Nematodes from the Tasmanian devil (Sarcophilus harrisii (Boitard)), with the description of Sarcophiloxyuris longus n. gen. and n. sp. (Oxyuridae).

The Tasmanian devil (Sarcophilus harrisii (Boitard)) is an endangered carnivorous marsupial, limited to the islands of Tasmania in southern Australia. The parasites of the Tasmanian devil are understudied. This study aimed to increase the knowledge of the nematode fauna of Tasmanian devils. Ten Tasmanian devils were examined for parasites from northern and southern Tasmania. Nematodes that were collected were morphologically characterized as two separate species. Molecular sequencing was undertaken to verify the identity of these species. A new genus and species of oxyurid nematode was collected from a single Tasmanian devil from the northern part of Tasmania. The nematode is differentiated from oxyurids described from other Australian amphibians, reptiles and marsupials by the characters of the male posterior end - that is, in having three pairs of caudal papillae, two pairs peri-cloacal, one large pair post-cloacal, a long tapering tail, a stout spicule and a gubernaculum and accessory piece, as well as its much larger overall size. Molecular sequencing was unsuccessful. The remaining nematodes collected from the Tasmanian devil in this study were all identified as Baylisascaris tasmaniensis Sprent, 1970, through morphology and molecular sequencing. This paper presents the first description of a new genus and species of oxyurid nematode from the Tasmanian devil, Sarcophiloxyuris longus n. gen., n. sp. The need to undertake more sampling of the parasites of endangered hosts, such as the Tasmanian devil, to assist with a better understanding of their conservation management, is discussed.

A new species of Wellcomia (Nematoda: Oxyuridae) in the plains viscacha (Rodentia: Chinchillidae) from Argentina, an emended diagnosis and an update of the genus Wellcomia.

Wellcomia species (Oxyuridae, Syphaciinae) parasitise several families of rodents from Africa, Asia and America with diverse ecological characteristics. A new species of Wellcomia is described based on specimens obtained from the plains viscacha Lagostomus maximus (Chinchillidae) from Argentina. The description includes morphometric and ecological aspects and an emended diagnosis of the genus Wellcomia. In addition, a molecular characterisation (18S rRNA) and an exploratory analysis of the genetic distances of the species included in this genus are provided. The new species, Wellcomia hugoti n. sp., differs from other species of the genus in the morphology of the cephalic plate, the ventral rugose area in males and the vulva in females. The new species showed a low prevalence (7.7%) and a high mean abundance (73.8). The genetic distances detected do not allow a comprehensive assessment of the monophyly of the genus. This is the seventh record of this genus in rodents from the Americas, the second in rodents from Argentina and the first record for the family Chinchillidae.

Oxyuricassis ekstromi n. sp. (Oxyurida: Pharyngodonidae) from Lasiancistrus saetiger (Siluriform: Loricariidae) from the Eastern Amazon.

Oxyuricassis ekstromi n. sp. is the third species of the genus described from the intestine of Lasiancistrus saetiger Armbruster in Brazil. This species can be easily differentiated from its congeners by the presence of a tooth-like sclerotized piece that occupies half of the stoma and absence of spine projections on the tail of both males and females. Also, males of the new species lack caudal alae present in Oxyuricassis coronatus and Oxyuricassis hexaspinatus. Additionally, we observed a different number and pattern of the distribution of cloacal papilla; males of O. coronatus and O. hexaspinatus have 1 pair of pre-cloacal and 2 pairs of post-cloacal papillae; while the new species has 1 pre-cloacal and 3 post-cloacal pairs of papillae.

Ecto- and endoparasites of the King's skink (Egernia kingii) on Penguin Island.

Wildlife species are often host to a diversity of parasites, but our knowledge of their diversity and ecology is extremely limited, especially for reptiles. Little is known about the host-parasite ecology of the Australian lizard, the King's skink (Egernia kingii). In spring of 2015, we carried out a field-based study of a population of King's skinks on Penguin Island (Western Australia). We documented five species of parasites, including two ectoparasitic mites (an undescribed laelapid mite and Mesolaelaps australiensis), an undescribed coccidia species, and two nematode species (Pharyngodon tiliquae and Capillaria sp.). The laelapid mite was the most abundant parasite, infesting 46.9% of the 113 captured lizards. This mite species increased in prevalence and abundance over the course of the study. Infection patterns of both mites varied with lizard life-stage; sub-adults were more commonly infested with laelapid mites than adults or juveniles, and sub-adults and adults were infested by more laelapid mites than juveniles. By contrast, adults had a higher prevalence of M. australiensis than juveniles or sub-adults. Among the gastrointestinal parasites, P. tiliquae was relatively common among the sampled lizards (35.3%). These results give new important information about reptiles as parasite hosts and what factors influence infection patterns.

