A third species of Nothoaspis Keirans & Clifford, 1975 (Acari: Argasidae): Nothoaspis setosus (Kohls, Clifford & Jones, 1969) n. comb.

In South America, early descriptions of soft tick species were based on examination of the external morphology of the larval stages. In many cases, specimens were collected only once as it is the case of some bat-associated Ornithodoros spp. If we are to understand the systematic scenario of South American soft ticks, these species become axial questions to be re-studied from a morphological and molecular point of view. The objective of this study was to assess the taxonomic identity of soft tick larvae collected on bats inhabiting crevices of a large rock in the Rondônia State (RO), Brazilian Amazon. After a detailed morphological analysis using light microscopy, three large engorged larvae sharing the same phenotype were identified as Ornithodoros setosus Kohls, Clifford & Jones, 1969, a species collected in 1964 on bats in RO. Remarkably, maximum parsimony and Bayesian phylogenetic analyses based on tick 16S rRNA mitochondrial gene sequences obtained from two of these specimens showed that O. setosus indeed corresponds to a species of Nothoaspis Keirans & Clifford, 1975. Therefore, a new combination, Nothoaspis setosus (Kohls, Clifford & Jones, 1969), is herein proposed. While an elongated triangular dorsal plate with a curvy-notched posterior margin, and bulges in the lateral margins of basis capitulum correspond to common characters in larvae of the genus Nothoaspis, polymorphic traits are represented by minute cornua in the basis of the capitulum, the dentition of the hypostomal tip, triangular spurs on coxae I, and the number of dorsal and circumanal setae.

Description of the larva of Amblyomma calcaratum Neumann, 1899 (Acari: Ixodidae) by light and scanning electron microscopy.

The larval stage of Amblyomma calcaratum Neumann is described using optical and scanning electron microscopy. Unfed larvae were obtained from a colony of A. calcaratum originating from engorged females collected on Tamandua tetradactyla in the Jaraguá Mountain (23°40'S, 45°44'W), São Paulo County, Brazil. Eleven larvae were prepared and mounted on slides and observed under a light microscope equipped with a drawing tube. Three specimens were prepared for SEM. Several morphological characters are described, including the chaetotaxy of the idiosoma, palpi, and Haller's organ, as well as morphological features of the idiosoma, gnathosoma, and legs of A. calcaratum larvae. In addition, topographical and numerical patterns of integumentary structures on the larval idiosoma are described using a recently proposed nomenclature. On the idiosoma, setaes, lyrifissures, small glands, and large wax glands were found. These structures were observed isolated or associated over the entire idiosoma, except on the scutum, which lacks large wax glands. The topographical and numerical patterns of integumentary structures of the A. calcaratum larva showed only minor differences when compared with patterns of other Amblyomma larvae; however, a few key features can be used to differentiate A. calcaratum from other members of this genus.

Ornithodoros peropteryx (Acari: Argasidae) in Bolivia: an argasid tick with a single nymphal stage.

By the end of the 1960s, the argasid tick Ornithodoros peropteryx was described from larval specimens collected from the bat Peropteryx macrotis in Colombia. Since its original description, no additional record of O. peropteryx has been reported, and its post-larval stages have remained unknown. During July 2010, 18 larvae were collected from 9 bats (Centronycteris maximiliani), resulting in a mean infestation of 2.0 ± 2.2 ticks per bat (range 1-8). These bats were captured in a farm in northeastern Bolivia close to Guaporé River in the border with Brazil. Morphological examinations of the larvae revealed them to represent the species O. peropteryx. One engorged larva that was kept alive in the laboratory moulted to a nymph after 9 days. Fourteen days after the larval moulting, the nymph moulted to an adult female without taking any blood meal during the nymphal period. This adult female was used for a morphological description of the female stage of O. peropteryx. In addition, the larvae were used for a morphological redescription of this stage. One larva and two legs extirpated from the adult female were submitted to DNA extraction and PCR targeting a fragment of the mitochondrial 16S rDNA gene, which yielded DNA sequences at least 11 % divergent from any available argasid sequence in Genbank. We show that O. peropteryx ontogeny is characterized by a single, non-feeding, nymphal stage. This condition has never been reported for ticks.

