Morphological, molecular and cross-breeding analysis of geographic populations of coconut-mite associated predatory mites identified as Neoseiulus baraki: evidence for cryptic species?

Surveys were conducted in Brazil, Benin and Tanzania to collect predatory mites as candidates for control of the coconut mite Aceria guerreronis Keifer, a serious pest of coconut fruits. At all locations surveyed, one of the most dominant predators on infested coconut fruits was identified as Neoseiulus baraki Athias-Henriot, based on morphological similarity with regard to taxonomically relevant characters. However, scrutiny of our own and published descriptions suggests that consistent morphological differences may exist between the Benin population and those from the other geographic origins. In this study, we combined three methods to assess whether these populations belong to one species or a few distinct, yet closely related species. First, multivariate analysis of 32 morphological characters showed that the Benin population differed from the other three populations. Second, DNA sequence analysis based on the mitochondrial cytochrome oxidase subunit I (COI) showed the same difference between these populations. Third, cross-breeding between populations was unsuccessful in all combinations. These data provide evidence for the existence of cryptic species. Subsequent morphological research showed that the Benin population can be distinguished from the others by a new character (not included in the multivariate analysis), viz. the number of teeth on the fixed digit of the female chelicera.

International Institute of Tropical Agriculture (IITA)

University of Amsterdam, The Netherlands, through Board of the Netherlands Foundation for the advancement of Tropical Research (WOTRO)