Proteocephalidean Cestode Research Articles

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.

A young parasite in an old fish host: A new genus for proteocephalid tapeworms (Cestoda) of bowfin (Amia calva) (Holostei: Amiiformes), and a revised list of its cestodes.

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.

Reappraisal of Goezeella Fuhrmann, 1916 (Cestoda: Proteocephalidae), parasites of Neotropical catfishes (Siluriformes), with description of a new species from Pimelodella cristata (Heptapteridae)

The cestode genus GoezeellaFuhrmann, 1916 is reviewed on the basis of taxonomic evaluation of type and newly collected material from pimelodid and heptapterid catfishes (Siluriformes) in the Amazon River basin, South America, and its generic diagnosis is amended. The genus is typified by the exclusively ventral position of the cortical vitelline follicles, the inner longitudinal musculature formed by dense individual muscle fibres, rather than forming bundles as in other proteocephalids, a well-developed metascolex and biloculate suckers. The type species, G. siluriFuhrmann, 1916, is redescribed based on its syntype from Cetopsis coecutiens (type-host) (Cetopsidae) and specimens from Pinirampus pirinampu (Pimelodidae). The validity of G. danbrooksi de Chambrier, Rego & Mariaux, 2004 from Ageneiosus pardalis (Auchenipteridae) is confirmed and some erroneous morphological traits are corrected based on examination of its holotype. A new species, Goezeella mariae sp. nov., is described from the heptapterid catfish Pimelodella cristata (Heptapteridae). The new species differs from congeners by its overall size (much smaller compared to G. siluri), morphology of the scolex (strongly wrinkled metascolex and weakly developed interlocular septum of suckers) and number of the testes. This is the third proteocephalid cestode described from a heptapterid catfish in South America and the first helminth parasite reported from P. cristata. Goezeella is unusual among other Neotropical proteocephalids by its occurrence in catfishes of as many as four families; all species of the genus are known only from the Amazon and Orinoco River basins. Molecular data on two of the three valid species and a key to their identification are provided.

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.

Kapsulotaenia tidswelli - an unusual cestode from the Australian goannas Varanus gouldii gouldii and V. giganteus.

Kapsulotaenia tidswelli is a proteocephalidean cestode that utilizes varanid lizards as definitive hosts. Fresh specimens of this cestode were observed with endogenous red pigmentation in the neck region that disappeared rapidly if specimens were not preserved in glutaraldehyde. The ultrastructural characteristics of the red pigment, which are described, suggest it is a carotenoid. Phylogenetic analysis confirmed a close relationship between K. tidswelli and other species of Kapsulotaenia for which sequence information is available. There is thus no reason to consider that the red pigmentation is because K. tidswelli is atypical, and it is proposed the carotenoids are likely to be associated with the diet of its varanid host.

A New Species of Synbranchiella (Cestoda: Proteocephalidae) from the Mountain Mullet (Dajaus monticola) in Costa Rica

A new species of the recently erected genus of proteocephalid cestodes, Synbranchiella Arredondo, Alves and Gil de Pertierra, 2017 , is described based on specimens found in the mountain mullet, Dajaus monticola (Bancroft, 1834), from Costa Rica. The new species is placed in Synbranchiella because of the cortical position of the genital organs (typical of the former subfamily Monticelliinae); a robust scolex (lacking a metascolex) having a dome-shaped apex and biloculate suckers (lacking free posterior margins); vitelline follicles in 2 narrow lateral bands; a vagina always anterior to the cirrus-sac; and a genital pore that is markedly pre-equatorial, i.e., close to the anterior margin of proglottids. The new species, Synbranchiella megacirrus, differs from the type and only other species of the genus, Synbranchiella mabelae Arredondo, Alves and Gil de Pertierra, 2017 , that infects the marbled swamp eel, Synbranchus marmoratus Bloch, 1795, in Argentina by the absence of preporal vitelline follicles (present in S. mabelae); a well-developed, large, elongate vaginal sphincter (small and ring-like in S. mabelae); and a large cirrus-sac relative to the proglottid size (cirrus-sac length is on average 48% of the proglottid width in S. megacirrus vs. 31% in the latter species). This is the first adult tapeworm reported from mountain mullet and the first record of the genus outside of South America, thereby greatly extending the range of distribution of species of Synbranchiella.

