A new species of Pomphorhynchus (Acanthocephala: Palaeacanthocephala) in freshwater fishes from central Chile

This study describes a new species of Pomphorhynchus collected from Percilia gillissi Girard, 1855 from the Za?artu canal, between the sister basins of the Itata and Laja rivers, in central Chile. Pomphorhynchus moyanoi n. sp. is characterized by an asymmetrical, well-differentiated subspherical bulb and 12-14 longitudinal rows of 13-14 hooks; the third and the fourth hook in each row are stout. Among South American species, P. moyanoi n. sp. shows some similarities to the Chilean species P. yamagutii Schmidt & Hugghins, 1973, but it differs in having a longer neck, larger bulb, and different proboscis armature arrangement. Pomphorhynchus moyanoi n. sp. differs from P. patagonicus Ortubay, Ubeda, Semenas & Kennedy 1991, in the bulb shape (protuberances), number of rows, fourth hook size and basal hook size. Pomphorhynchus moyanoi n. sp. also differs from P. sphaericus in the arrangement of hooks (number of rows and hooks per row), length and width of the proboscis, neck width, and symmetry of the bulb.     

Organisation of the praesoma in Acanthocephalus anguillae (Acanthocephala, Palaeacanthocephala) with special reference to the muscular system

The organisation of the praesoma in the parasite Acanthocephalus anguillae was studied on the light and electron microscopic level, with emphasis on the morphology of the musculature. The study was compiled to add new data to the ground pattern of the Acanthocephala for analysis of the phylogenetic relationships within the Gnathifera. In A. anguillae the praesomal epidermis and lemnisci form a coherent syncytium, separated from the epidermis of the trunk. Hooks are seen to be derivatives of the subepidermal basal lamina and are covered by the praesomal epidermis. The praesomal circular body wall musculature forms a network of anastomosing muscle fibres that lines the proboscis; a praesomal longitudinal body wall musculature does not exist. The truncal circular and longitudinal body wall musculature rise up to the praesomal proboscis. The unpaired proboscis retractor, consisting of longitudinal circomyar fibres, forms an outer and an inner concentric tube; the latter extends through the entire praesoma and penetrates the receptacle wall. The sack-like receptacle is surrounded by a receptacle constrictor. The nervous system of the praesoma consists of a prominent cerebral ganglion, three nerves which extend anteriorly, ramify and end within the praesomal musculature, and two strong lateral posterior nerves. A. anguillae lacks an apical organ, lateral organs and a support cell. Many of the features present in the praesoma of A. anguillae can be assumed as ground-pattern characteristics of the Acanthocephala. Accepted: 22 January 2001     

Validating the systematic position of Profilicollis Meyer, 1931 and Hexaglandula Petrochenko, 1950 (Acanthocephala: Polymorphidae) using cytochrome c oxidase (Cox 1)

Members of the Polymorphidae (Acanthocephala) are distributed worldwide as endoparasites of marine mammals, fish-eating birds, and waterfowl. The family contains 10 genera, with approximately 127 species. Polymorphids are characterized by having a spinose trunk with a bulbous proboscis, double-walled proboscis receptacle, long lemnisci, and 4 tubular cement glands. The taxonomic position of several genera within Polymorphidae has been controversial when considering morphological and ecological characters. The mitochondrial coding gene cytochrome-c oxidase representing species of 5 genera of polymorphids (Corynosoma, Lühe, 1904, Hexaglandula Petrochenko, 1950, Southwellina Witenberg 1932, Polymorphus Luh?, 1911, and Profilicollis Meyer, 1931) were sequenced to determine the sister-group relationships among 2 particular genera, i.e., Hexaglandula, and Profilicollis. Maximum likelihood and Bayesian analyses showed that Polymorphidae is a monophyletic assemblage, and that 3 major clades are present. Our results provide support for the idea that Hexaglandula represents an independent lineage, whereas, in the case of Profilicollis, there is no conclusive evidence that they are not members of Polymorphus. The analyses also confirm that Polymorphus is paraphyletic, suggesting that the genus represents a complex of species that should be reexamined and reclassified using morphological, ecological, and molecular data. Our observations suggest that decapods (intermediate hosts for the 2 genera under study) were independently colonized at least twice during the evolutionary history of the group.     

