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Ventral shields

In most cases identification of Mesostigmata to family or lower can be accomplished only if the specimen is an adult female.  The easiest way to determine the stage and sex of your specimen is to look at the intercoxal region.  Adult females have a genital opening that is almost invariably in the intercoxal region (species of Metagynella are exceptions) and covered by a sclerotized shield which may be truncate posteriorly or continue onto the ventral region.  Adult males and immature stages of both sexes have a continuous intercoxal shield that may be truncate or continue onto the ventral region or even incorporate the entire ventral region.  Adult males have a subcircular opening in the intercoxal shield (sometimes called a sternogenital or sternitogenital shield) somewhere between the posterior margins of coxae IV and the base of the tritosternum.  Immature stages (larva, protonymph, deutonymph) of Mesostigmata have no genital opening.