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. The species of Cordicestus are discussed, 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 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.

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.

TAPEWORMS (CESTODA: OPHIOTAENIA) FROM THE NORTHERN COTTONMOUTH (AGKISTRODON PISCIVORUS).

The northern cottonmouth, Agkistrodon piscivorus (Lacépède, 1789) (Viperidae: Crotalinae), occurs in the southeastern United States and is one of the few semiaquatic vipers in the world. Three proteocephalid tapeworms of the genus OphiotaeniaLa Rue, 1911 (Cestoda), have been described from this venomous snake. A critical evaluation of type specimens and tapeworms recently collected from A. piscivorus has revealed that only 2 species, Ophiotaenia marenzelleri (Barrois, 1898) and Ophiotaenia grandisLa Rue, 1911 (new synonym Ophiotaenia agkistrodontis [Harwood, 1933]), are specific parasites of this crotaline viper; both species are redescribed here. Ophiotaenia grandis was originally described from a mixture of 2 species: 'true' O. grandis, which is indistinguishable from O. agkistrodontis described 22 yr later and thus considered to be a junior synonym of O. grandis, and O. marenzelleri. Ophiotaenia marenzelleri, also reported from the pygmy rattlesnake, Sistrurus miliarius (Linnaeus, 1766), is a larger tapeworm with a massive scolex, a large cirrus sac, a very large, annular vaginal sphincter near the equatorial gonopore, and an oval, 3-layered embryophore surrounded by a nearly square hyaline outer membrane. Ophiotaenia grandis is much smaller and more slender and has a narrower scolex, a smaller cirrus sac and vaginal sphincter, a 2-layered embryophore, and a distinctly pre-equatorial gonopore. In addition to O. marenzelleri and O. grandis, other Ophiotaenia species typical of semiaquatic snakes (Colubridae: Natricinae) may be present in the northern cottonmouth, which serves only as a postcyclic or occasional host. There is also a tabular summary of 18 species of Ophiotaenia from semiaquatic snakes worldwide, with information on their hosts, distribution, and taxonomically important characters, including key measurements.

A global survey of tapeworms (Cestoda: Proteocephalidae) of 'true' frogs (Amphibia: Ranidae), including a tabulated list of all proteocephalids parasitising amphibians.

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.

A new tapeworm from Compsophis infralineatus (Pseudoxyrhophiidae), an endemic snake of Madagascar: Scratching the surface of undiscovered reptilian parasite diversity.

A new species of proteocephalid cestodes, provisionally assigned to the polyphyletic genus Ophiotaenia La Rue, 1911 (Cestoda: Proteocephalidae), is described from Compsophis infralineatus (Günther) (Serpentes: Pseudoxyrhophiidae) endemic to Madagascar. Ophiotaenia oreae n. sp. differs from all African and Asian species of Ophiotaenia by possessing more uterine diverticula (68-82 on one side). It is also characterised by the absence of an apical organ, the relative sizes of the cirrus-sac and ovary, the almost equatorial position of the gonopore, the diameter of the embryophore, and other biometric characteristics. Phylogenetic relationships of the new species indicate its relatedness to Indomalayan and Australasian proteocephalids from reptiles. Ophiotaenia oreae n. sp. formed a well-supported clade composed of species of Australophiotaenia de Chambrier, Beveridge and Scholz, 2018 from Australian snakes, Macrobothriotaenia ficta (Meggitt, 1931) from Xenopeltis unicolor Reinwardt in Boie from Vietnam, Ophiotaenia sp. from Trimeresurus flavomaculatus (Gray) from the Philippines, and Ophiotaenia bungari de Chambrier, Binh and Scholz, 2012 from Bungarus fasciatus (Schneider) from Vietnam. The only proteocephalid from Madagascan snakes sequenced so far, Ophiotaenia lapata Rambeloson, Ranaivoson and de Chambrier, 2012 from Madagascarophis colubrinus (Schlegel), does not form a monophyletic group with the new species. The actual species diversity of reptilian cestodes in Madagascar is undoubtedly underestimated. Because of the assumed strict (oioxenous) host specificity of reptilian proteocephalids and rich fauna of snakes occurring in Madagascar, it is plausible to expect the existence of dozens new species of proteocephalids on this island.

Description of the first species of Pseudoendorchis (Cestoda: Proteocephalidae) with uniloculate suckers from the pimelodid catfish Megalonema platycephalum, with comments on the taxonomic importance of the terminal vagina.

