Taxonomic status, redescription, and surface ultrastructure of Ascocotyle (Phagicola) pindoramensis n. comb. (Digenea: Heterophyidae)

Pygidiopsis pindoramensis Travassos, 1928, is redescribed from the holotype and specimens obtained from experimental infections of hamsters with metacercariae of the naturally infected poeciliids Poecilia vivipara and Phalloptychus januarius from Rio de Janeiro, Brazil. Ascocotyle (Phagicola) pindoramensis (Travassos, 1928) n. comb. is proposed, based on the presence of a solid, tapering muscular posterior prolongation of the oral sucker and Ascocotyle (Phagicola) mollienisicola (Sogandares-Bernal and Bridgman, 1960) is synonymized with A. (P.) pindoramensis because of the identical morphology and measurements of adults and metacercariae, similar spectrum of fish intermediate hosts (poeciliids), and the same site of infection of the metacercariae. Trematodes designated as Pygidiopsis pindoramensis, previously reported from Argentina and Mexico, represent another species of Pygidiopsis Looss, 1907, because they possess circumoral spines and their oral sucker is devoid of the posterior muscular prolongation. Data on the surface morphology of metacercariae and adults of A. (P.) pindoramensis are inferred from scanning electron microscopy observations.     

A new species of Ascocotyle (Trematoda: Heterophyidae) from the South American sea lion, Otaria flavescens, off Patagonia, Argentina

We describe a new heterophyid species, Ascocotyle (Ascocotyle) patagoniensis n. sp., based on specimens collected from the intestines of the South American sea lion Otaria flavescens from Patagonia (Argentina). Ascocotyle (A.) patagoniensis n. sp. is distinguished from the other species of the subgenus by the number of circumoral spines, which are arranged in 2 rows of 18 to 23. The new species also differs from the other species in having a gonotyl without papillae. The specimens exhibited the widest seminal receptacle described for a species of this subgenus. Species of the subgenus Ascocotyle usually infect fish-eating birds or mammals in freshwater or brackish habitats. Ascocotyle (A.) patagoniensis n. sp. is the first species of the subgenus described from a marine mammal. However, no metacercariae of Ascocotyle spp. were found in 542 marine teleosts from 20 species collected in the same locality. The life cycle of the marine species from the Ascocotyle -complex infecting pinnipeds remains elusive.     

Taxonomic study of Ascocotyle (Phagicola) longa Ransom, 1920 (Digenea: Heterophyidae) and related taxa

Species of Ascocotyle Looss, 1899 (subgenus Phagicola Faust, 1920) (Digenea: Heterophyidae) related to A. (P.) longa Ransom, 1920, i.e. those with a bipartite gonotyl and a single crown of 16 circumoral spines, were revised on the basis of examination of type and voucher specimens. The species A. (P.) arnaldoi Travassos, 1929, A. (P.) byrdi (Robinson, 1956) and A. (P.) longicollis (Kuntz & Chandler, 1956), all possessing 16 circumoral spines, are synonymised with A. (P.) longa. A. (P.) ascolonga Witenberg, 1929, the types of which were not available, is provisionally retained as a valid species despite its close similarity to A. (P.) longa (identical number of circumoral spines and morphology of the ventrogenital sac). It differs from A. (P.) longa in the presence of uterine loops posterior to the testes and intestinal caeca ending anterior to the ovary (versus the pretesticular uterus and intestinal caeca reaching to the posterior margin of the ovary in A. (P.) longa). A. (P.) inglei (Hutton & Sogandares-Bernal, 1959), found only once in a single specimen, is also tentatively considered a valid species because it differs in number of circumoral spines (19), slightly larger eggs (23–26×13–16 m) and the distribution of refractile bodies of the gonotyl arranged in four separate groups from A. (P.) longa and A. (P.) ascolonga (16 circumoral spines; eggs 15–20×–12 m; refractile bodies in two groups).     

Life history studies of heterophyid trematodes in the Neotropical region: Ascocotyle (Leighia) hadra sp. n.

The life cycle of Ascocotyle (Leighia) hadra n. sp. was experimentally reproduced, starting from cercariae from naturally infected Littoridina parchappei, collected from Los Ranchos stream, near Mercedes city, Buenos Aires Province, Argentina. Metacercariae were found encysted in the liver and mesentery of experimentally and naturally infected fishes Cnesterodon decemmaculatus and Jenynsia lineata. Adults were obtained experimentally in chicks and mice. The natural host is unknown. The new species is compared with Ascocotyle (Leighia) mcintoshi Price 1936 as described by Leigh, 1974, differing in behavior and morphology of cercarial, metacercarial and adult stages.     

