Hook Morphology Research Articles

A new combination and a new species of onchobothriid tapeworm (Cestoda: Tetraphyllidea: Onchobothriidae) from triakid sharks

A new combination and a new species of onchobothriid tapeworm are described from triakid sharks. We found Platybothrium xiamenensis Wang & Yang, 2001 and Erudituncus musteli (Yamaguti, 1952) from Hemitriakis japanica (Müller & Henle). Based on the morphology of the hooks P. xiamenensis is transferred to the genus Erudituncus Healy, Scholz & Caira, 2001. The specimens studied by us differ from the original description in the number of proglottids and testes and in the size of the cirrus-sac. However, we consider them conspecific with E. xiamenensis due to the consistent hook morphology and laciniations in both descriptions and believe the differences reflect intraspecific variation. The type-host of E. xiamenensis was reported as Mustelus griseus Pietschmann. However, in the present study, this parasite was found only in H. japanica and never in M. griseus although many specimens of the latter host were examined. This suggests that the type-host in the original description has probably been misidentified. We found another undescribed species in M. griseus, Calliobothrium shirozame n. sp., which is distinguished from the congeners by having a unique combination of the number of laciniations: four in the cephalic peduncle, six in the immature proglottids and four in the mature proglottids.

Levisunguis subaequalis n. g., n. sp., a tongue worm (Pentastomida: Porocephalida: Sebekidae) infecting softshell turtles, Apalone spp. (Testudines: Trionychidae) in the southeastern United States

A new tongue worm (Pentastomida) belonging to the Sebekidae Sambon, 1922 (Porocephaloidea Sambon, 1922) is described based on exemplars collected from softshell terrapins Apalone spinifera aspera (Agassiz) and Apalone ferox (Schneider) in the southeastern United States; a new genus is erected to accommodate the new species. The new species belongs in the Sebekidae because adults possess four simple hooks arranged in a trapezoid pattern on the ventral surface of the cephalothorax, a mouth opening between the anterior and posterior pairs of hooks, a terminal anus, an elongated uterus with preanal uterine pore, and a Y-shaped seminal vesicle. Nymphs possess geminate hooks, and the new species has an aquatic life-cycle in which nymphs become encapsulated in the body cavity of a freshwater fish and mature in the lungs of a terrapin. The new genus is distinct from other genera in the Sebekidae primarily by differences in hook morphology and the fact that representatives use a terrapin as a definitive host. Nymphs infecting fish and presumed to be the new species matured as postlarval juveniles conspecific with the new species when they were fed to the eastern mud turtle, Kinosternon subrubrum (Lacépède). Nymphs of the new species are anatomically similar to but larger than nymphs of Sebekia mississippiensis Overstreet, Self & Vliet, 1985 found in the mesentery of fishes captured in Florida, U.S.A. Adults of the new species differ from those of S. mississippiensis based on hook features, chloride cell pore pattern on annuli, body size, and use of a turtle rather than crocodilian definitive host. The new species is the third North American member of the Sebekidae.

First case of peritoneal cysticercosis in a non-human primate host (Macaca tonkeana) due to Taenia martis

BackgroundInfections with larval stages (metacestodes) of a variety of taeniid species have been described in primates, including humans, with partial to severe clinical consequences. Taenia martis is a tapeworm of mustelids, and martens are mainly their definitive hosts in Central Europe. In the rodent intermediate host cysticerci develop in the pleural and peritoneal cavities. The present report describes a case of T. martis peritoneal cysticercosis in a Tonkean macaque.FindingsAn abdominal mass was detected in a 3-year-old male Tonkean macaque (Macaca tonkeana) born and raised in a primate colony in France. Examination of the mass after laparotomy showed numerous vesicles identified as cysticerci of T. martis, based on the morphology of scolex and hooks, with confirmation by PCR amplification and sequence analysis of the mitochondrial cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1) genes. Exeresis of the lesion was not possible and praziquantel (5.7 mg/kg) was given twice at an interval of 3 days. The abdominal mass was greatly diminished upon examination 2 months later and no signs of recurrence were noticed during the following 4 years.ConclusionsThis is the first report of T. martis cysticercosis in a monkey. This record and the recent first description of an ocular T. martis cysticercosis in a human show the susceptibility of primates to T. martis and its zoonotic potential. This taeniid species must be considered in the differential diagnosis of cysticercosis in primates.

