Trypanorhynch Cestode Research Articles

The taxonomy of some Poecilacanthoidea (Eucestoda: Trypanorhyncha) from elasmobranchs off the southern coast of Brazil

Specimens of elasmobranchs, collected in the State of Santa Catarina, Brazil, were parasitized with Poecilacanthoidea trypanorhynch cestodes. Sharks of the species Prionace glauca harboured Callitetrarhynchus gracilis and Floriceps saccatus, and those of the species Sphyrna zygaena were infected with Callitetrarhynchus speciosus. Details of the proglottids of F. saccatus, provided by bright-field, and/or scanning electron microscopy, are described. Adults of F. saccatus are reported for the first time in the Brazilian coast.

FIRST EVIDENCE OF THE PRESENCE OF MICROTRICHES IN THE GYROCOTYLIDEA

The Gyrocotylidea, a small and enigmatic group of intestinal parasites of chimaeras, has been considered to be related either to the Monogenea, or, more frequently, to the most primitive monozoic tapeworms (Cestoda), i.e., the Amphilinidea and Caryophyllidea. The present study, based on transmission electron microscopical observations of a species of Gyrocotyle from the rabbit fish, Chimaera monstrosa, in the North Atlantic, demonstrates for the first time the presence of microtriches as surface structures of gyrocotylideans. Because microtriches are considered to be an autapomorphy of tapeworms (Cestoda), in which they differ from other Neodermata (Monogenea and Trematoda), the present data represent another source of evidence in support of a close relationship between the gyrocotylideans and the tapeworms sensu stricto (Eucestoda). Simple morphology, small size, and shape uniformity of the microtriches of Gyrocotyle sp. may indicate they represent an original (plesiomorphic) form that then evolved in more derived cestode groups into a variety of types present mainly on the scolex. The microtriches of Gyrocotyle sp. resemble those found in caryophyllidean, spathebothriidean, pseudophyllidean, and trypanorhynch cestodes, which are considered to represent the most basal groups of the Eucestoda.

Mode of attachment and lesions associated with trypanorhynch cestodes in the gastrointestinal tracts of two species of sharks collected from coastal waters of Borneo

Lesions associated with two species of tapeworms within the digestive tract of wild-caught specimens of the bull shark, Carcharhinus leucas, and the sicklefin weasel shark, Hemigaleus microstoma, from Malaysian Borneo are described. Portions of the glandular stomach and pyloric gut with parasites were removed and fixed in 10% formalin buffered in sea water. Whole mounts, histological sections of tissues with and without worms in situ, and scanning electron microscopy images of detached worms were examined. Both species of cestodes belonged to the trypanorhynch family Tentaculariidae. Heteronybelinia estigmena was found in large numbers parasitizing the pyloric gut of C. leucas; an unidentified tentaculariid was found in relatively small numbers in both the glandular stomach and pyloric gut of H. microstoma. Both species burrowed their scoleces deeply in the mucosa and attached via hooked tentacles and unciniform microtriches of the scolex. The lesions induced by the parasites were marked in both sharks and ranged from acute necrotizing to chronic granulomatous gastroenteritis. Regenerative hyperplasia and intestinal metaplasia of gastric epithelium were also present. The severity and character of pathology was causally linked to the intensity of infection, the attachment mode of the parasites, and to the anatomophysiological relationships within the gut of the host shark.

VARIATIONS IN THE PARASITE FAUNA OF THE PATAGONIAN TOOTHFISH (DISSOSTICHUS ELEGINOIDES SMITT, 1898), WITH LENGTH, SEASON, AND DEPTH OF HABITAT AROUND THE FALKLAND ISLANDS

