Larvae of the genus Antiporus (Coleoptera : Dytiscidae) and phylogenetic implications

Abstract

The larvae of Antiporus blakeii (Clark), A. femoralis (Boheman), A. gilbertii (Clark), A. hollingsworthi Watts, A. jenniferae Watts, A. uncifer Sharp and A. willyamsi Watts are described with an emphasis on chaetotaxy of the head capsule, head appendages, legs, last abdominal segment and urogomphi. A parsimony analysis based on 17 informative larval characteristics was conducted using the program PAUP*. The 11 most parsimonious trees support a monophyletic origin of the genera Antiporus Sharp, Nebrioporus Régimbart, Scarodytes Gozis, and Stictotarsus Zimmermann. Unambiguous synapomorphies supporting this clade are the presence of natatory setae on the femur, tibia and tarsus and the presence of a very elongate urogomphomere 1. It is postulated that these features evolved as swimming devices. The genus Oreodytes Seidlitz is postulated to represent the sister-taxon of Antiporus + Nebrioporus + Stictotarsus + Scarodytes and this clade is characterised by the absence of the maxillary cardo and insertion of the primary seta MX1 on the maxillary stipes.