First description of adults of the type species of the genus Glossocercus Chandler, 1935 (Cestoda: Gryporhynchidae)

The type species of the genus Glossocercus Chandler, 1935, G. cyprinodontis Chandler, 1935, was described as metacestode (larval stage) from the mesentery of the sheepshead minnow fish (Cyprinodon variegatus Lacépède) from Galveston Bay, Texas. The description was based on the morphology of the rostellar hooks; however, the features of the internal morphology of the proglottides could no be provided. In the present study we describe for the first time the features of the adult G. cyprinodontis from the intestine of Pelecanus occidentalis Linnaeus, Nycticorax nycticorax Linnaeus and Egretta rufescens Gmelin in Mexico. Glossocercus cyprinodontis possesses similar strobilar morphology with the two other congeneric species, both distributed in the Neartic and Neotropical regions, i.e. Glossocercus caribaensis (Rysavy et Macko, 1971) and Glossocercus auritus (Rudolphi, 1819). However, G. cyprinodontis differs mainly in the shape of the rostellar hooks (those of G. cyprinodontis possess the handle and the guard strongly sclerified compared to those of G. auritus and G. caribaensis) and their size (total length of 175-203 microm in G. cyprinodontis compared to 189-211 microm in G. caribaensis and 220-285 microm in G. auritus). Generic diagnosis of Glossocercus is emended: rostellar hooks in two rows with ten hooks of different shape and length in each, scolex large and globular, proglottides craspedote, wider than long, genital pores irregularly alternating, vagina transverse, surrounded by epithelial cells, ventral to cirrus-sac, uterus bar-shaped in mature proglottides, occupies all space between osmoregulatory ducts with eggs in gravid proglottides, ovary lobed in middle of proglottis, cirrus-sac elongate, between osmoregulatory canals, cirrus armed with spinitriches and apical tuft of slender spinitriches.

Paradiplozoon ichthyoxanthon n. sp. (Monogenea: Diplozoidae) from Labeobarbus aeneus (Cyprinidae) in the Vaal River, South Africa

A new species, Paradiplozoon ichthyoxanthon (Monogenea: Diplozoidae) is described from the gills of Labeobarbus aeneus (Cyprinidae) in the Vaal Dam and Vaal River Barrage in the Vaal River, South Africa. This species is the first in this genus from southern Africa; Paradiplozoon aegtyptense and Paradiplozoon ghanense have been described from northern Africa. The new species differs from all other Paradiplozoon species on the basis of the combination of morphological characteristics, namely disk-like haptor, eggs without filaments, clamp and central hook morphology and size of specimens. The species description is accompanied by a description of the reproductive organs. The internal transcribed spacer of the ribosomal gene (ITS2) was studied and the South African individuals formed a distinct clade, supporting the establishment of a new species.

Role of the Dc domain of the bacterial hook protein FlgE in hook assembly and function.

The bacterial flagellar hook acts as a universal joint to smoothly transmit torque produced by the motor to the filament. The hook protein FlgE assembles into a 55 nm tubular structure with the help of the hook cap (FlgD). FlgE consists of four domains, D0, Dc, D1 and D2, arranged from the inner to the outer part of the tubular structure of the hook. The Dc domain contributes to the structural stability of the hook, but it is unclear how this Dc domain is responsible for the universal joint mechanism. Here, we carried out a deletion analysis of the FlgE Dc domain. FlgEΔ4/5 with deletion of residues 30 to 49 was not secreted into the culture media. FlgEΔ5 and FlgEΔ6 with deletions of residues 40 to 49 and 50 to 59, respectively, still formed hooks, allowing the export apparatus to export the hook-filament junction proteins FlgK and FlgL and flagellin FliC. However, these deletions inhibited the replacement of the FlgD hook cap by FlgK at the hook tip, thereby abolishing filament formation. Deletion of residues 50 to 59 significantly affected hook morphology. These results suggest that the Dc domain is responsible not only for hook assembly but also for FlgE export, the interaction with FlgK, and the polymorphic supercoiling mechanism of the hook.