The proteocephalid genus Pseudoendorchis (Cestoda: Onchoproteocephalidea) has recently been proposed to accommodate seven species/species-level lineages of tapeworm parasites of catfishes (Siluriformes) in the Neotropical region, based on integration of genetic information, and morphological and ecological data. Its members are typified by having a large Mehlis' gland, representing more than 1/5 (usually 1/4-1/2) of proglottid width, and the vagina always anterior to the cirrus-sac. Critical examination of previously unstudied museum cestodes tentatively designated as Pseudoendorchis sp. 3 from Megalonema platycephalum (Pimelodidae) in the Peruvian Amazon made it possible to formally describe this taxon and to differentiate it from all congeneric species. The new species, which is the first parasite of M. platycephalum ever recorded, is characterised mainly by having the scolex bearing four uniloculate suckers (biloculate in all nominal species of the genus), the lowest relative surface of the ovary (ratio of its surface to that of the whole proglottid) among species of the genus (< 9% versus > 11%, usually 15-20%), and an extraordinarily large Mehlis' gland (its diameter represents 41-50% of proglottid width). Morphology of the terminal portion of the vaginal canals in proteocephalids is briefly discussed.

Ophiotaenia echidis n. sp. (Cestoda: Proteocephalidae) from the saw-scaled viper, Echis carinatus sochureki Stemmler (Ophidia: Viperidae), one of the world's deadliest snakes, from the United Arab Emirates.

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.

New arrangement of three genera of fish tapeworms (Cestoda: Proteocephalidae) in catfishes (Siluriformes) from the Neotropical Region: taxonomic implications of molecular phylogenetic analyses.

Tapeworms (Cestoda: Proteocephalidae) are the dominant component of communities of intestinal parasites in pimelodid and other catfishes (Siluriformes) from South America. Even though these parasites have been studied intensively over more than one century, molecular taxonomy and phylogenetics have questioned their morphology-based classification, thus raising doubts about the systematic value of traits commonly used to circumscribe individual taxa. In the present study, members of three morphologically well-characterized genera of proteocephalids from pimelodid (Hemisorubim platyrhynchos and Sorubim lima) and auchenipterid (Ageneiosus inermis) catfishes from the Paraná or Amazon River basins were subjected to DNA sequencing of the large subunit nuclear ribosomal RNA (lsrDNA) and complete mitochondrial cytochrome c oxidase subunit I (COI). Phylogenetic analyses revealed the sister relationship between Manaosia bracodemoca and Mariauxiella piscatorum, and among Mariauxiella pimelodi and Ageneiella brevifilis. As a result, Mar. piscatorum and A. brevifilis are transferred to Manaosia and Mariauxiella, respectively, as Manaosia piscatorum n. comb. and Mariauxiella brevifilis n. comb., and the genus Ageneiella is suppressed. Diagnoses of Manaosia and Mariauxiella are amended. In addition, the present study revealed misidentification of tapeworms whose sequences are deposited in the GenBank database.

Molecular data reveal unexpected species diversity of tapeworms of Australasian reptiles: revision of Kapsulotaenia (Cestoda: Proteocephalidae).

Species diversity and interrelationships of tapeworms of the genus Kapsulotaenia Freze, 1963 (Proteocephalidae: Acanthotaeniinae), parasites of lizards, especially monitors (Varanus spp.) in the Australasian region, were re-assessed using an interdisciplinary approach. Molecular phylogenetic analyses of newly characterized lsrDNA and cox1 sequences confirmed monophyly of the genus, which is typified by the presence of eggs in capsules, and also indicated a strict (oioxenous) level of host specificity of its species thus revealing unexpected species diversity. Diagnoses of insufficiently described species were amended based on a study of the types and freshly collected specimens and, in addition, three new species were described. A list of ten species of the genus recognized as valid is provided, including illustrations of taxonomically important structures of poorly known taxa. Kapsulotaenia beveridgei n. sp. from V. rosenbergi in Australia differs from all other species of Kapsulotaenia but K. frezei and K. saccifera by having a lower number of testes and an absence of banana-shaped clusters of eggs. Kapsulotaenia cannoni n. sp. from V. gouldii can be distinguished from all species but K. chisholmae by a smaller scolex diameter and from all remaining species by its bigger cirrus-sac ratio and a bigger Mehlis' gland/proglottid width ratio. Kapsulotaenia cannoni n. sp. differs from K. chisholmae, by the presence of an armed cirrus and a lower number of eggs in cluster (3-7 versus 8-13). Kapsulotaenia nybelini n. sp., which also occurs in V. gouldii, differs from K. tidswelli, K. frezei and K. beveridgei by having a greater number of testes, and it differs from K. varia by having a smaller relative size of the ovary. It differs from K. saccifera by the absence of banana-shaped cluster, and from K. pythonis by the number of eggs in clusters. Identification keys for all species of Kapsulotaenia and genera of the Acanthotaeniinae are also provided, together with SEM micrographs of three species, including two newly described species.

