Cystocercous Cercariae Research Articles

Phyllodistomum kupermani n. sp. from the European perch, Perca fluviatilis L. (Perciformes: Percidae), and redescription of Phyllodistomum macrocotyle (L\xfche, 1909) with notes on the species diversity and host specificity in the European Phyllodistomum spp. (Trematoda: Gorgoderidae)

BackgroundEuropean species of the large genus Phyllodistomum Braun, 1899 had historically been erected based solely on morphological characters. Unfortunately, many of them are still poorly known and inadequately described. Molecular approaches are critical to delineate species which were impossible to differentiate based on morphology alone.MethodsNew samples of adult Phyllodistomum spp. were collected from the urinary bladder and/or ureters of European freshwater fishes and fixed to conduct a light and scanning electron microscopy study, and to obtain sequences of nuclear (ITS2 spacer and 28S rRNA gene), to be analysed in the context of a molecular phylogeny.ResultsBased on new findings, a new species of Phyllodistomum from the urinary bladder of the European perch, Perca fluviatilis, in Volga River basin, Russia, is described. Additionally, new data on the morphology and tegumental surface topography of P. macrocotyle (Lühe, 1909) Odhner, 1911 from ureters of the common rudd, Scardinius erythrophthalmus, is presented. The host range of P. folium, confirmed by DNA analysis, is extended to other cyprinid fish species.ConclusionsThe present study has again shown that species of the genus Phyllodistomum are in dire need of revision based on both molecular analysis and detailed morphological redescriptions of the forms attributed to the genus. Morphologically, P. kupermani n. sp. most closely resembles P. pseudofolium, a highly host-specific parasite of Gymnocephalus cernuus (L.), but molecular phylogenetic analyses based on ITS2 and 28S rDNA sequences showed that these species are distantly related. Phyllodistomum kupermani n. sp. was found to be phylogenetically most closely related to the type-species of Phyllodistomum, P. folium. Phylogenetic analyses revealed that Phyllodistomum kupermani n. sp. and P. folium formed a clade with other freshwater species for which cystocercous cercariae develop in bivalves of the family Sphaeriidae. The micromorphology and tegumental surface topography of P. macrocotyle revealed in the present study provide a valuable taxonomic criterion for congeneric species differentiation.

Molecular and karyological identification and morphological description of cystocercous cercariae of Phyllodistomum umblae and Phyllodistomum folium (Digenea, Gorgoderidae) developing in European sphaeriid bivalves

Two cystocercous gorgoderid cercariae of the genus Phyllodistomum Braun, 1899, Phyllodistomum umblae (Fabricius, 1780) and Phyllodistomum folium (Olfers, 1816), developing in sphaeriid bivalves from Norway and Lithuania, were studied and compared. Our previous molecular studies revealed very close phylogenetic relation of these two species and proved that cystocercous cercariae of P. folium develop in sporocysts in the gills of sphaeriid bivalves. In the present study morphological descriptions are given for the two cercariae, together with karyological and molecular characteristics. Comparative karyological and sequence analysis using ITS2 and 28S rDNA revealed the conspecificity of cercariae emitted from Pisidium hibernicum and Sphaerium corneum with adult P. umblae from Thymallus thymallus and Coregonus albula. The cercariae of P. folium and P. umblae are very similar morphologically with main differences in the structure of the tail. The two species clearly differ in karyotype structure. The diploid set of P. folium is composed of 18 chromosomes, but 16 chromosomes with one pair of large metacentrics were found in mitotic cells of P. umblae. Interspecific karyotypic difference presumably arose from Robertsonian fusion of two uni-armed chromosomes.

European Phyllodistomum (Digenea, Gorgoderidae) and phylogenetic affinities of Cercaria duplicata based on rDNA and karyotypes

