Proteocephalids are a cosmopolitan and diverse group of tapeworms (Cestoda) that have colonized vertebrate hosts in freshwater and terrestrial environments. Despite the ubiquity of the group, key macroevolutionary processes that have driven the group's evolution have yet to be identified. Here, we review the phylogenetic relationships of proteocephalid tapeworms using publicly available (671) and newly generated (91) nucleotide sequences of the nuclear RNA28S and the mitochondrial MT-CO1 for 537 terminals. The main tree search was carried out under the parsimony optimality criterion, analysing different gene alignments simultaneously. Interestingly, we were not able to recover monophyly of the Proteocephalidae. Additionally, it was difficult to reconcile the tree with host and biogeographical data using traditional character optimization strategies in two dimensions. Therefore, we investigated if host and biogeographical data can be correlated with the parasite clades in a multidimensional space-thus considering multiple layers of information simultaneously. To that end, we used random forests (a class of machine learning models) to test the predictive potential of combined (not individual) host and biogeographical data in the context of the proteocephalid tree. Our resulting models can correctly place 88.85% (on average) of the terminals into eight representative clades. Moreover, we interactively increased the levels of clade perturbation probability and confirmed the expectation that model accuracy negatively correlates with the degree of clade perturbation. Our results show that host and biogeographical data can accurately predict proteocephalid clades in multidimensional space, even though they are difficult to optimize in the parasite tree. These results agree with the assumption that the evolution of proteocephalids is not independent of host and biogeography, and both may provide external support for our tree.

• MeSH
• Cestoda * genetics   classification   MeSH
• Phylogeny * MeSH
• Phylogeography MeSH
• Machine Learning * MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH

The parasite fauna of Neotropical reptiles is poorly known, and the number of parasites described in these hosts does not seem to correspond to the actual species diversity in this zoogeographical region. This also applies to tapeworms such as proteocephalids, which are rarely found in reptiles and are strictly specific to their reptilian hosts. In the present paper, three new species of Ophiotaenia La Rue, 1911 are described from three dipsadine snake species (Squamata: Colubridae) in Ecuador, namely O. jeanmarctouzeti sp. n. from the Neotropical blunt-headed treesnake Imantodes cenchoa (Linnaeus), O. barraganae sp. n. from the beautiful calico snake Oxyrhopus formosus (Wied-Neuwied) and O. velascoae sp. n. from the forest flame snake Oxyrhopus petolarius (Linnaeus). The new species are characterised by type 1 uterine development, the number and distribution of testes, the size of the scolex and other metric features. As no molecular data are available on the specimens collected more than 35 years ago, the phylogenetic relationships of the individual taxa are not known.

• Keywords
• Dipsadinae, Ophidia, South America, Tapeworms, morphology, species diversity, taxonomy,
• MeSH
• Cestoda * classification   isolation & purification   MeSH
• Cestode Infections veterinary   parasitology   epidemiology   MeSH
• Colubridae * parasitology   MeSH
• Species Specificity MeSH
• Phylogeny MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Ecuador MeSH

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.

• Keywords
• Morphology, Natricinae, Nearctic region, New species, Onchoproteocephalidea, Ophiotaenia, Taxonomy, Watersnakes,
• Publication type
• Journal Article MeSH

Proteocephalid tapeworms of frogs of the family Ranidae ('true' frogs) are reviewed with emphasis on their species diversity, host specificity and geographical distribution. New molecular data (nuclear lsrDNA and mitochondrial COI sequences) are presented for tapeworms of four species of ranid frogs in North America, including the poorly known Ophiotaenia saphena Osler, 1931 of Rana clamitans Latreille and R. catesbeiana (Shaw), which is redescribed using new material from Arkansas, USA. Tapeworms of R. sphenocephala (Cope) and R. pipiens Schreber, the latter previously identified as O. saphena, represent another, putative new species, but are not formally described due to insufficient available material. Proteocephalus papuensis Bursey, Goldberg et Kraus, 2008 from Sylvirana supragrisea (Menzies) is transferred to Ophiotaenia La Rue, 1911 as a new combination. After a critical review of the literature, only nine nominal species of Ophiotaenia are recognised as valid, which is in contrast to the large number of ranid frogs (> 440 spp.). The reasons for this striking disparity are briefly discussed, and a key based on morphology is presented for the identification of all species of Ophiotaenia from the Ranidae. Molecular data are available for only two taxa from North America that form a monophyletic group. The relationships among tapeworms of ranid frogs occurring in other zoogeographical regions are not yet known. The taxonomic status of Batrachotaenia Rudin, 1917, which was erected to accommodate proteocephalids from amphibians, is also discussed. To facilitate future studies, a tabulated summary of all 32 species of proteocephalids belonging to three genera reported from amphibians (frogs and salamanders) is presented, with information on their hosts, distribution, and taxonomically important characters, including key measurements.

