Tegument Ultrastructure and Morphology of the Capsule Surrounding the Tetrathyridia of the Genus Mesocestoides Vaillant, 1863 in the Liver of the Root Vole.

The ultrastructure of the tegument of encapsulated tetrathyridia of the genus Mesocestoides Vaillant, 1863 (Cestoda, Cyclophyllidea, Mesocestoididae) from the liver of root voles Microtus oeconomus (Pallas, 1776) and the structure of the three-layered capsule surrounding them were studied for the first time. Several types of extracellular structures were noted on the surface of the tetrathyridia tegument: vesicles, fine granular material, and vacuoles. In addition, the phenomenon of shedding microtriches, which have expanded parts, was found. Host cells in contact with extracellular material show signs of destruction. A characteristic feature of the capsules surrounding the tetrathyridia is the reticular structure of the fibrous layer containing both native and degenerating inflammatory cells.

Ultrastructure and histochemistry of the scolex of two Neotropical proteocephalidean species (Cestoda: Onchoproteocephalidea).

The internal ultrastructure of the scolex and the histochemical composition of the apical glands of two South American proteocephalideans cestodes, Monticellia magna and Proteocephalus pimelodi, were described for the first time. The study included the use of scanning and transmission electron microscopy to observe the tegumental ultrastructure, and histochemical techniques to detect types of gland secretion. Two types of glands were found in the scolex of M. magna and P. pimelodi. The pattern of microtriches described for M. magna was confirmed and that of P. pimelodi was described for the first time. Also, the internal ultrastructure of the microtriches in both species was described. Indications of the presence of sensory receptors were also found in M. magna. Finally, the systematic value of the characters studied is discussed, such as the internal structure of the gladiate spinitriches and the apocrine gland of M. magna.

Unravelling the anthelmintic bioactives from Jasminum grandiflorum L. subsp. Floribundum adopting in vitro biological assessment.

ETHNOPHARMACOLOGICAL RELEVANCE: Jasminum grandiflorum L. is a medicinal plant widely used in the traditional system of Medicine as an anthelmintic in ringworm infections, for treating ulcers, stomatitis, skin diseases, and wounds. AIM OF THE STUDY: The emergence of resistance by different parasites to currently used chemicals has been reported. There are increasing needs for more effective and safer parasiticides. Therefore, the current study was designed to investigate the methanolic extract of the aerial parts of J. grandiflorum subsp. Floribundum (JGTE) to confirm its traditional uses as anthelmintic through a bioassay-guided fractionation and isolation of the active components with anthelmintic activity. MATERIALS AND METHODS: The JGTE was partitioned into dichloromethane (DCM-F) and n-butanol (BuOH-F) fractions. The JGTE, fractions, and the isolated compounds were tested in vitro for their anthelmintic activity using two nematodes; one larval stage of cestode and one arthropod. Four major compounds were isolated from the most active fraction (BuOH-F) including two flavonoids and two secoirridoid glycosides, identified as kaempferol-3-O-neohesperoside (1), rutin (2), oleuropein (3), and ligstroside (4). RESULTS: Among the isolated compounds from most active fraction (BuOH-F), rutin (2) displayed the highest anthelmintic activity in a dose-dependent activity with IC50 of 41.04 µg/mL against H. muscae adult worm, followed by ligstroside (4) with IC50 of 50.56 µg/mL. CONCLUSIONS: These findings could advocate the traditional use of J. grandiflorum L. and provide further insight into the anthelmintic activity of flavonoids.

Crossing barriers of zoogeographical regions: Molecular evidence of vicariance of the only cestode parasite of loaches (Cobitidae) in the Indomalayan region, Paracaryophyllaeus lepidocephali (Cestoda: Caryophyllidea), and its redescription.