The parasite fauna of Dissostichus eleginoides was examined from locations around the Falkland Islands. In total, of 11,362 individual parasites of 27 taxa were recovered from 105 fish. Two species, Ceratomyxa dissostichi and Sphaerospora dissostichi, represent new host records. The nematode Ascarophis nototheniae and the larval acanothocephalan Corynosoma bullosum were found to be new locality records and add to the knowledge of the biogeography and host specificity of parasites on the Patagonian Shelf. There were no significant differences in the mean abundance and prevalence of parasites recovered between sexes. Therefore, sex was not considered in further analysis and the data were pooled. Cysts of unknown etiology (CUE), the monogenean Neopavlovskioides georgianus, the larval acanthocephalan Corynosoma bullosum, and the digenean Neolepidapedon magnatestis had significant positive correlations with increasing host length. The larval Trypanorhynch cestode Grillotia erinaceus and the digenean Elytrophalloides oatesi showed significant negative correlations with increasing host length. CUEs, N. georgianus, the digenean Gonocerca physidis and E. oatesi showed statistically significant prevalence between summer, winter, and spring. The effect of depth on parasite communities was also examined, initially using a linear discriminant function analysis. The prevalence of individual parasites was then compared between depth strata using the chi-square test. The parasite communities on the shelf and deep water (> 1,000 m) were found to be different, whereas those caught at intermediate depths on the shelf slope were found to have parasite communities that were intermediate, containing a mixture of shelf and deeper-water parasites. The causes of the variations in parasite faunas in association with these intrinsic and extrinsic factors are discussed.

Ultrastructure of the spermatozoon of Dollfusiella spinulifera (Beveridge and Jones, 2000) Beveridge, Neifar and Euzet, 2004 (Trypanorhyncha, Eutetrarhynchidae)

The ultrastructural organization of the mature spermatozoon of the trypanorhynch cestode Dollfusiella spinulifera is described. The spermatozoon is a long filiform cell, tapered at both ends, which lacks mitochondria. Its cytoplasm contains (1) two axonemes of different lengths of the 9+'1' pattern of trepaxonematan Platyhelminthes, (2) two rows of parallel cortical microtubules, each of which is adjacent to the opposite sides of the plasma membrane, (3) the nucleus, and (4) glycogen in the form of both alpha-glycogen rosettes and beta-glycogen particles. Unlike the majority of cestode spermatozoa, the spematozoon of D. spinulifera lacks crested bodies and periaxonemal sheath. In view of the present results, the postulated synapomorphic value of crested bodies for the Eucestoda is questioned.

Ultrastructure of vitellocytes in the cestode Progrillotia pastinacae Dollfus, 1946 (Trypanorhyncha, Progrillotiidae)

AbstractThe present study describes the ultrastructure of mature vitellocytes of the trypanorhynch cestode Progrillotia pastinacae Dollfus, 1946 (Progrillotiidae), a parasite of the common stingray Dasyatis pastinaca (Linnaeus, 1758) (Dasyatidae). The vitelline cells of this species measure about 24 μm in length and about 20 μm in width. They have small, elongated, slightly lobulated nuclei, about 4–5 μm in length, with large dense elongated nucleoli and numerous irregularly-shaped dense clumps of heterochromatin. The extensive cytoplasm is rich in numerous cell organelles and cell inclusions. While the perinuclear cytoplasm contains numerous long parallel cisternae of GER, ribo-and polyribosomes, several Golgi complexes and mitochondria, the peripheral cytoplasm contains predominantly three types of cell inclusions: a great number of large lipid droplets, several shell globule clusters, and a very small amount of glycogen-like particles. The most characteristic features of vitellocytes in P. pastinacae are having almost no traces of glycogen and the great number of large, highly osmiophobic lipid droplets representing saturated fatty acids. The presence of large amounts of lipids also in two other trypanorhynchs, Grillotia erinaceus (Beneden, 1858) Guiart, 1927 and Dollfusiella spinulifera (Beveridge et Jones, 2000) Beveridge, Neifar et Euzet, 2004, is in strong contrast to the condition in the most evolved cestodes, Cyclophyllidea, that usually show no trace of lipids.

Taxonomic reports of Homeacanthoidea (Eucestoda: Trypanorhyncha) in Lamnid and Sphyrnid elasmobranchs collected off the coast of Santa Catarina, Brazil

Elasmobranch specimens of lamnid and sphyrnid captured in 1999 in the State of Santa Catarina, Brazil, were parasitized with homeacanthoid trypanorhynch cestodes: Isurus oxyrinchus Rafinesque, 1810 with Nybelinia lingualis (Cuvier, 1817) Dollfus, 1929; Sphyrna zygaena (Linnaeus, 1758) with Heteronybelinia rougetcampanae (Dollfus, 1960) Palm, 1999. New details of internal morphology and/or scolex and/or proglottid surface ultrastructure are given. Adults of N. lingualis are reported for the first time in the Brazilian coast.