Redescription and surface ultrastructure of Pygidiopsis macrostomum (Digenea: Heterophyidae)

Pygidiopsis macrostomum Travassos, 1928, a poorly known species originally described from a single specimen from Rattus norvegicus (Erxleben, 1777) in Brazil, is redescribed on the basis of metacercariae from the mesenteries of naturally infected guppies Poecilia vivipara Bloch and Schneider, 1801 (Poeciliidae), and adults obtained from an experimental infection of hamsters. Pygidiopsis macrostomum is characterized by the absence of oral spines, vitellaria extending forward to ventral sucker, uterus reaching pharyngeal level, X-shaped excretory vesicle, and an oral sucker/acetabulum ratio of 1:0.8. The surface ultrastructure shows that the tegument of the metacercaria does not strongly differ from that of adults. The brush-shaped spines of P. macrostomum are similar to those reported for Pygidiopsis summa and Pygidiopsis ardeae, but no differences in spine shape were observed throughout the body.     

Life-history studies of heterophyid trematodes in the Neotropical Region: Ascocotyle (Phagicola) diminuta (Stunkard & Haviland, 1924) and A. (P.) angrense Travassos, 1916

The life-cycle of Ascocotyle (Phagicola) diminuta (Stunkard & Haviland, 1924) was reproduced experimentally, starting from cercariae from naturally infected Littoridina castellanosae and L. parchappei (Hydrobiidae) collected from artificial ponds in the Zoological Garden in Buenos Aires and from Los Ranchos stream, Buenos Aires Province, respectively. Metacercariae were found encysted in the gills of experimentally exposed Cnesterodon decemmaculatus (Poecilidae) and of other naturally infected freshwater fishes. Adults were obtained experimentally in chicks and mice and from a naturally infected egret, Egretta thula. A. (P.) angrense Travassos, 1916 was found parasitising the egret Ixobrychus involucris; it is considered a valid species and the morphological differences between it and A. (P.) diminuta were established. The “Phagicola-form” of the cercaria in the present life-cycle is also known in the genus Pygidiopsis.     

Hystrignathus ferox n.sp. and Xyo xiphacanthus n.sp. (Oxyurida: Hystrignathidae) with additional data on Carlosia tijucana Travassos & Kloss, 1957

Summary Two new species of hystrignathid nematode are described from passalid beetles in Trinidad, West Indies. Hystrignathus ferox n.sp., from the mid-gut caeca of Verres furcilabris (Esch.) is easily differentiated from H. rugosus Travassos & Kloss, 1958 and H. rescens Travassos & Kloss, 1958 on the character of the lateral alae. In H. rugosus the alae extend to the anus and in H. rescens to the vulva whereas in H. ferox n.sp. the alae are much shorter and terminate about two body-widths anterior to the vulva. Xyo xiphacanthus n.sp., from the mid-gut caeca of Veturius transversus var. trituberculatus (Esch.), is characterized by the cervical spines extending about an oesophagus length posterior to the basal bulb. No other nominal species of Xyo has the spines extending so far posteriorly. X. histrix Cobb, 1898 and X. histrix sensu Christie, 1934 are regarded as species inquirendae. Carlosia tijucana Travassos & Kloss, 1957 is illustrated and additional data provided. ac]19810415     

A new species of Paragonimus (Trematoda: Troglotrematidae) from a cat infected with metacercariae from mountain crabs Larnaudia larnaudii

The identification of Paragonimus spp. lung flukes is based on the morphology of both the metacercaria and the adult. A very small Paragonimus sp. metacercaria was found in a freshwater crab caught in Kanchanaburi Province, West Thailand, an area where metacercariae of Paragonimus heterotremus had not been found. The metacercariae cysts were 180-204 microm in diameter, which was smaller than metacercariae of P. heterotremus. The coefficient of difference in body size between this metacercaria and P. heterotremus was 1.69, which was greater than a subspecific difference. Adults recovered from the lungs of a cat fed with the metacercariae were morphologically similar to, but smaller than, P. heterotremus dissected from the lungs of a feline experimental host. The tegumental spines of the worm in this study were singly spaced in arrangement, which is similar to, but larger than, the spines of P. heterotremus. Therefore, Paragonimus pseudoheterotremus is proposed as a new species.     

Hystrignathus dearmasi sp. n. (Oxyurida, Hystrignathidae), first record of a nematode parasitizing a Panamanian Passalidae (Insecta, Coleoptera)

Hystrignathus dearmasi sp. n. (Oxyurida: Hystrignathidae) is described from an unidentified passalid beetle (Coleoptera: Passalidae) from Panama. It resembles Hystrignathus cobbi Travassos & Kloss, 1957 from Brazil, by having a similar form of the cephalic end, extension of cervical spines and absence of lateral alae. It differs from the latter species by having the body shorter, the oesophagus and tail comparatively larger, the vulva situated more posterior and the eggs ridged. This species constitutes the first record of a nematode parasitizing a Panamanian passalid.     

