Hydrophilini, sensu HANSEN, 1991

Minoshima, Yûsuke & Hayashi, Masakazu, 2011, Larval morphology of the Japanese species of the tribes Acidocerini, Hydrobiusini and Hydrophilini (Coleoptera: Hydrophilidae), Acta Entomologica Musei Nationalis Pragae (suppl.) 51, pp. 1-118 : 83

Key to the genera of the tribe Hydrophilini from Japan (all instars)

1. Frontal lines U-shaped ( Fig. 58A ); mandibles strongly asymmetrical, left mandible with one inner tooth, right mandible with two closely aggregated inner teeth ( Figs. 57 B–C). .............................................................................................. Hydrophilus Geoffroy, 1762

– Frontal lines V-shaped ( Fig. 54A ); mandibles almost symmetrical, both mandibles similar in shape and with the same number of inner teeth ( Figs. 53 B–C)...................................2

2. Nasale with five distinct teeth ( Figs. 60C , 62B ); each mandible with three inner teeth, distal two large, basal one small ( Figs. 61 B–C, 63C–D); abdominal segments with short lateral projections ( Fig. 51B ). .................................................... Sternolophus ( Fabricius, 1792)

– Nasale without distinct teeth, almost straight or slightly serrate ( Figs. 52C , 55A ); mandibles with two inner teeth, distal one large, basal one small ( Figs. 53 B–C, 55D–E); abdominal segments with long lateral projections ( Fig. 51A ). .............. Hydrochara Berthold, 1827

Figures

Fig. 58. Hydrophilus acuminatus Motschulsky, 1854, third instar. A – head, dorsal view; B – spiracular atrium, dorsal view.

Fig. 57. Head appendages of Hydrophilus acuminatus Motschulsky, 1854, first instar. A – antenna, dorsal view; B–C – mandibles, dorsal view; D – maxilla, dorsal view; E – maxilla, ventral view; F – labium, dorsal view; G – labium, ventral view.

Fig. 54. Hydrochara affinis (Sharp, 1873), third instar. A – head, dorsal view; B – spiracular atrium, dorsal view.

Fig. 53. Head appendages of Hydrochara affinis (Sharp, 1873), first instar. A – antenna, dorsal view; B–C – mandibles, dorsal view; D – maxilla, dorsal view; E – maxilla, ventral view; F – labium, dorsal view; G – labium, ventral view.

Fig. 60. Head capsule of Sternolophus (Sternolophus) rufipes (Fabricius, 1792), first instar. A – dorsal view; B – ventral view; C – detail of anterior margin of head capsule, dorsal view.

Fig. 62. Sternolophus (Sternolophus) rufipes (Fabricius, 1792), third instar, dorsal view. A – head; B – detail of anterior margin of head capsule; C – spiracular atrium.

Fig. 61. Head appendages of Sternolophus (Sternolophus) rufipes (Fabricius, 1792), first instar. A – antenna, dorsal view; B–C – mandibles, dorsal view; D – maxilla, dorsal view; E – maxilla, ventral view; F – labium, dorsal view; G – labium, ventral view.

Fig. 51. Habitus of Hydrophilini species, third instar, dorsal view. A – Hydrochara affinis (Sharp, 1873); B – Sternolophus rufipes (Fabricius, 1792).

Fig. 52. Head capsule of Hydrochara affinis (Sharp, 1873), first instar.A – dorsal view; B – ventral view; C – detail of anterior margin of head capsule, dorsal view.

Fig. 55. Hydrochara affinis (Sharp, 1873), third instar. A – clypeolabrum, dorsal view; B – antenna, dorsal view; C – antenna, detail of outer membranous area on pedicel; D–E – mandibles, dorsal view; F – maxilla, dorsal view; G – maxilla, ventral view; H – labium, dorsal view; I – labium, ventral view.