RESUMO
@#Abstract: Objective To understand the morphological characteristics and ultrastructure of the dominant species of Rhipicephalus sanguineus in Hainan at different developmental stages, and provide theoretical basis for the identification of the lineage and control of Rhipicephalus sanguineus. Methods The external morphology of different developmental stages of the dominant species of Rhipicephalus sanguineus, including larva, nymph and adult tick in Hainan were observed by scanning electron microscope. Results The division between each segment of larva pedipalps was not obvious, and setae was serrated; dental formula type 2 | 2; 3 pairs of podomere; a pair of setae on the anal valve; none of anal groove, spiracular plate, porous area and genital aperture. There was a clear boundary at the beginning of each segment of nymph pedipalps; dental formula type 2 | 2; 4 pairs of podomere; 3 pairs of setae on the anal valve; anal groove; none of porous area and genital aperture. The male adult tick's trichotheca are covered by the pedipalps, and the whole bristles are conical; dental formula type 3 | 3; 4 pairs of podomere; anal groove and paraprocts; 7 setae on the anal valve; genital aperture was oval. The female of adult tick can be distinguished by dental formula 3 | 3; pairs of podomere; porous areas with 3 short setae; anal groove; 4 pairs of setae and 2 pores on the anal valve; genital pore was broadly U-shaped. In addition, the male adult's scutum occupies almost the entire dorsal surface, the basis capituli of larva, nymph and adult tick all were hexagonal, and the existence of Haller's organ was found on the first pair of legs. Conclusions Scanning electron microscopy observation of the different developmental stages of R.sanguineus revealed clear morphological features, preliminarily suggesting that R.sanguineus in Hainan Province may belong to the tropical lineage, which provide a certain experimental basis for the identification of the tick and the comprehensive prevention and control of local tick-borne diseases.