buccula

Ventral coloration: head black with outer margin of buccula yellow; rostral segment I black, II dark orange, and III-IV yellow (apex of IV black); prothorax black with anterior margin yellow, and outer and posterior margin of propleuron shiny orange; mesothorax black, with posterior margin partially shiny orange; metathorax black; ostiolar peritreme black; coxae, trochanters, and femora shiny orange; tibiae and tarsi yellow; abdominal sterna black with upper margin of pleural margin shiny orange; genital capsule black.

2A); buccula slightly shorter than labial segment I and almost as long as distance between buccula to pronotum (Fig.

At the initiation of this study, two changes in the assemblage were expected: (1) the extirpation of the obligate riverine species Notropis buccula and Hybognathus placitus, which were believed to be unable to maintain permanent populations upstream from the impoundment in the absence of periodic immigration from downstream sites; and (2) a decline in relative abundance and species richness of minnows (family Cyprinidae), compared with pre-impoundment collections, as a result of the loss of N.

DIAGNOSIS: Distinguished by the dull black body; head reddish with eyes, antennae, maxillary plate, apex of buccula, labium, and a mark on frons black; ventral sides of collar, xyphus, propleura (partially), and middle area of hind femora reddish; first and second sterna of abdomen partially reddish.

COLORATION: Head: Dark brown to fuscous, sides (gena, lora) and clypeus paler brown, buccula pale brownish yellow; eyes brown to reddish brown.

Head partly pale brown; buccula reddish brown along ventral margin.

3A, H); antennal insertion situated close to margin of eye; buccula short, restricted to basal third of ventral side of head, labrum highly elevated, crestlike, semicircular in lateral view (Fig.

Head and thorax brown, buccular and genal regions reddish brown, first and second labial segments pale, third segment brown, membranous areas between buccula and first segment, first and second segment, and truncate tip of third segment whitish; scape and pedicel pale, basiflagellomere and distiflagellomere slightly darker (Fig.

2A, B); buccula shorter than gula; gena elongate; gula about the same length as postocular region; eyes removed from anterior margin of pronotum, located approximately on longitudinal midpoint of head (Figs.

Head: Vertex pale with brown, reddish or pale brown dots, transverse fasciae indistinct, orange or pale brown; mandibular and maxillary plates pale brown and orange, usually with whitish spot dorsally on mandibular plate; clypeus pale with dots, sometimes distally with brown transverse band and sometimes with transverse brown band across base; gena pale brown, orange or reddish brown; buccula whitish, gula pale, pale brown or reddish brown; antenna pale, first segment usually with brown or pale brown transverse bands, sometimes with brown dots, third and fourth segments slightly suffused with brown; labium pale, apical segment suffused with brown.

STRUCTURE: Head: Strongly declivent; anteocular region short, about a third of head length; frons weakly convex, nearly flat; gula shorter than buccula; eye big, surpassing dorsal margin of head in lateral view, interocular distance small (Fig.