Molecular phylogeny of the highly disjunct cliff water beetles from S outh A frica and C hina ( C oleoptera: A spidytidae)

The superfamily D ytiscoidea contains six families with an aquatic lifestyle, with most of its extant diversity in two families: the burrowing water beetles ( N oteridae) and the diving beetles ( D ytiscidae). The other families have few species (up to six) and generally highly disjunct extant distributions. Aspidytidae currently contains one genus with two species, one in C hina and one in S outh A frica. Here we provide the first molecular data for the C hinese species, allowing us to explore the phylogenetic relationships and position of both species of this small family for the first time. Based on a matrix of 11 genes we inferred a phylogenetic hypothesis for D ytiscoidea including all extant families. Unexpectedly, A spidytidae were consistently recovered as paraphyletic relative to A mphizoidae, despite being well characterized by apparently synapomorphic adult features. A re‐examination of larval characters in the two aspidytid species revealed that the larva of the C hinese species is strikingly similar to that of A mphizoidae. Both share a series of plesiomorphic features but also some potential synapomorphies, including a dense vestiture of short setae on the head capsule, anteriorly shifted posterior tentorial grooves and widely separated labial palps. Arguably these features may belong to the groundplan of the clade A spidytidae +  A mphizoidae, with far‐reaching secondary modifications (including reversals) in the S outh A frican A spidytes niobe . At present we retain the family A spidytidae, however, due to the strong adult morphological synapomorphies of the two extant species, and the fact that the molecular paraphyly of the family may result from the highly divergent nature of the two extant species. This long evolutionary separation and strong divergence, in terms of gene sequences and larval features, is undeniable, substantial levels of saturation in third codon positions of protein‐coding genes being present between the two taxa. We address this issue taxonomically by introducing the new genus Sinaspidytes gen. nov. for the C hinese A spidytes wrasei . The continued contentious relationships amongst D ytiscidae, H ygrobiidae, A spidytidae and A mphizoidae highlight the need for more data to address dytiscoid phylogenetics, possibly involving a genomic approach. © 2016 The Linnean Society of London