What is Paranoplocephala macrocephala (Douthitt, 1915) (Cestoda: Anoplocephalidae)?

Tapeworms in Rodents from the Lower Anabar River Basin, with a Review of Species Diversity of Cestodes in Yakutia, Russia

PURPOSE

We aimed to explore the first data on the fauna of cestodes in rodents from the Lower Anabar River Basin situated in extreme north-western Yakutia, Russia and to develop a biological and biogeographical framework for examination of the species diversity of cestodes from Yakutia, which is an important faunal transition zone in the eastern Palaearctic.

METHODS

Field inventory of cestodes from rodents was conducted for the first time in the region of north-western Yakutia. Species diversity, intensity and prevalence of infection were assessed.

RESULTS

It was noted a rather high (up to 82.5%) total cestode prevalence in rodents in the extreme north-western area of Yakutia. In Arvicolinae hosts, we collected specimens of six cestode species of four genera and three families. Arostrilepis microtis and Douthittia nordenskioeldi were first collected in voles Lasiopodomys gregalis from Yakutia (new host and geographical records). The zoonotic parasite Echinococcus multilocularis was found in the liver of L. gregalis. The list of cestodes from rodents in Yakutia based on review of previous publications and the material obtained in the present study includes 24 species of 16 genera and five families. Out of these, 17 parasitise rodents as adults stage and seven as larvae.

CONCLUSION

The fauna of rodent tapeworms from the south subarctic tundra and pre-tundra larch woodlands of the north-western Yakutia is characterised by relatively impoverished species diversity compared to the fauna of cestodes from the taiga zone of the central Yakutia. The decrease in the species diversity of tapeworms does not affect the total infection prevalence of the definitive hosts, which is relatively high in this region.

Checklist of tapeworms (Platyhelminthes, Cestoda) of vertebrates in Finland

A checklist of tapeworms (Cestoda) of vertebrates (fishes, birds and mammals) in Finland is presented, based on published observations, specimens deposited in the collections of the Finnish Museum of Natural History (Helsinki) and the Zoological Museum of the University of Turku, and additional specimens identified by the present author. The checklist includes 170 tapeworm species from 151 host species, comprising 447 parasite species/host species combinations. Thirty of the tapeworm species and 96 of the parasite/host species combinations have not been previously reported from Finland. The total number of tapeworm species in Finland (170 spp.) is significantly lower than the corresponding figure for the Iberian Peninsula (257 spp.), Slovakia (225 spp.) and Poland (279 spp.). The difference between Finland and the other three regions is particularly pronounced for anseriform, podicipediform, charadriiform and passeriform birds, reflecting inadequate and/or biased sampling of these birds in Finland. It is predicted that there are actually ca. 270 species of tapeworms in Finland, assuming that true number of bird tapeworms in Finland corresponds to that in other European countries with more comprehensive knowledge of the local tapeworm fauna. The other main pattern emerging from the present data is the seemingly unexplained absence in (northern) Fennoscandia of several mammalian tapeworms that otherwise have extensive distributions in the Holarctic region or in Eurasia, including the northern regions. Previously unknown type specimens, that is, the holotype of Bothrimonusnylandicus Schneider, 1902 (a junior synonym of Diplocotyleolrikii Krabbe, 1874) (MZH 127096) and the syntypes of Caryophyllaeidesfennica (Schneider, 1902) (MZH 127097) were located in the collections of the Finnish Museum of Natural History.

Afrojoyeuxia gen. n. and Hunkeleriella gen. n., two new genera of cestodes (Cyclophyllidea: Anoplocephalidae) from African rodents

Based on the study of type material, two new genera of cestodes (Cyclophyllidea: Anoplocephalidae) are proposed for Paranoplocephala Lüihe, 1910 sensu lato species from African rodents. Afrojoyeuxia gen. n., proposed for A. gundii (Joyeux, 1923) comb. n. from Ctenodactylus gundi (Rothmann) (Hystricomorpha: Ctenodactylidae), is characterized by a high length/width ratio of mature proglottids, longitudinally extensive testicular field positioned anterior to the female glands, an ovoid or subspherical cirrus-sac and a thick, conical cirrus. Hunkeleriella gen. n., proposed for H. dasymidis (Hunkeler, 1972) comb. n. from Dasymys incomtus (Sundevall) (Myomorpha: Muridae), differs from related genera mainly by its short (10-20 mm) and wide strobila and neck, unilateral genital pores (exceptionally with a few changes per strobila), the position of the genital pores (slightly anterior to the middle of proglottid margin) and initially tube-like early uterus (later reticulated). Parandrya Gulyaev et Chechulin, 1996, earlier suggested to be a junior synonym of Paranoplocephala, is considered to be a valid, independent genus. Evidence of non-monophyly and need for a taxonomic revision of Paranoplocephala sensu lato, as well as the phylogenetic position of A. gundii and H. dasymidis are discussed.

