Origin, evolution, phylogeny and taxonomy of Pulex irritans

Molecular Identification, Multigenic Characterization and Phylogenetic Analysis of Ctenocephalides Canis Fleas from Humans and Domestic Animals in Iran

BACKGROUND

Fleas belonging to the Pulicidae are prevalent ectoparasites infesting mammals and birds in Iran. This study focused on genetically identifying and characterizing Ctenocephalides canis collected both off-host and infesting humans and various domestic animals in the country.

METHODS

A total of 918 adult flea samples were collected from 10 sites in western and northwestern Iran between April 2018 and May 2019. Out of these, 71 specimens were found off-host, while the remaining fleas were collected from humans (121), sheep (126), goats (184), and dogs (416). Morphological identification at the genus level was performed on all fleas, and ten selected specimens selected based on the sampling sites and hosts were subjected to molecular detection at the species level by using partial amplification and sequencing of the internal transcribed spacer 1 and 2, as well as the cytochrome oxidase I (COXI) markers.

RESULTS

The morphological identification confirmed all fleas as Ctenocephalides spp. Alignment and phylogenetic analysis of nuclear and mitochondrial partial sequences confirmed the presence of C. canis. However, molecular divergence was observed among the ten isolates based on the ITS1 and ITS2 with diversity rates estimated at 0.15% and 3.36%, respectively. Notably, the analysis of the COXI marker revealed no molecular divergence among the partial sequences representing the ten studied isolates from C. canis.

CONCLUSIONS

This study explores the diversity of C. canis in the western and northwestern regions of Iran, providing insights into their molecular taxonomy and potential role as disease vectors in these areas.

Flea infestation of rodent and their community structure in frequent and non-frequent plague outbreak areas in Mbulu district, northern Tanzania

Understanding rodent-ectoparasite interactions and the factors driving them is important in understanding the epidemiology of diseases involving an arthropod vector. Fleas are the primary vector for Yersinia pestis, the bacteria that causes plague and monitoring of flea population is essential for planning the potential mitigation measures to prevent the disease outbreak. In this study, we investigated flea abundance, community structure and the potential factors driving flea infestation in areas with frequent (persistent) and non-frequent plague (non-persistent) outbreaks. We collected fleas from captured rodents in two villages with both forest and farm habitats. We found 352 fleas belonging to 5 species with Dinopsyllus lypusus the most abundant overall (57.10%) and Ctenophthalmus spp. the lowest (1.70%). There were no significant differences of flea abundance between study localities, habitats and seasons (p > 0.05) but, flea infestation was significantly positively associated with the persistent locality and with the short rain season (p < 0.05). Further, flea abundance increased significantly with rodent body weight (p < 0.05). Furthermore, we found fleas broadly structured into two communities varying between the dry, long rain and short rain seasons. These findings have important implications for public health, as they may be used to assess and control the risks of plague transmission and other flea borne diseases in the foci.

Detection of Rickettsia raoultii in Vermipsylla alakurt-Like Fleas of Sheep in Northwestern China

INTRODUCTION

To date, a total of 2574 validated flea species have been discovered. Vermipsyllidae is a family of fleas that comprises at least eight species. Vermipsylla is a genus of the family Vermipsyllidae within the order Siphonaptera of fleas. Here a novel Vermipsylla species was described, and rickettsial agent was also detected in it.

METHODS

A total of 128 fleas were collected directly from 260 pastured sheep in China. Of these, eight representative fleas (four males and four females) were identified by key morphological features. Meanwhile, 120 flea DNAs, including six flea samples for molecular taxonomy, were subjected to Rickettsia spp. DNA detection. The molecular identity of fleas was determined by amplification and sequenmce analysis of four genetic markers (the 28S rDNA genes, the 18S rDNA genes, the mitochondrial cytochrome c oxidase subunit I and subunit II). In addition, five Rickettsia-specific gene fragments were used to identify the species of the rickettsial agents. The amplified products were sequenced and phylogenetically analyzed.