Cucolepis cincta gen. n. et sp. n. (Cestoda: Cyclophyllidea) from the squirrel cuckoo Piaya cayana Lesson (Aves: Cuculiformes) from Paraguay

Cucolepis gen. n. is erected as monotypic for Cucolepis cincta sp. n., a new species of cyclophyllidean cestode of the family Paruterinidae. The new species is described from the squirrel cuckoo, Piaya cayana Lesson (Aves: Cuculiformes), taken from two localities in Paraguay in 1984 and 1985. This new genus is most similar to the genus Triaenorhina Spasskii et Shumilo, 1965 in terms of the hook morphology and large epiphyseal structures extending from both the handle and guard, but differs in several aspects of the strobilar morphology, such as the shape of the cirrus sac, genital atrium, uterus and paruterine organ. The strobilar morphology of the new genus strongly resembles that of the genus Francobona Georgiev et Kornyushin, 1994, especially the shape of the cirrus sac and genital atrium, yet Francobona spp. lack, the developed epiphyseal structures observed in species of Cucolepis and Triaenorhina. Previous records and the nature of parasite-host associations between cuculiform birds and their cestode parasites are discussed.

Perspectives on the Morphological Elements of Circle Hooks and Their Performance in Pelagic Longline Fisheries

Use of circle hooks is regarded as an effective method to reduce incidental mortality of non-targeted species (e.g., sea turtles) in longline fisheries. Currently, various types of circle hook are produced and distributed commercially. Many researchers worldwide have examined the effect of circle hooks on hooking location, catch rate, and/or mortality for various species, using different types of hooks of various shapes and sizes. However, much work remains to be done to quantify the effects of circle hooks on catch and mortality rates of both target and non-target species. Consideration of practical utility is also important to facilitate wider application of circle hooks in commercial fisheries. Here we focus on some elements of circle hook morphology, i.e., hook width, offset, and incurved point angle, and discuss their potential effects on hook function (i.e., hooking location, catch rate) and practical utility. Further empirical circle hook studies are required to verify the effects discussed here.

Influence of Bill and Foot Morphology on the Ectoparasites of Barn Owls

Preening is the principle behavioral defense used by birds to combat ectoparasites. Most birds have a small overhang at the tip of their bills that is used to shear through the tough cuticle of ectoparasitic arthropods, making preening much more efficient. Birds may also scratch with their feet to defend against ectoparasites. This is particularly important for removing ectoparasites on the head, which birds cannot preen. Scratching may be enhanced by the comb-like serrations that are found on the claws of birds in many avian families. We examined the prevalence and intensity of ectoparasites of barn owls (Tyto alba pratincola) in southern Idaho in relation to bill hook length and morphological characteristics of the pectinate claw. The barn owls in our study were infested with 3 species of lice (Phthiraptera: Ischnocera): Colpocephalum turbinatum , Kurodaia subpachygaster, and Strigiphilus aitkeni . Bill hook length was associated with the prevalence of these lice. Owls with longer hooks were more likely to be infested with lice. Conventional wisdom suggests that the bill morphology of raptors has been shaped by selection for efficient foraging; our data suggest that hook morphology may also play a role in ectoparasite defense. The number of teeth on the pectinate claw was also associated with the prevalence of lice. Owls that had claws with more teeth were less likely to be infested with lice, which suggests that larger pectinate claws may offer relatively more protection against ectoparasitic lice. Experiments that manipulate the bill hook and pectinate claw are needed to confirm whether these host characters are involved in ectoparasite defense. Finally, we recovered mammalian ectoparasites from 4 barn owls. We recovered species of mammalian lice (Phthiraptera:Anoplura) and fleas (Siphonaptera) that are commonly found on microtine rodents. The owls probably acquired these parasites from recently eaten prey. This represents 1 of the few documented cases of parasites "straggling" from prey to predator.