Tapeworms of the genus Paracaryophyllaeus Kulakovskaya, 1961 (Cestoda: Caryophyllidea) are specific parasites of loaches (Cypriniformes: Cobitoidea) and occur almost exclusively in the Palaearctic region. The only exception and example of vicariance over the borders of two zoogeographical regions is Paracaryophyllaeus lepidocephali (Kundu, 1985), an insufficiently known species described from the Indomalayan region, with uncertain generic allocation. In the present paper, the species is redescribed based on new material collected from the type host, Lepidocephalichthys guntea, in West Bengal, India. Molecular data reveal this species as a member of Paracaryophyllaeus, within which it is the most closely related to P. cf. gotoi from Misgurnus anguillicaudatus in China and Japan on the basis of large subunit of ribosomal nuclear DNA (28S rDNA). Generic position of P. lepidocephali examined herein is also confirmed by morphology including cross sections, in particular, by a small, cylindrical body, medullary testes with testicular fields crossing the anterior margin of the cirrus sac, medullary vitelline follicles, with some follicles paramuscular, a shallow common genital atrium, short vagina and uterus not extending anteriorly beyond the cirrus sac. It differs from all Palaearctic congeners but Paracaryophyllaeus vladkae Scholz, Oros and Aydogdu, 2014 by the testicular field crossing the anterior margin of the cirrus sac. It differs from P. vladkae by more anterior position of the first vitelline follicles compared to the first testes. This species is a unique example of a fish tapeworm crossing the borders of the Palaearctic and Indomalayan zoogeographical regions.

Structure of the Excretory System of the Plerocercoid Pyramicocephalus phocarum (Cestoda: Diphyllobothriidea): Proof for the Existence of Independent Terminal Cells.

The excretory system ultrastructure and immunocytochemistry have been investigated in the plerocercoid Pyramicocephalus phocarum. It has been shown that P. phocarum has independent terminal cells, cyrtocytes. The entire canal system is a single undivided syncytium, which includes nephridial funnels of the terminal tubules, and peripheral and central canals. The nephridial funnel and cyrtocyte form a filtration complex of the protonephridial type. In the caudal region, several peripheral canals open into a deep fold of the tegument, the urinary bladder. The excretory pores are separated from the tegument by annular septate desmosomes. There are no cell junctions inside the excretory system. The presence of the F-actin ring and the expression of non-synaptic serotonin in the collar area have been detected in cyrtocytes by immunocytochemistry methods.

First Report of Lecanicephalidean Tapeworms (Eucestoda) from Freshwater, Including Description of Three New Species of Tetragonocephalum Shipley and Hornell, 1905.

The lecanicephalidean cestodes parasitizing the spiral intestine of the endangered giant freshwater whipray, Urogymnus polylepis (Bleeker), are investigated for the first time. Eight host specimens were collected between 2002 and 2008 at 2 collecting sites off the eastern coast of Borneo: 6 from the Kinabatangan River (Malaysia) and 2 from a fish market in Tarakan (Indonesia). Two of these individuals were found to be infected with a total of 3 new species of TetragonocephalumShipley and Hornell, 1905. Tetragonocephalum georgei n. sp. and Tetragonocephalum opimum n. sp. were recovered from a host specimen from the Kinabatangan River, and Tetragonocephalum levicorpum n. sp. was found parasitizing a host specimen purchased at a fish market in Tarakan. Specimens of each of the new species were prepared for light microscopy; specimens of 2 of the new species were prepared for scanning electron microscopy, and histological sections were prepared for 1 of the new species. The 3 new species are distinct from the 9 valid species of Tetragonocephalum and the 1 species inquirendum based on, for example, total length, number of proglottids and testes, and size of the scolex and acetabula. Tetragonocephalum georgei n. sp. and T. levicorpum n. sp. are unusual among their congeners in that they are euapolytic (i.e., gravid proglottids were not observed) rather than apolytic. They differ from one another in scolex and acetabula size. Tetragonocephalum opimum n. sp. is unusual among its congeners in its possession of vitelline follicles arranged in 2, rather than 3, regions in the proglottid. These new species increase the total number of valid species of Tetragonocephalum to 12 and the total number of known cestodes from U. polylepis to 13 species across 6 genera in 4 orders. This is the first account of lecanicephalideans reported from freshwater. The taxonomic status of each of the 32 nominal taxa historically associated with Tetragonocephalum is re-assessed. Type host identities of all valid species are revised and discussed in light of recent taxonomic efforts in the Dasyatidae Jordan and Gilbert.

Electron microscopy reveals novel external specialized organs housing bacteria in eagle ray tapeworms.