Amendment of Rostellotaenia Freze, 1963 (Cestoda: Proteocephalidae) from African monitors (Varanus spp.) and a redescription of its type-species, R. nilotica (Beddard, 1913).

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).

Revision of Acanthotaenia von Linstow, 1903 (Cestoda: Proteocephalidae), parasites of monitors (Varanus spp.), based on morphological and molecular data.

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.

Tapeworms (Cestoda: Proteocephalidae) of Australian reptiles: hidden diversity of strictly host-specific parasites.

Reptilian fauna of Australia is extraordinarily rich and diverse, but very little is known about parasites of reptiles, including proteocephalid cestodes of the genus Ophiotaenia La Rue, 1911. In the present survey, data on these parasites are summarised for the first time based on detailed evaluation of all available type and voucher specimens. This survey includes five named species, with four species redescribed, namely O. amphiboluri (Nybelin, 1917), O. longmani Johnston, 1916, O. mjobergi (Nybelin, 1917), and O. striata (Johnston, 1914), and 9 putative new species which are not formally described because of their poor quality and scarce material. An identification key is given for the five named species and unnamed species are briefly characterised with focus on their differential characteristics to facilitate their description as new taxa in the future. Australian species of Ophiotaenia form a monophyletic lineage, whose members share several morphological traits which are absent or rare in other proteocephalids, such as a three-layered embryophore, a scolex with large, anteriorly directed suckers, eggs with thick-walled embryophores, exclusively dorsal and paramuscular position of vitelline follicles, and a postequatorial to equatorial genital pore in most species. A new genus, Australophiotaenia, is proposed to accommodate the species from Australian reptiles that share the above-mentioned characters.

Redescription of Sciadocephalus megalodiscus Diesing, 1850, An Unusual Neotropical Fish Tapeworm (Cestoda: Proteocephalidae).

The tapeworm Sciadocephalus megalodiscus Diesing, 1850 (Cestoda: Proteocephalidae), is redescribed based on newly collected specimens parasitizing tucunare peacock bass, Cichla monoculus Agassiz, 1831 (Perciformes: Cichlidae), in the Peruvian Amazon. Even though this cestode was redescribed 2 decades ago, that redescription did not report some of the unique features of this species. The most unusual characteristics of the species are (1) peculiar formation of the uterus, with fast formation of numerous, tightly packed diverticula protruding ventrally and dorsally, with simultaneous disintegration of the ovary and vitelline follicles in the first pregravid proglottids; (2) inverted umbrella-shaped scolex with a well-developed apical sucker; (3) a large-sized, follicular (grape cluster-like) ovary, which occupies most of the central (median) third of proglottids, with the ovarian isthmus situated almost equatorially; (4) regular alternation of genital pores; (5) a well-developed internal seminal vesicle; and (6) a small-sized strobila (shorter than 6 mm) consisting of few proglottids (15-20). Preliminary molecular data reveal S. megalodiscus to be most closely related to Cichlidocestus gillesi, the type species of the recently erected Cichlidocestus de Chambrier, Pinacho-Pinacho, Hernández-Orts, and Scholz, 2017. Species of both genera parasitize Neotropical cichlids and are unique among all proteocephalids in the shape and position of the ovary. They also share other morphological characteristics unusual among other proteocephalids, and thus these 2 genera can be considered good candidates to be placed in a new, higher-level taxon such as separate subfamily or even family when a new, more natural classification of the Proteocephalidae is proposed.

Annotated checklist of fish cestodes from South America.

