Cláudia Portes Santos

Morphological and Molecular Diagnosis of Anisakid Nematode Larvae from Cutlassfish (Trichiurus lepturus) off the Coast of Rio de Janeiro, Brazil

Anisakid nematode larvae from Trichiurus lepturus off coast of Rio de Janeiro were studied using light, laser confocal and scanning electron microscopy, in addition to a molecular approach. Mitochondrial cytochrome c-oxidase subunit 2 (mtDNA cox-2), partial 28S (LSU) and internal transcribed spacers (ITS-1, 5.8S, ITS-2) of ribosomal DNA were amplified using the polymerase chain reaction and sequenced to evaluate the phylogenetic relationships between the nematode taxa. The morphological and genetic profiles confirmed that, of the 1,030 larvae collected from the 64 fish examined, 398 were analysed, of which 361 were Hysterothylacium sp. and 37 were Anisakis typica. Larvae of Hysterothylacium sp. were not identified to the species level due to the absence of similar sequences for adult parasites; however, the ITS sequence clustered in the phylogenetic tree with sequences of H. deardorffoverstreetorum, whereas an mtDNA cox-2 and LSU concatenated phylogenetic analysis demonstrated the presence of two clades, both of them under the same name as the larval H. deardorffoverstreetorum. Data on the occurrence of parasites during the winter and summer months were compared using the t-test. The greatest prevalence and intensity of infection were recorded for larval Hysterothylacium, with a prevalence of 51.56% and an intensity of up to 55 parasites per fish. The larval Anisakis exhibit a higher abundance and intensity of infection in the winter months, and those of Hysterothylacium during the summer. However, the t-test indicated no significant differences between the abundance and intensity of infection recorded during the months of collection for either of these larval nematodes. All sequences generated in this study were deposited in GenBank.

Genetic characterization of Anisakis typica and Anisakis physeteris from marine mammals and fish from the Atlantic Ocean off Brazil.

Until now, Anisakis typica has been the sole anisakid identified by means of genetic markers from the Atlantic Ocean off Brazil. In this study we developed, and applied to larvae and adults, an A. typica-specific molecular identification protocol based on the complete intergenic transcribed spacer (ITS) region. Anisakids from the dolphin Sotalia guianensis and from the frigate tuna, Auxis thazard, caught off the coast of Brazil, were processed using two DNA extraction methods. Molecular diagnosis identified A. typica in 13 of 15 samples. Complete ITS analysis showed that the remaining two isolates were in fact A. physeteris. Maximum parsimony analysis of complete ITS region (915 bp) confirmed these results. Our study verified the dominance of A. typica infecting hosts from the Brazilian coast and showed, for the first time, the presence of A. physeteris in the intermediate/paratenic host A. thazard in this region.

The life cycle of Ascocotyle (Phagicola) longa (Digenea: Heterophyidae), a causative agent of fish-borne trematodosis

The complete life cycle of the trematode Ascocotyle (Phagicola) longa (Digenea: Heterophyidae) is elucidated by natural observation validated by experimental infections. The natural first intermediate host of A. (P.) longa, an agent of human heterophyiasis in Brazil, is the cochliopid snail Heleobia australis (new first intermediate host). Metacercariae were found encysted in the body musculature, heart, stomach, liver, kidney, spleen, gonads and mesentery of mullets Mugil liza. Hamsters Mesocricetus auratus were experimentally infected with metacercariae of A. (P.) longa obtained from the mullets, and the adults recovered were used to infect the snails H. australis. Rediae and cercariae of A. (P.) longa are described for the first time. The ultrastructure of the tegument of A. (P.) longa shows a change in spination pattern from the cercaria with single-pointed spines to the metacercaria and adult with multipointed, brush-shaped spines. The life cycle of A. (P.) longa is related to estuaries and coastal lagoons where the recruitment of mugilid juveniles occurs. The high prevalence (100%) of A. (P.) longa encysted in the mullets examined within the urban area of Rio de Janeiro indicates the potentially great public health impact of the consumption of raw mullets.

Life history of Acanthocollaritrema umbilicatum Travassos, Freitas and Bührnheim, 1965 (Digenea: Cryptogonimidae)

The trematode Acanthocollaritrema umbilicatum Travassos, Freitas and Bührnheim 1965 is redescribed and data on its life cycle are provided for the first time. Adults were obtained from the common snook, Centropomus undecimalis (Bloch 1792), and both rediae and cercariae from the snail Heleobia australis (d’Orbigny 1835), a new intermediate host. Metacercariae were found encysted among the scales, fins, and musculature and in the buccal cavity of naturally infected fishes, Poecilia vivipara Bloch and Schneider, 1801, Jenynsia multidentata (Jenyns 1842), and Phalloptychus januarius (Hensel 1868), all new intermediate hosts. The examination of the type and freshly obtained adults of A. umbilicatum has shown that they possess 54–64 circumoral spines, in a double row. Experimental infections were achieved in the intermediate hosts H. australis and P. vivipara.