Oxyurid nematodes of pet rodents in Slovakia - a neglected zoonotic threat / Nematódeos oxiurídeos de roedores de estimação na Eslováquia - uma ameaça zoonótica negligenciada

Abstract The role of rodents as reservoirs of helminths of public health importance is not well known. The zoonotic potential of Syphacia spp. has been confirmed; therefore, the study aimed to estimate the occurrence of oxyurid nematodes in small rodents from pet shops and breeding clubs in Slovakia. Fecal samples of 586 pet rodents kept in 133 cages were collected between 2016 and 2018 and examined by Faust´s flotation method. Four species of oxyurid nematodes, Syphacia muris, S. obvelata, Aspiculuris tetraptera and Paraspidodera uncinata were detected. A. tetraptera was found in the faecal samples of all rodent species included in this survey. The number of positive boxes varied from 5.4% in hamsters to 70.0% with mice. The prevalence of Syphacia muris was highest in Mongolian gerbils where up to 75.0% boxes were positive; S. obvelata was found in 26.7% of boxes with mice, 25.0% of boxes with Mongolian gerbils and 3.2% of boxes with rats. The high prevalence of Syphacia spp. in all animal species points out the infection risk for humans. Animals offered for sale are often in close contact with human beings; therefore they should be regularly tested for parasites and then effectively dewormed.

Resumo O papel dos roedores como reservatórios de helmintos de importância para a saúde pública não é bem conhecido. O potencial zoonótico de Syphacia spp. foi confirmado; portanto, o estudo teve como objetivo estimar a ocorrência de nematóides oxiurídeos em pequenos roedores de pet shops e clubes de reprodução na Eslováquia. Amostras fecais de 586 roedores mantidos em 133 gaiolas foram coletadas entre 2016 e 2018 e examinadas pelo método de flotação de Faust. Foram detectadas quatro espécies de nematódeos oxiurídeos, Syphacia muris, S. obvelata, Aspiculuris tetraptera e Paraspidodera uncinata, A. tetraptera foi encontrado nas amostras fecais de todas as espécies de roedores incluídas nesta pesquisa. O número de gaiolas positivas variou de 5,4% em hamsters a 70,0% em camundongos. A prevalência de Syphacia muris foi maior nos gerbilos da Mongólia, onde até 75,0% das gaiolas foram positivas; S. obvelata foi encontrada em 26,7% das gaiolas com camundongos, 25,0% das gaiolas com gerbilos da Mongólia e 3,2% das gaiolas com ratos. A alta prevalência de Syphacia spp. em todas as espécies animais aponta o risco de infecção para os seres humanos. Animais oferecidos para venda estão frequentemente em contato próximo com seres humanos; portanto, eles devem ser regularmente testados quanto a parasitas e, então, efetivamente desparasitados.

Oxyurid nematodes of pet rodents in Slovakia - a neglected zoonotic threat.

The role of rodents as reservoirs of helminths of public health importance is not well known. The zoonotic potential of Syphacia spp. has been confirmed; therefore, the study aimed to estimate the occurrence of oxyurid nematodes in small rodents from pet shops and breeding clubs in Slovakia. Fecal samples of 586 pet rodents kept in 133 cages were collected between 2016 and 2018 and examined by Faust´s flotation method. Four species of oxyurid nematodes, Syphacia muris, S. obvelata, Aspiculuris tetraptera and Paraspidodera uncinata were detected. A. tetraptera was found in the faecal samples of all rodent species included in this survey. The number of positive boxes varied from 5.4% in hamsters to 70.0% with mice. The prevalence of Syphacia muris was highest in Mongolian gerbils where up to 75.0% boxes were positive; S. obvelata was found in 26.7% of boxes with mice, 25.0% of boxes with Mongolian gerbils and 3.2% of boxes with rats. The high prevalence of Syphacia spp. in all animal species points out the infection risk for humans. Animals offered for sale are often in close contact with human beings; therefore they should be regularly tested for parasites and then effectively dewormed.

Unveiling patterns of genetic variation in parasite-host associations: an example with pinworms and Neotropical primates.

