Integrative taxonomy demonstrates the unexpected synonymy between two predatory mite species: Cydnodromus idaeus and C. picanus (Acari : Phytoseiidae)

Species of the mite family Phytoseiidae are well known as predators of mite pests all over the world. Theiridentification is thus of great interest for biological control. The specimens examined in this study belong to the speciesCydnodromus idaeus (described from Brazil) and C. picanus (described from Chile). They were collected together on thesame plant in Argentina. These species are mainly differentiated by the presence/absence of the dorsal solenostomes (glandopenings) gd2. Some morphometric differences were observed between the Argentinian specimens and the type material ofC. idaeus and C. picanus; however, they were not sufficient to support a species separation. Morphological and molecularanalyses with two mtDNA (12S rRNA, CytB) and a nuclear DNA (ITS) marker showed no difference between Argentinianspecimens with and without the solenostome gd2. Also, molecular differentiation between these latter specimens, C. picanusand C. idaeus, was very low, suggesting that all these individuals belong to the same species. Biological experiments confirmthese results, as 75% of the progeny resulting from females with gd2 had gd2 present whereas all the descendants resultingfrom the females without gd2 had gd2 present too. The presence/absence of this solenostome seems thus to be variable withina species and cannot be used diagnostically. We conclude that all specimens from Argentina belong to C. idaeus and thatC. picanus is a junior synonym of C. idaeus. The present results were unexpected as the presence/absence of solenostomes isused in Phytoseiidae identification keys and as one of a suite of diagnostic characters for discriminating between species. Theconsequences of these findings for the taxonomy of Phytoseiidae are discussed.