Description of adults and nymph, and redescription of the larva, of Ornithodoros marinkellei (Acari:Argasidae), with data on its phylogenetic position.

The argasid tick Ornithodoros marinkellei Kohls, Clifford, and Jones, 1969 was described 4 decades ago based on larval specimens collected from bats (Pteronotus spp.) in Colombia and Panama. Thereafter, larval O. marinkellei parasitizing bats were reported from Venezuela, Guyana, and Brazil. Herein, we describe the adults and nymph, and redescribe the larva of O. marinkellei based on specimens recently collected in the western Brazilian Amazon region. In contrast to all other known adult argasids, the idiosoma of both males and females of O. marinkellei is covered with sclerotized plaques. The idiosoma of the nymph of O. marinkellei is entirely micromamillated, and differs from the adults by the absence of plaques. The larva of O. marinkellei is morphologically similar to the larvae of the 2 other species belonging to the subgenus Subparmatus , i.e., Ornithodoros viguerasi Cooley and Kohls, 1941 and Ornithodoros mormoops Kohls, Clifford, and Jones, 1969 . Because of the long and narrow dorsal plate, the larva of O. marinkellei is readily distinguished from O. viguerasi and O. mormoops. Comparison of our larvae from Brazil with O. marinkellei paratype specimens from Colombia confirmed their taxonomic identification. However, a few morphological differences, particularly in the size of the gnathosoma, were observed. Further studies are necessary to clarify whether O. marinkellei is a complex of different species, or a single species represented by morphologically polymorphic, and geographically distinct populations. Partial mitochondrial 16S rDNA gene sequences were generated for O. marinkellei specimens from Brazil, and compared with available homologous sequences in GenBank. Phylogenetic analyses revealed O. marinkellei to be distinct from the remaining argasid species available in GenBank, including other bat-associated tick species that are found in sympatry with O. marinkellei in the Neotropical region.

Description of a new argasid tick (Acari: Ixodida) from bat caves in Brazilian Amazon.

Nothoaspis amazoniensis n. sp. (Acari: Ixodida: Argasidae) is described from adult and immature ticks (nymph II, nymph I, larva) collected from bat caves in the Brazilian Amazon. Also, 16S rDNA sequences are provided. The diagnostic characters for adults are the presence of false shield or nothoaspis, an anteriorly projecting hood covering the capitulum, a medial extension of palpal article I (flaps), genital plate extending from coxa I to IV, absence of 2 setae on the internal margin of the flaps, a minute hypostome without denticles, presence of a central pore in the base of hypostome, and a reticulate surface pattern on the posterior half of the nothoaspis in males. The nymph II stage is characterized by a hood that is small in relation to the capitulum, short coxal setae, palpal flaps lacking setae on the internal margin, long hypostome, pointed with dentition 4/4 apically, and the anterior half of the body is covered by a cell-like configuration. Nymph I stage is characterized by a hood, small in relation to the capitulum, dorsum of the body covered by a cell-like configuration, venter integument covered by a cell-like configuration, and hypostome dentition 4/4 with apices that are "V"-shaped. Diagnostic characters of the larvae are the number and size of dorsal setae, and the shape of scutum and hypostome. The new species appears to have a life cycle with a larva that feeds on bats, a non-feeding nymphal stage (nymph I), a feeding nymphal stage (nymph II), and adults that probably represent non-feeding stages.

Seroprevalence of anti-Leishmania spp. antibodies in rural dogs from the city of Monte Negro, State of Rondônia, Brazil.

