PRIMARY SETAE AND PORES ON THE CEPHALIC CAPSULE AND HEAD APPENDAGES OF LARVAL HYDROPORINAE (COLEOPTERA, DYTISCIDAE, HYDROPORINAE)

Through an analysis of the primary setae and pores of first-instar larvae of 30 Nearctic species of Hydroporinae (Coleoptera: Dytiscidae), 6 species belonging to other dytiscid subfamilies, and 1 species each of Amphizoidae, Gyrinidae, Haliplidae, Noteridae, and Hygrobiidae, the ancestral system of primary setae and pores of the cephalic capsule and head appendages of the Hydroporinae is deduced. Homology of setae and pores among larval Adephaga is attempted for all structures except the maxilla. Sixty-two setae and 39 pores have been assigned to the generalized hydroporine larva: 28 setae and 16 pores on the cephalic capsule, 5 setae and 8 pores on the antenna, 1 seta and 4 pores on the mandible, 15 setae and 3 pores on the labium, and 13 setae and 8 pores on the maxilla. Generic differences among the Hydroporinae are discussed in a phylogenetic perspective. Laccornis Des Gozis and Desmopachria Babington are confirmed as the first offshoot and the most derived lineage of Hydroporinae, respectively. Comparison of Desmopachria convexa with the Palaearctic Hyphydrus aubei Ganglbauer shows that they are closely similar, which suggests that Desmopachria convexa should remain a member of the Hyphydrini. There is much conflicting evidence suggestive of a more derived condition for Hygrotus Stephens (compared with Hydroporus Clairville). Oreodytes Seidlitz and Potamonectes Zimmermann share with Liodessus affinis (Say) and Desmopachria convexa a unique feature within the Hydroporinae: the absence of a maxillary cardo and insertion of seta 1 of the maxilla on the maxillary stipes. This feature might indicate a more derived condition for Oreodytes and Potamonectes within the Hydroporini.