On some morphological and ultrastructural features of the insemination system in five species of the genus Brevipalpus (Acari: Tenuipalpidae)

The genus Brevipalpus (Tenuipalpidae) includes 291 described species commonly found in the tropical and subtropical regions. Morphological characters considered in the taxonomy of Brevipalpus species are difficult to discern, which often leads to erroneous identifications and the presence of cryptic species within species is suspected. New morphological characters are now considered relevant for identification of Brevipalpus species; among them, the morphology of the seminal receptacle (spermatheca) of the female insemination system. This feature has not been considered relevant until now; thus, there is little information about the insemination system in the available species descriptions. Hence, in the present study, ultrastructural details are provided for the insemination system in five species of Brevipalpus, representing different morphological groups. The seminal receptacle (spermatheca) and the insemination duct are illustrated using light, transmission and scanning electron microscopy. The spermatheca proved to have specific morphological features that can be useful for taxonomic purposes. On the other hand, its appearance within a population might be variable in a way that needs to be ascertained and evaluated.