Review of the genus Tenuipalpus (Acari: Tenuipalpidae)

With over 300 described species, Tenuipalpus Donnadieu is the speciose genus of the family Tenuipalpidae. The descriptions of many of these species are not complete, and important information necessary for a correct identification is missing. The objective of this study was to re-describe species of Tenuipalpus, with a standard morphological format that facilitates future studies on the genus. The specimens studied are deposited mainly at the Smithsonian USNM Insect & Mite Collection, and included species described from different regions of the world. Phase Contrast, Differential Interference Contrast and Low Temperature Scanning Electron Microscopy (LT-SEM) techniques were used to analyze and identify new morphological characters of the mites. We verified that Tenuipalpus caudatus (Dugès), the type species of the genus, and a group of other described species share similar features (e.g. presence of projections anterior to sce setae and posterior to c3 setae). Some of these species also share the presence of crests on opisthosoma that can to occur in the position transversal and longitudinal or only longitudinal. Based on these characters Tenuipalpus sensu stricto can be defined. In addition, the type specimens of Tenuipalpus matthyssei (Pritchard & Baker), the type species of the genus Colopalpus Pritchard & Baker (1958), a synonym of Tenuipalpus was studied. This species has intermediate characteristics with the genera Tenuipalpus and Brevipalpus. The presence of long flagellate hysterosomal setae h2 and one unique genito-ventral plate are shared with Tenuipalpus, while the elongate-ovate body shape and the male without a narrow hysterosoma are more similar to Brevipalpus.