Behavioral responses of Poecilia vivipara (Osteichthyies: Cyprinodontiformes) to experimental infections of Acanthocollaritrema umbilicatum (Digenea: Cryptogonimidae)

The swimming behavior of Poecilia vivipara was evaluated using an image analysis system comparing laboratory-reared uninfected fish before and after experimental infection with different intensities of cercariae of the trematode Acanthocollaritrema umbilicatum. Two experiments were performed, each with 30 fish which were individually exposed to 30 and 50 cercariae, respectively, shed from experimentally infected molluscs, Heleobia australis. Before and after (17-27 days) infection, the behavior of each fish was monitored in terms of Distance travelled, Ambulatory time, Stereotypic time, Resting time and Average speed. At the end of the experiments, the fish were dissected to count the number of metacercariae recovered. In the experiment with 30 cercariae, fish with 2-10 metacercariae did not exhibit any significant differences in their swimming activity, but those with 11-22 metacercariae had a significantly enhanced Stereotypic time and a reduced Time Resting. In the experiment with 50 cercariae, fish with 5-22 metacercariae had an enhanced Distance travelled and a reduced Average speed; highly significant differences occurred with regard to all behavioral parameters when considering the subgroup 23-36 metacercariae: Distance travelled, Stereotypic time, Resting time, Ambulatory time and Average speed. The swimming behavior of P. vivipara changed influenced by an intensity-dependence on metacercariae of A. umbilicatum, supporting the prediction that parasites are able to alter the behavior of their hosts.

Capillostrongyloides arapaimae sp. n. (Nematoda: Capillariidae), a new intestinal parasite of the arapaima Arapaima gigas from the Brazilian Amazon

A new nematode species, Capillostrongyloides arapaimae sp. n., is described from the intestine and pyloric caeca of the arapaima, Arapaima gigas (Schinz), from the Mexiana Island, Amazon river delta, Brazil. It is characterized mainly by the length of the spicule (779-1,800 microm), the large size of the body (males and gravid females 9.39-21.25 and 13.54-27.70 mm long, respectively) and by the markedly broad caudal lateral lobes in the male. It is the third species of genus Capillostrongyloides reported to parasitize Neotropical freshwater fishes.

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.

Redescription of Synthesium pontoporiae n. comb. with notes on S. tursionis and S. seymouri n. comb. (Digenea: Brachycladiidae Odhner, 1905).

Synthesium pontoporiae n. comb. is redescribed, together with Synthesium tursionis and Synthesium seymouri n. comb.; the parasites were obtained from stranded and accidentally caught cetaceans. The sucker ratio (ratio between widths of the oral and ventral suckers) in S. pontoporiae was 1:1.8–3.0 (mean 1:2.2); in S. tursionis was 1:0.8–1.2; and in S. seymouri was 1:0.5–0.7. Synthesium pontoporiae differed from its congeners by additional diagnostic characters, including: oval to lobed testes; small cirrus with pyriform proximal region and flexible, tubular distal region formed by evagination of ejaculatory duct; and vitellarium in small follicles extending from the level of the seminal vesicle to the posterior extremity of the body and not forming dendritic radial bunches. Data on the morphology of adult S. pontoporiae and S. tursionis were inferred from confocal laser microscopical observations.

Pseudempleurosoma gibsoni n. sp., a new Ancyrocephalid Monogenean from Paralonchurus brasiliensis (Sciaenidae) from off the Southeastern Coast of Brazil

Pseudempleurosoma gibsoni n. sp. (Monogenea: Ancyrocephalidae) is described from the oesophagus of Paralonchurus brasiliensis (Steindachner) from off the coast of Brazil. The type-species of Pseudempleurosoma Yamaguti, 1965, P. carangis Yamaguti, 1965, is redescribed and the diagnosis of the genus is amended. Metadiplectanotrema Gerasev et al. 1987 is considered synonym of Pseudempleurosoma. This genus now contains four species, including P. carangis, P. caranxi Gerasev et al., 1987 n. comb., P. myripristi Gerasev et al., 1987 n. comb. and the one new species.

The life history of Pygidiopsis macrostomum Travassos, 1928 (Digenea: Heterophyidae)

The life history of the trematode Pygidiopsis macrostomum Travassos, 1928 is described for the first time. Rediae and cercariae were obtained from naturally infected snails Heleobia australis (d Orbigny), a new first intermediate host. Metacercariae were found encysted in the mesenteries of three naturally infected guppies, Phalloptychus januarius (Hensel), Jenynsia multidentata (Jenyns) (new host records) and Poecilia vivipara Bloch and Schneider. Experimental infections were successfully completed in the intermediate hosts H. australis and Poe. vivipara reared in the laboratory and hamsters Mesocricetus auratus Waterhouse were utilised as a definitive host.