Nutritionally-based mutualisms with bacteria are known to occur in a wide array of invertebrate phyla, although less commonly in the Platyhelminthes. Here we report what appears to be a novel example of this type of association in two geographically disparate and phylogenetically distant species of tapeworms of eagle rays-the lecanicephalidean Elicilacunosus dharmadii off the island of Borneo and the tetraphyllidean Caulobothrium multispelaeum off Senegal. Scanning and transmission electron microscopy revealed that the grooves and apertures on the outer surfaces of both tapeworms open into expansive cavities housing concentrations of bacteria. This led us to reject the original hypothesis that these structures, and their associated mucopolysaccharides, aid in attachment to the host mucosa. The cavities were found to be specialized in-foldings of the tapeworm body that were lined with particularly elongate filitriches. Given tapeworms lack a gut and employ filitriches to assist in nutrient absorption, enhanced nutrient uptake likely occurs in the cavities. Each tapeworm species appeared to host different bacterial monocultures; those in E. dharmadii were coccoid-like in form, while those in C. multispelaeum were bacillus-like. The presence of bacteria in a specialized structure of this nature suggests the structure is a symbiotic organ. Tapeworms are fully capable of obtaining their own nutrients, and thus the bacteria likely serve merely to supplement their diet. Given the bacteria were also extracellular, this structure is more consistent with a mycetome than a trophosome. To our knowledge, this is not only the first evidence of an external symbiotic organ of any type in a nutritionally-based mutualism, but also the first description of a mycetome in a group of invertebrates that lacks a digestive system. The factors that might account for the independent evolution of this unique association in these unrelated tapeworms are unclear-especially given that none of their closest relatives exhibit any evidence of the phenomenon.

Ultrastructure of the rhyncheal apparatus and other structures of the scolex of Grillotia (Christianella) carvajalregorum (Cestoda: Trypanorhyncha).

The scolex ultrastructure was studied in Grillotia (Christianella) carvajalregorum (Cestoda: Trypanorhyncha) using histochemistry and transmission electron microscopy. We show for the first time the presence of scolex glands arranged in two longitudinal acini at the pars vaginalis parenchyma. These glands, along with those scattered in bothrial parenchyma, produce potentially adhesive glycoprotein secretions that are discharged via ducts to the bothrial grooves and apex. A particular type of sensory receptor was found around frontal gland pores, with a possible function in regulating their secretion activity. The internal structure of microtriches varies according to their morphotype and distribution on the scolex, this study providing the first description of the ultrastructure of serrate lanceolate spinitriches. The projections that form serrate margins are an extension of the medulla, differing from similar projections of other spinitriches. The large caps observed in serrate lanceolate spinitriches may reflect their specialization in attachment to and abrasion of intestinal mucosa, while the short caps and large bases of acicular filitriches may reflect their involvement in nutrient absorption. We also describe the rhyncheal apparatus ultrastructure, showing a similar basic structure of tentacular walls than that of other trypanorhynchs. Some differences among species in the number of fibrous layers, composition of the apical cytoplasm and presence of microvilli-like projections were discussed. Finally, our study describes in detail the internal ultrastructure of hollow hooks, evidencing the presence of cytoplasm, mitochondria and fibrils. The location of these fibrils may increase the area of contact surface of hooks on tentacles, possibly allowing for a higher tensile strength than that of solid hooks. We consider that gland location and shape, composition of tentacular wall layers, and hook internal structure may serve as useful characters for the taxonomy and phylogeny of Trypanorhyncha. RESEARCH HIGHLIGHTS: This is the first description of scolex internal ultrastructure in Grillotia carvajalregorum, showing the presence of glands arranged in two longitudinal acini at the pars vaginalis parenchyma, with potentially adhesive functions. The internal ultrastructure of serrate lanceolate spinitriches and acicular filitriches may reflect their specialization in attachment to the host intestinal mucosa and their involvement in nutrient absorption, respectively. Internally, hollow hooks have cytoplasm with mitochondria and fibrils, which are more widely distributed than in solid hooks, possibly increasing their tensile strength.