Genetic markers of some European Gorgoderidae species, including potential adults of Cercaria duplicata, were obtained and used to clarify phylogenetic affinities within the genus Phyllodistomum and to verify conflicting data existing on their life cycles. Molecular data and karyotype, 2n = 18, provide further support for ascription of C. duplicata to the Gorgoderinae. Sequences of C. duplicata form a robustly supported major clade, phylogenetically distinct from other known gorgoderid species in both ITS2‐ and 28S‐based phylogenetic trees. The molecular data revealed no match between C. duplicata and any species of Phyllodistomum, including adults found in the experimental studies. One of them, P. elongatum, showed no differences from type species P. folium. Other, P. angulatum, forms a robustly supported clade, which is closely related to P. macrocotyle clade in all phylogenetic trees. This study supports the concept that only P. macrocotyle is a parasite of Dreissena polymorpha among the phyllodistomes and life cycle described for the type species P. folium by Sinitsin (1905) can apparently be discounted. Previously reported low host specificity of P. folium was justified. Adults of P. folium were detected in eight teleost species from five families and four orders. Cystocercous cercariae of P. folium were recorded in sphaeriid bivalves of the genus Sphaerium and Pisidium. According to our molecular data, P. simile, parasite of bullhead, must be regarded as synonym of P. folium. Phyllodistomum umblae is most closely related to P. folium in the all phylogenetic analyses. Molecular phylogenies support a presumption that Phyllodistomum species with cystocercous cercariae developing in sphaeriid bivalves should be regarded as Phyllodistomum sensu stricto. The results reveal a clear need for reconsideration of the knowledge on gorgoderid life cycles based on experimental studies and re‐evaluation of the validity of some nominal Phyllodistomum species.

Integrative taxonomy identifies a new species of Phyllodistomum (Digenea: Gorgoderidae) from the twospot livebearer, Heterandria bimaculata (Teleostei: Poeciliidae), in Central Veracruz, Mexico

Phyllodistomum inecoli n. sp. is described from the twospot livebearer, Heterandria bimaculata (Teleostei: Poeciliidae), collected in the Río La Antigua basin, Veracruz, Mexico. The new species is described and characterised by using a combination of morphology, scanning electron microscopy, and sequences of nuclear and mitochondrial genes. Diagnostic characters of the new species of Phyllodistomum include a genital pore opening at the level of the caecal bifurcation; oval vitellarium, situated just posterior to the ventral sucker and not extended laterally and anterior extracaecal uterine loops variable in extension (reaching the anterior, median or posterior margin of the ventral sucker). P. inecoli n. sp. most closely resembles P. brevicecum, a species described as a parasite of the central mudminnow, Umbra limi, in other parts of North America; however, the genital pore in P. brevicecum is situated between the caecal bifurcation and the ventral sucker, the ovary is larger, the vitellarium is lobed and extended laterally and the anterior portion of the uterus extends to the posterior margin of the ventral sucker. Comparison of about 1,500–2,200 nucleotides of cox1 and 28S rDNA and ITS1 strongly supports the status of P. inecoli as a new species. Bayesian inference analysis of combined datasets of 28S rDNA and cox1 sequences showed that P. inecoli n. sp. and the other species found in freshwater fishes of Mexico, including the species complex of P. lacustri, are not sister species. Phylogenetic analysis based on 28S rDNA sequences of several gorgoderid taxa revealed the close relationship of P. inecoli n. sp. with several species of Phyllodistomum, Gorgodera and Gorgoderina with cystocercous cercariae developing in sphaeriid bivalves. Dot-plot analysis of ITS1 sequences of P. inecoli n. sp. revealed the presence of eight repetitive elements with different length, which together represent almost half the length of ITS1.

A new species ofPhyllodistomum(Digenea: Gorgoderidae) from Australian and New Zealand freshwater fishes with notes on the taxonomy ofPhyllodistomumBraun, 1899

Phyllodistomum magnificum sp. nov., is described from the urinary bladder of Australian and New Zealand freshwater fish. Australian hosts were Anguilla reinhardtii, Tandanus tandanus, Hephaestus fuliginosus and Scortum hilli. New Zealand hosts were Anguilla australis and A. dieffenbachii. A presumed part of the life-cycle is described. Typical cystocercous cercariae are produced by sporocysts in the gills of a Pisidium species and are eaten by aquatic arthropods in which they encyst. The taxonomy of the genus Phyllodistomum is discussed and it is suggested that those species with cystocercous cercariae form a phylogenetic unit with Gorgodera, Gorgoderina, Progorgodera and Gorgotrema species.