An exhaustive literature search supplemented by a critical examination of records made it possible to present an annotated checklist of tapeworms (Cestoda) that, as adults or larvae (metacestodes), parasitize freshwater, brackish water and marine fishes, i.e. cartilaginous and bony fishes, in South America. The current knowledge of their species diversity, host associations and geographical distribution is reviewed. Taxonomic problems are discussed based on a critical evaluation of the literature and information on DNA sequences of individual taxa is provided to facilitate future taxonomic and phylogenetic studies. As expected, the current knowledge is quite uneven regarding the number of taxa and host-associations reported from the principal river basins and marine ecoregions. These differences may not only reflect the actual cestode richness but may also be due to the research effort that has been devoted to unravelling the diversity of these endoparasitic helminths in individual countries. A total of 297 valid species, 61 taxa identified to the generic level, in addition to unidentified cestodes, were recorded from 401 species of fish hosts. Among the recognized cestode orders, 13 have been recorded in South America, with the Onchoproteocephalidea displaying the highest species richness, representing c. 50% of all species diversity. The majority of records include teleost fish hosts (79%) that harbour larval and adult stages of cestodes, whereas stingrays (Myliobatiformes) exhibit the highest proportion of records (39%) among the elasmobranch hosts. Fish cestodes are ubiquitous in South America, being mostly recorded from the Warm Temperate Southeastern Pacific (WTSP; 31%) for marine hosts and the Amazon River basin (45%) for freshwater ones. The following problems were detected during the compilation of literary data: (i) unreliability of many records; (ii) poor taxonomic resolution, i.e. identification made only to the genus or even family level; (iii) doubtful host identification; and (iv) the absence of voucher specimens that would enable us to verify identification. It is thus strongly recommended to always deposit representative specimens in any type of studies, including faunal surveys and ecological studies. An analysis of the proportion of three basic types of studies, i.e. surveys, taxonomic and ecological papers, has shown a considerable increase of ecological studies over the last decade.

Untangling convoluted taxonomy of Chambriella Rego, Chubb & Pavanelli, 1999 (Cestoda: Proteocephalidae), with erection of Riggenbachiella n. g. and the description of a new species from pimelodid catfishes in the Neotropical Region.

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.

Proteocephalid tapeworms (Cestoda: Onchoproteocephalidea) of loaches (Cobitoidea): Evidence for monophyly and high endemism of parasites in the Far East.

The parasite fauna of loaches (Cypriniformes: Cobitoidea), a group of small bottom-dwelling freshwater fishes with a mostly Eurasian distribution, remains a largely unknown quantity. Here we revise the taxonomy of tapeworms of the genus Proteocephalus Weinland, 1858 (Cestoda: Proteocephalidae) that had been found in loaches from the Palaearctic Region (Central Europe, Japan and Russia [Primorsky Region]). Molecular phylogenetic analysis based on two nuclear (ssr- and lsrDNA) and two mitochondrial genes (cox1 and rrnL) revealed a monophyletic group consisting of four valid species nesting within the Proteocephalus-aggregate: (i) Proteocephalus sagittus (Grimm, 1872) from Barbatula barbatula (Europe, Russia and Tajikistan), (ii) Proteocephalus demshini n. sp. from Barbatula toni (Russian Far East - Primorsky Region), (iii) Proteocephalus midoriensis Shimazu, 1990 from Lefua echigonia (Japan) and L. costata (Russia) (new host and geographical record), and (iv) Proteocephalus misgurni n. sp. from Misgurnus anguillicaudatus (Russia; Primorsky Region). Proteocephalus sagittus and P. demshini, and P. midoriensis and P. misgurni were recovered as sister taxa, respectively. Proteocephalus sagittus and P. demshini are characterized by having proglottids that are wider than long, an elongate to pyriform cirrus-sac and the vitelline follicles that form wide lateral bands. Proteocephalus midoriensis and P. misgurni are characterized by having proglottids that are more elongate and an ovoid to almost spherical cirrus-sac and the vitelline follicles forming narrow lateral bands. Proteocephalus demshini differs from P. sagittus in the posterolateral extent of the vitelline follicles, whereas P. misgurni can be distinguished from P. midoriensis mainly by the relative size of the ovary, posterior extent of the vitelline follicles and width of the scolex. Unlike most species of the Proteocephalus-aggregate that possess an apical sucker, all species from loaches are devoid of any apical organ. The existence of two new species in loaches from the Primorsky Region of Russia indicates high endemism of fish parasites in this region. A key to the identification of recognized species from loaches is provided.