The present study assessed the prevalence of anti-Leishmania spp. antibodies in dogs from the city of Monte Negro, State of Rondônia, Brazil. ELISA (NE ≥ 3) and IFAT (≥ 1:40) were used to evaluate 161 serum samples collected from rural dogs from Monte Negro. Forty-five (27.9%) dogs were positive by ELISA tests and five (3.1%) were positive by IFAT. The present study showed for the first time the frequency of exposure to Leishmania spp. in dogs in the State of Rondônia, Amazon Region.

Seroprevalence of anti-Leishmania spp. antibodies in rural dogs from the city of Monte Negro, State of Rondônia, Brazil / Soroprevalência de anticorpos anti-Leishmania spp. em cães rurais do município de Monte Negro, Estado de Rondônia, Brasil

The present study assessed the prevalence of anti-Leishmania spp. antibodies in dogs from the city of Monte Negro, State of Rondônia, Brazil. ELISA (NE > 3) and IFAT (>1:40) were used to evaluate 161 serum samples collected from rural dogs from Monte Negro. Forty-five (27.9 percent) dogs were positive by ELISA tests and five (3.1 percent) were positive by IFAT. The present study showed for the first time the frequency of exposure to Leishmania spp. in dogs in the State of Rondônia, Amazon Region.

O presente estudo determinou a prevalência de anticorpos anti-Leishmania spp. em cães do município de Monte Negro, Estado de Rondônia, Brasil. Foram utilizados os testes de ELISA (NE > 3) e RIFI (>1:40) para avaliar 161 amostras de soro de cães da zona rural do município. Quarenta e cinco cães (27,9 por cento) reagiram no teste de ELISA e cinco (3,1 por cento) na RIFI. O presente estudo demonstra pela primeira vez a freqüência de exposição por Leishmania spp. em cães de Rondônia, Região Amazônica.

Comparison of two methods for collecting free-living ticks in the Amazonian forest.

In the present study, we compared 2 methods for collecting ixodid ticks on the verges of animal trails in a primary Amazon forest area in northern Brazil. (i) Dragging: This method was based on passing a 1-m(2) white flannel over the vegetation and checking the flannel for the presence of caught ticks every 5-10 m. (ii) Visual search: This method consisted of looking for questing ticks on the tips of leaves of the vegetation bordering animal trails in the forest. A total of 103 adult ticks belonging to 4 Amblyomma species were collected by the visual search method on 5 collecting dates, while only 44 adult ticks belonging to 3 Amblyomma species were collected by dragging on 5 other collecting dates. These values were statistically different (Mann-Whitney Test, P=0.0472). On the other hand, dragging was more efficient for subadult ticks, since no larva or nymph was collected by visual search, whereas 18 nymphs and 7 larvae were collected by dragging. The visual search method proved to be suitable for collecting adult ticks in the Amazon forest; however, field studies should include a second method, such as dragging in order to maximize the collection of subadult ticks. Indeed, these 2 methods can be performed by a single investigator at the same time, while he/she walks on an animal trail in the forest.

Seroprevalence of anti-Leishmania spp. antibodies in rural dogs from the city of Monte Negro, State of Rondônia, Brazil / Soroprevalência de anticorpos anti-Leishmania spp. em cães rurais do município de Monte Negro, Estado de Rondônia, Brasil

The present study assessed the prevalence of anti-Leishmania spp. antibodies in dogs from the city of Monte Negro, State of Rondônia, Brazil. ELISA (NE ≥ 3) and IFAT (1:40) were used to evaluate 161 serum samples collected from rural dogs from Monte Negro. Forty-five (27.9%) dogs were positive by ELISA tests and five (3.1%) were positive by IFAT. The present study showed for the first time the frequency of exposure to Leishmania spp. in dogs in the State of Rondônia, Amazon Region.

O presente estudo determinou a prevalência de anticorpos anti-Leishmania spp. em cães do município de Monte Negro, Estado de Rondônia, Brasil. Foram utilizados os testes de ELISA (NE ≥ 3) e RIFI (≥1:40) para avaliar 161 amostras de soro de cães da zona rural do município. Quarenta e cinco cães (27,9%) reagiram no teste de ELISA e cinco (3,1%) na RIFI. O presente estudo demonstra pela primeira vez a freqüência de exposição por Leishmania spp. em cães de Rondônia, Região Amazônica.

