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.

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.

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.

[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).

[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.

Variation in the sizes of eggs and oncospheres and the numbers and distributions of testes in the tapeworm, Hymenolepis diminuta.

Four "strains" of Hymenolepis diminuta were examined for morphological variation. These included the ARME "strain" (currently maintained at the University of Keele, U.K.), the OSU "strain" (currently maintained at The Ohio State University) and the TOR (or UT) "strain" (currently maintained at the University of Toronto), all of which were derived from the parental RICE "strain," and the ANU "strain" (currently maintained at the Australian National University). Additionally, 2 separate "clonal" populations (populations derived from single cysticercoids) from both the OSU and ANU "strains" were examined. All "strains" and "clones" were maintained under identical conditions using Tenebrio molitor and male Sprague-Dawley rats as the intermediate and definitive hosts, respectively. The lengths and widths of eggs and larvae (oncospheres) passed in the hosts' feces, and the numbers and distributions of testes in proglottids were quantified and the data analyzed. Although analyses of the lengths and widths of eggs and larvae demonstrated significant differences among some "strains" and "clones," a discriminate analysis of the data indicated these parameters to be of questionable taxonomic significance. The eggs of all "strains" and "clones" consisted of 2 distinct populations differing in density and size but not infectivity; the relative proportions of eggs in the 2 populations were not determined. Considering all possible numbers and distributions of testes, 17 variations were seen in the strobilae of tapeworms. Analyses of the data demonstrated that the "strains" and "clones" could be differentiated clearly using only the frequencies of the 1p2a (1 poral and 2 aporal testes) or 1p3a distribution, or the frequencies of proglottids containing 3 or 4 testes; all other variations failed to clearly differentiate or group the various "strains" and "clones."(ABSTRACT TRUNCATED AT 250 WORDS)

The occurrence and distribution of 5-hydroxytryptamine in Hymenolepis diminuta and H. nana.

The presence of 5-HT in Hymenolepis diminuta and Hymenolepis nana was detected by 2 biochemical methods and as yellow fluorescence in a histochemical method. In H. diminuta, 5-HT was found in a concentration of about 1.2 micron/g; this amount did not vary significantly in worms aged 6 to 18 days or more or in various regions of the worm. In H. nana, 5-HT was found in a concentration of about 1.8 micron/g. It was histochemically localized in H. diminuta and H. nana in a pattern similar to that of acetylcholinesterase previously described in these 2 cestodes, and it may be the opposing neuro-transmitter to acetylcholine. The lack of 5-HT in the vestigial rostellum of H. diminuta may be correlated with loss of function of this organ.

A unicellular endocrine gland in cestodes.

Unicellular glands are reported from the scolex and anterior neck region of Hymenolepis diminuta and H. nana. Despite positive staining reactions with the presumptive neurosecretory stains, paraldehyde-fuchsin and chrome-alum-hematoxylin, ultrastructurally these glands exhibit many non-neural characteristics. Glandular cell processes are frequently found in close proximity to muscular tissue, particularly in the suckers, suggesting a regulatory role in muscle modulation as a possible function. Two types of putative, neurosecretory cells are reported from the cephalic ganglia and the lateral nerve cords. Neurosecretory regulation of the unicellular endocrine glands is postulated based on the lack of direct innervation of the glands and the frequent close proximity of axons containing putative, neurosecretory granules.

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.

Axenic growth of oncospheres of Hymenolepis citelli (Cestoda) to fully developed cysticerocoids.

Cysticercoids of the cestode Hymenolepis citelli were grown axenically in vitro from the oncosphere to stages infective for the mammalian host. Reducing agents were an essential component of the culture medium. Of several reducing agents tested, L-cysteine was the most effective. Concentration of reducing agent was critical in that excessive amounts induced abnormal growth.

Structure-activity relationships of benzothiazole and benzimidazole anthelmintics: a molecular modeling approach to in vivo drug efficacy.