A New Genus and Two New Species of Proteocephalidean Tapeworms (Cestoda) from Cichlid Fish (Perciformes: Cichlidae) in the Neotropics.

Cichlidocestus n. gen. is proposed to accommodate 2 new species of proteocephalidean cestodes, Cichlidocestus gillesi n. sp. from Cichlasoma amazonarum in Peru (type species) and Cichlidocestus janikae n. sp. from Hypsophrys nicaraguensis (all Perciformes: Cichlidae) in Costa Rica. The new genus is unique among all but 1 proteocephalidean genera in the position of the ovary that occupies the middle and posterior thirds of the median region of proglottids (vs. the ovary in the posterior third of proglottids near their posterior margin in all but 1 remaining taxa). In addition, Cichlidocestus is typified by the presence of a voluminous, spherical, internal seminal vesicle, several pairs of ventral excretory canals in the medulla, a pyramidal, quadrilobed scolex with an apical muscular sucker, and the posterior extent of the testes that may reach almost to the posterior margin of proglottids. The new genus shares the position of the ovary and its extension with Sciadocephalus (also a parasite of cichlids in the Neotropics as the new taxon); in all remaining proteocephalideans the ovary occupies the posterior third only. Sciadocephalus differs from Cichlidocestus by a different morphology of the scolex, which possesses an umbrella-like metascolex that is markedly wider than the strobila, the number of ventral osmoregulatory canals, and development of the uterus, which forms capsule-like formations filled with eggs in Sciadocephalus megalodiscus (vs. simple lateral diverticula in Cichlidocestus spp.). Both new species of Cichlidocestus can be easily distinguished from one another by the anterior extent of the poral vitelline follicles (anterior to the cirrus-sac, i.e., preporal, in C. gillesi vs. posterior, i.e., only postporal in C. janikae), size of the eggs (diameter of the external layer of the embryophore of C. gillesi 30-33 µm vs. 44-46 µm in C. janikae), and the number of uterine lateral diverticula (16-21 on 1 side in C. gillesi vs. only 8-12 in C. janikae) and the testes (37-46 in C. gillesi vs. 63-74 in C. janikae). Based on a phylogenetic analysis of the 28S rRNA gene (lsrDNA) sequences, C. gillesi forms a lineage sister to S. megalodiscus, thus supporting the morphological similarity of both genera that occur in fishes of the same family in the same zoogeographical region.

A large 28S rDNA-based phylogeny confirms the limitations of established morphological characters for classification of proteocephalidean tapeworms (Platyhelminthes, Cestoda).

Proteocephalidean tapeworms form a diverse group of parasites currently known from 315 valid species. Most of the diversity of adult proteocephalideans can be found in freshwater fishes (predominantly catfishes), a large proportion infects reptiles, but only a few infect amphibians, and a single species has been found to parasitize possums. Although they have a cosmopolitan distribution, a large proportion of taxa are exclusively found in South America. We analyzed the largest proteocephalidean cestode molecular dataset to date comprising more than 100 species (30 new), including representatives from 54 genera (80%) and all subfamilies, thus significantly improving upon previous works to develop a molecular phylogeny for the group. The Old World origin of proteocephalideans is confirmed, with their more recent expansion in South America. The earliest diverging lineages are composed of Acanthotaeniinae and Gangesiinae but most of the presently recognized subfamilies (and genera) appear not to be monophyletic; a deep systematic reorganization of the order is thus needed and the present subfamilial system should be abandoned. The main characters on which the classical systematics of the group has been built, such as scolex morphology or relative position of genital organs in relation to the longitudinal musculature, are of limited value, as demonstrated by the very weak support for morphologically-defined subfamilies. However, new characters, such as the pattern of uterus development, relative ovary size, and egg structure have been identified, which may be useful in defining phylogenetically well-supported subgroups. A strongly supported lineage infecting various snakes from a wide geographical distribution was found. Although several improvements over previous works regarding phylogenetic resolution and taxon coverage were achieved in this study, the major polytomy in our tree, composed largely of siluriform parasites from the Neotropics, remained unresolved and possibly reflects a rapid radiation. The genus Spasskyellina Freze, 1965 is resurrected for three species of Monticellia bearing spinitriches on the margins of their suckers.

An annotated list of the species of Gangesia Woodland, 1924 (Cestoda: Proteocephalidea), parasites of catfishes in Asia, with new synonyms and a key to their identification.