Metacestodes of Glossocercus auritus (Cyclophyllidea, Gryporhynchidae) in Poecilia reticulata (Pisces, Poeciliidae) from Brazil

Studies on fish parasites in Pampulha dam, Belo Horizonte, Minas Gerais, Brazil, found specimens of Poecilia reticulata Peters, 1859 harboring natural infection by larval stages of tapeworms. A total of 250 specimens of P. reticulata were collected and analyzed between February and August 2010, of which 23 were found infected (prevalence 9.2%) with one metacestode each (mean intensity 1, mean abundance 0.09). The analyses of the parasites, particularly the morphology of rostellar hooks, made it possible to identify Glossocercus auritus (Rudolphi, 1818). This is the first report of G. auritus metacestode in South America and P. reticulata is a newly known host for this parasite.

Sperm competition does not influence sperm hook morphology in selection lines of house mice

Sperm show a remarkable degree of variation in size, shape and complexity. Murine rodents exhibit a sperm head morphology that differs greatly from the ovoid shape that is characteristic of most mammals. These rodents have sperm that bear one or more apical hooks, the function of which is currently surrounded by much controversy. It has been suggested that the hook serves to facilitate the formation of sperm groups, which in some species exhibit relatively faster velocities than single cells and thus, may provide an advantage when ejaculates are competing for fertilisations. In support of this hypothesis, a comparative study reported a positive association between the strength of sperm competition (estimated from testes size) and the curvature of the sperm hook amongst 37 murine species. Here, we assessed whether sperm competition influences sperm hookedness at the intra-specific level. Following 16 generations of selection, we used geometric morphometry (GM) to describe sperm head morphology in selection lines of house mice evolving with (polygamous) and without (monogamous) sperm competition. Although the GM analysis returned two relative warps that described variation in the curvature of the sperm hook, we found no evidence of divergence between the selection lines. Thus, we can conclude that sperm competition does not influence the degree of sperm hookedness in house mice.

Systematics of the Onychoteuthidae Gray, 1847 (Cephalopoda: Oegopsida)

