All known species of Ischyomius exhibit the same general facies: body elongate (length 5.9-13.4 mm; ratio of length: maximum width = 3.5-4.3), slightly flattened to relatively convex dorsally; eyes large, protruding; pronotum wide, at least indistinctly explanate
laterally; elytra widest anteriorly, distinctly tapered posteriorly, in most species with apices produced into spines (Pollock 1998, Fig.
Lateral margins of thoracic segments punctured, explanate
, and serrated (Fig.
Thorax: Pronotum subcampanulate, about 2.19x as broad as long; disk strongly convex, inclined forwards, densely transversely rugose punctuate; lateral margin finely explanate
, pale hyaline with reddish extremity; posterior margin sinuately convex to weakly bisinuate.
This genus is characterized by the moderately transverse pronotum, which lateral margins arcuate towards anterior angles which are strongly round, posterior angles obtusely rounded; the broadly and entirely explanate lateral margins of elytra; the narrow prosternal process, very slender palpi and distinctly appendiculate claws.
Elytral distinctly wider at base than pronotum, strongly convex; humeral calli rather prominent; lateral margins broadly and entirely explanate; humeral angles obtuse but not rounded; dorsal surface glabrous, punctuation on elytra slightly larger than those on head, each with a row of large punctures along the external side and with a row of gross punctures forming sutural striae expanding to apex of elytra.
Branch appendages: first branch underleaf divided to the base into a lanceolate, bifid segment and a explanate segment, first leaf transformed into one saccate lobule.
Leaf-lobules saccate or sometimes explanate, when saccate cylindric to clavate-cylindric, 220-250 x 80-110 [micro]m, distant to the stem.
Pronotum widely transverse, explanate
at sides; lateral margins thinly bordered, elongately bristled; hind angles quite rounded, feebly depressed; base bisinuate, not bordered.
2F, 3D, 4B); posterolateral lobes of male endosoma not expanded or explanate
Pronotum: Much wider than long, strongly declivous anteriorly; anterior collar distinctly developed, delimited posteriorly by a deep transverse furrow, lateral portions thickened; lateral margin narrowly explanate
, not projecting anteriad and ventrad, but distinctly elevated dorsad around its middle, distinctly emarginated anteriad of humeri in dorsal view; humeral angle rounded, obtuse, distinct; posterolateral angle very broadly rounded, obsolete (Figs.
and with basal fold; costal margin of hemelytra upturned; pronotal hood elongate, curved downward over head, with crest, and extending beyond antennal insertion Corythaica Stal
DIAGNOSIS: This species is only known from females and is recognized by the following combination of characters: uniformly dark reddish brown, apices of forewings narrowly whitish, abdominal connexiva reddish; clypeus shortened, not extending below bucculae; frons explanate
and raised posteriorly, crestlike in female (Fig.