Patterns of genetic variation among populations can reveal the evolutionary history of species. Pinworm parasites are highly host specific and form strong co-evolutionary associations with their primate hosts. Here, we describe the genetic variation observed in four Trypanoxyuris species infecting different howler and spider monkey subspecies in Central America to determine if historical dispersal processes and speciation in the host could explain the genetic patterns observed in the parasites. Mitochondrial (cox1) and ribosomal (28S) DNA were analysed to assess genetic divergence and phylogenetic history of these parasites. Sequences of the 28S gene were identical within pinworms species regardless of host subspecies. However, phylogenetic analyses, haplotype relationships and genetic divergence with cox1 showed differentiation between pinworm populations according to host subspecies in three of the four Trypanoxyuris species analysed. Haplotype separation between host subspecies was not observed in Trypanoxyuris minutus, nor in Trypanoxyuris atelis from Ateles geoffoyi vellerosus and Ateles geoffoyi yucatanensis. Levels of genetic diversity and divergence in these parasites relate with such estimates reported for their hosts. This study shows how genetic patterns uncovered in parasitic organisms can reflect the host phylogenetic and biogeographic histories.

A new species of Parapharyngodon Chatterji, 1933 (Oxyuroidea: Pharyngodonidae), parasitic in Osteocephalus taurinus (Anura: Hylidae) from Brazil.

Parapharyngodon politoedi n. sp. is described here, based on specimens found in the large intestines of Osteocephalus taurinus from the Caxiuanã National Forest, State of Pará, Brazil. The new species is assigned to Parapharyngodon based on the presence of non-embryonated eggs with sub-terminal opercula, when in the ovijector. Parapharyngodon politoedi belongs to a group of species with three pairs of cloacal papillae and differs from its congeners by morphometric aspects, such as the length of the spicule, and the combination of the following morphological characters: ovaries never encircling the oesophagus, tail shape in females, cloacal lips, sharply pointed spicule and presence of genital cone. This is the second species of nematode reported to parasitize O. taurinus and the eleventh species of Parapharyngodon from hylids in the Neotropical region.

Survey of intestinal helminths collected from pet rodents in México.

In this survey, intestinal helminths from pet rodents in Mérida, México, were analyzed. A total of 46 mice Mus musculus, 28 hamsters Mesocricetus auratus, 23 rats Rattus norvegicus, and 1 gerbil Meriones unguiculatus were purchased from six pet shops and one black market for wildlife in the city of Mérida. The overall prevalence of helminths in rodents was 61.2% (60/98). Six species of helminths were identified: the zoonotic cestode Rodentolepis nana, and the nematodes Aspiculuris tetraptera, Dentostomella translucida, Syphacia obvelata, Syphacia mesocriceti, and Syphacia muris. Of the 60 infected rodents, 25 (41.7%) harbored 2 or 3 species of helminths. Rodentolepis nana was found in 4.3% of mice and 17.9% of hamsters. This is the first report of infection with S. muris in pet rats. Considering the close physical contact between pet rodents and humans, the presence of R. nana in pets represents a potential risk of transmission, especially to children and immunocompromised individuals.

Lack of genetic structure in pinworm populations from New World primates in forest fragments.

Microevolutionary processes in parasites are driven by factors related to parasite biology, host abundance and dispersal, and environmental conditions. Here, we test the prediction that isolation of host populations results in reduced genetic diversity and high differentiation among parasite populations. We conducted a population genetic analysis of two pinworms, Trypanoxyuris minutus and Trypanoxyuris atelis, commonly found parasitizing howler and spider monkeys in tropical rainforests across south-eastern Mexico, whose populations are currently isolated due to anthropogenic habitat loss and fragmentation. Mitochondrial DNA was employed to assess parasite genetic patterns, as well as to analyse their demography and population history. Both pinworm species showed high haplotype diversity but, unexpectedly, lower nucleotide diversity than that reported for other parasites. No genetic differentiation or population structure was detected in either pinworm species despite habitat loss, fragmentation and host isolation. Several scenarios are discussed that could help to explain the genetic panmixia found in both pinworm species, including higher than expected primate inter-fragment dispersal movements, and passive dispersal facilitating gene flow between parasite populations. The results suggest that large population sizes of parasites could be helping them to cope with the isolation and fragmentation of populations, delaying the effects of genetic drift. The present study highlights the complexity of the drivers that intervene in the evolutionary processes of parasites. Detailed genetic studies are needed, both in host and parasite populations, to assess the effects that habitat perturbation and environmental changes could have on the evolutionary dynamics of pinworms and primates.