Squids in the family Onychoteuthidae Gray, 1847, have been reported from every ocean but the Arctic, are taken frequently in deep-sea fisheries bycatch, and are ecologically important in the diets of many marine predators including cetaceans, pinnipeds, sharks, and seabirds. However, the diversity and systematics of the family have remained poorly understood. Of the 60+ nominal species, 12–14 have generally been accepted in recent studies. Challenges to clarity include insufficient species descriptions, original descriptions published in eight languages and often based solely on early life stages, non-designation or subsequent loss of type material, and the existence of several unresolved species complexes. In light of the general systematic disarray of the Onychoteuthidae, a global revision of the family follows, based on ~1500 specimens examined from 19 repositories. Type material has been examined wherever possible (although, for some species, photographs of type specimens, original illustrations, and/or the original descriptions have provided the only information available). For all 25 species treated in this revision, descriptions and illustrations are provided to a consistent standard that will enable their reidentification. External and internal morphological characters and states are described for subadult to adult stages of most species, with external characters reported through ontogeny as permitted by available material. Historically important characters are treated (general external morphology, body proportions, tentacle clubs, photophores, gladius, lower beak, radula), augmented by several more recently recognised characters (palatine teeth, detailed morphology of the tentacular hooks in adults, tentacular suckers in paralarvae, chromatophore patterns). The systematic value of both historical and new morphological characters at the generic and species levels is discussed; at all ontogenetic stages, tentacular club and hook morphology are considered the most valuable characters, although body proportions and gladius also prove useful. In the interest of systematic stability, neotypes are also designated for four species in which type specimens were not previously designated [Onykia (Onykia) loennbergii Ishikawa & Wakiya, 1914; Onychoteuthis borealijaponica Okada, 1927] or have been subsequently lost [Onykia (Onykia) carriboea Lesueur, 1821; Onykia (Onykia) robsoni Adam, 1962]. Partial resolution of the Onychoteuthis banksii complex has been possible in the Pacific and Atlantic Oceans, resulting in: the resurrection of Onychoteuthis bergii Lichtenstein, 1818, and Onychoteuthis aequimanus Gabb, 1868; the description of two new species in an earlier publication (Onychoteuthis lacrima Bolstad & Seki, and Onychoteuthis prolata Bolstad, Vecchione & Young, in Bolstad, 2008) and another herein, Onychoteuthis horstkottei sp. nov.; and the expansion of one species’ recognised distribution (Onychoteuthis compacta Berry, 1913) to include the Atlantic Ocean. The genus Moroteuthis Verrill, 1881, is considered a junior synonym of Onykia Lesueur, 1821, in accordance with the findings of several earlier authors. However, morphological differences in the species ‘Moroteuthis’ ingens Smith, 1881, necessitate the resurrection of the subgenus Moroteuthopsis Pfeffer, 1908, with all other Onykia species placed into the nominate subgenus Onykia (Onykia). Sexual dimorphism is reported in the beaks of Onykia (Moroteuthopsis) ingens (new comb.). Morphological and historical genetic data suggest a more distant relationship between Onykia and the species ‘Moroteuthis’ knipovitchi Filippova, 1972, than was suggested by earlier classifications. This species is therefore placed into Filippovia gen. nov., described herein. ‘Onykia’ rancureli (Okutani, 1981) and C. youngorum sp. nov. are placed into Callimachus gen. nov., according to morphological and genetic data. Given that the majority of available onychoteuthid material was collected after 1950, resulting in the descriptions of over half of the generally accepted genera and species since 1960, ongoing collection programmes are necessary to further resolve onychoteuthid systematics.

Two new species ofProchristianellaDollfus, 1946 (Platyhelminthes, Cestoda) from the blue-spotted stingray,Neotrygon kuhlii(Müller & Henle, 1841) off New Caledonia

Beveridge I. & Justine J.-L. 2010. — Two new species of Prochristianella Dollfus, 1946 (Platyhelminthes, Cestoda) from the blue-spotted stingray, Neotrygon kuhlii (Müller & Henle, 1841) off New Caledonia. Zoosystema 32 (4) : 643-652.Prochristianella aciculata n. sp. and P. omunae n. sp. (Platyhelminthes, Cestoda, Trypanorhyncha, Eutetrarhynchidae) are described from the spiral valve of Neotrygon kuhlii (Müller & Henle, 1841) (Rajiformes, Dasyatidae) from Nouméa, New Caledonia, representing the first records of this cestode genus from the southern Pacific Ocean. Prochristianella aciculata n. sp. is distinguished from congeners by aciculate hooks in the principal rows of the metabasal tentacular armature and by the unique morphology of the first hooks in each row. Prochristianella omunae n. sp. is distinguished from congeners by its extended basal armature (20 rows of hooks) and the presence of enlarged hooks at the very base of the tentacle.

Rostellar hook morphology of larval Echinococcus granulosus isolates from the Indian buffalo and Iranian sheep, cattle and camel

Isolates of Echinococcus granulosus from the Indian buffalo and Iranian sheep, cattle and camels were characterized on the basis of rostellar hook morphology of the protoscolices. Results obtained indicated phenotypic polymorphism among parasites isolated from different host species. Isolates from buffalo are morphologically quite different from those of the more common sheep and cattle isolates and may represent a different strain, adapted to buffalo. In the Sari region of northern Iran, two morphologically distinct forms of E. granulosus, one in sheep and one in camels, were identified. Total length and handle length of both large and small hooks were considered the most variable characteristics which could be used not only for differentiating parasite isolates from different host species but also the origin of infection in the definitive host. We therefore suggest that larval hook morphology may be considered as a valid criterion for the identification of E. granulosus strains in Iran.