New reports of Antricola guglielmonei and Antricola delacruzi in Brazil, and a description of a new argasid species (Acari).

Adults of 3 tick species (Acari: Argasidae) identified as Antricola guglielmonei, Antricola delacruzi, and Carios rondoniensis n. sp. were collected on bat guano in a cave in the state of Rondônia, western Amazon, Brazil. Adults of C. rondoniensis possess a unique combination of characters that distinguish them from all described adults in the Argasidae, i.e., a large spiracular plate densely filled with small goblets, a well-developed flap covering the female genital opening, and palpi containing several tufts of long setae on articles 2 and 3. Unlike Ornithodoros or other Carios species, adults of C. rondoniensis have a scooplike hypostome devoid of denticles, as in Antricola spp. Conversely, the presence of a pair of long posthypostomal setae, and a slitlike transverse fissure at the capsule opening of the Haller's organ, are characters of C. rondonensis that are also found in species of Carios and Ornithodoros, but not in Antricola species. Molecular analyses inferred from a portion of the 16S rRNA mitochondrial gene indicate that C. rondoniensis is phylogenetically closest to species of Carios, followed by species of Antricola, and then Ornithodoros. Because the highest bootstrap value linking C. rondoniensis to Carios spp. was 62%, further phylogenetic studies are needed to better evaluate the taxonomic status of the former species.

Prevalence of Rickettsia infection in dogs from the urban and rural areas of Monte Negro municipality, western Amazon, Brazil.

The present study evaluated the rickettsial infection among dogs living in the rural and urban areas of Monte Negro, state of Rondônia, western Brazilian Amazon. Canine sera were tested by the indirect immunofluorescence assay (IFA) using six rickettsial antigens: Rickettsia bellii, Rickettsia amblyommii, Rickettsia rhipicephali, Rickettsia rickettsii, Rickettsia parkeri, and Rickettsia felis. While the first three Rickettsia species are known to occur in the study site, the latter three species are known to occur in southeastern Brazil. For each serum, end point titer reacting with each Rickettsia antigen was determined. Serum showing for a Rickettsia species titer at least fourfold higher than that observed for any other Ricketttsia species was considered homologous to the first Rickettsia species or to a very closely related genotype. A total of 164 rural and 153 urban dogs were tested. Overall, 19 (11.6%) and 6 (3.9%) dogs from rural and urban areas, respectively, reacted positively to at least one Rickettsia species. In the rural area, three sera showed titers to R. parkeri at least four-fold higher than any of the other five antigens. These sera were considered to be homologous to R. parkeri or a very closely related genotype. Using the same criteria, two rural sera were considered homologous to R. amblyommii, two other rural sera to R. rhipicephali, and one urban serum to R. parkeri. Because dogs living in the rural area of Monte Negro are commonly infested by the same tick species infesting humans, they indeed serve as sentinels for human rickettsial diseases. Thus, humans living in Monte Negro are likely to be infected by at least three Rickettsia species: R. parkeri, R. amblyommii, and R. rhipicephali. While R. parkeri is a known human pathogen, further studies are required to verify the potential role of R. amblyommii and R. rhipicephali as human pathogens.

Prevalence of Ehrlichia canis (Rickettsiales: Anaplasmataceae) in dogs and Rhipicephalus sanguineus (Acari: Ixodidae) ticks from Brazil.

