Larval morphology of the Japanese species of the tribes Acidocerini, Hydrobiusini and Hydrophilini (Coleoptera: Hydrophilidae) Author Minoshima, Yûsuke Author Hayashi, Masakazu text Acta Entomologica Musei Nationalis Pragae 2011 suppl. 2011-06-30 51 1 118 journal article 9575 10.5281/zenodo.4272324 28715dfb-d0e9-4da8-a9a7-6ee9d6ecd150 0374-1036 4272324 Genus Chasmogenus Sharp, 1882 Note. Two species of the genus Chasmogenus are known from Japan , but immature stages of these Japanese species are unknown. However, judging from a description of C. nitescens ( Fauvel, 1883 ) from Australia ( ANDERSON 1976 , as ‘ Helochares nitescens ’; described mainly according to third instar larvae), the third instar larvae of Chasmogenus should be distinguished from the larvae of remaining Japanese Acidocerini by the following characters: (1) frontal lines V-shaped; (2) clypeolabrum almost symmetrical ( ANDERSON 1976 : Fig. 9 ); (3) nasale with five equally large teeth, almost symmetrical ( ANDERSON 1976 : Fig. 9 ); (4) mandibles asymmetrical, left mandible with one tooth, right mandible with two teeth ( ANDERSON 1976 : Fig. 9 ); (5) abdominal segments with spinose prolegs.