Hymenolepidid cestodes: Diversity, morphological and molecular characterization of a new species, and phylogeny of parasitic species of rodents from North and South America.

Rodents are hosts of a wide diversity of cestodes. Fifteen genera included in the family Hymenolepididae parasitize rodents, and only four of these genera have been recorded from the Neotropical region. The purpose of this paper is to update species of Hymenolepididae from rodents, describe a new species of Hymenolepis based on morphological and molecular characterization (ITS1 rDNA and cox1 mtDNA), comparing the features among the species from North and South American rodents, and provide phylogenetic inferences of Hymenolepididae from rodents based on sequences available in the GenBank. Rodents were collected in the Parque Provincial Ernesto Tornquist, Buenos Aires, Argentina. Hymenolepis ivanovae n. sp. differs from other Hymenolepis species registered from North and South American rodents by body size, scolex, suckers, cirrus sac, cirrus, testes, and eggs, among others. Comparative morphometric data for Hymenolepis species from North and South American rodents is provided. Molecular analyses place H. ivanovae n. sp. within the genus Hymenolepis with strong support, and show it close to species of zoonotic importance. The new species is the first species of Hymenolepis described from Sigmodontinae rodents.

Hymenolepis folkertsi n. sp. (Eucestoda: Hymenolepididae) in the oldfield mouse Peromyscus polionotus (Wagner) (Rodentia: Cricetidae: Neotominae) from the southeastern Nearctic with comments on tapeworm faunal diversity among deer mice.

A previously unrecognized species of hymenolepidid cestode attributable to Hymenolepis is described based on specimens in Peromyscus polionotus, oldfield mouse, from Georgia near the southeastern coast of continental North America. Specimens of Hymenolepis folkertsi n. sp. differ from those attributed to most other species in the genus by having testes arranged in a triangle and a scolex with a prominent rostrum-like protrusion. The newly recognized species is further distinguished by the relative position and length of the cirrus sac, shape of seminal receptacle, and relative size of external seminal vesicle and seminal receptacle. Hymenolepidid cestodes have sporadically been reported among the highly diverse assemblage of Peromyscus which includes 56 distinct species in the Nearctic. Although the host genus has a great temporal duration and is endemic to the Nearctic, current evidence suggests that tapeworm faunal diversity reflects relatively recent assembly through bouts of host switching among other cricetid, murid, and geomyid rodents in sympatry.

Description of two new species of Hymenolepis Weinland, 1858 (Cestoda: Hymenolepididae) from rodents on Luzon Island, Philippines.

Our helminthological examination of murid rodents on Luzon Island, Philippines, revealed a remarkable diversity of Hymenolepis Weinland, 1858. Here we describe two new species based on specimens from murid rodents Rattus everetti (Günther) and Apomys datae (Meyer) collected from Luzon Island. Hymenolepis alterna n. sp. differs from all known species of Hymenolepis in having irregularly alternating genital pores. This feature has not been reported from any previously known member of Hymenolepis. Additionally, Hymenolepis alterna n. sp. also differs from other Hymenolepis spp. in the relative position of both poral and antiporal dorsal osmoregulatory canals which are shifted towards the middle of the proglottis in relation to the ventral canals on both sides of the proglottides, and in having curved or twisted external seminal vesicle, covered externally by a dense layer of intensely stained cells. Hymenolepis bilaterala n. sp. differs from all known species of Hymenolepis in the relative position of both poral and antiporal dorsal osmoregulatory canals, which are shifted bilaterally towards the margins of proglottides in relation to the ventral canals, and in possession of testes situated in a triangle and eggs with very thin outer coat. A total of seven species of Hymenolepis are known from the Philippine archipelago. This total includes the cosmopolitan species Hymenolepis diminuta (Rudolphi, 1819), which was likely introduced to the island with invasive rats. Strikingly, all seven known species occur on the island of Luzon alone. By comparison, only six Hymenolepis spp. are known from the whole Palaearctic and seven from the Nearctic despite a much better level of knowledge of rodent helminths in these zoogeographical regions, as well as vast territories, diverse landscapes and very rich rodent fauna. This suggests that Hymenolepis spp. may have undergone an unusually active radiation in the Philippines. Possible explanations of this phenomenon are discussed.

Two new species of Hymenolepis (Cestoda: Hymenolepididae) from murid rodents (Rodentia: Muridae) in the Philippines.