An investigation of the biochemical effects of an anthelmintic, tioxidazole (TIOX, methyl 6-[n-propoxy]benzothiazole-2-carbamate), on Hymenolepis diminuta in experimentally infected rats is reported. The chemotherapeutic actions of TIOX on H. diminuta in vivo were accompanied by marked changes in worm weight and chemical composition. Tapeworms recovered from rats that had received a therapeutically effective dose of TIOX 24 hr earlier were significantly smaller and contained much less glycogen (as a percentage of the wet weight) than worms from untreated controls. In TIOX-treated worms, protein concentrations rose at a rate sufficient to offset the decline in glycogen concentration. Glycogen/protein ratios in TIOX-treated worms were considerably lower than the corresponding control-values. Differences in the absolute amounts of glycogen and protein between control and drug-treated worms were even more pronounced. Administration of a subcurative dose of TIOX to the rat produced in H. diminuta another change, the onset of which preceded the gross alterations in worm weight and chemical composition. In vitro studies, carried out 18 hr after treatment, revealed that TIOX-treated worms absorbed and metabolized much smaller quantities of exogenous glucose than did the controls and that the ability of the worm to accumulate glucose against a concentration difference was significantly depressed. A mode of action common to the structurally related benzothiazole and benzimidazole anthelmintics is indicated by the similarity of their biochemical and physiological effects on the tapeworms and their time course of action when administered to rats infected with H. diminuta. Molecular modeling revealed that the benzothiazole and benzimidazole anthelminitics are congruent electronically and structurally. In vivo drug efficacy depends upon the magnitude of the molecular dipole moment and the percentage of polar surface area. Within the benzimidazole series, structural and electronic congruence is found between the 2-thiazolyl and 2-methyl carbamate groups, suggesting that these groups behave similarly in transport to, and binding at, the active site. Finally, anthelmintics that have the 5' substituents twisted out-of-plane were more active than those anthelminitics with 5' substituents in-plane. All of these factors implicate a highly polar, L-shaped cleft to which the anthelmintics bind at the active site.

Ultrastructure of the cyst of Hymenolepis diminuta larvae.

Electron microscopical studies of the cyst of 1-month-old H. diminuta larvae revealed considerable thickening of the superficial syncytium of tegument and formation of a large number of cavities and canals. The cytoplasm of the tegument is filled with microtubules produced by cytons of parenchymal layer which are analogs of tonofibrils. These peculiarities, together with numerous processes of the external fibrous layer, are regarded as adaptative to the changes of the hydrostatic pressure of the hemocoel of the intermediate host. The superficial syncytium is covered with microvilli and keeps polycellular cytoplasmatic bonds with cytons, which ensures energetic and plastic requirements for the stabilization of the hypertrophied syncytium and its physiological regeneration. Accumulations of fibres identical with those of the connective tissue were found in the cytons of the tegument. The cyst parenchyma consists mostly of cells with widened canals of granular endoplasmic reticulum associated with the microfibrils and production of fibrous filaments. The internal fibrous layer is produced by typical fibroblasts. The tegument of the cercomer is thinner and is considered to be less differentiated.

Morphology of the cysticercoid of Hymenolepis erinacei (Gmelin, 1789).

The morphology of the cysticercoid of H. erinacei has been studied for the first time by histological methods. The cysticercoid consists of a tailed cyst enclosing the neck and scolex of the cestode. The outer limiting layer surrounds the surface of the cyst, neck and scolex. The tegument of the cyst is characterized by circular and longitudinal layers of fine connective tissue fibres. The tegument of the proximal part of neck and scolex is characterized by microtriches. The basement layer is of fibrous character. The subtegument of the cyst, neck and scolex is formed by outer circular and longitudinal muscle and connective tissue layers and a layer of pyriform cells. The subtegument of the cyst is further formed by an inner longitudinal muscle and connective tissue layer with distinctly prevailing connective tissue fibres forming a lamellar structure. Under the subtegument of the cyst is an inner zone consisting of oval nuclei and cytoplasmic processes, without distinct cellular borders. The parenchyma is situated under the subtegument of the neck and scolex. The inner edge of the cyst and neck is bordered by the inner limiting layer.

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.

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.

[Classification of Hymenolepis macrorchida in the genus Idiogenoides (Cestoda, Davaineidae)]. / O prinadlezhnosti Hymenolepis macrorchida k rodu Idiogenoides (Cestoda, Davaineidae).

Hymenolepis macrorchida (Kotlan, 1921), a cestode of New Guinea parrots, possessing a small number (3 to 4) of testicles, belonging to the family Hymenolepididae to which it has been assigned for more than half of the century, is transferred to the family Davaineidae and designated as Idiogenoides macrorchida (Kotlan, 1921) comb. n.

[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.