The First Report and Description of a New Species of Rhinebothrium from a Dasyatid Stingray from the Brazilian Northeastern Coast with a Review of the Distribution of the Genus throughout Endemic Marine Ecoregions.

Here we describe a new species of RhinebothriumLinton, 1890, from Hypanus guttatus (Bloch and Schneider). Rhinebothrium ramosi n. sp. can be differentiated from all 51 valid species of the genus by having 4-5 testes and uterus that extends throughout the entire length of the proglottid. Only 8 of the above species closely resemble R. ramosi in total length (Rhinebothrium bunburyense, Rhinebothrium chollaense, Rhinebothrium corbatai, Rhinebothrium dasyatidis, Rhinebothrium kruppi, Rhinebothrium lintoni, Rhinebothrium margaritense, and Rhinebothrium reydai). Despite the resemblance, R. bunburyense, R. corbatai, R. dasyatidis, R. lintoni, and R. margaritense can be distinguished from the new species by possessing a larger number of proglottids. The remaining 3 species (R. chollaense, R. kruppi, and R. reydai) overlap in total length and number of proglottids with R. ramosi. However, they can be distinguished from the new species by possessing a single posterior-most bothridial loculus instead of arranged as a pair, as found in the new species. This is the first report of the genus from the coastal waters of Brazil and brings to 52 the number of valid species for this genus. Additionally, we use the patterns of infection and distribution for species of Rhinebothrium to make predictions of expected diversity within the genus, especially for unsurveyed hosts in endemic marine ecoregions of the world.

Three New Species of Rhinebothrium (Cestoda: Rhinebothriidea) from the Leopard Whipray, Himantura Leoparda, in Australia.

Examination of 4 specimens of the leopard whipray Himantura leoparda, a dasyatid stingray from northern Australia, led to the discovery of 3 new species of Rhinebothrium. Rhinebothrium leopardensis n. sp., Rhinebothrium nandoi n. sp., and Rhinebothrium ruhnkei n. sp. are described, increasing the diversity of the genus to 51 species globally. All 3 new species differ from their congeners in terms of testis number, proglottid number, loculus number, and size. With respect to one another, R. leopardensis n. sp. has bothridia that are weakly constricted at their centers and has a greater number of proglottids than the other 2 species (93-108 vs. 11-15, and 48-78, respectively). Rhinebothrium nandoi n. sp. is the smallest of the 3 species found in H. leoparda (3.6-5 vs. 10-15 mm and 10.1-15.8 mm in total length [TL], respectively) and bears bothridia that are constricted at their centers. Rhinebothrium ruhnkei n. sp. bears bothridia that are conspicuously constricted at their centers and has more testes than R. leopardensis and fewer than R. nandoi (7-10 vs. fewer than 7 and 21-33, respectively). Before this study, 56% (27 of 48) of Rhinebothrium species had been described from the freshwater river systems of South America and the marine waters surrounding South and North America. In contrast, despite the remarkably diverse nature of its batoid fauna, only 19 species were known from the Indo-Pacific region. Our work increases this number to 22, emphasizing the highly underestimated nature of Rhinebothrium diversity in this region of the globe. The discovery of these 3 new species was not unexpected, given the relatively poor status of our current knowledge of the cestode faunas of dasyatid stingrays in the Indo-Pacific region, and given the fact that it is common for a single batoid species to host 2 or more species of Rhinebothrium. Our results suggest that additional work on the cestode faunas of the batoids, especially dasyatids, from the Indo-Pacific region is likely to be highly productive in terms of contributing to the knowledge of Rhinebothrium diversity.

A NEW SPECIES OF ACANTHOBOTHRIUM (CESTODA: ONCHOPROTEOCEPHALIDEA) FROM THE SMALLEYE PYGMY SHARK, SQUALIOLUS ALIAE (CHONDRICHTHYES: SQUALIFORMES: DALATIIDAE), FROM TAIWAN.

