Polyodontotrochus inpa, new species

(Figs. 2, 10, 14, 18, 35–37)

Diagnosis. Suprahumeral horns of pronotum smaller, but broadly expanded, apices truncate in dorsal view. In dorsal and lateral views neither exceeding or attaining anteriorly or dorsally beyond pronotal median carina, indistinct lateral carinae present.

Description. Color. Head, legs, and abdomen light brown, pronotum various shades of tawny brown, darkest on underside of suprahumeral horns.

Head. Ratio of distance between inner margin of eye to outer edge of nearest ocellus 0.87 × distance between inner edges of ocelli; frontoclypeal sutures wider than tall, converging in arch; head in anterior view with postclypeus concave, ratio of head width between eyes to height along midline 2.2; vertex with weak rugae absent. Thorax. Pronotum. With broadly auriculate, almost apically truncate suprahumeral horns projecting laterally, in lateral view lower than highest point of pronotal median carina (Fig. 17), in dorsal view not attaining most anterior part of metopidium (Fig. 13); median carina weakly elevated, in lateral view with vertical metopidium, dorsum weakly sinuous in anterior half and evenly declivous in posterior half, four weak, irregular lateral carinae present. Forewing. Costal cell narrow; s crossvein present, short as a single point, distad of r-m crossvein; 2 m-cu crossveins. Legs. Prothoracic femora ventrally with approximately 8 strongly sclerotized studs present along entire length of femora in single row, with longitudinal ventral groove present only distally; prothoracic tibia with 2 complete rows of strongly sclerotized studs ventrally; mesothoracic trochanters with 3–5 strongly sclerotized studs; mesothoracic femora ventrally with strongly sclerotized studs present at base but not in single row, with longitudinal ventral groove present only distally. Abdomen. Male genitalia (Figs. 35–37). Subgenital plate distally subtriangular in ventral view; lateral plate of pygofer without vertical ridge; aedeagus narrowest preapically in anterior view, with a longitudinal division at apex of posterior shaft; its ridges oriented vertically.

Dimensions of male (mm). Length 5.3, maximum width (across suprahumeral horns) 3.8, height above humeral angles (excluding suprahumeral horns) 0.9, ratio of length to width 1.4.

Etymology. The specific name is named in honor of the Instituto Nacional de Pesquisas da Amazonia, the source of this species. It is an invariable noun.