The genus Oligonychus Berlese (Acari, Prostigmata, Tetranychidae): taxonomic assessment and a key to subgenera, species groups, and subgroups

A comprehensive taxonomic assessment of the most agriculturally important and highly diverse spider mite genus, Berlese (Acari: Tetranychidae) was performed. The sub-generic division, species groups, doubtful species, species complexes and the interpretation of a key generic character are discussed. Based on the orientation of the male aedeagus, only two subgenera, namely Berlese (aedeagus downturned) and Tuttle & Baker (aedeagus upturned), are valid in the genus . The subgenera Wainstein, Wainstein, and Tuttle & Baker are considered to be synonyms of the subgenus Oligonychus, whereas the subgenus Pritchardinychus Wainstein is proposed as a synonym of the subgenus Reckiella. Moreover, based on female morphological characters, four species groups ( , , , and ) and 11 species subgroups ( , , , , , , , , , , and ) are suggested in the subgenera and . Fourteen species are proposed as species inquirendae, and potential cryptic species complexes in the genus are briefly highlighted. It is agreed that the clunal seta is always absent, while the para-anal setae and are always present in the genus A key to subgenera, species groups, and species subgroups of the genus is provided.