Two previously unrecognized species of the genus Hymenolepis are described based on specimens obtained from murid rodent species Bullimus luzonicus , Apomys microdon , and Rattus everetti collected on Luzon Island, Philippines. Hymenolepis bicauda n. sp. differs from all known Hymenolepis spp. in relative position of the poral dorsal and ventral osmoregulatory canals, gravid uterus occupying less than half the length of proglottid, relatively few eggs, and the highly characteristic longitudinal split of proglottids at the end of the gravid strobila. Hymenolepis haukisalmii n. sp. differs from all known Hymenolepis spp. in the relative position of both poral and aporal dorsal and ventral osmoregulatory canals and uterus lacking dorsal and ventral diverticula. The shift in the relative position of the dorsal and ventral osmoregulatory canals was not known in Hymenolepis from rodents in other regions of the world and is reminiscent of the situation observed in Hymenolepis erinacei, parasitic in hedgehogs, and members of the genus Talpolepis, parasitic in moles. The cosmopolitan species Hymenolepis diminuta was the only member of the genus previously reported from the Philippines.

Two new species of Hymenolepis (Cestoda: Hymenolepididae) from Spalacidae and Muridae (Rodentia) from eastern Palearctic.

Previously unrecognized species of the genus Hymenolepis are described based on specimens from spalacid and murid (Murinae) rodents. Hymenolepis rymzhanovi sp. nov. from the Siberian zokor, Myospalax myospalax (Laxmann), from East Kazakhstan, and H. apodemi sp. nov. from Eurasian field mice, Apodemus peninsulae (Thomas), A. uralensis (Pallas) and A. agrarius (Pallas), from the south of Russian Far East, western Siberia and south-eastern Kazakhstan are characterized. The new species differ from other species of the genus by the morphology of the scolex, the relative position and length of the cirrus-sac and the relative position and arrangement of the testes. Differential criteria of species of Hymenolepis (sensu stricto) are also discussed.

Morphological features of Cloacotaenia megalops (Nitzsch in Creplin, 1829) (Cestoda, Hymenolepididae) from different hosts.

The tapeworm species Cloacotaenia megalops (Nitzsch in Creplin, 1829) is characterized by a very specific morphology. A particularly distinct feature is a large almost square scolex in which four fleshy suction cups are embedded and a rudimentary rostellum. During standard studies of wild duck cestode fauna in northwestern Poland, some morphological differences were observed among specimens, mainly in the shape of scolices and hermaphroditic proglottids of C. megalops isolated from different bird species. This paper attempts to demonstrate the impact of the host species on morphology of the parasite. The study material consisted of 39 individuals of C. megalops (19 from Aythya fuligula, 10 from Anas platyrhynchos, 4 from Bucephala clangula, 4 from Aythya marila and 2 from A. ferina). The isolated parasites were fixed and stored in 70% ethanol and solid preparations were made. Selected external and internal structures of the parasite were measured and photographed using a Zeiss microscope, a microscope camera Opta Tech 2.1 and Opta View 6.0.2.2. It was stated that the sizes of the most important elements of the parasite morphology are generally consistent with those presented in the available literature, nevertheless some differences were observed in both morphology and sizes of some anatomical structures, especially in the form of scolices and hermaphroditic proglottids between specimens isolated from hosts representing three different eco-tribes (Aythyini, Anatini and Mergini).

[First record of Microsomacanthus tuvensis Spasskaya et Spasskii, 1961 (Cestoda, Hymenolepididae) in Poland]. / Microsomacanthus tuvensis Spasskaya et Spasskii, 1961 (Cestoda, Hymenolepididae) po raz pierwszy notowany w Polsce.

During standard parasitological studies of the tufted duck Aythya fuligula, obtained from fishermen from West Pomerania in December 2007, three cestode specimens were found in the jejunum of one male host. They were determinated as Microsomacanthus tuvensis (Spasskaya et Spasskii, 1961) on the basis of the cirrus's and cirrus sac's size and vagina's shape. This is the first record of this species in Poland.

[On the species independence of Mathevolepis larbicus Karpenko, 1982 (Cyclophyllidea, Hymenolepididae, Ditestolepidini)].

The cestode species Mathevolepis larbicus Karpenko, 1982 parasitizing shrews in Russian Far East is restored. As the holotype was lost, the neotype is selected. The redescription and differential diagnosis of the species are given.