Gyrodactylus eyipayipi sp. n. (Monogenea: Gyrodactylidae) from Syngnathus acus (Syngnathidae) from South Africa

Gyrodactylus eyipayipi sp. n. is described from the skin, gills, flute and male brood pouch of captive specimens of the greater pipefish Syngnathus acus L., collected for and maintained at the Two Oceans Aquarium in Cape Town, South Africa. It is the first marine Gyrodactylus species reported from the African continent. The new species is compared to the three known Gyrodactylus species affecting syngnathiform hosts (G. pisculentus Williams, Kritsky, Dunnigan, Lash et Klein, 2008, G. shorti Holliman, 1963, and G. syngnathi Appleby, 1996). Although all four species have similar-sized and shaped attachment hooks with some overlap, separation of the species is possible using marginal hook morphology. The marginal hooks of G. eyipayipi measure (mean) 30 pm in total length and are larger than those of the three other species (mean, 24-28 tm). Gyrodactylus eyipayipi can also be discriminated based on differences in the shape of the marginal hook sickle notably by its long sickle point which extends far beyond the toe, its blunt rounded toe and, by the approximate rectangular shape to the base of the sickle. By comparison, the sloping toe regions of G. pisculentus and G. syngnathi give the sickle bases an approximately triangular shape, whilst the short sickle point and open aperture to the sickles of G. shorti allow for their discrimination from G. eyipayipi.

New name for Progrillotia dollfusi Carvajal et Rego, 1983 (Cestoda: Trypanorhyncha): description of adults from Squatina guggenheim (Chondrichthyes: Squatiniformes) off the coast of Argentina

Examination of the type material of Progrillotia dollfusi Carvajal et Rego, 1983, and of new specimens recently collected off the coast of Argentina (including plerocerci from 10 species of teleosts and adults from Squatina guggenheim Marini), allowed a detailed redescription of this species and the evaluation of its current taxonomic status. The following characters that have been treated inconsistently by different authors have been herein corrected or confirmed: band of hooklets on external surface restricted to the base of the tentacle, external surface of metabasal region with 3-5 intercalary hooks arranged in a single row merging immediately to a cluster of 3-4 hooklets arranged in two rows; retractor muscle originating in the posterior third of the bulb, hollow hooks, and posterior margin of bothria notched. These features along with the presence of postovarian testes in the adults clearly confirm the placement of P. dollfusi in the genus Grillotia Guiart, 1927. In order to avoid the homonymy with Grillotia dollfusi Carvajal, 1971, a new name, Grillotia carvajalregorum nom. n., is proposed. This species differs from the 16 valid species in the genus in the combination of the following characters: number and morphology of hooks in principal rows in proximal metabasal region of the tentacle, number and distribution of intercalary hooks, presence of clusters of hooklets, extent of band of hooklets on external surface of basal armature, site of origin of the retractor muscle, and features of the terminal genitalia. The present study describes the plerocerci and adult worms, and provides detailed description of the microthrix pattern and histology of this species for the first time.

Sperm competition and the evolution of the sperm hook in house mice

Sperm morphology varies considerably both between and within species. The sperm of many muroid rodents bear an apical hook at the proximal end of the head. The curvature of the sperm hook varies greatly across species, however the adaptive significance of the sperm hook is currently not known. In wood mice the apical hooks intertwine to form sperm 'trains', which exhibit faster swimming velocities than single cells. Thus, it has been suggested that if sperm 'trains' were advantageous in a competitive situation, then the apical sperm hook might be an evolutionary product of selection via sperm competition. A comparative study of rodent species provided support for the hypothesis, and showed that species with higher levels of sperm competition had more reflected sperm hooks. Here, we tested this hypothesis at the intraspecific level. We quantified sperm hook morphology from seven house mouse populations, and found that interpopulation variation in hook curvature was not explained by variation in sperm competition risk. Furthermore, observations of ejaculated sperm revealed that sperm groups are not a common characteristic of mouse ejaculates. We suggest that selection for sperm attachment to the oviduct epithelium, and thus better retainment of sperm fertilizing potential, may provide a more general explanation of the evolutionary relationship between sperm competition risk and the curvature of the sperm hook among rodents, and provide a phylogenetic comparison among rodent species that supports our hypothesis.

