ABSTRACT
Head not completely concealed by pronotum, at least partially visible from above; head strongly prognathous (e.g., Chauliognathus, Podabrus) to somewhat deflexed (e.g., Silis), rarely hypognathous (Ichthyurus), someare abruptly constricted behind eyes (Podabrini). Compound eyes more or less entire, moderately to strongly protruding, often sexually dimorphic (smaller in females); ocelli absent. Antennae elongate, pubescent, with eleven
antennomeres, filiform in most, infrequently serrate (e.g., most Tytthonyx, some Ditemnus), rarely pectinate or flabellate (Tytthonyx subgenus Thinalmus); flagellomeres in some with longitudinal sensory grooves (e.g., Polemius); antennal insertions exposed from above, most with insertions moderately to widely separated, rarely contiguous (Ichthyurus). Frontoclypeal (epistomal) suture absent in most (present in Chauliognathini); anterior margin of clypeus varied, entire to distinctly emarginate. Labrum free, membranous, often concealed beneath clypeus or apparently absent. Mandibles elongate in most, curved, with an acute apex; mola and prostheca absent; most with mandibles simple, falciform (e.g., Podabrus), with inner margin unidentate in some (e.g., Frostia, most Chauliognathus), uncommonly with inner margin serrate (e.g., some Malthodes). Maxillae with densely setose galea and lacinia in most, some with lacinia reduced or absent, some with apical lobes fused; maxillary palpi 4-segmented, apical palpomere securiform to cultriform, some ovate and terminating in an acute point (Malthininae). Labium with ligula undivided, finely cleft, or deeply bilobed; labial palpi 3-segmented, apical palpomere slightly to strongly expanded. Gular sutures distinctly separated (e.g., Cantharini), confluent (e.g., Podabrini) or apparently absent.
