Is Meru a specialized noterid (Coleoptera, Adephaga)?

Larval characters of Meru were extracted from the recently published description and added to an extensive data matrix from an earlier study on the phylogenetic position of the genus and family. The results confirm the earlier postulated clade Meruidae + Noteridae with strong support. The larvae share several characteristics with noterid larvae, notably the specific head shape, with the greatest width close to the foramen occipitale, the fissure-shaped posterior tentorial grooves at the posterior margin of the head capsule and the anteriorly cleft prementum. From a formal point of view, it would be justified to treat Meru as a subgroup of Noteridae (if the larva is properly identified). We refute the placement of Meruidae as a sister group of the remaining Dytiscoidea (including Noteridae). The new larval characters are valuable and informative, but a small set of external features is not sufficient for a reliable placement of Meruidae.