Larval morphology of the Australian radiation Sternopriscina (Coleoptera: Dytiscidae, Hydroporinae): description and phylogenetic placement of the genus Chostonectes Sharp, 1882

Abstract

The larvae of the Australian endemic species Chostonectes gigas (Boheman, 1858) and C. johnsonii (Clark, 1862) are described and illustrated for the first time, with detailed morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, last abdominal segment and urogomphi. A parsimony analysis based on 83 informative larval characteristics of six species in four genera of the subtribe Sternopriscina was conducted using the program TNT. The monophyletic origin of the four Sternopriscina studied was strongly supported. Members of Paroster Sharp, 1882 characterise by the presence of three labial palpomeres, a unique feature within the subfamily Hydroporinae. Larvae of Barretthydrus Lea, 1927, Antiporus Sharp, 1882 and Chostonectes Sharp, 1882 evolved the presence of natatory setae on femora, tibia and tarsi. At the moment, Chostonectes is postulated to be closely related phylogenetically to Antiporus in the context of this study.