A redescription of three species of Monoecocestus (Cestoda: Anoplocephalidae) including Monoecocestus threlkeldi based on new material

Because we have new and detailed data on species in the genus, herein we redescribe both Monoecocestus macrobursatus and M. minor based on existing museum specimens. We also redescribe M. threlkeldi (Parra, 1952) using material collected in Bolivia. Based on the specimens representing M. thelkeldi, we affirm that Perutaenia Parra, 1953 should remain a junior synonym of Monoecocestus.

Revision of the Progamotaenia zschokkei (Janicki, 1905) complex (Cestoda: Anoplocephalidae), with the description of six new species

A review of cestodes currently attributed to Progamotaenia zschokkei (Janicki, 1905) (Cestoda: Anoplocephalidae) suggests that six additional species are present: Pr. tenuis n. sp. found in Thylogale stigmatica (Gould) and T. thetis (Lesson), Pr. lomatosoma n. sp.from Macropus agilis (Gould), Pr. petrogale n. sp. from Petrogale spp. and Macropus dorsalis(Grey), Pr. fimbriata n.s p. from Lagorchestes conspicillatus Gould and L. hirsutus Gould, Pr. obesa n. sp. from Onychogalea fraenata (Gould) and O. unguifera (Gould) in north-eastern Australia and Pr. kellerae n. sp. from O. unguifera in north-western Australia. The new species are differentiated by a combination of characters: prominence of scolex lobes, number of lobes in the fimbriated velum, testis number and distribution, size of the cirrus-sac, morphology of the uterus and presence or absence of a pyriform apparatus in eggs from terminal segments. The morphological differences found support earlier molecular studies, in that cestodes within each host genus are distinct, with the exception that considerable morphological variation exists within Pr. petrogale. Principal components analysis suggested that most of the cestodes from Petrogale spp. belonged to Pr. petrogale. The status of specimens from Pe. lateralis is unclear. More detailed molecular studies are required to determine the significance of the morphological variation within this taxon. A key is provided to species within the complex and the related species Pr. villosa (Lewis, 1914).

Morphological and molecular characterisation of Paranoplocephala buryatiensis n. sp. and P. longivaginata Chechulin & Gulyaev, 1998 (Cestoda: Anoplocephalidae) in voles of the genus Clethrionomys

A new species, Paranoplocephala buryatiensis n. sp. (Cestoda:Anoplocephalidae), is described from the grey-sided vole Clethrionomys rufocanus (Sundevall) in the Republic of Buryatia (Russian Federation) and compared with P. longivaginata Chechulin & Gulyaev, 1998, a parasite of the red vole C. rutilus (Pallas) in the same region. P. buryatiensis n. sp. and P. longivaginata both have an exceptionally long vagina and cirrus, unique features among known species of Paranoplocephala Lühe, 1910. The new species differs from P. longivaginata primarily by its wider and more robust body, lower length/width ratio of mature proglottides, tendency of testes to occur in two separate groups, seminal receptacle of a different shape and the position of the cirrus-sac with respect to the ventral longitudinal osmoregulatory canal. The cytochrome oxidase subunit I (COI) sequence data support the independent status of these species, and show that they form a monophyletic assemblage within Paranoplocephala (sensu lato). Assuming cospeciation, an indirect calibration using host speciation dates estimated a rate of mtDNA substitution of 1.0-1.7% pairwise (0.5-0.85% per lineage) sequence divergence per million years. A faunistic review of Paranoplocephala species in C. rufocanus and C. rutilus in the Holarctic region is presented.

Duplication, balancing selection and trans-species evolution explain the high levels of polymorphism of the DQA MHC class II gene in voles (Arvicolinae)

Major histocompatibility complex (MHC) genes play important role in host-parasite interactions and parasites are crucial factors influencing the population dynamics of hosts. We described the structure and diversity of exon 2 of the MHC class II DQA gene in three species of voles (Arvicolinae) exhibiting regular multi-annual fluctuations of population density and analysed the processes leading to the observed MHC polymorphism. By using cloning-sequencing methodology and capillary electrophoresis-single strand conformation polymorphism, we described seven sequences in the water, eight in the common, and seven in the bank voles coming from an area of 70 km(2) around the Nozeroy canton in the Jura Mountains (Franche Comté, France). All exon 2 sequences translate to give unique amino acid sequences and positive selection was found to act very intensively on antigen binding sites. We documented the presence of recombination at vole DQA region but its importance in generating allelic polymorphism seems to be relatively limited. For the first time within rodents, we documented the duplication of the DQA gene in all three species with both copies being transcriptionally active. Phylogenetic analysis of allelic sequences revealed extensive trans-species polymorphism within the subfamily although no alleles were shared between species in our data set. We discuss possible role of parasites in forming the recent polymorphism pattern of the DQA locus in voles.