• Keywords
• Amphibia, Anura, Nearctic region, Onchoproteocephalidea, Ophiotaenia, global diversity, molecular data, morphology, redescription, taxonomy,
• MeSH
• Cestoda * MeSH
• Cestode Infections * epidemiology   veterinary   MeSH
• Ranidae MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Geographicals
• North America MeSH

The tapeworms of fishes (Chondrichthyes and Actinopterygii) account one-third (1670 from around 5000) of the total tapeworm (Platyhelminthes: Cestoda) species diversity. In total 1186 species from 9 orders occur as adults in elasmobranchs (sharks, rays and chimaeras), and 484 species from 8 orders mature in ray-finned fishes (referred to here as teleosts). Teleost tapeworms are dominated by freshwater species (78%), but only 3% of elasmobranch tapeworms are known from freshwater rays of South America and Asia (Borneo). In the last 2 decades, vast progress has been made in understanding species diversity, host associations and interrelationships among fish tapeworms. In total, 172 new species have been described since 2017 (149 from elasmobranchs and 23 from teleosts; invalidly described taxa are not included, especially those from the Oriental region). Molecular data, however, largely limited to a few molecular markers (mainly 28S rDNA, but also 18S and cox1), are available for about 40% of fish tapeworm species. They allowed us to significantly improve our understanding of their interrelationships, including proposals of a new, more natural classification at the higher-taxonomy level (orders and families) as well as at the lower-taxonomy level (genera). In this review, we summarize the main advances and provide perspectives for future research.

• Keywords
• DNA sequencing, Distribution, elasmobranchs, host associations, pathogens, phylogenetic relationships, ray-finned fish, species diversity, taxonomy,
• MeSH
• Cestoda * genetics   MeSH
• Cestode Infections * epidemiology   veterinary   MeSH
• Diphyllobothrium * MeSH
• Elasmobranchii * MeSH
• Phylogeny MeSH
• Fish Diseases * epidemiology   MeSH
• Fishes MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH

A new genus, Laruella n. gen., is proposed for the proteocephalid cestode L. perplexa (La Rue, 1911) n. comb. (syn. Proteocephalus perplexus La Rue, 1911), a parasite of a 'living fossil', the bowfin (Amia calva), in North America. The new genus is differentiated from other proteocephalid genera by having a massive four-lobed scolex without an apical organ and bearing suckers possessing tear-shaped sphincters on their inner rim, vitelline follicles forming L-shaped lateral fields, with the vitellarium turned inwards (medially) ventrally alongside the posterior margin of the ovary, a ring-like vaginal sphincter situated at a considerable distance from the genital atrium, and ellipsoid eggs resembling those of bothriocephalid and diphyllobothriid tapeworms, except for the absence of an operculum. Phylogenetic relationships of the new genus are not resolved, but it belongs to the so-called Neotropical clade of the Proteocephalidae, which is composed mainly of Neotropical tapeworms of siluriforms and other teleosts, but also Nearctic and Palaearctic species of Ophiotaenia La Rue, 1911 from snakes and amphibians. A morphologically similar species, Proteocephalus ambloplitis (Leidy, 1887) from bass (Micropterus spp.) in North America, is provisionally retained in Proteocephalus Weinland, 1858 because its relationships to L. perplexa are not yet clear. The former species differs from L. perplexa by the presence of a large apical organ, large, elongate vaginal sphincter situated near the genital atrium, vitelline follicles limited to lateral longitudinal fields, strongly coiled vas deferens within the cirrus sac, and a convoluted vaginal canal anterior to the ovarian isthmus. Laruella perplexa reportedly has a s broad spectrum of hosts but most are likely postcyclic or accidental hosts. A list of cestode parasites reported from bowfin is provided; it includes eight species and three taxa not identified to the species level. However, only three adult cestodes, L. perplexa and two species of Haplobothrium Cooper, 1914, are typical tapeworm parasites of bowfin, but previous molecular studies indicate possible existence of a putative new species in bowfin.