Evaluation of Anthelmintic Resistance and Exhaust Air Dust PCR as a Diagnostic Tool in Mice Enzootically Infected with Aspiculuris tetraptera.

The entry of infectious agents in rodent colonies occurs despite robust sentinel monitoring programs, strict quarantine measures, and stringent biosecurity practices. In light of several outbreaks with Aspiculuris tetraptera in our facilities, we investigated the presence of anthelmintic resistance and the use of exhaust air dust (EAD) PCR for early detection of A. tetraptera infection. To determine anthelmintic resistance, C57BL/6, DBA/2, and NCr nude mice were experimentally inoculated with embryonated A. tetraptera ova harvested from enzootically infected mice, followed by treatment with 150 ppm fenbendazole in feed, 150 ppm fenbendazole plus 5 ppm piperazine in feed, or 2.1 mg/mL piperazine in water for 4 or 8 wk. Regardless of the mouse strain or treatment, no A. tetraptera were recovered at necropsy, indicating the lack of resistance in the worms to anthelmintic treatment. In addition, 10 of 12 DBA/2 positive-control mice cleared the A. tetraptera infection without treatment. To evaluate the feasibility of EAD PCR for A. tetraptera, 69 cages of breeder mice enzootically infected with A. tetraptera were housed on a Tecniplast IVC rack as a field study. On day 0, 56% to 58% of the cages on this rack tested positive for A. tetraptera by PCR and fecal centrifugation flotation (FCF). PCR from EAD swabs became positive for A. tetraptera DNA within 1 wk of placing the above cages on the rack. When these mice were treated with 150 ppm fenbendazole in feed, EAD PCR reverted to pinworm-negative after 1 mo of treatment and remained negative for an additional 8 wk. The ability of EAD PCR to detect few A. tetraptera positive mice was investigated by housing only 6 infected mice on another IVC rack as a field study. The EAD PCR from this rack was positive for A. tetraptera DNA within 1 wk of placing the positive mice on it. These findings demonstrate that fenbendazole is still an effective anthelmintic and that EAD PCR is a rapid, noninvasive assay that may be a useful diagnostic tool for antemortem detection of A. tetraptera infection, in conjunction with fecal PCR and FCF.

Oxyuricassis coronatus n. gen. n. sp. and O. hexaspinatus n. sp. (Oxyurida: Pharyngodonidae): Parasites of Lasiancistrus saetiger (Siluriformes: Loricariidae) in Freshwater Rivers of the Brazilian Amazon.

A new nematode genus is described from intestines of Lasiancistrus saetiger Ambruster from freshwater rivers in the Brazilian Amazon. Oxyuricassis n. gen. is characterized by a cephalic cone, small buccal cavity, long esophagus with a well-developed isthmus, and a conical tail with spines. Two new species are described: Oxyuricassis coronatus n. sp. is characterized by the absence of lateral alae, a conical tail with truncated extremity with spine-like sclerotized projections around the tail tip, and caudal alae in males expanded. Oxyuricassis hexaspinatus n. sp. is characterized by lateral alae, a conical tail with tapered extremity, with 2 pairs of proximal spines at the posterior extremity of the tail, 1 dorsal pair and 1 ventral pair, plus a pair of lateral spines that vary in position between sexes, and male of O. hexaspinatus has narrow caudal alae. Both species were found co-parasitizing all of the analyzed host specimens.

The Missing Fellow: First Description of the Trypanoxyuris pigrae Male (Nematoda: Oxyuridae), a Parasite of the Black Howler Monkey (Alouatta pigra) in Mexico.

The first morphological description of the male of Trypanoxyuris pigrae Solórzano-García, Nadler, and Pérez-Ponce de León, 2016 , is presented in this study. Morphological data are supported by molecular data. Specimens of T. pigrae were recovered after the necropsy of a roadkill black howler monkey (Alouatta pigra) in southeastern Mexico. Males of T. pigrae are characterized by having 3 notched lips and a long esophagus with a posterior bulb; they also show a single crested lateral alae, a single spicule, and 4 caudal papillae. Morphological features coincide with those of the previously described T. pigrae females, and molecular profiles confirmed species identification. Males of T. pigrae are very similar to those of Trypanoxyuris minutus, another species of pinworm that also parasitizes the black howler monkey, A. pigra; however, the shape of the lips represents a very reliable diagnostic feature. Because of this, detailed en face observations are recommended to discriminate between these pinworm species.