RESULTS

The morphological characteristics of the flea species identified in this study were similar to Vermipsylla alakurt, but presented difference in hair number of the metepimeron, the third tergum, the genitals and the tibiae of hind leg. The 18S rDNA, 28S rDNA and COII genetic markers from fleas showed the highest identity to those of V. alakurt, shared 98.45% (954/969), 95.81% (892/931) and 85.86% (571/665) similarities, respectively. However, the COI sequence showed the highest identity to that of Dorcadia ioffi with 88.48% (576/651) similarity. Rickettsia raoutii tested positive in 14.17% (17/120) flea DNA samples.

CONCLUSION

Our study reports the detection of R. raoultii in V. alakurt-like fleas infesting sheep in China.

Complete mitochondrial genome of Ctenophthalmus quadratus and Stenischia humilis in China provides insights into fleas phylogeny

Fleas (Order Siphonaptera) are common blood-feeding ectoparasites, which have important economic significance. Limited mitochondrial genome information has impeded the study of flea biology, population genetics and phylogenetics. The Ctenophthalmus quadratus and Stenischia humilis complete mt genomes are described in this study. The samples were collected from Jianchuan, Yunnan plague foci, China. The mt genomes of C. quadratus and S. humilis were 15,938 bp and 15,617 bp, respectively. The gene arrangement of mt genome was consistent with that of other fleas, which include 22 tRNA genes, 13 protein-coding genes, and two rRNA genes, with a total of 37 genes. The relationship between C. quadratus and S. humilis in fleas was inferred by phylogenetic analysis of mt genome sequence datasets. Phylogenetic analyzes showed that the C. quadratus and S. humilis belonged to different species in the same family, and were closely related to Hystrichopsylla weida qinlingensis in the same family; and revealed that the family Hystrichopsyllidae is paraphyletic, supporting the monophyly of the order Siphonaptera. This study decodes the complete mt genomes of the C. quadratus and S. humilis for the first time. The results demonstrate that the C. quadratus and S. humilis are distinct species, and fleas are monophyletic. Analysis of mt genome provides novel molecular data for further studying the phylogeny and evolution of fleas.

Complete mitogenomes characterization and phylogenetic analyses of Ceratophyllus anisus and Leptopsylla segnis

Fleas are one of the most common ectoparasites in warm-blooded mammals and an important vector of zoonotic diseases with serious medical implications. We sequenced the complete mitochondrial genomes of Ceratophyllus anisus and Leptopsylla segnis for the first time using high-throughput sequencing and constructed phylogenetic relationships. We obtained double-stranded circular molecules of lengths 15,875 and 15,785 bp, respectively, consisting of 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNAs, and two control regions. AT-skew was negative in both C. anisus (-0.022) and L. segnis (-0.231), while GC-skew was positive in both (0.024/0.248), which produced significant differences in codon usage and amino acid composition. Thirteen PCGs encoding 3,617 and 3,711 codons, respectively, isoleucine and phenylalanine were used most frequently. The tRNA genes all form a typical secondary structure. Construction of phylogenetic trees based on Bayesian inference (BI) and maximum likelihood (ML) methods for PCGs. The results of this study provide new information for the mitochondrial genome database of fleas and support further taxonomic studies and population genetics of fleas.

New Insights into the Taxonomy of Malacopsylloidea Superfamily (Siphonaptera) Based on Morphological, Molecular and Phylogenetic Characterization of Phthiropsylla agenoris (Malacopsyllidae) and Polygenis (Polygenis) rimatus (Rhopalopsyllidae)

From a phylogenetic point of view, the Malacopsyllidae family and the Rhopalopsillidae family (comprising Parapsyllinae and Rhopalopsyllinae subfamilies) have been traditionally classified within the Malacopsylloidea superfamily, mostly restricted to South America. The phylogenetic relationships and taxonomic status of Malacopsyllidae and Rhopalopsillidae have never been assessed since no molecular loci of Malacopsyllidae have been sequenced by any authors, and the phylogeny provided so far was not based on any sort of formal quantitative analysis of flea morphology. Based on these precedents, the objective of this study was to carry out a comparative phylogenetic, molecular and morphological study of two different species belonging to each family, Phthiropsylla agenoris (Malacopsylla) and Polygenis (Polygenis) rimatus (Rhopalopsyllidae, Rhopalopsyllinae). In this study, we demonstrated the usefulness of several morphological features as diagnostic characters to differentiate between P. (P.) rimatus and P. agenoris. Using molecular and phylogenetic data, we easily discriminated between the two taxa (P. agenoris and P. (P.) rimatus) by comparing both nuclear and mitochondrial markers. This fact proves the usefulness of ITS2, EF1−α, cox1, cytb and cox2 as molecular diagnostic markers to characterize and identify different Siphonaptera taxa. Additionally, the phylogenetic results confirm, for the first time, the monophyly of the Malacopsyllidae family and suggest a clear paraphyletic position of the Paraspsyllinae subfamily and, consequently, the Rhopalopsyllidae family.