The current study evaluated the prevalence of Ehrlichia canis Donatien and Lestoquard in domestic dogs, Canis familiaris L., and Rhipicephalus sanguineus (Latreille) (Acari: Ixodidae) ticks from different areas of Brazil. In Monte Negro County (state of Rondônia, Brazilian western Amazon), the indirect immunofluorescence assay detected E. canis-reactive antibodies (titer > or = 40) in 58/153 (37.9%) and 40/161 (24.8%) dogs from the urban and rural areas, respectively. These values were significantly different between the two areas. Ticks from a household in the urban area of Monte Negro, and from households in three other localities (162-165 adult ticks per household) in the state of São Paulo (SP) were tested by polymerase chain reaction (PCR) targeting an erlichial dsb gene fragment. The prevalence of infected ticks (given as minimal infection rate) was 2.3, 6.2, and 3.7% for populations 1 (Monte Negro), 2 (Jundiaí, SP), and 3 (São Paulo I, SP), respectively, which were statistically similar. In contrast, no infected tick was detected in population 4 (São Paulo II, SP). DNA sequences were determined for some of the PCR products generated from ticks and dogs from populations 1-3, being all identical to each other and to available sequences of E. canis in GenBank. These results reinforce previous records of E. canis-infecting dogs in Brazil. Natural infection of R. sanguineus ticks by E. canis is reported for the first time in Brazil, where this tick is the commonest species infesting dogs.

A preliminary investigation of Ehrlichia species in ticks, humans, dogs, and capybaras from Brazil.

A molecular epidemiologic investigation in two Brazilian states (Rondônia and São Paulo) was undertaken to determine if Ehrlichia species responsible for human and animal ehrlichioses in North America could be found in Brazilian vectors, potential natural mammalian reservoirs and febrile human patients with a tick bite history. Samples, including 376 ticks comprising 9 Amblyomma species, 29 capybara (Hydrochaeris hydrochaeris) spleens, 5 canine blood, and 75 human blood samples from febrile patients with history of tick bites were tested by a real-time PCR assay targeting a fragment of the Ehrlichia dsb gene. Ehrlichia DNA was not detected in any tick, capybara or human samples. In contrast, 4 out of 5 dogs contained Ehrlichia canis DNA in their blood, which were sequenced, representing the first report of E. canis infecting dogs in the Amazon region of Brazil. Further studies are needed to evaluate the presence of other agents of human and animal ehrlichioses in Brazil.

Prevalence of anti-Neospora caninum antibodies in cattle and dogs from Western Amazon, Brazil, in association with some possible risk factors.

For evaluation of the prevalence of anti-Neospora caninum antibodies and its associated risk factors, serum samples from 2109 cattle (11 beef, 50 dairy and 25 mixed farms) and 174 dogs were examined in the State of Rondônia, Western Amazon, Brazil. An inquiry was applied in each farm. Sera were examined by the Indirect Fluorescence Antibody Test (IFAT) using cut off dilution of 1:25 for cattle and 1:50 for dogs. Statistical association between the serologic status and several variables were analyzed by linear and logistic regression. The overall herd prevalence of anti-N. caninum antibodies for 86 farms was 72% (61.3-81.2%). Prevalence values were 100, 70 and 64% in beef, dairy and mixed herds, respectively. Herd prevalence in beef herds was significantly different (P<0.05) from dairy and mixed herds. The overall animal prevalence of N. caninum in cattle was 8.8%. Prevalence values by animal were similar in different production types (P>0.05), with values of 9.5, 11.2 and 9.7% for beef, dairy or mixed cattle, respectively. Antibodies were found in 12.6% of the 174 examined dogs. Sixteen (22.8%) out of 70 farms with dogs had at least one dog with anti-N. caninum antibodies. The occurrence of antibodies in cattle was statistically associated with farms having more than 25 cows (OR 9.7, 95% IC 2.9-32.2; P=0.0002). There was no significant association between the presence of the dogs, jungle contact or reproductive variables with the occurrence of antibodies in cattle.

Amblyomma latepunctatum, a valid tick species (Acari: Ixodidae) long misidentified with both amblyomma incisum and Amblyomma scalpturatum.