The cestode fauna of Squaliolus aliae was examined for the first time following the collection of elasmobranch specimens from Taiwan in 2005, 2013, and 2017. This small shark was found to host 2 tapeworm species. These consist of Acanthobothrium katherineae n. sp., which is new to science and is described herein, and a second species, in the genus Scyphophyllidium, which also appears to be new, but which is represented by insufficient material for formal description. Acanthobothrium katherineae is a category 5 species. It can be distinguished from 5 of the 19 other category 5 species in that it is apolytic, retaining proglottids on its strobila until they are gravid. This new species differs from the remaining 14 category 5 species in its combination of the following features: It is a smaller worm, has fewer than 100 proglottids, has a relatively short cephalic peduncle, and differs in bothridial size and loculus ratio. Sequence data for the D1-D3 region of the 28S rDNA gene were generated for one specimen of A. katherineae. This sequence, along with comparable sequence data for adults of 14 described and 2 undescribed species as well as specimens of 6 undescribed larval members of the genus, was included in a maximum likelihood phylogenetic analysis. The resulting tree places the shark-hosted A. katherineae within a clade of stingray-hosted species, with Acanthobothrium romanowi as its sister taxon. Acanthobothrium katherineae is 1 of only 19 Acanthobothrium species known to parasitize sharks. The tree resulting from this study, which is preliminary given the relatively poor taxon sampling of the diversity in the genus, included 3 of the shark-parasitizing Acanthobothrium species and suggests that all 3 represent host-switching events. This is the first report of an Acanthobothrium species from the family Dalatiidae and the first report of a Scyphophyllidium species from the order Squaliformes. These findings suggest that other members of the Squaliformes, many of which have not previously been examined for parasites, may host additional novel cestode taxa.

Ex Uno Plures? Morphotype and Lineage Diversity of Bothriocephalus (Cestoda: Bothriocephalidea) in North American Freshwater Fishes.

Morphological and molecular evaluation of tapeworms of the genus Bothriocephalus Rudolphi, 1808 (Cestoda: Bothriocephalidea), based on newly collected and uniformly fixed worms from freshwater fishes in Canada and the United States has revealed unexpected diversity. With a combination of selected morphological features and 4 molecular markers (18S rDNA V8 region, ITS1, ITS2, and COI gene sequences), the following morphotypes and lineages of the Bothriocephalus cuspidatus Cooper, 1917 complex were identified, several of which are specific to their respective fish definitive hosts and may represent separate species: B. cuspidatus sensu stricto from walleye, Sander vitreus (type host), which likely includes a miniature morphotype from Johnny darter, Etheostoma nigrum (both Percidae); Bothriocephalus morphotype from pumpkinseed, Lepomis gibbosus (Centrarchidae); and Bothriocephalus morphotype from rock bass, Ambloplites rupestris (Centrarchidae). The Bothriocephalus morphotype from goldeye, Hiodon alosoides (Hiodontidae), may also represent a separate lineage (possibly Bothriocephalus texomensisSelf, 1954) but requires additional studies. A morphotype from smallmouth bass, Micropterus dolomieu, based on a single specimen, is morphologically and genetically very similar to the morphotype from rock bass. Morphological study of the scolex and strobila of heat-killed and fixed specimens has revealed consistent differences, often subtle, that allowed us to differentiate between these morphotypes.

Ultrastructural patterns of the excretory ducts of basal neodermatan groups (Platyhelminthes) and new protonephridial characters of basal cestodes.

BACKGROUND: The flatworms (Lophotrochozoa: Platyhelminthes) are one of the major phyla of invertebrates but their interrelationships are still not well understood including unravelling the most closely related taxon of the Neodermata, which includes exclusively obligate parasites of all main groups of vertebrates with some 60,000 estimated species. Recent phylogenomic studies indicate that the freshwater 'microturbellarian' Bothrioplana semperi may be the closest ancestor to the Neodermata, but this hypothesis receives little morphological support. Therefore, additional morphological and ultrastructural characters that might help understand interrelations within the Neodermata are needed. METHODS: Ultrastructure of the excretory ducts of representatives of the most basal parasitic flatworms (Neodermata), namely monocotylid (Monopisthocotylea) and chimaericolid (Polyopisthocotylea) monogeneans, aspidogastreans (Trematoda), as well as gyrocotylidean and amphilinidean tapeworms (Cestoda), were studied using transmission electron microscopy (TEM). RESULTS: The present study revealed the same pattern of the cytoarchitecture of excretory ducts in all studied species of the basal neodermatans. This pattern is characterised by the presence of septate junctions between the adjacent epithelial cells and lateral ciliary flames along different levels of the excretory ducts. Additionally, a new character was observed in the protonephridial terminal cell of Gyrocotyle urna, namely a septate junction between terminal and adjacent duct cells at the level of the distal extremity of the flame tuft. In Amphilina foliacea, a new type of protonephridial cell with multiple flame bulbs and unique character of its weir, which consists of a single row of the ribs, is described. A remarkable difference has been observed between the structure of the luminal surface of the excretory ducts of the studied basal neodermatan groups and B. semperi. CONCLUSIONS: The present study does not provide ultrastructural support for a close relationship between the Neodermata and B. semperi.