Morphometrics as a Complementary Tool in the Differentiation of Two Cosmopolitan Flea Species: Ctenocephalides felis and Ctenocephalides canis

Fleas (Siphonaptera) are one of the most important ectoparasites that represent a potential danger for the transmission of pathogens in our environment. The cat flea, Ctenocephalides felis (Bouché, 1835), and the dog flea, Ctenocephalides canis (Curtis, 1826) are among the most prevalent and most frequently studied species throughout the world. However, the variations observed in their morphological characteristics complicate their correct identification, especially when there is a lack of access to the equipment and funds required to carry out molecular biology techniques. With the objective to provide an additional tool to help in the differentiation of Ctenocephalides species, a principal component analysis was carried out for the first time in the present work on populations of C. felis and C. canis from countries in three continents, namely Spain (Europe), South Africa (Africa) and Iran (Asia). The factor maps assisted in the differentiation of both species and the detection of differences in overall size, although morphological ambiguity prevented the delimitation in populations of the same species. Thus, morphometrics represents a complementary tool to other traditional and modern techniques, with great potential to assist in the differentiation of fleas, particularly species that have historically been difficult to identify.

Population genetics and genetic variation of Ctenocephalides felis and Pulex irritans in China by analysis of nuclear and mitochondrial genes

Background

Fleas are the most economically significant blood-feeding ectoparasites worldwide. Ctenocephalides felis and Pulex irritans can parasitize various animals closely related to humans and are of high veterinary significance.

Methods

In this study, 82 samples were collected from 7 provinces of China. Through studying the nuclear genes ITS1 and EF-1α and two different mitochondrial genes cox1 and cox2, the population genetics and genetic variation of C. felis and P. irritans in China were further investigated.

Results

The intraspecies differences between C. felis and P. irritans ranged from 0 to 3.9%. The interspecific variance in the EF-1α, cox1, and cox2 sequences was 8.2–18.3%, while the ITS1 sequence was 50.1–52.2%. High genetic diversity was observed in both C. felis and P. irritans, and the nucleotide diversity of cox1 was higher than that of cox2. Moderate gene flow was detected in the C. felis and P. irritans populations. Both species possessed many haplotypes, but the haplotype distribution was uneven. Fu's Fs and Tajima's D tests showed that C. felis and P. irritans experienced a bottleneck effect in Guangxi Zhuang Autonomous Region and Henan province. Evolutionary analysis suggested that C. felis may have two geographical lineages in China, while no multiple lineages of P.irritans were found.

Conclusions

Using sequence comparison and the construction of phylogenetic trees, we found a moderate amount of gene flow in the C. felis and P. irritans populations. Both species possessed many haplotypes, but the distribution of haplotypes varied among the provinces. Fu’s Fs and Tajima’s D tests indicated that both species had experienced a bottleneck effect in Guangxi and Henan provinces. Evolutionary analysis suggested that C. felis may have two geographical lineages in China, while no multiple lineages of P.irritans were found. This study will help better understand fleas' population genetics and evolutionary biology.

Graphical Abstract

Mitochondrial phylogenomics provides insights into the taxonomy and phylogeny of fleas

Background

Fleas (Insecta: Siphonaptera) are obligatory hematophagous ectoparasites of humans and animals and serve as vectors of many disease-causing agents. Despite past and current research efforts on fleas due to their medical and veterinary importance, correct identification and robust phylogenetic analysis of these ectoparasites have often proved challenging.