Cystic echinococcosis in Tunisia: analysis of hydatid cysts that have been surgically removed from patients

Echinococcosis/hydatidosis caused by Echinococcus granulosus has a widespread distribution in the human population of Tunisia, particularly in the north-west and centre-west of the country. In a recent study, the morphological features, fertility and viability of hydatid cysts that had been excised from patients in Tunis were explored, and the E. granulosus strain or genotype involved in each case was identified from morphology of the protoscolex hooks and the results of molecular genotyping. The hepatic cysts investigated came from 41 patients [31 women and 10 men, with a mean (S.E.) age of 43.41 (14.25) years] who were treated for cystic echinococcosis, by surgery but rarely with chemotherapy, at the La Rabta Hospital in Tunis, in the 12 months ending in June 2008. Most (56%) of these patients originated from rural areas in endemic governorates. Of the 60 hepatic cysts that were studied, 38.3% were located in the right lobe of the liver and 35.0% each involved both hepatic lobes. Almost a third (31.7%) of the excised cysts were degenerating, with the rest considered viable and either multivesicular (38.3%) or univesicular (30.0%). Almost all (93.3%) of the cysts were categorized as fertile, with a mean protoscolex viability of 21.8%. Protoscolex viability was relatively high in the viable univesicular cysts with a visible cyst wall and in the multivesicular and multiseptate cysts with daughter cysts, and lowest in the cysts that appeared to be solid calcified masses. The observed variation in protoscolex viability with cyst type, in cysts excised from patients before any chemotherapy, supports the cyst classification recommended by the World Health Organization but could also be compatible with the imaging-based 'Gharbi' classification. The results of the molecular genotyping showed that all 23 cysts investigated (which came from 20 of the patients) were caused by E. granulosus of the G1 genotype (also known as the 'sheep' or 'sheep-dog' strain).

Acanthobothrium minusn. sp. (Tetraphyllidea : Onchobotriidae) parasite deRaja asterias(Elasmobranchii : Rajidae) en Méditerranée

Among tetraphyllidean cestodes, parasitic in the spiral valve of Raja asterias Delaroche, colected from Algerian coasts, we obtained an onchobothriid of the genus Acanthobothrium, differing from all species of Acanthobothrium previously reported from Rajidae from Mediterranea and european Atlantic coast. This Cestode is characterized by its very small size (1-2 mm), its number of segments of the strobila (4-8), the morphology and size of hooks, the limited number (17-25) of testes and ovarian morphology. Together, these features places this Acanthobothrium in group "2" as defined by Ghoshroy & Caira (2001). We describe this onchobothriid as Acanthobothrium minus n. sp.

Echinococcus granulosus from Mexican pigs is the same strain as that in Polish pigs

Samples of Echinococcus granulosus from seven pigs from Mexico were compared with isolates of the parasite from pigs in Poland and representative strains and species of Echinococcus. Isolates from pigs in Mexico were found to be genetically identical to E. granulosus from Polish pigs and distinct from other major genotypes by sequencing part of the mitochondrial cytochrome c oxidase I (COI) mtDNA locus, restriction fragment length polymorphism (RFLP) of the polymerase chain reaction (PCR) amplified rDNA internal transcribed spacer (ITS) 1 using five different enzymes, and random amplified polymorphic DNA (RAPD) analysis. These results were complemented by data on hook morphology and together strengthen the view that Echinococcus maintained in a cycle involving pigs and dogs is a distinct strain that is conserved genetically in different geographical areas. The present study supports the close relationship of the cervid, camel and pig strains and raises the question of their taxonomic status.