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 Key to the known species of the genus Helochares from Japan (all instars) 2 1. Secondary sensilla between PA6 and PA7 absent ( Fig. 29A ); mandible with two setae (MN1 and MN5) ( Figs. 30 B–C); distal part of outer face of stipes with two setae ( MX 5 and MX 6) ( Figs. 30 D–E); lateral face of mentum without stout setae ( Figs. 30 F–G). First instar. ............................................................................................................................... 2 - Secondary sensilla between PA6 and PA7 present ( Figs. 34 , 43 ); mandible with more than two setae ( Figs. 33 C–D); distal part of outer face of stipes with three setae ( Figs. 33 E–F); lateral face of mentum with stout setae ( Figs. 33 G–H). Second and third instars. ......... 4 2. Epistomal lobe with one short scale-like seta and two short, trichoid to spiniform setae ( Fig. 29C ). ..................................................... H. ( Helochares ) pallens ( MacLeay, 1825 ) - Epistomal lobe with two short scale-like setae and two short, trichoid to spiniform setae ( Fig. 36C ). ....................................................................................................................... 3 3. Seta PA7 trichoid ( Fig. 36A ). ....................... H. ( Hydrobaticus ) anchoralis Sharp, 1890 - Seta PA7 scale-like ( Fig. 38A ). ............... H. ( Hydrobaticus ) nipponicus Hebauer, 1995 4. Epistomal lobe with one short scale-like seta and two short, trichoid to spiniform setae ( Fig. 33A ). ..................................................... H. ( Helochares ) pallens ( MacLeay, 1825 ) - Epistomal lobe with two short scale-like setae and two short, trichoid to spiniform setae ( Fig. 42A ). ............................................... H. ( Hydrobaticus ) nipponicus Hebauer, 1995