The anterior tail chamber and survival of Gorgoderina vitelliloba

Mitchell J. B., Mason A. R. and Whalley A. J. S. 1980. The anterior tail chamber and survival of Gorgoderina vitelliloba. International Journal for Parasitology 10: 181–182. Survival in pond water of intact cystocercous cercariae of Gorgoderina vitelliloba was significantly better than that of isolated cercarial bodies, although the latter were able to survive in Ringer's Solution. Survival of cercarial bodies in water was improved somewhat when sterility was maintained. It is suggested that the wall of the anterior tail chamber protects the body from the osmotic stress imposed by life in fresh water.

The life cycle of Gorgoderina rochalimai Pereira and Cuocolo, 1940, a Digenea parasite of Bufo marinus in Guadeloupe

The sporocysts of G. rochalimai were found in Guadeloupe, in the bivalve Mollusc Sphaeriidae Eupera viridans. The cystocercous cercariae are ingested by Odonatan larvae in which the encystement occurs. The Toad Bufo marinus is the definitive host of the parasite. The life-cycle of G. rochalimai shows close similarities with the ones already known in many other speicies of Gorgoderidae.

The Life History of Phyllodistomum staffordi Pearse, 1924 (Trematoda: Gorgoderidae Looss, 1901)

Mother and daughter sporocysts and cystocercous cercariae develop in the fingernail clam, Musculium ryckholti. Following emergence, the cercariae are eaten by naiads of damselflies and trichopterous larvae in which they encyst. The adult Phyllodistomum staffordi develops in the urinary bladder of the brown bullhead, Ameiurus nebulosus, which acquires the parasite by eating the infected insects. The most complete account of a life history for the genus Phyllodistomum Braun, 1899 is that of Goodchild (1940, 1943) for P. solidum Rankin, 1937, a parasite in the urinary bladder of the northern dusky salamander, Desmognathus fuscus fuscus (Raf., 1820). Through experimental infections he demonstrated that mother and daughter sporocysts and cystocercous cercariae (Cercaria conica Goodchild, 1939) developed in the fingemail clam, Pisidium abditum Haldeman, 1841. Ingested cercariae encysted in odonatan naiads of the genera Ischnura, Argia, Enallagma, and Libellula. Sexual maturity was attained in the definitive host in 95 to 130 days. A very brief account of the life cycle of P. americanum Osborn, 1903 (without illustrations) was published by Crawford (1939, 1940). Definitive hosts are the mountain toad, Bufo boreas boreas Baird and Girard, 1852, and the tiger salamander, Ambystoma tigrinum (Green, 1825). Cystocercous cercariae from Pisidium spp. encysted in the wall of the esophagus of trichopteran larvae and the larvae of diving beetles and in naiads of damselflies. Excysted metacercariae, in the definitive host, first migrated to the kidneys for 2 weeks then to the urinary bladder where they developed to sexual maturity in 5 weeks. Beilfuss (1954) briefly described the life cycle of P. lohrenzi Loewen, 1935 and P. caudatum Steelman, 1938 (without illustrations). The green sunfish, Lepomis cyanellus Raf., 1819, is the definitive host for P. lohrenzi which underwent its larval development in Musculium transversum (Say, 1829). The cercaria (C. coelocerca Steelman, 1939) encysted either in the daughter sporocyst or in trichopteran larvae. The life cycle of P. caudatum is Received for publication 28 November 1966. similar except for lack of a known second intermediate host. The adult of this species developed in the black bullhead, Ameiurus melas (Raf., 1820) and the larvae in Musculium elevatum (Haldeman, 1840). The miracidium

Activation of Gorgodera amplicava cercariae by molluscan sera

The sera of 5 species of freshwater molluscs, Viviparus maleatus, Helisoma trivolvis, H. anceps, Physa gyrina, and Musculium partumeium were found to activate the quiescent cystocercous cercariae of Gorgodera amplicava. When cercariae were exposed to the various sera, the distomate body proper became very active and generally succeeded in escaping from the cystic portion of the tail. The ability of the various sera to activate the cercarial body varied, with that of V. maleatus being the greatest followed by that of P. gyrina. The sera of H. trivolvis and H. anceps were less effective while that of M. partumeium had the least effect. The activating ability of the sera does not appear to be due to their pH. The activating influence of molluscan sera on the normally quiescent cercaria is believed to play an important role in the adaptation of this cercaria to the second intermediate host.