[The evolution of forms of hermaphroditism in Cyclophyllidea (Cestoda). 1. Morpho-functional causes of the formation of tapeworms with the protandrous type of genital apparatus development].

Morpho-fuctional causes of the formation of protandrous Cyclophyllidea (tapeworms) have been studied. Two forms of protandry are described. The protandry type I is typical for polymeric (polysegmental) Hymenolepididae. It appears independently in different taxa of this family (Aploparaksis, Echinatrium, Wardium, Diorchis and others) while the narrow-strobila forms with a low prolificacy of proglottids are formed. The development of this living form of hymenolepidids is ecologically caused by the high density of their aggregation in intestines of hosts. The primordium results in the development of genitals in the juvenile strobila proglottids with the limited internal space. Due to this process, parallel morphogenesis of male and female gonads is proved to be impossible. A selection leading to the overtaking development of testicles and copulative apparatus regarding morphogenesis of ovary and vitellarium is based an earlier maturation of testicles and group copulation of proglottids with and underdeveloped ovary that is typical in original euandrogyne forms. The group insemination of proglottids from a polysegmented strobila reduces the number of copulation and improves an efficiency of cross-copulation of tapeworms and. As a result, morpho-functional zones of male proglottids characterized by an immature ovary and those of fertile female segments losing their testicles are differentiated in the strobila. The protandry type II is typical of mesomeric tapeworms (Dilepididae, Schistotaeniidae, Anoplocephalidae). It is also resulted from a limited space of proglottids for developing the hermaphroditic genital apparatus. This is caused by the shift of genital morphogenesis process into juvenile proglottids and also by the enlargement of gonad sizes as the result of a selection for a higher prolificacy of proglottids. The dissociation of the development of male and female gonads takes place because of the retardation of ovary morphogenesis.

[Cestode of the family Hymenolepididae from ducks of Chukotka: Microsomacanthus parasobolevi sp. n.--a widely distributed parasite of eider ducks].

A new species of the genus Microsomacanthus Lopez-Neyra, 1942 is described. The material was collected from eider ducks (Somateria mollissima, S. fischeri, and S. spectabilis) in the Chaunskaya lowland (North-Western Chukotka). Microsomacanthus parasobolevi sp. n. differs from the closest species of this genus (M. polystictae Regel, 1988, M. sobolevi Spassky et Jurpalova, 1964; M. strictophalius Tolkatchieva, 1966) by the structure and size of the copulatory organ. Wide distribution of the new species was detected based on the cestodes collections from eider ducks of the Eastern Chukotka, Lena River mouth (in the museum of the Institute of the Parasitology RAS) and Iceland (Karl Skirnisson's cestode collection of the common eider). Furthermore, this species was reported once of the common eider in Newfoundland and Labrador, but erroneously identified as Hymenglejns (Microsomacanthnis) formosoides Spasskaja et Spassky, 1961 by Bishop and Threlfall (1974).

Morphometric and genetic variability of Rodentolepis asymmetrica (Hymenolepididae) from the Pyrenean mountains.

Rodentolepis asymmetrica (Janicki, 1904), is a common hymenolepidid cestode recorded in several vole species (rodents) in the Palearctic. Here, we report a detailed analysis of this species, which includes metrical features and multilocus enzyme electrophoresis. Worms isolated from 4 species of arvicolid hosts in 3 localities in Spain and France from 1994 to 1997 were studied. All the worms used in the morphological study ranged between I and 5 individuals per host. Furthermore, all individuals were analyzed electrophoretically. Statistical analysis of metrical features in scolex, sexual segments, and eggs was carried out, and significant differences were detected only in sexual structures of mature segments. These differences were found in worms from each host species in different localities and in the same host species in 2 localities. Multivariate statistical analysis shows correct classification of worms in all cases. Surprisingly, we observed a lack of genetic variability at the 11 enzymatic loci analyzed, which could be explained by 2 nonexclusive hypotheses: (1) a preferential selfing mode of reproduction for these parasites, and (2) a weak effective size of parasite populations.

Tapeworm identification in the fat sand rat (Psammomys obesus obesus).

