Diversity and biology of Spirometra tapeworms (Cestoda: Diphyllobothriidea), zoonotic parasites of wildlife: A review.

Tapeworms of the genus Spirometra Faust, Campbell et Kellogg, 1929 have long been known as intestinal parasites of carnivores and their larvae (spargana) have been found in various vertebrates. Nevertheless, their species diversity, host associations and geographical distribution remain poorly understood. Molecular data clearly confirm the validity of the genus, which has been synonymised by several authors with Diphyllobothrium Cobbold, 1858. Despite morphological similarities between the species of the two genera, they are not closely related and also differ in their life cycle. The present review provides a list of the species recognised as valid and additional genotypes that may represent other species, with a basic characterisation of each taxon and comments on their validity, the probable range of definitive and intermediate hosts, and their distribution. The existing taxonomic problems and the insufficient knowledge of the host specificity and distribution of Spirometra tapeworms can only be solved by combining molecular and morphological data, i.e. by comparing genetically characterised specimens with corresponding morphological vouchers (hologenophores). Further targeted sampling and surveys are required to clarify the distribution and host associations.

Tapeworms (Cestoda: Proteocephalidae) of the gars (Lepisosteidae), living fossils in America, including proposal of a new genus and a new species.

A new genus, Cordicestus, is proposed to accommodate proteocephalid tapeworms parasitising gars (Lepisosteiformes: Lepisosteidae) in North and Central America that were previously placed in the polyphyletic genus Proteocephalus Weinland, 1858. The new genus differs from other proteocephalid genera by the particular morphology of the scolex, which is small, protrudes apically but has no apical organ, and bears flat, heart-shaped (= cordis) suckers. In addition, the species of the new genus have an elongated cirrus sac with an almost straight internal vas deferens and wide, sinuous ventral osmoregulatory canals with secondary canals directed outwards. The type species of the new genus, Cordicestus singularis (La Rue, 1911) n. comb., is redescribed based on new material from the shortnose gar, Lepisosteus platostomus Rafinesque (type host), and the spotted gar, L. oculatus Winchell, in the United States. Cordicestus rafaeli n. sp. is described from the tropical gar, Atractosteus tropicus Gill, in Mexico. The new species differs from its relatives primarily by the presence of craspedote proglottids (acraspedote in other species) and some biometric features. All species of Cordicestus are revised, including unidentified specimens from A. tropicus and the Cuban gar A. tristoechus (Bloch and Schneider) in Nicaragua and Cuba, respectively, which may be new species, and a key to the identification of these taxa is provided. Molecular data available for two nominal species of the new genus indicate the possible existence of another species of Cordicestus in Lepisosteus in the USA.

Small intestinal flukes of the genus Metagonimus (Digenea: Heterophyidae) in Europe and the Middle East: A review of parasites with zoonotic potential.

The heterophyid trematode Metagonimus romanicus (Ciurea, 1915) (Digenea) is redescribed on the basis of type material from domestic dogs (Canis familiaris) in Romania, vouchers from experimentally infected cats (Felis catus) and adults recovered from golden hamsters (Mesocricetus auratus) infected with metacercariae from scales of chub (Squalius cephalus) and common nase (Chondrostoma nasus) (Cypriniformes: Leuciscidae) in Hungary. This trematode, endemic to Europe and neighbouring regions (northwestern Türkiye), was previously misidentified as M. yokogawai (Katsurada, 1912), a zoonotic parasite of humans in East Asia. However, the two species differ considerably both genetically and morphologically, e.g., in the position of the ventral sucker, the presence of the prepharynx, the anterior extent of the vitelline follicles and the posterior extent of the uterus. Metagonimus ciureanus (Witenberg, 1929) (syn. Dexiogonimus ciureanus Witenberg, 1929), described from domestic cats and dogs in Israel, is a valid species distributed in the Middle East and Transcaucasia, which is also confirmed by molecular data. It differs from all Metagonimus species, including M. romanicus, in having symmetrical testes instead of the oblique testes of the other congeners. The zoonotic significance of M. romanicus and M. ciureanus is unclear, but appears to be low in Europe, mainly because raw or undercooked, whole fish with scales are generally not consumed. Accidental infection of fishermen by metacercariae in the scales when cleaning fish is more likely, but has never been reported. Remains of cyprinoids with scales infected with metacercariae of Metagonimus spp. can be an important natural source of infection for dogs, cats, and other carnivores, which can serve as a reservoir for these parasites.