The diversity and evolution of nematodes (Pharyngodonidae) infecting New Zealand lizards.

Host-parasite co-evolutionary studies can shed light on diversity and the processes that shape it. Molecular methods have proven to be an indispensable tool in this task, often uncovering unseen diversity. This study used two nuclear markers (18S rRNA and 28S rRNA) and one mitochondrial (cytochrome oxidase subunit I) marker to investigate the diversity of nematodes of the family Pharyngodonidae parasitizing New Zealand (NZ) lizards (lygosomine skinks and diplodactylid geckos) and to explore their co-evolutionary history. A Bayesian approach was used to infer phylogenetic relationships of the parasitic nematodes. Analyses revealed that nematodes parasitizing skinks, currently classified as Skrjabinodon, are more closely related to Spauligodon than to Skrjabinodon infecting NZ geckos. Genetic analyses also uncovered previously undetected diversity within NZ gecko nematodes and provided evidence for several provisionally cryptic species. We also examined the level of host-parasite phylogenetic congruence using a global-fit approach. Significant congruence was detected between gecko-Skrjabinodon phylogenies, but our results indicated that strict co-speciation is not the main co-evolutionary process shaping the associations between NZ skinks and geckos and their parasitic nematodes. However, further sampling is required to fully resolve co-phylogenetic patterns of diversification in this host-parasite system.

Parasites and invasions: changes in gastrointestinal helminth assemblages in invasive and native rodents in Senegal.

Understanding why some exotic species become widespread and abundant in their colonised range is a fundamental issue that still needs to be addressed. Among many hypotheses, newly established host populations may benefit from a parasite loss ("enemy release" hypothesis) through impoverishment of their original parasite communities or reduced infection levels. Moreover, the fitness of competing native hosts may be negatively affected by the acquisition of exotic taxa from invaders ("parasite spillover") and/or by an increased transmission risk of native parasites due to their amplification by invaders ("parasite spillback"). We focused on gastrointestinal helminth communities to determine whether these predictions could explain the ongoing invasion success of the commensal house mouse (Mus musculus domesticus) and black rat (Rattus rattus), as well as the associated decrease in native Mastomys spp., in Senegal. For both invasive species, our results were consistent with the predictions of the enemy release hypothesis. A decrease in overall gastrointestinal helminth prevalence and infracommunity species richness was observed along the invasion gradients as well as lower specific prevalence/abundance (Aspiculuris tetraptera in Mus musculus domesticus, Hymenolepis diminuta in Rattus rattus) on the invasion fronts. Conversely, we did not find strong evidence of GIH spillover or spillback in invasion fronts, where native and invasive rodents co-occurred. Further experimental research is needed to determine whether and how the loss of gastrointestinal helminths and reduced infection levels along invasion routes may result in any advantageous effects on invader fitness and competitive advantage.

The use of epifluorescence microscopy and fluorescent dyes for visualization of Oxyuris equi eggs.

This study presents a new method for visualization of Oxyuris equi eggs collected by means of a clear adhesive tape applied to the perianal region of horses. The obtained results indicate that this protocol permits a quick, easy, clear and selective visualization of Oxyuris equi eggs even in the presence of feces and other material. Another advantage of this method is that it can be used with fluorescent dyes solubilized in water, which will stain biologic material without dissolving or altering the adhesive tape and is also environmentally safe. Other dyes currently used for staining biologic materials use organic solvents, which may be combined with acids or bases in their formulation, preventing their use with the tape method.

New species of Parapharyngodon (Nematoda: Pharyngodonidae) in Phymaturus spp. (Iguania: Liolaemidae) from Argentina.

Parapharyngodon sanjuanensis sp. nov. (Nematoda: Pharyngodonidae) from the large intestines of Phymaturus punae and Phymaturus williamsi (Squamata: Liolaemidae) from province of San Juan, Argentina, is described and illustrated. Parapharyngodon sanjuanensis sp. nov. is the 54th species assigned to the genus and the 8th from the Neotropical region. It differs from other species in the genus in that males possess 8 caudal papillae, 6 of which are large and pedunculate, 2 are small, almost inconspicuous; anterior lip echinate, posterior lip bilobate; females possess prominent vulva and short stiff tail spike.

Syphacia obvelata (Nematode, Oxyuridae) infecting laboratory mice Mus musculus (Rodentia, Muridae): phylogeny and host-parasite relationship.