Anoplocephalid cestodes of wood rats (Neotoma spp.) in the western U.S.A

This study reviews the taxonomy of anoplocephaline cestodes of wood rats, Neotoma cinerea, N. fuscipes and N. mexicana (Sigmodontinae) in the western and south-western U.S.A. The anoplocephaline fauna included five species, only one of which, Andrya neotomae Voge, 1946, was relatively common and occurred in all three host species. Other species were Paranoplocephala freemani Haukisalmi, Henttonen et Hardman, 2006, P. primordialis (Douthitt, 1915), both host-generalist species of North American rodents, and two apparently undescribed species of Paranoplocephala s. str. Aprostatandrya octodonensis Babero et Cattan, 1975 from the indigenous South American rodent Octodon degus is regarded as a junior synonym of A. neotomae. A redescription is provided for A. neotomae.

Morphological Characterisation of Andrya Railliet, 1893, Neandrya n. g. and Paranoplocephala Lühe, 1910 (Cestoda: Anoplocephalidae) in Rodents and Lagomorphs

The taxonomic significance of the main morphological features of the 25 species allocated to Andrya Railliet, 1893 and Paranoplocephala Lühe, 1910 is re-evaluated in the light of the recent molecular phylogenetic hypotheses for anoplocephaline cestodes. The present analysis and the existing phylogenetic data suggest that the structure and complexity of the early uterus are not, as previously assumed, the main phylogenetic or systematic determinants for anoplocephaline cestodes. Instead, the position of the early uterus with respect to other organs, combined with the morphology of the female genitalia, appear to allow a fairly straightforward discrimination of the three genera recognised here, without contradicting current phylogenetic hypotheses. A new genus, Neandrya n. g., is proposed for N. cuniculi (Blanchard, 1891) n. comb. (previously in Andrya), amended diagnoses are provided for Andrya and Paranoplocephala and a diagnostic key to these three genera is presented.

Molecular Phylogeny and Systematics of Anoplocephaline Cestodes in Rodents and Lagomorphs

A molecular phylogenetic hypothesis is presented for the anoplocephaline cestodes of placental mammals based on sequence data from the mitochondrial cytochrome c oxidase I (COI) gene, the nuclear-encoded 28S rRNA gene and the internal transcribed spacer region I of rRNA (ITS1). The material consists of 35 species representing nine genera of cestodes, with emphasis on taxa parasitising rodents and lagomorphs in the Holarctic region. The resulting phylogenies show considerable disagreement with earlier systematic and phylogenetic hypotheses derived from morphology. Specifically, the results contradict the view of uterine morphology being the primary determinant of deeper phylogenetic splits within Anoplocephalinae. Also, the role of genital duplication as a means of generic divergence was not found to follow consistently the pattern suggested by earlier hypotheses. Colonisation of novel host lineages has evidently been the predominant mode of diversification in anoplocephaline cestodes of placental mammals; evidence for phyletic co-evolution was obscure. The phylogenies consistently distinguished a large monophyletic group including all species from arvicoline rodents (voles and lemmings), primarily representing the genera Anoplocephaloides Baer, 1923 and Paranoplocephala Lühe, 1910. Phylogenetic relationships within the "arvicoline clade" of cestodes were generally poorly resolved. Consistent support for nodes above and below the unresolved polytomy indicates a rapid radiation involving a nearly simultaneous diversification of many lineages, a scenario also proposed for the arvicoline hosts.

Morphometric analysis of four species of Eubothrium (Cestoda: Pseudophyllidea) parasites of salmonid fish: An interspecific and intraspecific comparison

Four species of the genus Eubothrium (E. crassum, E. fragile, E. rugosum and E. salvelini) were subjected to morphometric comparison. Discriminant analysis was conducted utilising 17 characters measured on the scolex and strobila of 101 specimens. Univariate statistics were first used to detect features that were useful for separating individual Eubothrium species and two different host populations of E. salvelini. Subsequent multivariate discriminant analysis, combining all the measured variables, made it possible to separate all four species. A comparison of the four taxa revealed that (1) E. fragile is the most distinct species, possessing a much smaller scolex than the other congeners, and its similarity with the other marine species E. crassum is not proven; (2) the two freshwater taxa, E. rugosum and E. salvelini are the most similar; (3) the characters most suitable for species differentiation are the length of the scolex, the width of the apical disc, the width of the neck and its area, the width of eggs and the number of testes; (4) the width of the apical disc was confirmed to be the most stable character at the intraspecific level (within E. salvelini host populations) and is therefore considered to be a trait of the highest discriminative power in the subset of four Eubothrium species.

Morphological characterisation of Paranoplocephala bairdi (Schad, 1954) (Cestoda: Anoplocephalidae) in heather voles Phenacomys spp. and tree voles Arborimus spp., and related species in voles and lemmings (Muridae: Arvicolinae)

The taxonomical status of Paranoplocephala bairdi (Schad, 1954)-like cestodes (Anoplocephalidae) in heather voles Phenacomys spp. and tree voles Arborimus spp. (Muridae: Arvicolinae) and their discrimination from five related species of Paranoplocephala is assessed using uni- and multivariate morphometrics. The analyses support the independent status and conspecificity of specimens from Phenacomys spp. and Arborimus spp., and P. bairdi is therefore suggested to be a host-specialist species of heather and tree voles with a wide geographical distribution in North America. A redescription is presented for P. bairdi.