The brain structure of selected trypanorhynch tapeworms.

The brain architecture in four species of tapeworms from the order Trypanorhyncha has been studied. In all species, the brain consists of paired anterior and lateral lobes, and an unpaired central lobe. The anterior lobes connect by dorsal and ventral semicircular commissures; the central and lateral lobes connect by a median and an X-shaped crisscross commissure. In the center of the brain, five well-developed compact neuropils are present. The brain occupies a medial position in the scolex pars bothrialis. The ventral excretory vessels are situated outside the lateral lobes of the brain; the dorsal excretory vessels are located inside the brain and dorsal to the median commissure. The brain gives rize four anterior proboscis nerves and four posterior bulbar nerves with myelinated giant axons (GAs). The cell bodies of the GAs are located within the X-commissure and in the bulbar nerves. Highly developed serotonergic neuropils are present in the anterior and lateral lobes; numerous 5-HT neurons are found in the brain lobes including the central unpaired lobe. The X-cross commissure consists of the α-tub-immunoreactive and 5-HT-IR neurites. Eight ultrastructural types of neurons were found in the brain of the three species investigated. In addition, different types of synapses were present in the neuropils. Glial cells ensheath the brain lobes, the neuropils, the GAs, and the bulbar nerves. Glia cell processes form complex branching patterns of thin cytoplasmic sheets sandwiched between adjacent neural processes and filling the space between neurons. Multilayer myelin-like envelopes and a mesaxon-like structure have been found in Trypanorhyncha nervous system. We compared the brain architecture of Trypanorhyncha with that of an early basal cestode taxon, that is, Diphyllobothriidea, and present a hypothesis about the homology of the anterior brain lobes in order Trypanorhyncha; and the lateral lobes and median commissure are homologous brain structures within Eucestoda.

Two new species of Acanthobothrium Blanchard, 1848 (Cestoda: Onchoproteocephalidea) from rajiform batoids off Argentina.

Two new species of Acanthobothrium Blanchard, 1848 were collected from rajiform batoids along the coast of Argentina. They are Acanthobothrium carolinae sp. n. from Bathyraja magellanica (Philippi) and Acanthobothrium domingae sp. n. from Dipturus brevicaudatus (Marini). Both belong to category 1 and 2 because their total length is lower than 15 mm, they have fewer than 50 proglottids, fewer than 80 testes and a symmetric or asymmetric ovary. Acanthobothrium carolinae sp. n. differs from all congeners by the following combination of features: proglottid apolysis, hook morphology, microthrix pattern on the cephalic peduncle and distribution of the vitelline follicles. Acanthobothrium domingae sp. n. is unique in the combination of proglottid apolysis, total length, number of proglottids, hook and septal morphology, microthrix pattern on the cephalic peduncle, number and distribution of testes, cirrus sac length, distribution of the vitelline follicles and genital pore position. The discovery of these species increases the number of species of Acanthobothrium parasitising rajiform batoids off Argentina from one to three. All three species have a unique pattern of distribution of the gladiate spinitriches along the length of the cephalic peduncle, i.e., gladiate spinitriches being interrupted in a medial line both dorsally and ventrally.

Anthelmintic activity of praziquantel and Spilanthes acmella extract on an intestinal cestode parasite.

