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Background: The rock cavy Kerodon rupestris (Wied-Neuwied, 1820) is a rodent species endemic to northeastern Brazil. Earlier studies have associated the argasid tick Ornithodoros talaje (Guérin-Méneville, 1849) with rocky cavy; however, a recent study proposed that O. talaje is not established in Brazil, where previous reports of this species were possibly misidentifications of closely related species, yet to be properly determined. Here, we describe a new species of Ornithodoros Koch, 1844 associated with rock cavies in northeastern Brazil. Methods: During 2012-2013, Ornithodoros ticks were collected from K. rupestris resting places in Paraíba State (PB) and Piauí State (PI), northeastern Brazil. These ticks were brought alive to the laboratory, and used to form two laboratory colonies (PB and PI ticks). Field-collected adults and laboratory-reared larvae were used for morphological description through light and scanning electron microscopy. DNA sequences of the mitochondrial 16S rRNA gene were generated from nymphal ticks and used to conduct phylogenetic analyses along with other Ornithodoros spp. sequences from GenBank. Reproductive compatibility of crosses between PB and PI adult ticks was evaluated, as well as analyses of hybrid ticks through larval morphology by a principal components analysis (PCA) and DNA sequences of the second internal transcribed spacer (ITS2) region from adult ticks. Results: Morphological analysis allowed recognizing these ticks as a new species, Ornithodoros rietcorreai n. sp. The larva of O. rietcorreai is distinct from those of other Ornithodoros spp. by the combination of the following character states: 14 pairs of dorsal setae, dorsal plate pyriform, hypostome with pointed apex and dental formula 3/3 anteriorly, 2/2 posteriorly, and anal valves with long and pointed leaf-shaped ends. There were a few larval morphological differences between PB and PI ticks, and their mitochondrial 16S rDNA sequences diverged by 3.3 %. On the other hand, cross-mating experiments showed that PB and PI ticks were reproductive compatible, indicating that they represent a single species. Analyses of ITS2 sequences and PCA corroborated this assumption. Conclusion: Ornithodoros rietcorreai is described as a new species associated with K. rupestris in Brazil, increasing the Brazilian tick fauna to 70 species. [ABSTRACT FROM AUTHOR]

Background: Until recently, Amblyomma cajennense (Fabricius, 1787) was considered to represent a single tick species in the New World. Recent studies have split this taxon into six species. While the A. cajennense species complex or A. cajennense (sensu lato) (s.l.) is currently represented by two species in Brazil, A. cajennense (sensu stricto) (s.s.) and Amblyomma sculptum Berlese, 1888, their geographical distribution is poorly known. Methods: The distribution of the A. cajennense (s.l.) in Brazil was determined by morphological examination of all lots of A. cajennense (s.l.) in two large tick collections of Brazil, and by collecting new material during three field expeditions in the possible transition areas between the distribution ranges of A. cajennense (s.s.) and A. sculptum. Phylogenetic analysis inferred from the ITS2 rRNA gene was used to validate morphological results. Morphological description of the nymphal stage of A. cajennense (s.s.) is provided based on laboratory-reared specimens. Results: From the tick collections, a total 12,512 adult ticks were examined and identified as 312 A. cajennense (s.s.), 6,252 A. sculptum and 5,948 A. cajennense (s.l.). A total of 1,746 ticks from 77 localities were collected during field expeditions, and were identified as 249 A. cajennense (s.s.), 443 A. sculptum, and 1,054 A. cajennense (s.l.) [these A. cajennense (s.l.) ticks were considered to be males of either A. cajennense (s.s.) or A. sculptum]. At least 23 localities contained the presence of both A. cajennense (s.s.) and A. sculptum in sympatry. DNA sequences of the ITS2 gene of 50 ticks from 30 localities confirmed the results of the morphological analyses. The nymph of A. cajennense (s.s.) is morphologically very similar to A. sculptum. Conclusion: Our results confirmed that A. cajennense (s.l.) is currently represented in Brazil by only two species, A. cajennense (s.s.) and A. sculptum. While these species have distinct distribution areas in the country, they are found in sympatry in some transition areas. The current distribution of A. cajennense (s.l.) has important implications to public health, since in Brazil A. sculptum is the most important vector of the bacterium Rickettsia rickettsii, the etiological agent of Brazilian spotted fever. [ABSTRACT FROM AUTHOR]

Ticks are among the most important pathogen vectors worldwide, and the knowledge of their internal and external morphology may provide relevant information that will allow an adequate control of these animals. In this sense, the integument gains prominence, not only because of its wide capacity of expansion, but also due to the fact that this region is usually the first site of contact with natural and synthetic acaricides. Therefore, this study aimed to describe the morphology of alloscutal integument of R. sanguineus female ticks in three different feeding stages by means of histological and ultramorphological analysis. Significant differences were observed in all stages, with respect to the size of cells and layers, and to cuticle unfolding throughout the feeding process. Cuticle is divided into two main layers, the epicuticle and the procuticle, and is separated from a unistratified epithelium by a subcuticular layer. Procuticle, in turn, is divided into two layers, the endocuticle and exocuticle. Unfed female ticks showed cuticle with numerous folds, which decrease in quantity as the feeding expansion of the whole animal occurs. Opening of dermal glands and presence of setae also differed among groups. [ABSTRACT FROM AUTHOR]

The tick species Amblyomma cajennense is of great medical importance, as it is the vector of the Rickettsia rickettsii, agent of Rocky Mountain spotted fever. The objective of this study was to perform a morphological and histological analysis of the male reproductive system of fed and unfed A. cajennense. The male reproductive system is formed by a pair of tubular testes dorsolaterally arranged in opisthosoma. They were divided into three regions: proximal region (next to vas deferens), median region and distal region (nearest to the blind ending of testis). Proximal regions are connected to the seminal vesicles by the deferent ducts and to accessory glands, similar to what was observed for other Ixodidae. Feeding plays a fundamental role in the development of the reproductive system, as in unfed individuals, the testes, the seminal vesicles and the accessory glands were smaller comparing with the fed individuals. In addition, the prospermia, precursors of the spermatozoa, were only observed in fed individuals. The germ cells were organized in spermatocysts, enveloped by a connective tissue. The cells in more advanced stages of spermatogenesis were localized in the distal region, in accord with studies in other ticks, but opposite to what was observed for other arthropods. [ABSTRACT FROM AUTHOR]