Gastrointestinal parasites of common African toad (<i>Bufo regularis</i>) in Umuahia South, Abia State, Nigeria

Information on the parasites of common African toads ( Bufo regularis ) is still limited, judging by the global efforts to conserve amphibians. This informed the decision to provide baseline data of the gastrointestinal parasites of B. regularis of Umuahia South Local Area (LGA) of Abia State, Nigeria. Using standard methods, 321 B. regularis comprised of males, n =145, 45.17% and females n =176, 54.83% were collected from five communities (Old Umuahia, Amakama, Okwu, Ubakala and Agbama) in Umuahia South LGA, between June and November 2014. They were later examined for gastrointestinal parasites using standard procedures. Data analysis revealed that male B. regularis had more (n = 61, 19.03%) gastrointestinal parasites than the females (n = 58, 18.69%). Different species of gastrointestinal parasites belonging to class Cestoda ( Osphiotaenia nigriocollis, Lanfrediella sp and Proteocephalid Cestode larva ); Trematoda ( Messoceolium monody and Echinostoma revolutum ), Nematoda ( Amplicaecum africanum, Rhabdias bufonis, Ascaridoid, Oswaldocruzia pipiens and Camallanus sp ) and Protozoa ( Nyctotheroides bambuiensis, Lankesterellla bufonis and Protoopolina sp ) were identified with prevalence 20.25%, 4.36%, 7.48% and 4.98%, respectively. Prevalence of parasites varied significantly (p<0.05) across the gastrointestinal regions. Though no symptom of disease condition was established in all the B. regularis examined, high presence of gastrointestinal parasites could pose a threat to their existence. Keywords : Bufo regularis; cestoda; gastrointestinal parasitism.

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.

Towards a robust systematic baseline of Neotropical fish tapeworms (Cestoda: Proteocephalidae): amended diagnoses of two genera from the redtail catfish, Phractocephalus hemioliopterus.

Species of two monotypic genera, Ephedrocephalus Diesing, 1850 and Zygobothrium Diesing, 1850 (Cestoda: Proteocephalidae), parasites of one of the most basal members of the catfish family Pimelodidae, the redtail catfish, Phractocephalus hemioliopterus, in the Neotropical Region, are redescribed based on the evaluation of type specimens and newly collected material. Generic diagnoses are amended to provide a robust baseline for the future re-arrangement of the classification of proteocephalid cestodes. Ephedrocephalus is typified by the medullary position of the ovary and uterus, the cortical distribution of vitelline follicles (dispersed throughout almost the entire ventral cortex) and the testes in one dorsal field. Zygobothrium is primarily characterized by its possession of a robust scolex bearing four uniloculate suckers with two openings each and by the tetralobed velum (laciniations) on every proglottid (two on the ventral and two on the dorsal side). The redtail catfish is the definitive host of as many as seven species of proteocephalid cestodes, which, however, do not represent a monophyletic group. Some species, including Z. megacephalum, are among the earliest diverged parasites of Neotropical catfishes, being closely related to African and North American proteocephalids from catfishes, whereas others such as E. microcephalus belong to more recently diverged taxa with uncertain interrelations. Unlike most proteocephalids of the redtail catfish, which almost always infect the anterior parts of the host intestine, E. microcephalus and Z. megacephalum occur exclusively in its posterior third. A key to the identification of the proteocephalid species parasitizing P. hemioliopterus is also presented.

A new genus of proteocephalid tapeworm (Cestoda) from the marbled swamp eel Synbranchus marmoratus Bloch (Synbranchiformes: Synbranchidae) in the River Paraná basin, Argentina.