Spilanthes acmella Murr., popularised as toothache plant, is a well-known culinary and medicinal plant for different purposes, but its use as an anthelmintic is apparently exclusive to the Mizo people of India and Myanmar. A chloroform extract of Spilanthes acmella Murr. was analysed in a single quadrupole GC-MS system, from which it was found that the major compound was an alkylamide, N-isobutyl-(2E,4Z,8Z,10E)-dodecatetraenamide. A comparative study was performed on the anthelmintic activity of the plant extract and praziquantel (PZQ) against an intestinal cestode, Raillietina echinobothrida. In terms of efficacy, PZQ was more potent, but the plant extract was also effective at all concentrations tested. PZQ caused severe shrinkage and folds of the tegument, constriction of the suckers, dislocation of spines and erosion of microtriches. The plant extract caused shrinkage and folds on the main body but not on the scolex. Damage on the suckers is more pronounced than in PZQ-treated cestodes. The spines were completely removed. The current findings indicate that S. acmella is a good source of compounds with anthelmintic activity.

Morphological variation in the hyperapolytic lecanicephalidean species Anteropora japonica (Yamaguti, 1934) (Eucestoda).

In November of 2013, a specimen of Japanese sleeper ray, Narke japonica (Temminck et Schlegel), caught off Nanfang-ao, Taiwan was found to be parasitised by the cestode Anteropora japonica (Yamaguti, 1934). Specimens comprised whole worms and free proglottids, both of varying degrees of maturity. This material allowed for the opportunity to examine in detail the developmental progression of this hyperapolytic lecanicephalidean species with regard to overall size, scolex dimensions, and microthrix pattern. Complete immature worms ranged in size from 2.4 mm to 14 mm. The smallest scoleces were half as wide as larger scoleces and exhibited a much smaller ratio of apical organ width to bothridial width. Proglottids more than quadrupled in length during maturation from terminal attached immature to detached proglottids. In addition, a change in microthrix pattern was observed on the anterior region of the proglottids from immature to gravid proglottids; the anterior region of attached immature proglottids is covered with gladiate to coniform spinitriches with capilliform filitriches only rarely visible, whereas this region in detached proglottids is covered with gladiate to coniform spinitriches and conspicuous capilliform filitriches. This is the first report of A. japonica from outside Japan expanding its distribution south to Taiwan. In addition, a preliminary phylogenetic analysis of the genus is presented that suggests congeners from the same host species are not each other's closest relatives, nor is there an apparent phylogenetic signal for apical organ type or reproductive strategy (apolysis). However, reproductive strategy does seem to be correlated with host group such that euapolytic species parasitise dasyatid stingrays while hyperapolytic species parasitise either torpediniform rays or orectolobiform sharks.

Tapeworms (Cestoda) of Ictalurid Catfishes (Siluriformes) in North America: Redescription of Type Species of Two Genera and Proposal of Essexiellinae n. Subfam.

Ictalurid catfishes (Siluriformes) in North America harbor proteocephalid tapeworms of the subfamily Corallobothriinae. Type species of 2 of 3 genera of these tapeworms from ictalurids are redescribed, based on museum and newly collected material. Essexiella fimbriata (Essex, 1928) is typified mainly by a wide, umbrella-shaped scolex with a metascolex formed by numerous folds of tissue, anteriorly directed suckers without sphincters, vitellarium bent inwards posteriorly, "flower-shaped" uterus (with anterior, lateral, and posterior diverticula), and a conspicuously pre-equatorial genital atrium. Verified host records of this cestode are only from 3 species of Ictalurus Rafinesque, 1820. Megathylacoides giganteum (Essex, 1928), which seems to be specific to the channel catfish (Ictalurus punctatus), possesses a globular scolex, with a weakly developed metascolex formed by tissue folds posterior to the suckers, anterolaterally directed suckers with large semilunar sphincters, proglottids that are widest at the level of the genital atrium at the anterior third of the proglottid, and uterine diverticula that do not reach the vitelline follicles laterally. A new subfamily, Essexiellinae Scholz and Barcák, is proposed to accommodate species of EssexiellaScholz, de Chambrier, Mariaux and Kuchta, 2011 (type genus), MegathylacoidesJones, Kerley and Sneed, 1956, and CorallotaeniaFreze, 1965 from ictalurid catfishes in the Nearctic Region. These tapeworms possess a metascolex, medullary genital organs, uterus lined with numerous chromophilic cells, pre-equatorial genital atrium, and uterine development of type 2. The new subfamily was monophyletic in all molecular phylogenetic analyses, being most closely related to 3 Neotropical proteocephalids from the redtail catfish, Phractocephalus hemioliopterus (Bloch and Schneider, 1801), but distant from all remaining proteocephalid tapeworms from freshwater fishes in North America.

