Genus Agraphydrus Régimbart, 1903 (Figs. 1A, 7–12, 44A, 45A) Diagnosis. The genus Agraphydrus is similar to other genera of the Japanese Acidocerini, but is distinguished from them by the following characters: (1) head capsule with long scale-like setae (Figs. 7, 9A, 10, 12C); (2) nasale with distinct teeth, not serrate or smooth (Figs. 7C, 10C); (3) antennal sensorium (SE1) rather long (Figs. 8A, 11A); (4) mandibles asymmetrical, left mandible with one inner tooth, right mandible with two teeth (Figs. 8 B–C, 11B–C); (5) abdominal segments with spinose prolegs (Figs. 12 A–B).

Published as part of Minoshima, Yûsuke & Hayashi, Masakazu, 2011, Larval morphology of the Japanese species of the tribes Acidocerini, Hydrobiusini and Hydrophilini (Coleoptera: Hydrophilidae), pp. 1-118 in Acta Entomologica Musei Nationalis Pragae (suppl.) (suppl.) 51 on page 17, DOI: 10.5281/zenodo.4272324