Comparison of the external morphology of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) ticks from Brazil and Argentina Patrı ´cia Rosa de Oliveira a , Gerva ´sio Henrique Bechara b , Sandra Eloisi Denardi a , Kelly Cristina Saito a , Erika Takagi Nunes a , Matias Pablo Juan Szabo ´ c , Maria Izabel Camargo Mathias a, * a Departamento de Biologia, I.B., Universidade Estadual Paulista Ju ´lio de Mesquita Filho, UNESP, Av. 24A 1515, Cx. Postal 199, CEP 13506-900, Rio Claro, SP, Brazil b Departamento de Patologia Veterina ´ria, FCAV, UNESP, Via de acesso Prof. Paulo Castellane s/n, CEP 14884-900, Jaboticaal, SP, Brazil c Faculdade de Medicina Veterina ´ria, Universidade Federal de Uberla ˆndia, Av: Para ´, 1720/Campus Umuarama, Bloco 2T, CEP: 38400-902, Uberla ˆndia, MG, Brazil Accepted 1 January 2005 Abstract In the present study the external morphology of semi-engorged Rhipicephalus sanguineus females ticks from Brazil and Argentina were compared by scanning electron microscopy. Many differences were detected among the R. sanguineus collected at the two localities, such as body size, shape of the genital pore, and morphology of the sensory structures. All these characteristics are fundamental for the diagnosis of species of the genus Rhipicephalus and thus indicate the need for further comparisons and, the taxonomical revision of this species of tick in the Neotropics. # 2005 Elsevier B.V. All rights reserved. Keywords: Rhipicephalus sanguineus; Ixodidae; External morphology; Brazil; Argentina 1. Introduction All superior vertebrates are subject to attack by ticks. Nevertheless, due to endothermy, mammals are frequent hosts for this kind of parasite. Rhipicephalus sanguineus, known as the brown dog tick is a cosmopolitan species and presents a characteristic reddish-brown coloration (Flechtmann, 1973). Although dogs are the most common host of this tick (Walker, 1994), it has also been recovered from other animals, such as cats, rabbits, camels, bovines in general, goats, horses, sheep, bats, reptiles, and ground feeding birds (Flechtmann, 1973) and humans (Walker et al., 2000). www.elsevier.com/locate/vetpar Veterinary Parasitology 129 (2005) 139–147 * Corresponding author. Tel.: +55 19 3526 4135; fax: +55 19 3526 4136. E-mail address: micm@rc.unesp.br (M.I.C. Mathias). 0304-4017/$ – see front matter # 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.vetpar.2005.01.001