Scolex morphology of monozoic tapeworms (Caryophyllidea) from the Nearctic Region: taxonomic and evolutionary implications.

A comparative study of the scoleces of monozoic tapeworms (Cestoda: Caryophyllidea), parasites of catostomid and cyprinid fishes (Teleostei: Cypriniformes) in the Nearctic Region, was carried out using light and scanning electron microscopy. Scoleces of 22 genera of North American caryophyllideans were characterised and their importance for taxonomy, classification and phylogenetic studies was critically reviewed. Nearctic genera exhibit a much higher variation in the shape and form of scoleces compared with taxa in other biogeographical regions. The following basic scolex types can be recognised in Nearctic caryophyllideans: monobothriate (Promonobothrium Mackiewicz, 1968), loculotruncate (Promonobothrium, Dieffluvium Williams, 1978), bothrioloculodiscate (Archigetes Leuckart, 1878, Janiszewskella Mackiewicz et Deutsch, 1976, Penarchigetes Mackiewicz, 1969, Pseudoglaridacris Oros, Uhrovic et Scholz, 2018), fixomegabothriate (Capingens Hunter, 1927), bulbate and bulboacuminate (Atractolytocestus Anthony, 1958), cuneiloculate (Hypocaryophyllaeus Hunter, 1927, Rowardleus Mackiewicz et Deutsch, 1976, Spartoides Hunter, 1929), biacetabulate, bulboloculate, bothrioloculodiscate (Biacetabulum Hunter, 1927), tholate (Hunterella Mackiewicz et McCrae, 1962), cuneifimbriate (Khawia Hsü, 1935), cuneiform (Calentinella Mackiewicz, 1974, Caryophyllaeides Nybelin, 1922, Edlintonia Mackiewicz, 1970), hastate (Pseudolytocestus Hunter, 1929), loculotholate (Bialovarium Fischthal, 1953, Pliovitellaria Fischthal, 1951), and cuneiformoloculate (Glaridacris Cooper, 1920, Isoglaridacris Mackiewicz, 1965). The same type of scolex may be shared by species of different genera or families and species of the same genus can have a scolex of conspicuously different morphology, e.g. in Promonobothrium. Scolex morphology may be therefore of limited use in generic designation.

A New Onchoproteocephalidean Cestode Species from the Spot-Tail Shark, Carcharhinus sorrah (Müller et Henle), in the Persian Gulf.

INTRODUCTION: Members of the onchoproteocephalidean genus Phoreiobothrium Linton, 1889 infect carcharhinid and sphyrnid sharks. Although the Persian Gulf harbors a rich fauna of sharks, the taxonomic diversity of Phoreiobothrium in this region has been explored little. A new species of Phoreiobothrium is herein described from Carcharhinus sorrah (Müller et Henle) off southern Iran. METHODS: Cestodes were isolated from the spiral intestine of Carcharhinus sorrah, fixed in 10% seawater-buffered formalin, and stored in 70% ethanol. For morphological examinations, worms were stained using acetic carmine; a subset was prepared for SEM. RESULTS: Phoreiobothrium sorrahcola n. sp. is the first record of the genus from C. sorrah and most closely resembles Phoreiobothrium rozatii Alijanpour Darvishi et Haseli, 2019 recently described from the Gulf of Oman. However, it differs from P. rozatii in its possession of the rectangular, rather than triangular, bothridia, a longer cephalic peduncle (878-1300 vs 466-841), the longer axial prongs of lateral and medial hooks (B 56-80 vs 43-52; B' 66-98 vs 46-62), and a greater maximum width of worm at level of scolex (302-415 vs 215-298). CONCLUSIONS: With the description of this new species, three species of Phoreiobothrium have been reported so far from the southern waters of Iran. Phoreiobothrium now includes 17 valid species infecting 16 shark species.