Synbranchiella gen. n. is proposed to accommodate Synbranchiella mabelae sp. n. (Proteocephalidae: Monticelliinae) from the intestine of the marbled swamp eel Synbranchus marmoratus Bloch, in the River Colastiné, a tributary of the middle River Paraná in Argentina. The new genus is placed in the Monticelliinae because of the cortical position of the genital organs. It differs from all known monticelliine genera by the following combination of characters: (i) scolex robust, with a conical apex, without metascolex; (ii) biloculate suckers with a conspicuous septum separating unequally-sized loculi and a robust non-adherent area, lacking free posterior margin; (iii) vitelline follicles in two narrow lateral bands, extended throughout the nearly entire proglottid length; (iv) vagina always anterior to the cirrus-sac, with an inconspicuous vaginal sphincter; (v) a genital pore pre-equatorial. Scanning electron microscopy revealed three types of microtriches on the tegument surface: acicular and capiliform filitriches and gladiate spinitriches. A phylogenetic analysis of the large subunit nuclear ribosomal RNA gene (lsrDNA, D1-D3 domains) confirms that S. mabelae represents an independent lineage within a large clade comprised mainly from Neotropical taxa parasitising catfishes. This is the second proteocephalidean cestode described from a Neotropical synbranchiform fish host.

Molecular analysis of a novel species, Gangesia punjabensis (Family: Proteocephalidae, Subfamily: Gangesiinae) infecting an Indian freshwater cat fish, Wallago attu evidencing species complex.

In the present study, from August 2015 to July 2016, a total of 159 specimens of Wallago attu Bloch and Scheider, 1801 vern. mully were collected from the Ropar wetland, Punjab, India and were examined for the presence of intestinal tapeworms. The infection rate was 12.5%, out of which, two fishes were heavily infected with a proteocephalidean cestode belonging to the genus Gangesia in the month of February. Gangesia punjabensis sp. nov. was identified and described on the basis of morphology and partial amplification of LSUrDNA (28S rDNA). The histopathogenesis caused by these parasites have also been studied in histological sections. About 9-35 number of worms were collected from a single host. The length of worms ranged from 6.0 to 6.2cm. The strobila consisted of an armed scolex, neck, immature proglottids (approximately 90 in number) and mature proglottids (approximately 7 in number) and gravid proglottids were not detected. Analysis of 28S large subunit (LSU) rDNA sequence of the isolate of G. punjabensis n. sp. demonstrated maximum similarity of 99% with G. bengalensis, 98% with G. vachai, 97% with G. macrones. The phylogenetic tree based on the final edited alignment (822bp) with Neighbour-Joining showed the highest bootstrap value of 100 and placed G. punjabensis n. sp. with G. bengalensis and G. macrones in the same clade showing them to be a species complex. The intestinal mucosal lining exhibited blister formation, haemorrhagia and inflammation due to the presence of deeply embedded scolices. Histopathology caused was evident due to disruption of villous surface and cellular infiltration. This is the first report of cestodes belonging to the genus Gangesia from Ropar wetland, Punjab, India.

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.

A new species of Pseudocrepidobothrium (Cestoda: Proteocephalidea) from Pseudoplatystoma reticulatum (Pisces: Siluriformes) in the Paraná River basin (Argentina)

This study describes the proteocephalidean tapeworm Pseudocrepidobothrium chanaorum sp. n. (Proteocephalidae: Proteocephalinae), which was found in the intestine of Pseudoplatystoma reticulatum (Eigenmann et Eigenmann) from the Colastiné River, a tributary of the Paraná River. The new species differs from the two other species of the genus, P. eirasi (Rego et de Chambrier, 1995) and P. ludovici Ruedi et de Chambrier, 2012, parasites of Phractocephalus hemioliopterus (Bloch et Schneider) from the Amazon River in Brazil, in having fewer proglottides (4-8 without ventral appendages vs 7-12 with ventral appendages and 20-36 without ventral appendages, respectively), a smaller scolex (350-450 μm wide vs 495-990 μm and 515-1020 μm wide, respectively), in the total number of testes (21-25 vs 21-51 and 37-79, respectively), a cirrus-sac usually directed anteriorly if the vagina is posterior to the cirrus-sac vs transversely situated in the known species. The study of the tegumental surface of Pseudocrepidobothrium spp. revealed the presence of four types of microtriches: papilliform, acicular and capilliform filitriches, and gladiate spinitriches. The three species have a similar microthrix pattern, with minor differences on the immature proglottis surface. Pseudocrepidobothrium chanaorum sp. n. is the ninth proteocephalid reported from P. reticulatum.