Phylogenetic relationships of Palaeacanthocephala (Acanthocephala) inferred from SSU and LSU rDNA gene sequences

The Palaeacanthocephala is traditionally represented by 2 orders, Echinorhynchida and Polymorphida, with 10 and 3 families, respectively. To test the monophyly of the class, these 2 orders, and certain families, phylogenies were inferred using nuclear small-subunit (SSU) and large-subunit (LSU) ribosomal DNA sequences obtained for 29 species representing 10 families, 2 other classes of acanthocephalans, and 3 rotifer outgroups. Phylogenetic relationships were inferred by analyzing combined SSU and LSU sequences using maximum parsimony (MP) and maximum likelihood (ML) methods. Parsimony and ML trees inferred from combined analysis of these rDNA data strongly supported monophyly of Palaeacanthocephala and provided good resolution among species. Neither Polymorphida nor Echinorhynchida was monophyletic. Gorgorhynchoides bullocki (Echinorhynchida) was nested within the 6 species representing Polymorphida, and this clade was nested within species representing Echinorhynchida. Three of 4 palaeacanthocephalan families that could be evaluated were not monophyletic, and this finding was strongly supported. These results indicate that the family level classification of palaeacanthocephalans, which is mainly based on combinations of shared characters (not shared derived characters), needs to be reevaluated with respect to comprehensively sampled phylogenetic hypotheses.     

Molecular phylogeny of the Acanthocephala (class Palaeacanthocephala) with a paraphyletic assemblage of the orders Polymorphida and Echinorhynchida

Acanthocephalans are attractive candidates as model organisms for studying the ecology and co-evolutionary history of parasitic life cycles in the marine ecosystem. Adding to earlier molecular analyses of this taxon, a total of 36 acanthocephalans belonging to the classes Archiacanthocephala (3 species), Eoacanthocephala (3 species), Palaeacanthocephala (29 species), Polyacanthocephala (1 species) and Rotifera as outgroup (3 species) were analyzed by using Bayesian Inference and Maximum Likelihood analyses of nuclear 18S rDNA sequence. This data set included three re-collected and six newly collected taxa, Bolbosoma vasculosum from Lepturacanthus savala, Filisoma rizalinum from Scatophagus argus, Rhadinorhynchus pristis from Gempylus serpens, R. lintoni from Selar crumenophthalmus, Serrasentis sagittifer from Johnius coitor, and Southwellina hispida from Epinephelus coioides, representing 5 new host and 3 new locality records. The resulting trees suggest a paraphyletic arrangement of the Echinorhynchida and Polymorphida inside the Palaeacanthocephala. This questions the placement of the genera Serrasentis and Gorgorhynchoides within the Echinorhynchida and not the Polymorphida, necessitating further insights into the systematic position of these taxa based on morphology.     

A new Acanthocephala Breizacanthus ligur sp. n. (Palaeacanthocephala: Arhythmacanthidae Yamatugi, 1935) parasite of some species of benthic fishes from the Ligurian Sea]

Breizacanthus ligur sp.n. is described and figured from several benthic fishes from the Ligurian Sea. The host species are: Argentina sphyraena, Chlorophthalmus agassizi, Gadiculus argenteus, Phycis blennoides, Coelorhynchus coelorhynchus, Capros aper, Callionymus phaeton, Helicolenus dactylopterus. The parasites were considered as belonging to the family Arhythmacanthidae Yamaguti, 1935 and to the genus Breizancanthus Golvan, 1969. Breizancanthus ligur differs from the only two known species of the genus B. irenae and B. chabaudi for the number of longitudinal rows of hooks and-or numbers of hooks in each longitudinal row, arrangment of cement glands, length of body and lenght of male genital apparatus ratio, lenght of female genital apparatus and shape of embroyophore.     

Morphological and molecular differentiation of two new species of Pseudoacanthocephalus Petrochenko, 1958 (Acanthocephala: Echinorhynchidae) from amphibians and reptiles in the Philippines, with identification key for the genus

The genus Pseudoacanthocephalus Petrochenko, 1958 currently includes 14 species of acanthocephalans parasitic in amphibians and reptiles worldwide. This work describes two new species of Pseudoacanthocephalus from amphibians and reptiles collected in several localities on Luzon Island, Philippines. Pseudoacanthocephalus nickoli n. sp. was found in two species of frogs, Rana luzonensis Boulenger and Rana similis (Günther), and Pseudoacanthocephalus smalesi n. sp. was found in a scincid lizard, Sphenomorphus abdictus Brown & Alcala. Differential diagnoses of the two new species of Pseudoacanthocephalus from their congeners are provided. Comparative analysis of nuclear ribosomal rRNA sequences encompassing the 3′ end of 18S nuclear rDNA gene, internal transcribed spacer region (ITS1+5.8S+ITS2), and 5′ end of the 28S gene strongly corroborated the morphological evidence and demonstrated significant differences between the two new species as well as between these species and closely related species from continental China and Vietnam. No intraspecific sequence variability was detected among different individuals representing each of the examined species. This is the first report of Pseudoacanthocephalus in the Philippines. A key to known species of Pseudoacanthocephalus is provided.     