Three new genera of trypanorhynch cestodes from Australian elasmobranch fishes

Three new genera of trypanorhynch cestodes from Australian elasmobranch fishes collected in the Arafura Sea, off the Northern Territory, are described. Fossobothrium perplexum n. g., n. sp. (Otobothriidae), from the spiral valves of Anoxypristis cuspidata (Latham) and Pristis zijsron Bleeker, is similar to the otobothriid genera Pseudotobothrium Dollfus, 1942 and Poecilancistrium Dollfus, 1929 in possessing bothrial pits and a band of hooks on the tentacle, but differs from all known otobothriid genera in having the pits joined by a prominent velum. Iobothrium elegans n. g., n. sp. (Otobothriidae), from the spiral valve of Himantura jenkinsi (Annandale), is placed in the Otobothriidae because it possesses bothrial pits, but differs from Otobothrium Linton, 1890 and other genera in lacking intercalary hooks between the principal rows and in possessing a chainette on the external surface of the tentacle in the metabasal region. Oncomegoides celatus n. g., n. sp. (Eutetrarhynchidae), from the spiral valve of Dasyatis microps (Annandale) and Himantura jenkinsi, resembles Oncomegas Dollfus, 1929 in possessing two bothria and a megahook on the bothrial surface of the basal armature, but differs in possessing an extra row consisting of four intercalary hooks formed by the overlapping of two intercalary hooks on the external tentacular surface between each of the opposing principal rows and is therefore an atypical heteroacanth.

Taxonomic reports of Otobothrioidea (Eucestoda, Trypanorhyncha) from elasmobranch fishes of the southern coast off Brazil.

Specimens of elasmobranch fishes, captured in the states of Paraná and Santa Catarina, of the southern coast off Brazil, represented by three families, four genera, and four species, were parasitized with otobothrioid trypanorhynch cestodes: Heptranchias perlo (Bonnaterre, 1788), Squalus sp. and Carcharhinus signatus (Poey, 1868) were parasitized with Progrillotia dollfusi Carvajal & Rego,1987; Prionace glauca (Linnaeus, 1758) with Molicola horridus (Goodsir, 1841) Dollfus, 1942. Details of internal morphology and/or scolex and/or proglottids surface ultrastructure, that expanded the description of M. horridus, through observations with lightfield, and/or scanning eletronic microscopy, are provided. The known geographical distribution for the species M. horridus is enlarged. P. dollfusi is reported for the first time in elasmobranchs.

Metazoan parasites and food composition of juvenile Etmopterus spinax (L., 1758) (Dalatiidae, Squaliformes) from the Norwegian Deep.

A total of 37 juvenile Etmopterus spinax from the Norwegian Deep were examined for stomach contents and metazoan ecto- and endoparasites. These squaliform elasmobranchs were caught by benthopelagic net in May 2001 at a depth of 194-214 m. The euphausiid Meganyctiphanes norvegica and the teleost Maurolicus muelleri were the principal prey organisms. With increasing total length of E. spinax, the frequency of Meganyctiphanes norvegica prey decreased and that of M. muelleri increased. Seven different metazoan parasite species were found: adult Monogenea (2), larval and adult Cestoda (3), and larval Nematoda (2). The predominant parasites were an unidentified monocotylid monogenean and the cestode Aporhynchus norvegicus, with respective prevalences of infestation of 83.8% and 81.1%. The sites of infestation were the gills ( Squalonchocotyle spinacis, Monogenea), nasal cavities (Monocotylidae indet.), body cavity ( Lacistorhynchus tenuis, Cestoda), stomach wall and organs of the body cavity ( Anisakis simplex, Nematoda), and stomach and spiral valve ( A. norvegicus and Pseudophyllidea indet., Cestoda; Hysterothylacium aduncum, Nematoda). No other metazoan parasite taxa were found, and the musculature was free of parasites. Five new host and three new locality records were established. M. muelleri seems to be an important intermediate host for the endoparasitic nematodes which were found, with E. spinax serving as a paratenic host. E. spinax also serves as an intermediate host for the trypanorhynch cestode L. tenuis, and as the definitive host for the two monogeneans and the trypanorhynch A. norvegicus. The latter uses Meganyctiphanes norvegica as the second intermediate host in the Norwegian Deep. The relationship between the feeding ecology, habitat, and vagility of E. spinax and the resulting parasite fauna is discussed.