In 2000, we initiated an investigation on the tick fauna of Rondônia State, where we collected many specimens of Amblyomma scalpturatum Neumann, 1906 and Amblyomma incisum Neumann, 1906. In addition, we also collected a third group of ticks that were morphologically closely related to those 2 species, but sufficiently different to be considered a distinct species; members of this group were subsequently identified as Amblyomma latepunctatum Tonelli-Rondelli, 1939, through comparison with the type specimens of this taxon. Herein, we redescribe both sexes of A. scalpturatum and A. incisum, the female of A. latepunctatum, and provide the first description of the male of this latter species. Molecular analysis of the second internal transcribed spacer (ITS2) from rDNA of specimens of the 3 species supports morphological results. Examination of both A. scalpturatum and A. incisum deposited in different tick collections revealed that A. latepunctatum appeared relatively frequently in the vials believed to contain specimens of A. incisum or A. scalpturatum. Before this study, A. latepunctatum was considered a synonym of A. scalpturatum. Herein, we provide morphological and molecular evidence to validate the species A. latepunctatum. The South American tapir (Tapirus terrestris) seems to be the primary host for the adult stage of A. latepunctatum, A. scalpturatum, and A. incisum.

Detection of a spotted fever group Rickettsia in the tick Haemaphysalis juxtakochi in Rondonia, Brazil.

The tick genus Haemaphysalis is represented by four species in the New World, of which only the species Haemaphysalis leporispalustris has been associated with Rickettsiae. The present study reports for the first time the presence of a Rickettsia strain in the tick Haemaphysalis juxtakochi. A free-living male of H. juxtakochi, collected in the state of Rondonia, Western Amazon, Brazil, was subjected to DNA extraction and tested by PCR targeting the four rickettsial genes: gltA, 17-kDa, ompA and ompB. The nucleotide sequences obtained from the PCR products were, by BLAST analyses, closest to Rickettsia rhipicephali sharing 99.7% (1147/1150), 98.8% (429/434), 99.0% (486/491) and 99.0% (809/817) identities with the partial sequences of the gltA, 17-kDa, ompA and ompB genes, respectively. Phylogenetic analyses inferred from the four rickettsial genes showed a high-degree of similarity of this H. juxtakochi-Rickettsia with R. rhipicephali. These two agents grouped together in all trees, always with high bootstrap support (75-96%). This study gives molecular evidence for the presence of a Rickettsia species, designated as strain R300, in the tick H. juxtakochi from the Western Amazon area of Brazil. Genetic analyses showed R300 to be closely related to R. rhipicephali.

First report of the male of Amblyomma rotundatum (Acari: Ixodidae) from a field-collected host.

An adult male of the tick Amblyomma rotundatum Koch was collected on a naturally infested lizard, Tropidurus sp. (Squamata: Tropiduridae), at Monte Negro, State of Rondonia, Brazil. The tick's identity was confirmed morphologically and by analysis of the second internal transcribed spacer of the ribosomal DNA. This is the third known male specimen of A. rotundatum, a species that has been shown to reproduce exclusively by parthenogenesis. The two previously reported male specimens seemed to be partially teratological or gynandromorphic, whereas the present specimen shows no visible genetic or developmental anomaly.

Rickettsia bellii and Rickettsia amblyommii in Amblyomma ticks from the State of Rondônia, Western Amazon, Brazil.

