DESCRIPTION OF THE LARVAL STAGES OF HETEROSTERNUTA-DIVERSICORNIS (SHARP) (COLEOPTERA, DYTISCIDAE, HYDROPORINAE)

Description of structures of all three larval instars of Heterosternut a diversicornis (Sharp) is presented. The chaetotaxy and porotaxy of t he cephalic capsule, head appendages, legs, last abdominal segment, an d urogomphi are discussed in detail. A close similarity between larvae of H. diversicornis, H. wickhami Zaitzev and H. cocheconis (Fall) is confirmed. All three species distinguish from the closely related spec ies of the genus Neoporus Guignot by (i) a very short and constricted siphon, (ii) the primary setae FE8 and FE9 which are subequal in lengt h to the maximum width of the metafemur (first instar), (iii) the abse nce of natatory setae on all tibiae and tarsi, and (iv) the contiguous position of the primary setae UR2 and UR3 on the urogomphomere 1.