Grillotia borealis sp. n. (Cestoda: Trypanorhyncha) from five species of Bathyraja (Rajiformes: Arhynchobatidae) in the North Pacific Ocean with comments on parasite enteric distribution.

A new trypanorhynch cestode, Grillotia borealis sp. n., is described from the spiral intestines of softnose skates of the genus Bathyraja collected from subarctic waters of the North Pacific Ocean: B. parmifera (Bean) (type host), B. aleutica (Gilbert) and B. interrupta (Gill et Townsend) from the Bering Sea and B. minispinosa Ishiyama et Ishihara and B. sminovi (Soldatov et Pavlenko) from the Sea of Okhotsk off Japan. The new species is distinguished from other species of Grillotia by possession of the following combination of characters: four hooks per principal row, hooks 4(4') distinctly separated from hooks 3(3') of principal row, principal rows separated by 13-15 intercalary hooks in 2-3 rows, hooks 2(2') and 3(3') change in form along their respective files, hooks 1(1') do not change in form along the file, a broad band of microhooks on the external tentacular face, intermediary hooks are lacking, absence of a special basal armature, origin of the retractor muscle near middle of the bulb, average scolex ratio of 1:3:2:0.1, and a hermaphroditic sac. Grillotia borealis consistently favoured the most anterior regions of the spiral intestine. Seventy-one per cent of 21 attached worms occupied the most anterior chamber of the spiral valve and 52 per cent were embedded in the anterior surface of the spiral valve whorls. Factors which may limit the distribution of G. borealis within the spiral intestine of its host are discussed. Statistically significant differences occur in the mucosal morphology of B. aleutica and B. parmifera for villus length, diameter, spatial arrangement and number per unit area along the antero-posterior axis of the spiral intestine.

New records of trypanorhynch cestodes from the Gulf of Mexico, including Kotorella pronosoma (Stossich, 1901) and Heteronybelinia palliata (Linton, 1924) comb. n.

Four trypanorhynchs, Kotorella pronosoma (Stossich, 1901), Nybelinia cf. bisulcata (Linton, 1889), Nybelinia scoliodoni (Vijayalakshmi, Vijayalakshmi et Gangadharam, 1996), and Dasyrhynchus pacificus Robinson, 1965 are reported for the first time from the Gulf, which is now known to harbour at least 34 different species. In addition to the range extension for the trypanorhynchs listed above, 21 new host records are reported involving 13 cestode species. Characters of the genus Kotorella Euzet et Radujkovic, 1989 are emended, Nybelinia narinari MacCallum, 1917 is considered ajunior synonym of Kotorellapronosoma (Stossich, 1901), and Heteronybelinia palliata (Linton, 1924) comb. n. is redescribed. The usefulness of the bulb ratio as a means to distinguish different tentaculariid species is discussed, and the importance of shallow water localities for the life cycle of trypanorhynch cestodes is emphasised.

Sensory receptors and surface ultrastructure of trypanorhynch cestodes

The scolices of six different trypanorhynch species--Heteronybelinia alloiotica (Dollfus, 1960), Pseudolacistorhynchus noodti Palm, 1995, Otobothrium cysticum (Mayer, 1842), O. penetrans Linton, 1907, Poecilancistrum caryophyllum (Diesing, 1850), and Prochristianella hispida (Linton, 1890)--were examined for surface morphology and the occurrence of sensory receptors. Filamentous microtriches with different internal ultrastructural features were found. Acerosate, hook-like, and spiniform microtriches were detected on the surface of the tentaculariid H. alloiotica. Their internal structure clearly differed from that of pectinate microtriches observed in the other five trypanorhynch species lacking a basal and a junctional region. All pectinate microtriches had the same general architecture, independent of the number of digitiform processes. All trypanorhynchs studied harbored ciliated sensory receptors within the tegument. Even though sensory receptors were scarce in H. alloiotica, they were more abundant in the lacistorhynchid P. noodti and the otobothriids P. caryophyllum and O. penetrans, which exhibited two, six, and three kinds of receptors, respectively. Bothridial pits in O. penetrans and O. cysticum were invaginations of the bothridial surface, being characterized by the lack of sensory receptors and the presence of characteristic microtriches. These differed from other microtriches in that they were larger and had a base consisting of a widely enlarged matrix. The occurrence of different kinds of microtriches and sensory receptors within trypanorhynch cestodes is summarized, and the meaning of these surface structures and of bothridial pits as characters within future trypanorhynch classification is emphasized.