The identification of a tapeworm (Rodentolepis nana, formerly named Hymenolepis nana) infection in a research breeding colony of sand rats (Psammomys obesus obesus) was complicated because of the unexpected long length (< 150 mm) of the worms. Other morphologic features that were consistent with this identification included the number (24), size (16 mm), and shape of the hooks on the rostellum. No evidence of intermediate hosts was found in the colony. Previous surveys of natural populations of sand rats had not identified this tapeworm. However, a detailed search of the literature revealed that variation in the size of R. nana had been reported, thus supporting the final identification of the tapeworm. R. nana is important and interesting because of its zoonotic potential and because it is the only tapeworm that is able to infect its definitive host without use of an intermediate host. This report is presented to help clarify the ambiguity found in the laboratory animal literature about the differences in the size of R. nana among rodent species used in research.

Digeneans and cestodes parasitic in the white-faced ibis Plegadis chihi (Aves: Threskiornithidae) from Argentina.

Some digeneans and cestodes parasitic in a population of the white-faced ibis Plegadis chihi (Vieillot) from Buenos Aires province, Argentina, are presented. The digeneans Dietziella egregia (Dietz, 1909), Patagifer bilobus (Rudolphi, 1819), Ascocotyle (Leighia) hadra Ostrowski de Nuñez, 1992 and Posthodiplostomum nanum Dubois, 1937 from the intestine; Prosthogonimus ovatus (Rudolphi, 1803) from the cloaca; Athesmia heterolecithodes (Braun, 1899) from the bile ducts and the cestode Hymenolepis megalops (Nitzsch in Creplin, 1829) from the cloaca, were recorded. The discovery of D. egregia, P. ovatus, A. heterolecithodes and P. nanum constitute new host and/or new geographical records. Adults of A. (L.) hadra, previously described in experimental definitive hosts, are first reported from a naturally infected bird. Hymenolepis megalops, a cestode of Anseriformes is first reported from Ciconiiformes.

Allometric growth of the proglottids and strobila of the tapeworm, Hymenolepis diminuta.

HYMENOLEPIS DIMINUTA: adults were killed and fixed in fully extended positions, and the total lengths of the strobilae, numbers of proglottids, and distances of proglottids along the strobilae were determined. The relationship of proglottid number to distance along the strobila was exponential. Beginning at proglottid 100 (P100), the lengths and widths of proglottids at 100 proglottid intervals were determined, and the surfaces areas were calculated. The relationships of proglottid length and width to proglottid number were linear, but the relationship of proglottid number to surface area (SA) was exponential. The volumes of proglottids were calculated, and the relationship of volume (V) to proglottid number was exponential. The relationship of surface area to volume ratio (SAVR) to proglottid number was exponential; at the anterior end of the worm (P100), the SAVR was 14.6, while at the posterior end of the worm (P1300) the ratio was 4.2. A single exponential equation describing the relationships among proglottid number, SA, and V was derived.

Palaearctic species of the genus Confluaria Ablasov (Cestoda, Hymenolepididae): a redescription and synonymy of C. capillaris (Rudolphi, 1810).

The types of Confluaria capillaris (Rudolphi, 1810) from Podiceps auritus in (?) Germany and the types of C. capillaroides (Fuhrmann, 1906) from Podiceps dominicus in Brazil are redescribed. C. capillaroides is recognised as a junior synonym of C. capillaris (new synonymy). Data on specimens of the same species from P. cristatus and P. grisegena in Bulgaria are also presented. The previous records of the two nominal species are critically analysed in view of the present redescriptions. The host range of C. capillaris includes only grebes of the genus Podiceps, i.e. P. auritus, P. cristatus, P. grisegena, P. dominicus and P. nigricollis; the records in other hosts (Gaviiformes, Charadriiformes and Passeriformes) are considered erroneous or doubtful. The geographical range includes Europe, Central Asia and northern South America.

Fimbriaria fasciolaris and Cloacotaenia megalops (Eucestoda, Hymenolepididae), cestodes from Brazilian waterfowl

Two cestodes species, Fimbriaria fasciolaris (Pallas, 1781) Frolich, 1802 Cloacotaenia megalops (Nitzch in Creplin, 1829) Wolffhugel, 1938 collected from Anas bahamensis Linné, 1758 and Amazonetta brasiliensis (Gmelin, 1758) in lagoons of the Maricá District, State of Rio de Janeiro, Brazil, are described. This is the first record of E. fasciolaris parasitizing A. bahamensis. The prevalence, intensity of infection, and mean intensity of infection for both species are given. Overdispersion distribution is reported for F. fasciolaris with 535 specimens collected in a single A. bahamensis. A key for the genera in the Fimbriariinae is presented. Anatomical features of F. fasciolaris and C. megalops are discussed.