Molecular identification of developmental stages in Opecoelidae (Digenea)

Nuclear ribosomal DNA sequences represent a useful tool for distinction of poorly differentiated developmental stages, such as trematode cercariae or metacercariae. Here, the complete internal transcribed spacer region of the ribosomal DNA (ITS 1 + 5.8S + ITS 2) was sequenced for 29 specimens of the digenean family Opecoelidae, including 16 adult specimens and 13 undescribed larval stages (nine cercariae and four metacercariae) occurring in various marine host organisms. Six cercariae and three metacercariae were found to match their corresponding adult form. This work also revealed that cercariae of the same species are able to infect more than one gastropod host species, suggesting that the specificity for the first intermediate host within the Digenea may be lower than previously thought.     

Conspicuous behaviour of Fundulus heteroclitus associated with high digenean metacercariae gill abundances

Fundulus heteroclitus from six sites throughout the Hackensack Meadowlands District in northern NJ, U.S.A., were examined. Differences in behaviour (surfacing, conspicuousness and activity) were compared to gill infection intensity. Fish from populations infected with >1500 digenean metacercariae of Ascocotyle phagicola diminuta and Echinochasmus schwartzi , spent significantly more time at the water surface and exhibited significantly more conspicuous behaviour ( e.g. jerking) than fish from less parasitized populations. This more conspicuous behaviour has the potential to increase trophic transmission of the parasite to its definitive wading-bird host.     

Life-cycle ofEchinochasmus macrocaudatus n. sp. (Trematoda: Echinostomatidae)

The life-cycle ofEchinochasmus macrocaudatus n. sp., from mother-sporocyst to adult, was studied under natural and experimental conditions. The aquatic snailsPyrgophorus coronatus (Prosobranchia: Hydrobiidae) from cenotes (sinkholes) of the Yucatan Peninsula, Mexico, served as the first intermediate host of this parasite, liberating cercariae possessing an extremely large tail (zygocercous cercaria). Metacercariae of the fluke were encysted on the gills of the characid fishAstyanax fasciatus (natural infection); the poeciliidsXiphophorus variatus andPoecilia velifera were suitable experimental hosts. Feeding experiments withE. macrocaudatus metacercariae resulted in finding adult trematodes, possessing 22 collar spines (with 2 angle spines on each side), in the intestine of chicks and ducks.E. macrocaudatus differs from the most closely related species,E. schwartzi Price, 1931, by its larger oral sucker (138–170×118–176 m) and by the position of the acetabulum which is situated at two-fifths of the body length.     

First record and description of metacercariae of Curtuteria arguinae n. sp. (Digenea: Echinostomatidae), parasite of cockles Cerastoderma edule (Mollusca: Bivalvia) in Arcachon Bay, France

A new Himasthlinae species, Curtuteria arguinae, is described as metacercariae from the cockle Cerastoderma edule (L.), collected at Banc d'Arguin (southwestern France). These metacercariae encysted preferentially in the mantle and also in the foot of cockles. Encysted and chemically excysted metacercariae were studied by light microscopy and scanning electron microscopy, respectively. Excysted metacercariae were elongated and curved ventrally. They bore a 33-spine circumoral collar. Sensory papillae were arranged around the oral sucker and also symmetrically along the ventral surface body, from the collar to the acetabulum. The dorsal and ventral tegument surfaces were densely packed with similar pointed spines. The posterior end of the body was without any spines. Among the Curtuteria species described previously, only Curtuteria haematopodis Smogorjewskaja and Iskova, 1966 had the same number of circumoral collar spines. A 6-yr field survey showed that the cockle population at Banc d'Arguin was subjected to a summer infection of C. arguinae. Curtuteria arguinae phenology of infection is characterized by interannual variability and seasonality (beginning in July-August and maximum in autumn). The first intermediate and final hosts remain unknown.     

Phenology of recruitment and infection patterns of Ascocotyle pachycystis, a digenean parasite in the sheepshead minnow, Cyprinodon variegatus

In northwest Florida, Cyprinodon variegatus are parasitized by Ascocotyle pachycystis, a digenean parasite that forms metacercarial cysts in the lumen of the bulbus arteriosus. Field experiments revealed that fish accumulated parasites at an uneven rate within the highly seasonal trematode recruitment period. Older (= larger) fish had higher rates of parasite recruitment and higher parasite prevalences and densities (numbers of metacercariae per individual fish) than did younger (= smaller) fish. Nearly all adults were parasitized (prevalence range 70-100%), and parasite densities ranged from zero to 6800 per fish. Parasite distributions were clumped (= aggregated) in fish of all age classes but were less heterogeneous in early juveniles and adults than they were in late juveniles. Parasites affected the population dynamics of sheepshead minnows by causing reduced winter survivorship, as evidenced by an increase in the average size of fish and a decrease in the average infection intensity over the winter. This revised version was published online in July 2006 with corrections to the Cover Date.     