Trypanorhynch cestodes from Indonesian coastal waters (East Indian Ocean).

Results of a study on trypanorhynch cestodes of fishes from Indonesian coastal waters are presented. A new species, Dasyrhynchus thomasi sp. n., is described, and five species are recorded which all represent new locality records: Tentacularia coryphaenae Bosc, 1797; Nybelinia africana Dollfus, 1960; Nybelinia scoliodoni (Vijayalakshmi, Vijayalakshmi et Gangadharam, 1996); Sphyriocephalus dollfusi Bussieras et Aldrin, 1968; and Otobothrium penetrans Linton, 1907. Their known ranges of distribution are extended to the East-Indian Ocean. Scanning and transmission electron microscopy was used to clarify details of the tentacular armature and surface morphology of T. coryphaenae, D. thomasi and O. penetrans. In T. coryphaenae, hook-like microtriches along the bothridial tegument are embedded in the distal cytoplasm, sometimes showing a split base. The solid tentacular hooks are embedded into a fibrillar, highly ordered tentacular wall. D. thomasi is distinguished by its characteristically shaped bothridia and a triple chainette with winged hooks on the external surface of the tentacle. Tufts of microtriches with ciliated sensory receptors are regularly arranged on the bothridial surface of O. penetrans. They show similarities to sensory receptors reported from other trypanorhynch cestodes. Otobothrium pephrikos Dollfus, 1969 is considered a junior synonym for O. penetrans, and the variability of the scolex within trypanorhynch cestodes is emphasised.

Otobothrium cysticum (Cestoda: Trypanorhyncha) from the muscle of butterfishes (Stromateidae).

On the basis of the tentacular armature, surface ultrastructure, and morphological measurements of plerocerci obtained from the musculature of butterfishes (Stromateidae), we corroborate an earlier proposal that Otobothrium crenacolle, a commonly reported trypanorhynch cestode from the northwestern Atlantic coast, is a junior synonym of O. cysticum. This action exemplifies at least an Atlantic Ocean and Indian Ocean distribution for O. cysticum. The infection in commercially important butterfishes shows that an otobothriid trypanorhynch may heavily infect fish flesh and influence the market value of some fish species yet also be restricted to the body cavity of other fish intermediate hosts. Infections of O. cysticum in the flesh of Peprilus burti (Gulf butterfish) and P. alepidotus (harvestfish) in the Gulf of Mexico has varied annually since 1970, with samples ranging in prevalence between 20% and 100% and in mean intensity between 1 and 3,500 or more plerocerci per fish. Comparative infections in P. burti from the Gulf of Mexico and P. triacanthus (butterfish) from the Atlantic Ocean demonstrate a present geographic difference in infections. The prevalence and mean intensity in 4 collections of butterfishes ranged from 9% to 98% of the fish and from 1 to 678 plerocerci in a subsample of tissue, respectively, with prevalent and heavy infections being observed in the Gulf of Mexico fish and relatively few individuals being infected with few worms in the Atlantic fish. A slight host response in the butterfishes involving some fatty infiltration and inflammatory infiltration was associated with the metacestode. In some larger fish, encapsulations were yellow, and in a few cases, worms had degenerated. This finding and an increase in intensity with fish weight suggest a continual accumulation of the worms in association with little host resistance.

Ultrastructural study of the papillae and presumed sensory receptors in the scolex of the Gymnorhynchus gigas plerocercoid (Cestoda: Trypanorhyncha).