• Keywords
• Actinopterygii, Morphology, North America, Onchoproteocephalidea, Tapeworms, Taxonomy,
• Publication type
• Journal Article MeSH

Ophiotaenia echidis n. sp. (Cestoda: Proteocephalidae) is described from the intestine of one of the world's deadliest snakes, the saw-scaled viper Echis carinatus sochureki Stemmler (Ophidia: Viperidae) in the United Arab Emirates. The new species differs from other species of the non-monophyletic Ophiotaenia by the position of testes in two longitudinal lines on both sides of the uterus, and by the large size of an embryophore (diameter of 44-55 μm versus less than 40 μm in other species). Phylogenetic reconstructions based on lsrDNA and concatenated lsrDNA + COI datasets place the new species among proteocephalids from unrelated zoogeographical realms but mostly infecting venomous snakes. In all analyses, O. echidis n. sp. exhibited a strongly supported sister relationship with O. lapata Rambeloson, Ranaivoson et de Chambrier, 2012, a parasite of a pseudoxyrhophiid snake endemic to Madagascar. Despite a shared close evolutionary history between these taxa, morphological synapomorphies remain unclear, which impedes the erection of a new genus to accommodate them. A list of the 71 tapeworms of the former, non-monophyletic subfamily Proteocephalinae, parasitising snakes and lizards, including species inquirendae, and the phylogenetically closely related Thaumasioscolex didelphidis from opossum, with selected characteristics, is also provided, together with a checklist of helminth parasites reported from E. carinatus.

• Keywords
• Morphology, Onchoproteocephalidea, Phylogenetic relationships, Snakes, Tapeworms, Taxonomy, United Arab Emirates,
• Publication type
• Journal Article MeSH

Based on morphological evaluation of type-specimens and new material collected in three species of monitor lizards (Squamata: Varanidae), the diagnosis of the monotypic Rostellotaenia Freze, 1963 (Proteocephalidae: 'Acanthotaeniinae') is amended. The genus differs from Acanthotaenia von Linstow, 1903, with which it was previously synonymised, by the shape of the scolex with a wide, dome-shaped rostellum, the posterior extent of the uterus, which does not overpass the ovarian isthmus posteriorly, well-developed retractor muscles connecting the rostellum with the neck region, absence of a well-developed, ring-like vaginal sphincter, shorter and wider proglottides, and geographical distribution (Ethiopian region only). The type- and only species, R. nilotica (Beddard, 1913), is redescribed and two new definitive hosts, Varanus albigularis Daudin and V. exanthematicus (Bosc), are reported. Host specificity of R. nilotica, which exhibits remarkable morphological variability, is stenoxenous, i.e. it occurs in several congeneric species of African monitor lizards, unlike species of Acanthotaenia, which are strictly specific (oioxenous).