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.

Macrobothriotaenia ficta (Cestoda: Proteocephalidea), a parasite of sunbeam snake (Xenopeltis unicolor): example of convergent evolution.

The poorly known proteocephalidean cestode Macrobothriotaenia ficta (Meggitt, 1931) from the sunbeam snake Xenopeltis unicolor (Ophidia: Xenopeltidae) is redescribed on the basis of re-examination of its type specimens from Burma (Myanmar), and vouchers from Thailand and Vietnam. The peculiar morphology of the scolex, which is formed by four pedunculate lobe-bearing pincer-shaped suckers, is described for the first time using scanning electron microscopy. In scolex morphology, M. ficta closely resembles phyllobothriidean cestodes, parasites of elasmobranchs. However, this similarity does not reflect phylogenetic relatedness of these cestodes but instead presents an example of convergent morphological evolution of attachment organs of unrelated groups of cestodes that parasitize different groups of vertebrates. Besides scolex morphology, the genus is characterised by the possession of a very large cirrus-sac, which may reach up to the midline of proglottides, few testes (less than 60), vitelline follicles limited to the dorsal side of proglottides, a large vaginal sphincter, and eggs with a three-layered embryophore covered with rounded projections. Numerous errors in the diagnosis of M. ficta, which appeared in the literature as a result of uncritical compilation of data without examination of original material, are corrected. Multilocus phylogenetic analysis of nuclear ribosomal RNA genes ssr- and lsr-DNA and mitochondrial genes rrnL and cox1 place this species among other snake-parasitizing proteocephalideans of the genus Ophiotaenia. The convergent evolution of scolex morphology across distantly related taxa is discussed.

A new species of Australotaenia (Cestoda: Proteocephalidea) from a snake in Cambodia: host switching or postcyclic parasitism in a distant region?

Australotaenia de Chambrier et de Chambrier, 2010 has been proposed to accommodate two species of proteocephalidean cestodes from hylid frogs (Litoria spp.) in Australia. Recently, apparently congeneric cestode, for which the name A. bunthangi sp. n. is proposed, was found in the homalopsid snake Enhydris enhydris (Schneider) (Serpentes: Homalopsidae) from South-East Asia (Cambodia). This finding indicates a much wider range of definitive hosts of species of this genus, i.e. amphibians and reptiles, which is exceptional among proteocephalideans. Postcyclic parasitism, i.e. predation of the definitive host infected with sexually mature parasites, cannot be excluded but does not seem to be probable. In addition, the occurrence of A. bunthangi in the former Indochina extends the range of the geographical distribution of the genus to another zoogeographical region. The new species differs from both species of Australotaenia in the relative size of an apical organ, the diameter of which equals to that of suckers (versus much smaller in the remaining species, in which the width of the apical organ represents less than 2/3 of the diameter of the suckers), much smaller scolex and suckers (width 150 microm and diameter of suckers 50-55 microm versus 245-420 microm and 100-140 microm, respectively), and longer body (224 mm versus 57-121 mm). In addition, A. bunthangi differs from A. hylae (Johnston, 1912) (type-species of the genus) by the number of testes (46-64 versus 74-106 in A. hylae) and by the ovary width/proglottis width ratio (55-65% versus 68-71% in A. hylae). Australotaenia bunthangi differs from A. grobeli de Chambrier et de Chambrier, 2010 by relative size of the cirrus-sac (its length represents 18-24% of the width of the proglottis versus 27-33% in A. grobeli) and by the diameter of the embryophore (25-27 microm versus 18-23 microm in A. grobeli).