The ultrastructure of the papillae and presumed sensory receptors in the tegument of the scolex of Gymnorhynchus gigas plerocercoid were investigated by scanning and transmission electron microscopy. Four distinct types of putative sense receptor (including three uniciliated and one nonciliated) are described for the first time in G. gigas, and this investigation is the first detailed ultrastructure study of tegumental receptors carried out in trypanorhynch cestodes. Microtriches arranged in clusters with a dome-shaped pattern seemed to be papillae that contained a ciliated sensory receptor (type I). The density of these papillae was greater in the center of the bothridial adherent surface near the tentacle orifice than in the lateral margins of the bothridia or in the pars post-bothridialis. The type I receptor is characterized by a long cilium anchored in the nerve bulb by a dense basal body but lacks rootlets. The bulb contains one or two electron-dense collars, numerous electron-lucent neurovesicles, and some mitochondria. The type II receptor presents a short cilium retracted into an invagination of the tegument that arises from the basal body. The bulb contains one electron-dense collar and numerous electron-lucent vesicles, but the rootlets are absent. The type III receptor is also a ciliated receptor embedded in a bulb wider than that of types I and II, and it differs from type II in that it possesses two electron-dense collars and small rootlets associated with the basal body. No electron-lucent vesicle was found in the bulb of this type III receptor. The type IV receptor is a nonciliated receptor localized under the surface with no contact to the outside. It consists of a flattened bulb that contains two electron-dense collars and striated rootlets associated with a band of microfilaments. A comparison of the ultrastructural features of receptors in different cestodes is presented.

Paroncomegas araya (Woodland, 1934) n. gen. et comb. (Cestoda: Trypanorhyncha: Eutetrarhynchidae) from the Freshwater Stingray Potamotrygon motoro in South America

The trypanorhynch cestode originally designated Tentacularia araya is redescribed from its type host, Potamotrygon motoro (Potamotrygonidae), from specimens recently collected in Argentina and type material. The armature combines features of Eutetrarhynchus, Oncomegas, and Dollfusiella, indicating that its current placement in Eutetrarhynchus is incorrect and that the species represents a new genus. Paroncomegas n. gen. is proposed within the Eutetrarhynchidae Guiart, 1927, to accommodate Tentacularia araya as Paroncomegas araya n. comb. Eutetrarhynchus differs from Paroncomegas in the absence of a basal armature and basal swelling on the tentacles, from Dollfusiella by lacking macrohooks associated with the basal armature, and from Oncomegas, which possesses an asymmetrical basal swelling on the internal face of the tentaclc and a single macrohook on the external face of the basal armature. Paroncomegas is unique among these genera in possessing a chainette in the basal armature. All other genera currently recognized within the Eutetrarhynchidae can be distinguished from Paroncomegas by a distinct spatial divergence of hooks files 1(1'), resulting in a prominent space in views of the internal face. Two different morphotypes of P. araya can be distinguished in the material from Argentina, both infecting the same individual host specimens. They differ in the number and size of mature and gravid segments. Other characters concerning the tentacle armature, scolex features, and reproductive anatomy remain comparable.

Surface ultrastructure of plerocercoids of Bombycirhynchus sphyraenaicum (Pintner, 1930) (Cestoda: Trypanorhyncha).

Light microscopy studies have previously shown that Bombycirhynchus sphyraenaicum is an exceptional trypanorhynch cestode, characterised by a poeciloacanthous armature and two enormous bothridia, which overlap parts of the pars bulbosa, a character combination unique within the trypanorhynchs. Plerocercoids of B. sphyraenaicum from the fish Lates calcarifer (Centropomidae) were investigated by scanning and transmission electron microscopy. Results revealed that the tegument of the anterior margin of the distal bothridial surface bears three kinds of microtriche; palmate microtriches, 8 microns high, with seven to eight digitiform processes; equalized filamentous microtriches, 5-6 microns long, with cap and base each forming 50% of the length, borne on undulations beneath the palmate microtriches, and cap-dominated filamentous microtriches, 5-6 microns long, with the cap forming 75% of the length, borne on the apex of putative sensory papillae. Integumental connections link the bases of the palmate microtriches, forming transverse girdles around the worm, which may serve to coordinate traction. At regular intervals between the palmate microtriches are papillae, covered with filamentous microtriches extending above the palmate microtriches. A cilium emerges from a bulb at the apex of each papilla; other structures in the bulb include an electron-dense cuff, and two electron dense collars. The posterior part of the bulb tapers and passes into the tegumental cytoplasm. These adorned papillae, observed for the first time in trypanorhynch cestodes, are identified as putative mechanoreceptors.