Syphacia obvelata is a pinworm nematode parasite infecting man and laboratory animals in high abundance. This parasitological study was carried out during the period of March 2014-February 2015 to investigate the helminth parasites infecting the laboratory mice Mus musculus in the Animal House at Cairo University, Egypt. The prevalence of S. obvelata in M. musculus was 75.0 %. The extent of infection with S. obvelata is analyzed according to the sex of the host mice. It was shown that the prevalence of male infection was greater than female worms. Morphological characterization revealed that the present Oxyurid species possesses a rounded cephalic end with less developed lips, esophagus divided into cylindrical corpus, and globular bulb supported internally with valvular apparatus; three mamelons are located at the ventral surface with a single chitinized spicule and a gubernaculum provided with an accessory hook in males, and ovijector apparatus opens ventrally by the vulva surrounded by protruded lips in female worms. Body of the male was 0.623-1.130 (0.830 ± 0.11) mm long and 0.092-0.130 (0.110 ± 0.01) mm wide; the esophagus was 0.164-0.280 (0.210 ± 0.01) mm long; the nerve ring and excretory pore are located at 0.035-0.132 (0.073 ± 0.01) and 0.087-0.191 (0.145 ± 0.01) mm from the anterior end, respectively, while the female measured 2.930-4.650 (3.540 ± 0.1) mm long and 0.120-0.232 (0.156 ± 0.001) mm wide; the esophagus was 0.213-0.410 (0.342 ± 0.01) mm long; the nerve ring, excretory pore, and vulval opening are located at 0.026-0.157 (0.121 ± 0.01), 0.134-0.243 (0.195 ± 0.01), and 0.323-0.632 (0.546 ± 0.11) mm from the anterior end, respectively; eggs measured 0.120-0.139 (0.129 ± 0.001) mm long and 0.030-0.052 (0.045 ± 0.001) mm wide. It compared morphometrically with other Syphacia species described previously and showed little differences in measurements. Molecular characterization based on small subunit ribosomal DNA (rDNA) was done to confirm the obtained morphological and morphometric results. A preliminary genetic comparison between SSU rDNA of the present parasite and other species of Oxyuridae places it as a putative sister taxon to other S. obvelata.

Morphology of the oxyurid nematodes Trypanoxyuris (T.) cacajao n. sp. and T. (T.) ucayalii n. sp. from the red uakari monkey Cacajao calvus ucayalii in the Peruvian Amazon.

Cacajao calvus ucayalii (Thomas, 1928) (Primates: Pitheciidae), a subspecies endemic to the Peruvian Amazon, occurs in patchy and sometimes isolated populations in north-eastern Peru and is in a vulnerable situation, mainly due to habitat loss and hunting. This rareness and remote distribution means that, until now, parasitical studies have been limited. Based on optical and scanning electron microscopy of specimens of both sexes, we report two new species of Trypanoxyuris pinworms occurring in the large intestine of the Peruvian red uakari, namely Trypanoxyuris (Trypanoxyuris) cacajao and Trypanoxyuris (Trypanoxyuris) ucayalii. Both species showed a distinct morphology of the lips and cephalic structure. Sexual dimorphism in the lateral alae was observed in both male and the female worms, with ventral ornamentation being shown in the oesophageal teeth. The finding of these new pinworm species highlights the possibility of discovering other species.

The complete mitochondrial genome of rabbit pinworm Passalurus ambiguus: genome characterization and phylogenetic analysis.

Passalurus ambiguus (Nematda: Oxyuridae) is a common pinworm which parasitizes in the caecum and colon of rabbits. Despite its significance as a pathogen, the epidemiology, genetics, systematics, and biology of this pinworm remain poorly understood. In the present study, we sequenced the complete mitochondrial (mt) genome of P. ambiguus. The circular mt genome is 14,023 bp in size and encodes of 36 genes, including 12 protein-coding, two ribosomal RNA, and 22 transfer RNA genes. The mt gene order of P. ambiguus is the same as that of Wellcomia siamensis, but distinct from that of Enterobius vermicularis. Phylogenetic analyses based on concatenated amino acid sequences of 12 protein-coding genes by Bayesian inference (BI) showed that P. ambiguus was more closely related to W. siamensis than to E. vermicularis. This mt genome provides novel genetic markers for studying the molecular epidemiology, population genetics, systematics of pinworm of animals and humans, and should have implications for the diagnosis, prevention, and control of passaluriasis in rabbits and other animals.