Harriscolex nathaliaeN. Sp. (Cestoda: Proteocephalidea) fromPseudoplatystoma corruscans(Siluriformes: Pimelodidae) in the Paraná River Basin, Argentina

The proteocephalidean cestode Harriscolex nathaliae n. sp. (Proteocephalidae: Zygobothriinae) is described from the intestine of the spotted sorubim Pseudoplatystoma corruscans (Spix and Agassiz) (Siluriformes: Pimelodidae) from the Paraná River basin in Argentina. This new species differs from the only species of the genus, Harriscolex kaparari (Woodland, 1935), which is a parasite of Pseudoplatystoma tigrinum (Linnaeus) from the Amazon River in Brazil, by its larger scolex (width of 450-750 μm vs. 305-340 μm), the position of the vagina in relation to the cirrus sac (anterior and posterior vs. only anterior), an asymmetrical vaginal sphincter, the arrangement of vitelline follicles (1 narrow longitudinal band on each side of the proglottid vs. 2 pairs of wide longitudinal bands on dorsal and ventral sides), and a higher number of uterine diverticula (22-45 vs. 16-20). Harriscolex nathaliae is covered with 2 types of microtriches, acicular filitriches and gladiate spinitriches.

Margaritaella gracilis gen. n. et sp. n. (Eucestoda: Proteocephalidea), a parasite of Callichthys callichthys (Pisces: Siluriformes) from the Paraná River basin, Argentina

Margaritaella gracilis gen. n. et sp. n. (Proteocephalidea: Proteocephalinae) found in the intestine of Callichthys callichthys (Linnaeus) from the Paraná River basin is described. The new genus is placed in the Proteocephalinae because of the medullary position of the genital organs. It differs from all known genera included in the Proteocephalinae by the following combination of characters: 1) scolex with a conspicuous cluster of drop-shaped gland cells posterior to suckers; 2) strobila with a low number of proglottides, all much longer than wide; 3) testes arranged in one field, composed of two parallel rows of testes separated by the uterus; 4) ovary delicate, H-shaped, with branches slender and deeply folliculate at the edges, located at 25-35% from the posterior end; 5) uterus largely extended posterior to the ovary but not reaching the end of proglottis; and 6) vitelline follicles in two narrow lateral bands, largely extended posterior to the ovary. Scanning electron microscopy revealed three types of microtriches on the tegument surface: acicular and capiliform filitriches and gladiate spinitriches. The relative size of the ovary, a character recently used in the systematics of the proteocephalidean cestodes, was calculated for the new species and compared with other species of the group. M. gracilis is the first record of a proteocephalidean cestode parasitizing a callichthyid catfish.

A New Genus and Species of Proteocephalidean Tapeworm (Cestoda) From Pangasius larnaudii (Siluriformes: Pangasiidae) In Southeast Asia

A new proteocephalidean cestode is described from spot pangasius, Pangasius larnaudii (Siluriformes: Pangasiidae), from Tonle Sap Lake in Cambodia and a new genus, Pangasiocestus , is proposed to accommodate it. The genus is placed in the Gangesiinae because its scolex possesses a large rostellum-like apical organ and its genital organs (testes, ovary, vitellarium, and uterus) are situated in the medulla, with some vitelline follicles paramuscular. Pangasiocestus romani n. gen. and n. sp., the type and only species of the new genus, is characterized mainly by its rosette-like scolex composed of 4 lobes bearing a small sucker in their center, and the apical part with a large, discoidal, rostellum-like apical organ devoid of hooks, by weakly developed inner longitudinal musculature formed by very few isolated muscle fibers, uneven size of testes in immature and mature proglottids, with lateral testes smaller and more dense than median ones, by very narrow lateral bands of vitelline follicles, formed usually by single follicles, and by the vagina anterior to the cirrus sac. This is the first proteocephalidean cestode from a pangasiid catfish identified to the species level (proteocephalidean cestodes from 3 Pangasius spp. reported in an unpublished account from Vietnam, misidentified as Proteocephalus osculatus (Goeze, 1782) [ = Glanitaenia osculata ], are not considered).