Methods

We decoded the complete mitochondrial (mt) genome of the human flea Pulex irritans and nearly complete mt genome of the dog flea Ctenocephalides canis, and subsequently used this information to reconstruct the phylogeny of fleas among Endopterygota insects.

Results

The complete mt genome of P. irritans was 20,337 bp, whereas the clearly sequenced coding region of the C. canis mt genome was 15,609 bp. Both mt genomes were found to contain 37 genes, including 13 protein-coding genes, 22 transfer RNA genes and two ribosomal RNA genes. The coding region of the C. canis mt genome was only 93.5% identical to that of the cat flea C. felis, unequivocally confirming that they are distinct species. Our phylogenomic analyses of the mt genomes showed a sister relationship between the order Siphonaptera and orders Diptera + Mecoptera + Megaloptera + Neuroptera and positively support the hypothesis that the fleas in the order Siphonaptera are monophyletic.

Conclusions

Our results demonstrate that the mt genomes of P. irritans and C. canis are different. The phylogenetic tree shows that fleas are monophyletic and strongly support an order-level objective. These mt genomes provide novel molecular markers for studying the taxonomy and phylogeny of fleas in the future.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05334-3.

Genetic Evidence of an Isolation Barrier between Flea Subspecies of Citellophilus tesquorum (Wagner, 1898) (Siphonaptera: Ceratophyllidae)

Simple Summary

We studied field collections of two flea subspecies that are plague vectors on the vast Palearctic territory. Analysing the molecular–genetic, geographical, morphological, and reproductive isolation criteria, we conclude that these subspecies could be considered different species.

Abstract

This study investigated the relationship between two subspecies of the Citellophilus tesquorum flea, C. t. altaicus and C. t. sungaris, which are vectors of the bacterium Yersinia pestis that causes human plague across the vast territories of the Palearctic. Adult fleas were collected from 16 localities and 11 populations in 2019 and 2020. Specimens were morphologically verified for subspecies status and analysed for mitochondrial cytochrome c oxidase subunit I (COI) DNA, nuclear ribosomal cluster internal transcribed spacer 1 (ITS1) and ITS2, and Wolbachia-infection status. Our results demonstrated a genetic difference between C. t. altaicus and C. t. sungaris. According to mitochondrial data, the genetic distance between clades of C. t. altaicus and C. t. sungaris was comparable with the species divergence of the genus Callopsylla, which is closely related to Citellophilus. All studied populations of C. t. altaicus were Wolbachia-infected, whereas all studied populations of C. t. sungaris were symbiont-free. Data for ITS1 and ITS2 had much lower phylogenetic signals than mitochondrial data; however, diagnostic substitutions for C. t. altaicus and C. t. sungaris delimitation were also revealed. Analysis of a hardly accessible report on cross experiments allowed us to conclude the partial postzygotic isolation between these subspecies. Taken together, the molecular-genetic, geographical, morphological, and reproductive isolation findings verified that C. t. altaicus and C. t. sungaris subspecies could be considered as different species.

Combination of nuclear and mitochondrial markers as a useful tool to identify Ctenophthalmus species and subspecies (Siphonaptera: Ctenophthalmidae)

Ctenophthalmus is considered the largest genus within the Order Siphonaptera. From a morphological point of view, only males of this genus can be identified at species and subspecies levels using morphological keys, whereas there are no morphological criteria in order to classify females at these taxonomical levels. Furthermore, the amount of available molecular and phylogenetic data for this genus is quite scarce so far. The main objective of this work was to assess the utility of the combination of nuclear and mitochondrial markers with respect to their ability to differentiate among different subspecies within the Ctenophthalmus genus. With this purpose, we carried out a comparative morphological and molecular study of three different subspecies (Ctenophthalmus baeticus arvernus, Ctenophthalmus nobilis dobyi, and Ctenophthalmus andorrensis catalaniensis) in order to clarify and discuss its taxonomic status. In addition, our study complemented the molecular data previously provided for Ctenophthalmus baeticus boisseauorum and Ctenophthalmus apertus allani subspecies. We sequenced five different molecular markers: EF1-α, ITS1, ITS2, cox1, and cytb. Our results confirmed that morphological data by themselves are not able to discriminate among Ctenophthalmus female taxa; however, the combination of the nuclear marker EF1-α together with mtDNA markers cytb and cox1 constituted a useful taxonomical and phylogenetic tool to solve this issue. Based on these results, we consider that the use of this molecular approach should be gradually used within Ctenophthalmus genus in order to complement its classical taxonomy and clarifying the complex taxonomy of other congeneric species of fleas.