Re-examination of the trypanorhynch cestode collections of A.E. Shipley, J. Hornell and T. Southwell, with the erection of a new genus, Trygonicola, and redescriptions of seven species

Cestodes named by A.E. Shipley, J. Hornell and T. Southwell in the collections of the British Museum (Natural History) and the Naturhistorisches Museum, Vienna, are redescribed and re-illustrated. New synonymies and synonymies confirmed by examination of types are: Shirleyrhynchus aetobatidis (Shipley & Hornell, 1906) n. comb. (syn. S. butleri Beveridge & Campbell, 1988); Paranybelinia balli (Southwell, 1929) n. comb. (syn. Otobothrium balli Southwell, 1929); Calliterarhynchus gracilis (Rudolphi, 1819) (syn. Tetrarhynchus ceylonicus Southwell, 1929, Tentacularia macfiei Southwell, 1929); Poecilancistrium caryophyllum (Diesing, 1850) (syn. Tetrarhynchus gangeticus Shipley & Hornell, 1906); Mecistobothrium johnstonei (Southwell, 1929) n. comb. (syn. Tentacularia johnstonei Southwell, 1929); Trygonicola macroporus (Shipley & Hornell, 1906) n. comb., n. g. (syn. Tetrarhynchus macroporus Shipley & Hornell, 1906); Grillotia matheri (Southwell, 1929) n. comb. (syn. Tetrarhynchus matheri Southwell, 1929); Dasyrhynchus pillersi (Southwell, 1929) (syn. Tentacularia pillersi Southwell, 1929); Grillotia shipleyi (Southwell, 1929) n. comb. (syn. Tetrarhynchus shipleyi Southwell, 1929, Tetrarhynchus sp. (? matheri) of Southwell, 1929 and Grillotia overstreeti Sakanari, 1989); and Bombycirhynchus sphyraenaicum Pintner, 1931 (syn. Tetrarhynchus sp. of Shipley & Hornell, 1906, Patellobothrium quinquecatinatum Beveridge & Campbell, 1989).

Pterobothrioides, a new genus of tapeworms (Cestoda: Trypanorhyncha: Pterobothriidae) from dasyatid stingrays in the Eastern Atlantic and Pacific Oceans

Two new species of pterobothriid trypanorhynch cestodes representing a new genus are described from dasyatid stingrays taken in Pacific coastal waters off Mexico and Costa Rica and from Atlantic waters off Senegal, West Africa. Pterobothrioides carvajali n. g., n. sp. is described from Dasyatis longus (Garman) from Pacific coastal waters off Mexico and Costa Rica. P. petterae n. g., n. sp. is described from Gymnura altavela (Linnaeus) from Atlantic coastal waters off West Africa. Both species resemble other pterobothriids in their possession of four pedicellate bothridia in a cruciform arrangement, elongated scolex and bulbs, heteroacanthous armature with five hooks per principal row, one or more intercalary rows and a band consisting of irregular files of microhooks on the external tentacular surface. Both new species are unique in the possession of a simple chainette of hooks in addition to a band of microhooks in the tentacle armature. The chainette hooks of P. carvajali are robust, rose-thorn-shaped hooks with large rounded bases. The chainette of P. petterae consists of smaller uncinate hooks that are most distinct in the basal region of the tentacle armature and progressively decrease in size until they become almost indistinguishable from the band microhooks in the distal metabasal region. A new genus, Pterobothrioides, is proposed to accommodate these two new species, combining a chainette, considered characteristic of poeciloacanths, with the band of hooks characteristic of atypical heteroacanths. It is suggested that through changes in hook number and arrangement the typical heteroacanths, having bands of hooks, evolved into poeciloacanths with chainettes and that clades are now apparent in the family Pterobothriidae.