Molecular Correlation between Larval, Deutonymph and Adult Stages of the Water Mite Arrenurus (Micruracarus) Novus .

The systematics of many groups of organisms has been based on the adult stage. Morphological transformations that occur during development from the embryonic to the adult stage make it difficult (or impossible) to identify a juvenile (larval) stage in some species. Hydrachnidia (Acari, Actinotrichida, which inhabit mainly continental waters) are characterized by three main active stages-larval, deutonymph and adult-with intermediate dormant stages. Deutonymphs and adults may be identified through diagnostic morphological characters. Larvae that have not been tracked directly from a gravid female are difficult to identify to the species level. In this work, we compared the morphology of five water mite larvae and obtained the molecular sequences of that found on a pupa of the common mosquitoCulex(Culex)pipienswith the sequences of 51 adults diagnosed asArrenurusspecies and identified the undescribed larvae asArrenurus(Micruracarus) novus. Further corroborating this finding, adultA. novuswas found thriving in the same mosquito habitat. We established the identity of adult and deutonymphA. novusby morphology and by correlating COI and cytB sequences of the water mites at the larval, deutonymph and adult (both male and female) life stages in a particular case of 'reverse taxonomy'. In addition, we constructed the Arrenuridae phylogeny based on mitochondrial DNA, which supports the idea that threeArrenurussubgenera are 'natural':Arrenurus,MegaluracarusandMicruracarus, and the somewhat arbitrary distinction of the species assigned to the subgenusTruncaturus.