Marked host association and molecular evidence of limited transmission of ticks and fleas between sympatric wild foxes and rural dogs

Wild and domestic carnivores share ectoparasites, although molecular evidence is lacking. The goals of this study were to describe tick and flea infestation in sympatric free-ranging dogs Canis lupus familiaris (Linnaeus, 1758) (Carnivora: Canidae) and Andean foxes Lycalopex culpaeus (Molina, 1782) (Carnivora: Canidae) and to determine whether interspecific transmission occurs. Fleas and ticks retrieved from 79 foxes and 111 dogs in the human-dominated landscapes of central Chile were identified and a subset of specimens characterized by PCR and amplicon sequencing. Each ectoparasite species was clearly associated with a host: abundance and occurrence of Rhipicephalus sanguineus (Latreille 1806) (Acari: Ixodidae) and Ctenocephalides spp. (Siphonaptera: Pulicidae) were significantly higher in dogs than in foxes, whereas the opposite was true for Amblyomma tigrinum (Koch, 1844) (Acari: Ixodidae) and Pulex irritans (Linnaeus, 1758) (Siphonaptera: Pulicidae). Genetic analyses of a subset of ectoparasites revealed that dogs and foxes shared a limited number of nucleotide sequence types, suggesting that the interspecific transmission of these ectoparasites happens infrequently. Data also indicated that the ecological association and biological cycles of ticks and fleas determine the ectoparasite fauna of sympatric carnivores. In conclusion, our study shows that cross-species transmission should be assessed at a molecular level.

MORPHOLOGICAL AND MOLECULAR CHARACTERIZATION OF THE PLAGUE VECTOR XENOPSYLLA BRASILIENSIS

Members of the flea family Pulicidae have been the focus of many studies due to their significance as diseases vectors of medical and veterinary importance and their cosmopolitan distribution. They often exhibit variation in morphological features that can make correct species identification and management challenging. This may also apply to Xenopsylla brasiliensis (Baker, 1904), an important plague vector. In the current study, we aimed to provide genetic tools for reliable species identification using a DNA barcoding approach. A total of 73 flea specimens was collected from a native host (Namaqua rock mouse, Micaelamys namaquensis) in South Africa and identified morphologically. In addition, we took measurements of 7 morphological characteristics. Subsequently, we successfully generated barcodes of the mitochondrial cytochrome c oxidase subunit I (COI) gene for X. brasiliensis. We validated this approach by comparing our data to COI sequences from Rwandan X. brasiliensis. While sequences from both regions suggested a close relationship between the 2 X. brasiliensis populations, both haplotype and nucleotide diversity were substantially larger for the South African specimens. This may be attributed to human-assisted spread, differences in habitat, and/or host species sampled and merits further study in the future.

Poor vector competence of the human flea, Pulex irritans, to transmit Yersinia pestis

Background

The human flea, Pulex irritans, is widespread globally and has a long association with humans, one of its principal hosts. Its role in plague transmission is still under discussion, although its high prevalence in plague-endemic regions and the presence of infected fleas of this species during plague outbreaks has led to proposals that it has been a significant vector in human-to-human transmission in some historical and present-day epidemiologic situations. However, based on a limited number of studies, P. irritans is considered to be a poor vector and receives very little attention from public health policymakers. In this study we examined the vector competence of P. irritans collected from foxes and owls in the western United States, using a standard protocol and artificial infection system.

Methods

Wild-caught fleas were maintained in the laboratory and infected by allowing them to feed on human or rat blood containing 2 × 10⁸ to 1 × 10⁹Y. pestis/ml. The fleas were then monitored periodically for infection rate and bacterial load, mortality, feeding rate, bacterial biofilm formation in the foregut (proventricular blockage), and ability to transmit Y. pestis after their single infectious blood meal.

