Exploring the phylogenetic history of water striders (Hemiptera: Heteroptera: Gerromorpha) using genome-skimming

Abstract

The family Gerridae, commonly known as water striders, are true bugs (Hemiptera, Heteroptera) that skate on the surface of waterbodies ranging from small streams to large rivers, ponds, lakes and even the open ocean. Eight extant subfamilies and eight tribes are traditionally recognized in this family. Furthermore, Microveliinae and Haloveliinae (traditionally in Veliidae) have also been classified as Gerridae by some authors lately. Here, we used a low-coverage shotgun sequencing to infer the phylogenetic relationships of Gerridae, showing new insights into the evolutionary history and taxonomic status of this taxon. Our study represents the first molecular analysis that includes representatives of all subfamilies and tribes. Nineteen specimens analysed were from museum collections and over 25 years old. Maximum-likelihood and Bayesian inference analyses support the monophyly of all subfamilies except Gerrinae, which is paraphyletic. Our analyses further revealed the non-monophyly of Gerrini, Metrobatini and Trepobatini, as well as for the genera Aquarius Schellenberg and Tenagogonus Stål (both Gerrinae). A molecular clock analysis showed that Gerridae originated during the mid-Cretaceous, with most subfamilies diversifying during the Late Cretaceous or early Paleogene. The results highlight issues with the current classification of Gerridae and the need for a careful taxonomic review of some taxa of this family.