An annotated list of tapeworms of the genus Gangesia Woodland, 1924 (Cestoda: Proteocephalidea), parasites of siluriform fishes in Asia, is provided. Based on the morphological examination of museum specimens and newly collected material from China, Japan and Russia, as well as the results of a previous revision of the Indomalayan species, only eight of more than 50 nominal taxa are considered to be valid. These are: from India and neighbouring countries, Gangesia bengalensis (Southwell, 1913) (type-species), G. agraensis Verma, 1928, both from Wallago attu (Bloch & Schneider) (Siluridae), G. macrones Woodland, 1924 from Sperata seenghala (Sykes) (Bagridae) and G. vachai (Gupta & Parmar, 1988) from different catfishes (type-host Eutropiichthys vacha (Hamilton); Schilbeidae), and, from the Palaearctic, G. margolisi Shimazu, 1994, a parasite of Silurus biwaensis (Tomoda) (Siluridae) in Japan, G. oligonchis Roitman & Freze, 1964 from Tachysurus fulvidraco (Richardson) (Bagridae) in Russia, and G. parasiluri Yamaguti, 1934 and G. polyonchis Roitman & Freze, 1964, both from Silurus asotus L. (Siluridae) in Japan and Russia, respectively. The poorly known G. oligonchis is redescribed. Seven new synonyms are proposed: G. chauhani Mathur & Srivastav, 2000, G. wallaguae Pradhan, Kulkarni, Kale & Wakle, 2010 and G. shivajiraoi Dhole, Waghmare & Chavan, 2012 are synonymised with G. agraensis; G. striatusii Bhure & Nanaware, 2012 and Silurotaenia govindii Sawarkar, 2013 with G. macrones; G. spasskajae Demshin, 1987 with G. polyonchis; and Silurotaenia spinula Chen, 1984 with Postgangesia orientalis Akhmerov, 1969. Gangesia pseudobagrae Chen, 1962 is considered to be a species inquirenda, whereas G. chauhani Mathur, 1992 and G. dineshei Jaysingpure, 2002 are recognised as unavailable names. An amended generic diagnosis of Gangesia and a key to the identification of its recognised species are also provided.

Taxonomic status of Woodland's enigmatic tapeworms (Cestoda: Proteocephalidea) from Amazonian catfishes: back to museum collections.

Poorly known proteocephalidean cestodes of peculiar morphology, described by Woodland (1934) from pimelodid catfishes in Amazonia, Brazil, were studied. Re-examination of their type-specimens and evaluation of newly-collected material from Brazil and Peru made it possible to clarify their taxonomic status. Brayela karuatayi (Woodland, 1934), the type-species of the monotypic Brayela Rego, 1984, which has never been recorded since its original description, is redescribed and its scolex morphology, which has been misinterpreted in the original description, was studied using scanning electron microscopy (SEM). The actual definitive host of B. karuatayi is not a species of Glanidium Lütken (Auchenipteridae), but coroatá, Platynematichthys notatus (Jardine) (Pimelodidae). Peru is a new geographical record for B. karuatayi. The definitive host of other two proteocephalidean cestodes, Megathylacus jandia Woodland, 1934 and Proteocephalus jandia Woodland, 1934, is not a species of Rhamdia Bleeker (family Heptapteridae), but the pimelodid Zungaro zungaro (Humboldt) [syn. Paulicea luetkeni (Steindachner)]. Proteocephalus jandia is in fact conspecific with Travassiella avitellina Rego & Pavanelli, 1987, type-species of Travassiella Rego & Pavanelli, 1987. As a result, a new combination, Travassiella jandia (Woodland, 1934), is proposed. Megathylacus jandia Woodland, 1934 is considered conspecific with M. brooksi Rego & Pavanelli, 1985 described from the congeneric host [Zungaro jahu (Ihering)] from the Paraná River in Brazil; the latter species becomes its new junior synonym. The validity of M. travassosi Pavanelli & Rego, 1992, a parasite of Pseudoplatystoma corruscans (Spix & Agassiz) in the Paraná River basin in Brazil, is confirmed by a study of its type- and voucher specimens. The present account provides strong arguments to always study museum specimens in taxonomic studies; it also represents an evidence of the importance of depositing types and vouchers in internationally recognised collections. Based on the new information provided in this study, the generic diagnoses of Brayela and Megathylacus Woodland, 1934 are amended.