Results

P. irritans were susceptible to infection, with more than 30% maintaining high bacterial loads for up to 20 days. Transmission during this time was infrequent and inefficient, however. Consistent with previous studies, a low level of early-phase transmission (3 days after the infectious blood meal) was detected in some trials. Transmission at later time points was also sporadic, and the incidence of proventricular blockage, required for this mode of transmission, was low in fleas infected using rat blood and never occurred in fleas infected using human blood. The highest level of blockage and transmission was seen in fleas infected using rat blood and allowed to feed intermittently rather than daily, indicating that host blood and feeding frequency influence vector competence.

Conclusions

Our results affirm the reputation of P. irritans as a feeble vector compared to rodent flea species examined similarly, and its vector competence may be lower when infected by feeding on bacteremic human blood.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04805-3.

Molecular Identification, Transcriptome Sequencing and Functional Annotation of Pulex irritans

PURPOSE

Pulex irritans are vectors of various zoonotic pathogens. However, molecular studies on P. irritans and flea-borne diseases are limited due to the lack of molecular data. This study aimed to conduct transcriptome sequencing, functional annotation, and pathogen analysis of P. irritans.

METHODS

Fleas collected from a dog were identified morphologically and molecularly. RNA was extracted for transcriptome sequencing and functional annotation. Open reading frames (ORFs) of unigenes were confirmed by employing bioinformatics strategies, and maximum likelihood (ML) trees were reconstructed based on the highly expressed genes of ejaculation globulin-specific 3-like protein, salivary protein, and actin for phylogenetic relationship analysis.

RESULTS

The obtained mitochondrial 16S rRNA gene sequences showed 99.71% of similarity with P. irritans obtained from GenBank database. Transcriptome sequencing generated 74,412 unigenes, of which 53,211 were functionally annotated. A total of 195 unigenes were assigned to fleas, of which 69 contained complete ORFs. Phylogenetic trees of both ejaculatory globulin and salivary protein genes demonstrated that P. irritans first clustered with Pulicidae sp., indicating the reliability of transcriptome data. It is noteworthy that 1070 unigenes were assigned to Hymenolepis microstoma and Dipylidium caninum, of which 62 contained complete ORFs. The phylogenetic tree of the actin gene showed that the unigenes had closer relationships with Echinococcus sp., suggesting the role of P. irritans as intermediate hosts of tapeworms.

CONCLUSION

The results of this study provide the possibility for functional exploration of important genes and lay foundations for the prevention and control of P. irritans and flea-borne diseases.

The complete mitochondrial genome sequences of the cat flea Ctenocephalides felis felis (Siphonaptera: Pulicidae) support the hypothesis that C. felis isolates from China and USA were the same C. f. felis subspecies

The cat flea Ctenocephalides felis (Siphonaptera: Pulicidae) is the most important ectoparasite in cats and dogs worldwide. Over the years, there has been much dispute regarding the taxonomic and systematic status of C. felis. Mitochondrial (mt) genome sequences are useful genetic markers for the identification and differentiation of ectoparasites, but the mt genome of C. felis and its subspecies has not yet been entirely characterized. In the present study, the entire mt genome of C. f. felis from China was sequenced and compared with that of C. felis from the USA. Both contain 37 genes and a long non-coding region of >6 kbp. The molecular identity between the Chinese and American isolates was 99%, except for the non-coding region. The protein-coding genes showed differences at both the nucleotide (1.2%) and amino acid (1%) levels. Interestingly, the cox1 gene of the Chinese isolate had an unusual putative start codon (TTT). Taken together, our analyses strongly support the hypothesis that C. felis isolates from China and the USA were the same C. f. felis subspecies. The mt genome sequence of the C. f. felis China isolate presented in this study provides useful molecular markers to further address the taxonomy and systematics of C. felis.