This study evaluates the rickettsial presence in Amblyomma ticks from eight areas of the Amazon forest in Rondônia, Brazil. The following tick species (number in parentheses) were examined: Amblyomma ovale Koch (121), Amblyomma cajennense (F.) (41), Amblyomma naponense (Packard) (36), Amblyomma scalpturatum Neumann (35), Amblyomma oblongoguttatum Koch (30), Amblyomma incisum Neumann (27), Amblyomma rotundatum Koch (16), Amblyomma coelebs Neumann (10), and Amblyomma humerale Koch (6). Ticks were examined individually or in pools (2-10 ticks) by polymerase chain reaction (PCR) targeting the gltA gene. The PCR-determined minimal infection rate for each tick species was A. ovale 28%, A. cajennense 27%, A. naponense 0%, A. scalpturatum 11%, A. oblongoguttatum 3%, A. incisum 0%, A. rotundatum 87%, A. coelebs 10%, and A. humerale 50%. Partial sequences of the gltA gene of Rickettsia from A. ovale, A. scalpturatum, A. oblongoguttatum, A. rotundatum, and A. humerale were 99.9% (349/350) identical to Rickettsia bellii. DNA sequences of PCR products from A. cajennense and A. coelebs were 100% (350/350) identical to Rickettsia amblyommii. R. bellii organisms were isolated in Vero cells from A. scalpturatum, A. ovale, A. rotundatum, and A. oblongoguttatum, but only one of the isolates, cultured from A. scalpturatum, was established in continuous cell culture passage. R. amblyommii was isolated from A. cajennense and was successfully established in continuous passage in cell culture. R. amblyommii infection of Vero cells was analyzed by transmission electron microscopy. This study adds South America to the known geographic distribution of R. amblyommii and reports rickettsiae in six Amblyomma species for the first time.

Molecular evidence for a spotted fever group Rickettsia species in the tick Amblyomma longirostre in Brazil.

Two Amblyomma longirostre adult male ticks were collected from a Brazilian porcupine Coendou prehensilis L. in the state of Rondonia, Western Amazon, Brazil. The two ticks were pooled for DNA extraction and tested for the presence of rickettsial DNA by amplifying portions of the gltA, 17-kDa, ompA, and ompB rickettsial genes by polymerase chain reaction (PCR). Portions of the four genes were amplified from the sample and subsequently sequenced. These results indicated the presence of a Rickettsia strain infecting A. longirostre, which was designated as strain Aranha. Compared with homologous ompA rickettsial sequences, "Rickettsia amblyommii" ompA seemed to be the closest relative to Aranha (similarity values: 99.0-99.3%). Phylogenetic analyses of more conserved genes including 17-kDa and gtlA partial sequences indicated that this Rickettsia sp. is a spotted fever group rickettsia. The partial ompB sequence of strain Aranha was distinct from all homologous sequences available in GenBank. Although our ompA analysis suggested a very close molecular phylogenetic relationship of Aranha with "R. amblyommii," we cannot at this time determine if Aranha is a new strain of "R. amblyommii" or a new Rickettsia species in South America.

Notes on parasitism by Amblyomma humerale (Acari: Ixodidae) in the state of Rondônia, western Amazon, Brazil.

The tick Amblyomma humerale Koch is endemic to South America. All host records refer to the adult stage parasitizing tortoises, mostly yellow-footed tortoise, Geochelone denticulata (L.), and red-footed tortoise, Geochelone carbonaria (Spix). The current study reports the presence of A. humerale in the state of Rondônia, Brazil. A total of 215 adult ticks (201 males, 14 females) was collected from six G denticulata in an Indian reserve and nine Geochelone sp. in rural Monte Negro County, giving an overall mean infestation of 14.3 +/- 12.0 (range: 2-44) ticks per tortoise. Male ticks always outnumbered females on the host and nine tortoises had only male ticks. Male ticks were mostly attached in clusters on the ventral sides of the carapace near the anterior and posterior margins, and more rarely on the outer margin of the plastron. All females were found attached to the tortoise skin, at different sites such as head, neck, shoulders or legs. Male ticks were rarely observed attached to the body skin. Seven engorged nymphs collected on small vertebrates from Monte Negro County molted to adults of A. humerale. This included one nymph each on the seven-colored lizard, Plica plica (L), green tree climber, Plica umbra (L.), and wide-foraging lizard, Kentropyx calcarata Spix,three nymphs on the common opossum, Didelphis marsupialis L., and one nymph on the silky anteater, Cyclopes didactylus L. These constitute the first host records for the immature stages of the tick A. humerale.