• MeSH
• Cestoda anatomy & histology   classification   MeSH
• Species Specificity MeSH
• Phylogeny MeSH
• Lizards parasitology   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

A morphological and molecular phylogenetic study of proteocephalid tapeworms of the genus Acanthotaenia von Linstow, 1903, parasites of monitors (Varanidae), was carried out. The type species, A. shipleyi von Linstow, 1903, which was originally described based on an immature specimen from Sri Lanka, is redescribed based on new material from the type host, Varanus salvator, in Sri Lanka, Malaysia, and Vietnam, and its neotype is designated. In addition, Acanthotaenia susanae n. sp. is described from Varanus nebulosus in Vietnam. The new species differs from congeners by the large size of the scolex, width of the rostellum and the number of testes. New molecular data (sequences of lsrDNA and cox1) revealed Acanthotaenia paraphyletic with the inclusion of Australotaenia bunthangi de Chambrier & Scholz, 2012, a parasite of Enhydris enhydris (Ophidia: Homalopsidae) in Cambodia. Molecular data confirm a wide distribution of A. shipleyi (isolates from Malaysia and Vietnam were almost identical) and indicate a strict host specificity (oioxeny) of individual species of the genus. Type specimens of four species made it possible to supplement their morphological descriptions. A survey of all species of Acanthotaenia recognised as valid is presented and the following taxonomic changes are proposed: Acanthotaenia pythonis Wahid, 1968 described from the green python, Morelia viridis, in a zoo, is transferred to Kapsulotaenia as Kapsulotaenia pythonis (Wahid, 1968) n. comb., because it possesses intrauterine eggs grouped in capsules. Acanthotaenia gracilis (Beddard, 1913) from Varanus varius in Australia is considered to be species inquirenda because its original descriptions did not contain sufficient data for adequate circumscription and differentiation from congeners and type material was not available. Generic diagnosis of Acanthotaenia is amended and a key to its seven species is provided.

• Keywords
• Acanthotaeniinae, Eucestoda, Onchoproteocephalidea, Phylogeny, Reptiles, Taxonomy, cox1, lsrDNA,
• MeSH
• Cestoda classification   genetics   growth & development   isolation & purification   MeSH
• Cestode Infections parasitology   veterinary   MeSH
• Phylogeny MeSH
• Snakes parasitology   MeSH
• Lizards parasitology   MeSH
• Parasites MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Australia MeSH
• Cambodia MeSH
• Malaysia MeSH
• Vietnam MeSH

As part of a complex revision of proteocephalid cestodes parasitic in freshwater bony fishes of the Neotropical Region, the genus Chambriella Rego, Chubb & Pavanelli, 1999 is redefined based on detailed examination of type-specimens and newly collected material of both nominal species of the genus. This examination revealed that the type-species C. agostinhoi (Pavanelli & Santos, 1992) from Zungaro jahu (Ihering) (type-host) and Z. zungaro (Humboldt) is indistinguishable from Lenhataenia megacephala (Woodland, 1934) from Sorubimichthys planiceps (Spix & Agassiz) (all hosts Siluriformes: Pimelodidae), the type- and only species of the genus. New molecular data (partial sequences of the large subunit nuclear ribosomal RNA gene) support the conspecificity of these taxa. As a result, Lenhataenia de Chambrier & Scholz, 2008 becomes a junior synonym of Chambriella and its type-species, C. agostinhoi, a junior synonym of C. megacephala (Woodland, 1934) n. comb. The second species of Chambriella, C. paranaensis (Pavanelli & Rego, 1989) from Hemisorubim platyrhynchos (Valenciennes), is transferred to a new genus, Riggenbachiella n. g., as R. paranaense (Pavanelli & Rego, 1989) n. comb. Riggenbachiella amazonense n. sp. (syn. Chambriella sp. of de Chambrier & Scholz, 2008) from S. planiceps (type-host), Phractocephalus hemioliopterus (Bloch & Schneider) and Z. zungaro is described and designated as the type-species of the new genus. Riggenbachiella n. g. is placed in the subfamily Monticelliinae Mola, 1929, because of the cortical position of the testes, ovary, vitelline follicles and uterus, and is mainly characterised by the possession of a sigmoid cirrus-sac with voluminous, chambered internal seminal vesicle, and bi-loculate suckers.

• MeSH
• Cestoda anatomy & histology   classification   genetics   MeSH
• DNA, Helminth genetics   MeSH
• Species Specificity MeSH
• Rivers MeSH
• Intestines parasitology   MeSH
• Catfishes parasitology   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Brazil MeSH
• Names of Substances
• DNA, Helminth MeSH