A new cercaria and metacercaria of Acanthoparyphium (Echinostomatidae) found in an intertidal snail Zeacumantus subcarinatus (Batillaridae) from New Zealand

A new 23-collar-spined cercaria and metacercaria are described from intertidal molluscs of the coast of New Zealand. The new cercaria found emerging from the mud snails Zeacumantus subcarinatus (Sowerby) (Prosobranchia: Batillariidae) is characterized mainly by the number and arrangement of the cephalic glands, the size of the suckers, and the size and number of the collar spines. The cercaria encysts in the cockle Austrovenus stutchburyi (Wood) (Bivalvia: Veneridae) which lives in sympatry with the first intermediate host throughout New Zealand. Laboratory infections of cockles by cercariae from naturally infected snails resulted in metacercariae identical to those found in naturally infected cockles. The main features of the cercaria and metacercaria are the presence of a reniform collar with 23 spines, two pairs of small cephalic glands at the oral sucker level, another two pairs of much longer ones posterior to the pharynx, and the excretory vesicle Y-shaped with the main collecting canals extending to the anterior level of the ventral sucker. Each of the main collecting canals had 10-11 pairs of bilateral diverticula between the anterior edge of the ventral sucker and anterior body end. A brief discussion of its possible life cycle and ecology is also provided.     

Mactra veneriformis, an intertidal clam, as a new second intermediate host for Acanthoparyphium marilae (Digenea: Echinostomatidae)

Metacercariae of Acanthoparyphium marilae Yamaguti, 1934 (Digenea: Echinostomatidae) were discovered in an intertidal clam, Mactra veneriformis, in a southwestern coastal area of the Republic of Korea. A total of 128 metacercariae were detected from 10 clams examined. They were round, 320 microm in average diameter, with 23 collar spines. They were fed experimentally to chicks, and 10 days later adult flukes were obtained. The adults were morphologically characterized by the head collar with a single row of 23 dorsally uninterrupted spines, without special end group spines, a round ventral sucker, 2 round and tandem testes, and vitellaria extending at lateral fields from the posterior extremity not beyond the middle level of the posterior testis. The most characteristic feature of this species was the limited distribution of vitellaria, which differs from Acanthoparyphium tyosenense Yamaguti, 1939, the metacercariae of which are encysted in the same mollusk species. This is the first report in which the metacercariae of this species were detected, and the intertidal bivalve, M. veneriformis, has been identified as a second intermediate host for A. marilae.     

Surface ultrastructure of Stictodora tridactyla (Trematoda: Heterophyidae) from Kuwait Bay

The surface morphology of Stictodora tridactyla recovered from a kitten that was fed the killifish, Aphanius dispar, naturally infected with the metacercariae was studied using scanning electron microscopy. The body comprised a rounded head, elongate neck, and widely pyriform hind-body. The head bore a circular oral sucker on the ventral side, and concentric rows of peg-like cephalic spines on the dorsal side. The oral sucker was armed with pre-oral spines similar in shape and size to the cephalic spines. The neck and hind-body were densely covered with scale-like multipointed spines, the size and density of which decreased from anterior to posterior parts of the body. Ciliated dome-shaped papillae were found solitarily or as conjugated groups on the head apex and lips of the oral sucker. Non-ciliated dome-shaped papillae were restricted to the lower lip of the oral sucker. The body was devoid of a ventral sucker. The genital opening appeared as a round depression of the tegument at about the anterior third of the body. This is the first record of the occurrence of S. tridactyla in the Arabian Gulf region and A. dispar is a new second intermediate host.     

Acanthotrema felis n. sp. (Digenea: Heterophyidae) from the small intestine of stray cats in the Republic of Korea

Acanthotrema felis n. sp. (Digenea: Heterophyidae) is described from adult flukes recovered in the small intestine of stray cats caught in the southwestern part of the Republic of Korea. The worms were characterized by minute body size, the presence of a bipartite seminal vesicle, and a ventral sucker associated with a ventrogenital sac, which enclosed 3 sclerites (2 long and pointed, and I short and thumblike), and an unarmed gonotyl. They were assigned to Acanthotrema Travassos, 1928, which currently contains 4 species. The new species resembles A. acanthotrema, the type species, because both have 3 sclerites on the ventrogenital sac. However, all 3 sclerites in the new species are armed with minute spines on their base, whereas only 2 sclerites in A. acanthotrema have minute spines near their tips. Three species of Stictodora Looss, 1899, namely,Stictodora tridactyla Martin and Kuntz, 1955, S. cursitans Kinsella and Heard, 1974, and S. tanayensis Velasquez, 1973, are transferred to Acanthotrema, and the new species is distinguished from them particularly in terms of the number and shape of its sclerites. The generic diagnosis of Acanthotrema is emended.