Comparative ultrastructural study of the cuticle of larvae and adults of Centrorhynchus milvus Ward, 1956 (Acanthocephala, Centrorhynchidae).

The cuticle of Centrorhynchus milvus acanthella and cystacanth larvae, obtained from the terrestrial crustacean Porcellionides pruinosus, is roughly 0.2 micron thick. The cuticle of juveniles encysted in toads, paratenic hosts, measures up to 0.5 micron whereas that of adults may exceed 2 microns in thickness. In all cases it is perforated by numerous pores that communicate with the hypoderm. During larval development, the numerous endocytotic vacuoles observed in acanthella 3, 4, and 5 and cystacanths became elongated canals in juveniles and adults. There is no significant ultrastructural modification in the cuticle. In the larvae, on the other hand, there was progressive thickening of the cyst wall.     

New and already known acanthocephalans from amphibians and reptiles in Vietnam, with keys to species of Pseudoacanthocephalus Petrochenko, 1956 (Echinorhynchidae) and Sphaerechinorhynchus Johnston and Deland, 1929 (Plagiorhynchidae)

Adults of 2 new species in 2 orders of acanthocephalans obtained from the intestines of terrestrial amphibians and reptiles collected between 1998 and 2004 in Vietnam are described here. Pseudoacanthocephalus nguyenthileae n. sp. (Palaeacnthocephala: Echinorhynchidae) was collected from 5 species of terrestrial amphibians: (1) the common Sunda toad Bufo melanostictus Schneider (Bufonidae); (2) Paa verucospinosa (Bourret); (3) Gunther's Amoy frog Rana guentheri Boulenger; (4) Taipei frog R. taipehensis Denburgh (Ranidae), and (5) the Burmese whipping frog Polypedates mutus (Smith) (Racophoridae); as well as from the Chinese cobra Naja atra Cantor (Reptilia: Elapidae) and house gecko Hemidactylus frenatus Dumeril and Bibron (Reptilia: Gekkonidae). Sphaerechinorhynchus maximesospinus n. sp. (Plagiorhynchidae: Sphaerechinorhynchinae) was isolated from a king cobra Ophiophagus hannah (cantor) (Reptilia: Elapidae). Cystacanths of Porrorchis houdemeri (Joyeux and Baer, 1935) Schmidt and Kuntz, 1967 (Plagiorhynchidae: Porrorchinae) obtained from the mesenteries of banded krait Bungarus fasciatus (Schneider) (Reptilia: Elapidae), a paratenic host, are reported for the first time. Keys to the species of Pseudoacanthocephalus and Sphaerechinorhynchus are included. Characteristic features distinguishing the new species from related taxa include: P. nguyenthileae has 15-19 (usually 16-18) proboscis hook rows, each with 5-6 hooks that progressively increase in length and size posteriorly. The largest, intermediate, and smallest proboscis hooks of S. maximesospinus are the middle, anterior, and posterior hooks, respectively; the proboscis and neck are enclosed in a membrane. Morphometric characteristics of P. nguyenthileae show host-related variability.     

A new ganglion in male Moniliformis moniliformis (Acanthocephala)

A new ganglion identified as the bursal ganglion is described from male Moniliformis moniliformis. This ganglion is located adjacent to the pseudocoel and longitudinal muscle fibers and medial to the dorsal lacunar canal about 1 mm from the posterior end of males with non-everted bursa The ganglion consists of four large club-shaped cells with single nuclei and bipolar neurons. The ganglion cells are paired with one neuron from each cell innervating the opposite side of the worm.     

齿茎马颖蜡蝉的再研究(半翅目:蜡蝉总科:颖蜡蝉科)

对齿茎马颖蜡蝉Magadha denticulata Fennah,1956做了进一步研究,证实该种不属于马颖蜡蝉属Ma-gadhaDistant,1906,而是半贝颖蜡蝉属Semibetatropis Chen,Yang et Wilson,1988种类;同时提供该种雄、雌虫体的鉴别特征图。检视标本保存于美国加州科学院(CAS)。     

Ultrastructure of the eggs of Polymorphus magnus (Acanthocephala, Polymorphidae)

The ultrastructure of Polymorphus magnus acanthocephalan eggs has been studied. The eggshell consists of four envelopes that are morphologically similar to those of the eggs of other Palaeacanthocephala representatives. The studied acanthors are formed by the cortical syncytium and "central nuclear mass". In the anterior part of acanthors there is a penetration gland. Its secret may provide the larvae migration into intermediate host's organism. "Central nuclear mass" consists of several germinative nuclei and numerous fibrillar bodies, formed as a result of germinative nuclei degradation.