Predictability of morphological gradients in the tapeworm, Hymenolepis diminuta.

The strobila of an adult tapeworm represents a continual gradient of developmental stages from immature to gravid proglottids. The purpose of this study was to determine if organogenesis (as measured by the developmental gradient) in tapeworms within a single host and among different hosts occurred at the same rates. Rats were infected with Hymenolepis diminuta and the tapeworms were recovered 20 days post-infection. The total number of proglottids in each worm was determined, and five 'benchmarks' of organogenesis were quantified. The data demonstrated that organogenesis in worms from a single host occurred at a relatively constant rate, but that rates in tapeworms from different hosts were different.

[Hereditary character of feature variability in Hymenolepis diminuta bred from oncospheres of defined origin]. / Dziedziczny charakter zmiennosci cech u Hymenolepis diminuta wyhodowanych z onkosfer okreslonego pochodzenia.

Three groups of tapeworms obtained 2.5 month after the administration to rats of a dose of 6 cysticercoids proceeding from oncospheres of the 24th generation of Hymenolepis diminuta were compared. Group I came from the oncospheres of only one proglottid of H. diminuta WMS "strain" tapeworm. Group II proceeded from 6 proglottids obtained each from another tapeworm of this "strain". Group III came from 6 proglottids, each from another tapeworm of H. diminuta WMS inbred line 1 (il1). The average number of type 0p3a proglottids in group I and II was similar and amounted to 4.0% and 4.7%, respectively, while in group III it was significantly higher than in the first two groups and reached an average of 8.4% (P < 0.01). There are also other significant differences between the two breeding lines-H. diminuta WMS "strain" and WMS il1 with respect to the number of typical 1p2a proglottids, type 1p3a proglottids, the second after 0p3a most common deviation from the typical 1p2a as well as all deviations taken together. This points to the influence of different breeding condition: non-inbred in case of H. diminuta WMS "strain" and inbred in case of H. diminuta WMS il1 on the investigated features.

[Comparison of the variability of tapeworms obtained as a result of infecting rats with Hymenolepis diminuta larvae of different ages]. / Porównanie zmiennosci tasiemców uzyskanych w wyniku zarazenia szczurów larwami Hymenolepis diminuta w róznym wieku.

In Hymenolepis diminuta WMS "strain" tapeworms which were obtained 2.5 months after the administration to rats of 2-month old larvae--cysticercoids++, isolated from Tribolium destructor, only one-sided position of genital pores (PGP) developed. The extended 7-month duration of the invasion of H. diminuta larvae stimulates the development of variable PGP already in 14.1% of 2.5-month tapeworms. In tapeworms with exclusively one-sided PGP in the first of the two groups mentioned, the number of type 1p2a proglottids (1 testis on the poral side and 2 testes on the aporal side) as well as type 0p3a, 1p3a and 2p1a amounted to 88.2%, 5.5%, 4.2% and 0.5%, respectively and similarly in the second group--88.3%, 5.6%, 4.5% and 0.6%, respectively. In tapeworms with variable PGP the mean number of the types of proglottids mentioned was different from (86.0%, 4.1%, 3.8% and 4.1%, respectively) the same figure in tapeworms with one-sided PGP. Particularly high correlation was found to occur between the number of PGP variations and type 2p1a proglottids (r = +0.928, P < 0.01).

Intensified morphological variability during patency in Hymenolepis diminuta originating from inbred tapeworm--WMS IL1.

Variable position of genital ducts and pores (PGP) was found in 23.3% of five months old tapeworms obtained as a result of administering to rats a dose of 6 cysticercoids proceeding from the third generation of inbred Hymenolepis diminuta--WMS il1. In tapeworms coming from generations no 18 and 32 PGP changes were reported only in 7.5 month, with only 5.9% of strobilas in the 32 generation group being characterized by this feature. These results indicate a time shift with respect to the appearance of PGP changes in tapeworms proceeding from latter inbred generations to a further period of tapeworm invasion in rats. The number of PGP changes is positively correlated with the number of type 2p1a proglottids (two testes on the poral and one on the aporal side). The average number of type Op3a proglottids increases with the number of generations. In 5-month old tapeworms of unilateral PGP coming from generation no 3, 18 and 32 it amounts to 5.9%, 6.6% and 8.1%, respectively.