NOTES ON THE LIFE-CYCLE OF AZYGIA ACUMINATA GOLDBERGER, 1911 (AZYGIIDAE-TREMATODA)

1. Stages in the life-cycle of Azygia acuminata are described and figured. Cystocercous cercariae develop from rediae in the snail, Campeloma decisum. The cercaria is morphologically distinct from other described cystocercous cercariae. Rediae are similar to the same stage described for other members of the genus, but are unique since they develop in the uterus of female Campeloma decisum.2. The excretory system of the cercaria is complex, showing a formula of 2 (11 x 32) or 704 flame cells for the distome portion and 2 (5 x 32) or 320 flame cells in the tail. The excretory formula of the cercariae is thus 2 (16 x 32) or 1,024 flame cells.3. Attempts to experimentally infect small snails, taken from the uterus of a Campeloma decisum, by feeding them eggs of A. acuminata were not successful.4. Various small fishes were utilized as paratenic hosts by the young distomes. Infections in sticklebacks, Eucalia inconstans, and small eels, Anguilla rostrata, resulted in more active and vigorous worms than did infe...

Studies on the Trematode Family Azygiidae. I. The Morphology and Life Cycle of Proterometra macrostoma Horsfall

In 1931 while collecting and examining snails for larval stages of trematoda a very interesting form of the Mirabilis group of Cystocercous Cercariae was discovered in snails, Goniobasis livescens correcta, from the Des Plaines River west of Evanston, Illinois and in Hickory Creek at New Lenox, Illinois. The large size of this larva and its swimming behavior suggested fish as the final host. Permission was obtained from the Illinois Department of Conservation to seine in the Des Plaines River below dams number one and two where some of the infected snails were obtained. Of the fish obtained only the Crappie, Pomoxis sparoides; Blue Gills, Helioperca incisor; and Sunfish, Eupomotis gibbosus contained in their short oesophagus a trematode which was identical, in all respects, with the distome of the cercaria. Horsfall (1933) reported finding a similar trematode which she named Proterometra macrostoma nov. gen. The trematode found by the writer and that described by Horsfall are undoubtedly identical, and represent a new genus and species which the writer had given another name in an unpublished paper, previous to Horsfall's publication. It has been the writer's endeavor since discovering this new form to determine experimentally its complete life cycle and to show the relationship of the Family Azygiidae to the Mirabilis group of Cystocercous Cercariae.

A New Cystocercous Cercaria

The cercaria described in this paper was found in the liver of Goniobasis livescens taken in the Oneida River near the outlet of Lake Oneida, in the State of New York. To it may be given the name Cercaria fusca. Twenty-three snails of the above mentioned species were examined, and of these, four were infected with small numbers of this cercaria. The color of the living worms is brown, the tail being much darker brown than the body. They were very sluggish when taken from the snails and moved very little, and made no swimming motions. The length of the extended live cercaria was about 3 mm., the body being about 1 mm. in length and the tail 2 mm.; the length of the flat tail-forks was about 0.5 mm. (Fig. la). Sporocysts were also found in the snails, which contained each from one to four or five cercaria in various stages of growth. The sporocysts are mostly lenticular in shape and 2 or 3 mm. in length. The largest of them contained but a single cercaria, which thus had the appearance of being encysted. One sporocyst observed, in which were several cercariae of different sizes, contained one apparently full grown, the tail of which projected freely from the sporocyst, giving the impression of a sporocyst with a tail. These observations seem to support the statement of Faust (1918: 149) that the cystocercous cercariae may be cannibalistic. The largest cercaria in a sporocyst seems to feed upon, or at least absorb, the smaller ones until it is finally the only one left. I did not observe in the material studied any instance of the direct attack of a large cercaria upon a smaller one. Cercaria fusca is similar to C. brookoveri Faust, 1918, in that the young distome is not surrounded by the walls of the anterior portion of the tail, as is the case in other cystocercous cercariae observed, but is joined with the tail by a short fold. The shape of the body of the full-grown cercaria is pyriform (Fig. 2), the hinder end being the broader, where the width is 0.65 mm. The cross section is oval in shape, the thickness being 0.40 mm. The suckers are large. The oral sucker is an elongated organ 0.52 mm. long, 0.35 mm. wide and ventral in position. The acetabulum is