Title: Petits trématodes intestinaux du genre Metagonimus (Digenea : Heterophyidae) en Europe et au Moyen-Orient : revue de parasites à potentiel zoonotique. Abstract: Le trématode Heterophyidae Metagonimus romanicus (Ciurea, 1915) (Digenea) est redécrit sur la base de matériel type provenant de chiens domestiques (Canis familiaris) en Roumanie, de vouchers issus de chats (Felis catus) infectés expérimentalement et d'adultes collectés chez des hamsters dorés (Mesocricetus auratus) infectés par des métacercaires provenant d'écailles de chevesne commun (Squalius cephalus) et de nase commun (Chondrostoma nasus) (Cypriniformes : Leuciscidae) de Hongrie. Ce trématode, endémique d'Europe et des régions voisines (nord-ouest de la Turquie), avait été précédemment identifié à tort comme étant M. yokogawai (Katsurada, 1912), un parasite zoonotique des humains en Asie de l'Est. Cependant, les deux espèces diffèrent considérablement sur le plan génétique et morphologique, par exemple par la position de la ventouse ventrale, la présence du prépharynx, l'étendue antérieure des follicules vitellins et l'étendue postérieure de l'utérus. Metagonimus ciureanus (Witenberg, 1929) (syn. Dexiogonimus ciureanus Witenberg, 1929), décrite chez des chats et des chiens domestiques en Israël, est une espèce valide répartie au Moyen-Orient et en Transcaucasie, ce qui est également confirmé par des données moléculaires. Cette espèce diffère de toutes les espèces de Metagonimus, y compris M. romanicus, par ses testicules symétriques au lieu des testicules obliques des autres congénères. L'importance zoonotique de M. romanicus et M. ciureanus n'est pas claire, mais semble faible en Europe, principalement parce que les poissons n'y sont généralement pas consommés crus ou insuffisamment cuits et entiers avec les écailles. L'infection accidentelle des pêcheurs par des métacercaires présents dans les écailles lors du nettoyage du poisson est plus probable mais n'a jamais été signalée. Les restes de poissons cyprinoïdes avec les écailles, infectés par des métacercaires de Metagonimus spp. peuvent être une source naturelle importante d'infection pour les chiens, les chats et autres carnivores, qui peuvent servir de réservoir à ces parasites.

Gaps in parasitological research in the molecular era.

We live in the age of molecular biology and '-omics', and molecular methods have opened up unimagined possibilities for biological research, including parasitology. However, too one-sided a focus on new approaches can lead to major gaps as less 'cool' topics are neglected. Selected areas of research are briefly discussed to highlight the gaps caused by the current excessive focus on molecular and '-omics' methods. It is crucial to combine both 'classical' and modern methods without neglecting the complexity of the interactions of parasites with their hosts and the environment (One Health concept), which is even more urgent in today's rapidly changing world. Parasitologists should be more involved in field studies and multidisciplinary assessment of parasites.

Discovering high species diversity of Ophiotaenia tapeworms (Cestoda: Proteocephalidae) of watersnakes (Colubridae) in North America.

Tapeworms of the genus Ophiotaenia La Rue, 1911 parasitize herptiles (= amphibians and 'reptiles') throughout the world, with about 100 species recognised as valid. In the present work, the North American species found in watersnakes (Colubridae) are reviewed. An examination of the holotype of Ophiotaenia perspicua La Rue, 1911, the type species of the genus, and other specimens from Nerodia rhombifer (Hallowell) revealed that two species were used for the species description. The 'true' O. perspicua has a small scolex and small, round suckers. This species is redescribed based on new material from Oklahoma, USA. The other species from N. rhombifer, Ophiotaenia laruei n. sp., has a larger scolex and larger, almost triangular suckers. Examination of the types of O. variabilis (Brooks, 1978) from N. rhombifer and N. cyclopion (Duméril, Bibron et Duméril) from Louisiana, USA has revealed that it is a mixture of two or more species. Because of poor quality of these specimens, it is not possible to adequately characterise O. variabilis, which is considered a species inquirenda. In addition, two new species are described from Nerodia fasciata confluens (Blanchard). Ophiotaenia currani n. sp. from Mississippi, USA is characterised by elongate, narrow proglottids, few testes, and a relatively long cirrus sac. Ophiotaenia tkachi n. sp. from Louisiana, USA is characterised by relatively short and wide proglottids, more testes, and an unusual terminal part of the vagina with folds. Morphologically similar tapeworms of N. fasciata confluens, N. erythrogaster (Förster), N. sipedon (Linnaeus), and Agkistrodon piscivorus (Lacépède) (Viperidae) from Arkansas and Oklahoma, USA, which are genetically nearly identical, are considered to be conspecific with O. tkachi n. sp. The present data suggest a high, previously undescribed species diversity of proteocephalid tapeworms in watersnakes in North America, and generally strict host specificity of these tapeworms.