Acratus is considered a genus between the Ithystenini and the Nemocephalini (SOARES, 1970); it differs from slender Proteramocerus and Teramocerus by the sturdy body (except Acratus apicalis); the head and rostrum are shorter than either Proteramocerus or Teramocerus; the prothorax
is pyriform or cylindrical, sulcate; the elytral apex is rounded; the first tarsal segment is almost as long as the length of 2nd and 3rd together.
The major differences are in the structural composition of the head and the prothorax
, both are more elongated in dolenterus.
Similarly to juveniles the prothorax
appeared to reflect less intensely to other body pans.
Undulambia has a somewhat rugose, broadly flattened prothorax
with two anterolateral horn-like structures that protrude twice as much as in the smooth prothorax
Dorsum of prothorax
with transverse row of 9 long, slender setae.
In the prothorax
the furcal bases are separated and the furca has no association with the pleural arm, which is absent.
with three pairs of lightly pigmented callosities, the most prominent one on dorsum, the other two on lateral and dorso-lateral position.
was characterized by small paired sternites and a notum bearing hair-like sensilla anteriorly and on lateral margins.
At intervals of 6-22 min, the male moved abruptly forward on the female, pulling the tip of her abdomen dorsally with his genitalia while he rapidly tapped the sides of her prothorax
with alternate strokes of his antennae for about 10s.
Head black, except mandible, clypeus, anterior region of face (more along orbits) and part of ventral side testaceous; antenna brown, except segment 1 testaceous; prothorax
black, except posterior margin of pronotum testaceous; scutum dark testaceous, except anterior and posterior margin black; rest of mesosoma black; metasoma brown; foreleg brown, except tarsus testaceous; mid- and hindleg brown, except tarsal segments 1-4 testaceous.
Thorax arched, sparsely pubescent, finely rugulose; prothorax
convex, roof-shaped, descending, with two foveal impression on each lateral side; prescutum broader than long, broadest posterior to center, narrower anteriorly, angulate laterally and on posterior margin; scutum much broader than long, slilghtly shorter than prescutum, weakly depressed dorso-medianally, angulate laterally, posterior margin weakly invaginated along scutellum; scutellum trapezoid, broad anteriorly and narrow posteriorl, about twice as broad as long.
Hemelytra: reddish brown, finely maculate with dark yellow, veins creamy white flecked with small black dashes, wing membrane dark brown to black, hemelytral apices reaching to posterior margin of abdominal tergite VI; dorsal prothorax
and hemelytra bearing scattered short, stout, erect, pale setae.