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

Abstract

A comprehensive taxonomic assessment of the most agriculturally important and highly diverse spider mite genus, Oligonychus 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 Oligonychus Berlese (aedeagus downturned) and Reckiella Tuttle & Baker (aedeagus upturned), are valid in the genus Oligonychus. The subgenera Homonychus Wainstein, Metatetranychoides Wainstein, and Wainsteiniella 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 (coffeae, exsiccator, iseilemae, and peruvianus) and 11 species subgroups (aceris, biharensis, coffeae, comptus, exsiccator, gossypii, iseilemae, peruvianus, pritchardi, smithi, and subnudus) are suggested in the subgenera Oligonychus and Reckiella. Fourteen Oligonychus species are proposed as species inquirendae, and potential cryptic species complexes in the genus Oligonychus are briefly highlighted. It is agreed that the clunal seta h1 is always absent, while the para-anal setae h2 and h3 are always present in the genus Oligonychus. A key to subgenera, species groups, and species subgroups of the genus Oligonychus is provided.

Evidence for Reconsidering the Taxonomic Status of Closely Related Oligonychus Species in punicae Complex (Acari: Prostigmata: Tetranychidae)

“…Oligonychus Berlese is the largest genus of spider mites in the family Tetranychidae Donnadieu (Acari: Prostigmata), with 212 species that have been reported so far [ 1 , 2 ]. Differentiation of Oligonychus species is difficult and usually depends on the morphology of the male aedeagus [ 3 , 4 ].…”

“…Moreover, the key differential character of the male aedeagus becomes unreliable with improperly mounted specimens (not in a lateral position) or brief morphological descriptions without illustrations of the aedeagus [ 8 , 9 ]. Recently, a comprehensive taxonomic assessment of Oligonychus revealed the presence of various doubtful species [ 1 ].…”

“…In the genus Oligonychus, the coffeae species subgroup (= ununguis and bicolor subgroups, sensu Pritchard and Baker) was characterized by Mushtaq et al and assigned 44 species [ 1 ]. This subgroup comprises many related Oligonychus species with similar morphological characteristics [ 4 , 10 ].…”

Pest categorisation of Oligonychus perseae

“…Junior synonyms include Oligonychus ( Homonychus ) perseae Tuttle, Baker and Abbatiello, 1976. The taxonomy of the genus Oligonychus was fully revised in 2021 (Mushtaq et al, 2021 ).…”

“…The identification of O. perseae requires microscopic examination of slide‐mounted adult males and verification of the presence of key morphological characteristics as given by Mushtaq et al ( 2021 ).…”