Laccobius Erichson, 1837

Minoshima, Yûsuke N., Iwata, Yasuyuki, Fikáček, Martin & Hayashi, Masakazu, 2017, Description of immature stages of Laccobius kunashiricus, with a key to genera of the Laccobiini based on larval characters (Coleoptera: Hydrophilidae), Acta Entomologica Musei Nationalis Pragae 57 (1), pp. 97-119 : 100

Genus Laccobius Erichson, 1837

Diagnosis of larva. Surface of head capsule smooth; frontal lines parallel, coronal line absent ( Fig. 3A ); nasale with median projection bearing a few teeth ( Figs 4A , 9A ); each epistomal lobe strongly projecting anteriorly, left lobe bearing a group of stout setae anteriorly, right lobe without setae ( Figs 4A , 9A ); mandibles strongly asymmetrical, apical inner tooth of left mandible with a group of ca. four to six seta-like projections ( Figs 5C–D , 10C–D ); submentum completely fused to head capsule (not even remnants of submental line are present); labium small, more or less reduced ( Figs 5G–H , 10G–H ); ligula reduced ( Figs 5G–H , 10G–H ); cervical sclerites present but narrow and indistinct ( Fig. 7A ); prosternal sclerite divided into two sclerites ( Fig. 7B ); mesonotum with three mesonotal sclerites on each side, posterior sclerites largest ( Figs 2A , 7C ); abdominal segments weakly lobate laterally ( Fig. 2A ); spiracular atrium developed, but small ( Fig. 7D ).

The larva of Laccobius is most similar to that of Oocyclus Sharp, 1882 , which has similar head morphology. On the basis of the description of the first instar larva of Oocyclus sp. by ARCHANGELSKY (1997), they are distinguishable by the following characters: sensillum SE1 is narrow and long in Laccobius , whereas short and stout in Oocyclus ; dorsal cuticular spines on mentum are absent in Laccobius , whereas present in Oocyclus ; frontal lines are parallel in Laccobius , whereas lyriform in Oocyclus ; MX 8 and MX 9 slender setae in Laccobius , whereas stout setae bearing subapical tooth in Oocyclus ; and mesonotal sclerites of Laccobius proportionally smaller than those of Oocyclus .

Figures

Fig. 3. First instar larva of Laccobius kunashiricus Shatrovskiy, 1984, head capsule, dorsal (A) and ventral (B) view.

Fig. 4. First instar larva of Laccobius kunashiricus Shatrovskiy, 1984, anterior margin of head capsule, dorsal (A) and ventral (B) view (both views drawn from a slide with the head capsule mounted with dorsal side up).

Fig. 9. Third instar larva of Laccobius kunashiricus Shatrovskiy, 1984, anterior margin of head capsule, dorsal (A) and ventral (B) (both drawn from dorsal).

Fig. 5. First instar larva of Laccobius kunashiricus Shatrovskiy, 1984, head appendages.A–B – antenna, dorsal (A) and ventral (B) view; C–D – mandible, dorsal view; E–F – maxilla, dorsal (E) and ventral (F) view; G–H – labium, dorsal (G) and ventral (H) view. Asterisk (*) in the scale bar means same scale.

Fig. 10. Third instar larva of Laccobius kunashiricus Shatrovskiy, 1984, head appendages.A–B – antenna, dorsal (A) and ventral (B) view; C–D – mandible, dorsal view; E–F – maxilla, dorsal (E) and ventral (F) view; G–H – labium, dorsal (G) and ventral (H) view.

Fig. 7. Third instar larva of Laccobius kunashiricus Shatrovskiy, 1984.A – head, dorsal view; B – prosternal sclerite, ventral view; C – mesonotal sclerites, dorsal view; D – spiracular atrium, dorsal view.

Fig. 2.Laccobius kunashiricus Shatrovskiy, 1984.A – third instar larva; B – feeding behaviour of larva; C–D – pupa in pupal chamber.