Flea Communities on Small Rodents in Eastern Poland

Fleas are hematophagous insects infesting mainly small mammals and, less frequently, birds. With their wide range of potential hosts, fleas play a significant role in the circulation of pathogens in nature. Depending on the species, they can be vectors for viruses, bacteria, rickettsiae, and protozoa and a host for some larval forms of tapeworm species. The aim of this study was to determine the species composition of fleas and their small rodent host preferences in eastern Poland. Animals were captured in traps in various types of ecological habitats (a site covered by grassland vegetation within city limits, an unused agricultural meadow, and a fallow land near a mixed forest). The following rodent species were caught: Apodemus agrarius, Apodemus flavicollis, Microtus arvalis, and Myodesglareolus. Additionally, Ctenophthalmus agyrtes, Ctenophthalmus assimilis, Hystrichopsylla talpae, and Nosopsyllus fasciatus flea species were identified. The peak of the flea activity was noted in summer months. C. agyrtes was found to be the most abundant flea species in eastern Poland, while the greatest numbers of fleas were collected from the rodent species A. agrarius.

Ctenophthalmus baeticus boisseauorum (Beaucournu, 1968) and Ctenophthalmus apertus allani (Smit, 1955) (Siphonaptera: Ctenophthalmidae) as synonymous taxa: morphometric, phylogenetic, and molecular characterization

The family Ctenophthalmidae (Order Siphonaptera) has been considered as a 'catchall' for a wide range of divergent taxa showing a paraphyletic origin. In turn, Ctenophthalmus sp. (Ctenophthalmidae) includes 300 valid described taxa. Within this genus, males are easily distinguishable basing on the size, shape, and chaetotaxy of their genitalia; however, females show slight morphological differences with each other. The main objective of this work was to carry out a comparative morphometric, phylogenetic, and molecular study of two different subspecies: Ctenophthalmus baeticus boisseauorum and Ctenophthalmus apertus allani in order to clarify and discuss its taxonomic status. From a morphological and biometrical point of view, we found clear differences between modified abdominal segments of males of both subspecies and slight differences in the margin of sternum VII of all female specimens which did not correspond with molecular and phylogenetic results based on four different molecular markers (Internal Transcribed Spacer 1 and 2 of ribosomal DNA, and the partial cytochrome c oxidase subunit 1 and cytochrome b of mitochondrial DNA). Thus, we observed a phenotypic plasticity between both subspecies, which did not correspond with a real genotypic variability nor different environmental or ecological conditions. Basing on these results, we could consider that there are no solid arguments to consider these two 'morphosubspecies' as two different taxa. We propose that C. b. boisseauorum should be considered as a junior synonym of C. a. allani.

Differentiation of Trichuris species using a morphometric approach

Trichuris trichiura is a nematode considered as the whipworm present in humans and primates. The systematics of the genus Trichuris is complex. Morphological studies of Trichuris isolated from primates and humans conclude that the species infecting these hosts is the same. Furthermore, numerous molecular studies have been carried out so far to discriminate parasite species from humans and Non-Human Primates using molecular techniques, but these studies were not performed in combination with a parallel morphological study. The hypothesised existence of more species of Trichuris in primates opens the possibility to revise the zoonotic potential and host specificity of T. trichiura and other putative new species of whipworms.

In the present work, a study of Trichuris Roederer, 1761 (Nematoda:Trichuridae) parasitizing C. g. kikuyensis, P. ursinus, Macaca sylvanus, Pan troglodytes, and Sus scrofa domestica has been carried out using modern morphometric techniques in order to differentiate populations of Trichuris isolated from four species of captive NHP from different geographical regions, and swine, respectively.

The results obtained revealed strong support for geometrical morphometrics as a useful tool to differentiate male Trichuris populations. Therefore, morphometrics in combination with other techniques, such as molecular biology analyses, ought to be applied to further the differentiation of male populations.

On the other hand, morphometrics applied to female Trichuris species does not seem to contribute new information as all the measurements combinations of obtained from females always showed similar results.

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Geometrical morphometrics is an useful tool to differentiate male Trichuris populations.

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Geometrical morphometrics results are in agreement with the molecular biology analysis applied to the adult male samples that allow the identification of different species of Trichuris.

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The hypothesised existence of different species of Trichuris in primates opens the possibility to revise the zoonotic potential and host specificity of T. trichiura and other putative new species of whipworms.