seen on either M. packardii or M. fluviatilis. As a rule of thumb, in a given area, M. foedus is the largest of the three, but this is not constant enough to be a reliable distinguishing trait. M. packardii has different internal male genitalia from M. foedus & M. fluviatilis, but in coloring it is much like M. foedus, differing in the same ways from M. fluviatilis. As compared to M. foedus, it is usually darker with more developed dark postoccular bars (but rarely black), more grayish to olivaceus in overall coloring, and in areas of overlap most often with hind tibiae blue, but other colors may predominate in some areas (especially red). From M. fluviatilis it differs in having the pale lateral stripes on top of the pronotum prominent, and only rarely has distinct bars across the outer face of the hind femur. Usually the lower edge and inner face of the hind femur not strongly reddish. It also favors open non-riparian habitats, but otherwise is something of a generalist (though favoring areas of heavier or rocky soils). M. fluviatilis might be confused with dark/dull colored individuals of M. angustipennis, and they commonly occur together, but M. fluviatilis is larger and stockier, and usually of a more dull coloring than is M. angustipennis. Males of M. angustipennis have longer furculae, and sometimes have a notch at the tip of the subgenital plate. M. fluviatilis is sometimes similar to M. differentialis in appearance (particularly in Texas and Oklahoma), but that species is larger, and has the distinct black herringbone pattern on the hind tibia. |
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