Nematodes of elasmobranch fishes from the southern coast of Brazil

Taxonomy and morphology of the skate genus Atlantoraja (Rajiformes: Arhynchobatidae)

Abstract The skate genus Atlantoraja is composed of three species (A. castelnaui, A. cyclophora, and A. platana) which differ from the other Riorajini species, Rioraja agassizii, in regards to their clasper features, squamation and presence of a caudal fin. Despite of being distributed along Southwestern Atlantic and commonly captured by fisheries in Brazil, Uruguay and Argentina, detailed accounts on external and internal morphology are scarce and the taxonomic status of Atlantoraja species was not revised so far. The aim of this study, therefore, is to review the taxonomy of the genus Atlantoraja, updating information on type specimens and clarifying misidentifications among species, and to describe in detail anatomical structures such as neurocranium, visceral arches, pelvic girdle, dermal denticles and teeth. Lectotypes and paralectotypes are designated for Atlantoraja castelnaui and A. cyclophora. Notes on intraspecific variation within species are also provided. Atlantoraja cyclophora and A. platana are more similar to each other than to A. castelnaui in regards to the squamation (body dorsal surface smooth vs. densely covered by prickles) and color pattern of body dorsal surface, position of orbital foramina, overall shape of neucrocranium and body measurements. Lastly, we discuss the morphological differences among species of Atlantoraja and recommend the inclusion of characters presented here in future cladistic analyses.

Description of Piscicapillaria bursata sp. nov. (Capillariidae) and Redescription of Parascarophis sphyrnae Campana-Rouget, 1955 (Cystidicolidae), Two Nematode Parasites of Hammerhead Sharks (Sphyrna spp.) off Australia

PURPOSE

Data on helminth parasites in hammerhead sharks are scarce and, therefore, new examinations of these hosts are needed to recognize the species composition of their parasites, including nematodes.

METHODS

Helminthological examinations of hammerhead sharks, Sphyrna lewini (Griffith et Smith) (209 specimens) and Sphyrna mokarran (Rüppell) (57 specimens) (Sphyrnidae, Carcharhiniformes), from off the northern coast of Australia revealed one new and one insufficiently known species of intestinal nematode parasites. These were studied with the use of light and scanning electron microscopy.

RESULTS

Both nematode species are described. Piscicapillaria bursata sp. nov. (Capillariidae) from S. mokarran (type host) and S. lewini differs from its congeners mainly in the spicule length (330 µm), body length of gravid females 12.80-21.26 mm and in possessing a subterminal female anus. The specimens of Parascarophis sphyrnae Campana-Rouget, 1955 (Cystidicolidae) (type species of Parascarophis Campana-Rouget, 1955) collected from S. lewini made it possible to redescribe the female and, for the first time, to describe the male; the same species was also found in S. mokarran. Amended diagnosis of Parascarophis is provided. Parascarophis is mainly characterized by the presence of lateral alae, a unique feature within the Cystidicolidae, and by the cephalic structures (presence of a cuticular hood and a pair of anterolateral plate-like structures in the mouth).

CONCLUSIONS

In addition to the discovery of a new nematode species, Pi. bursata sp. nov., the finding of Pa. sphyrnae in Australian waters represents a new geographical record of this parasite outside the Atlantic Ocean. The species of Parascarophis previously described from teleosts, P. bharatii Agrawal, 1965, P. oteroi Arya, 1992 and P. mulloidi Imam, Tawfik et Abdel Hady, 1982, are designated as species inquirendae and incertae sedis. The finding of P. sphyrnae in Australian waters represents a new geographical record of this parasite outside the Atlantic Ocean. Pa. sphyrnae had not been reported previously from beyond the Atlantic Ocean.

Contracaecum larvae: morphological and morphometric retrospective analysis, biogeography and zoonotic risk in the amazon

Abstract In Brazil there are several records of parasitic nematodes of fish with zoonotic potential, especially those belonging to the family Anisakidae. This study considers the morphology, morphometry and prevalence of Contracaecum in Astronotus ocellatus , fish consumed in the Amazon and sold as ornamental and it also performs a retrospective analysis of the diversity of fish with larvae of Contracaecum, in studies carried out in Brazil over a period of 90 years. 40 specimens of A. ocellatus were necropsied, and the nematodes were collected and fixed in 93 parts 70% ethyl alcohol, 5 parts formaldehyde, and 2 parts glacial acetic acid (AFA) for morphological analysis under light microscopy and scanning electron microscopy. Of the 40 fish collected during this work, 27 were parasitized by Contracaecum larvae with a total intensity of 150 larvae. Retrospective analysis of intermediate host diversity for Contracaecum larvae resulted in 16 orders, 49 families, 96 genera, 140 species and a hybrid morphotype. In the retrospective study, half of the fish were from freshwater, with the order Perciformes being the most representative, with 16 families, 30 genera and 37 species. In Brazil, the occurrence of larvae of Contracaecum in fish was reported in 15 of the 26 states, with Rio de Janeiro presenting the most information regarding fish harboring Contracaecum larvae.

Prey species of franciscana Pontoporia blainvillei as paratenic hosts of helminths

The distribution of franciscana Pontoporia blainvillei Gervais & d'Orbigny, 1884, is restricted to the estuarine and coastal waters of the southwestern Atlantic. The diet of this dolphin is composed of fishes, squids, and shrimps, many of which harbor helminths that may infect franciscana. Larval forms of the trematode Synthesium pontoporiae and the acanthocephalan Bolbosoma turbinella have been recorded in franciscana; however, they have not yet been identified in any of the prey species of this cetacean. We evaluated 3 components of the diet of franciscana as possible transmission sources of parasitiasis. Specimens of São Paulo squid Doryteuthis sanpaulensis (n = 50), banded croaker Paralonchurus brasiliensis (n = 43), and rough scad Trachurus lathami (n = 50) were necropsied. Organs were washed and examined under a stereomicroscope. Helminths were collected and mounted on slides. None of the species analyzed showed infection by metacercariae of S. pontoporiae. Helminths found in São Paulo squid have not been recorded in franciscana. Cistacanths of Corynosoma australe were found in the coelomic cavity and mesentery of croaker (prevalence [P] = 53.49%; mean infection intensity [MII] = 6.74) and scad (P = 4%; MII = 1.50). Cistacanths of B. turbinella were also found in the same sites in scad (P = 14%; MII = 2.14). Banded croaker and rough scad are recorded in this study as new paratenic hosts for C. australe, while scad is a new paratenic host for B. turbinella.

Endohelminths in Cichla piquiti (Perciformes, Cichlidae) from the Paraná River, São Paulo State, Brazil

Fifty specimens of Cichla piquiti were collected from the Paraná River downstream of the Ilha Solteira Hydroelectric Power Station in Brazil and surveyed for endohelminth parasites. All fish were parasitised by at least one helminth species (overall prevalence [P] = 100%). Eight parasite taxa were present: the nematode Procamallanus (Procamallanus) peraccuratus in the intestines; third-stage larvae of the anisakids Contracaecum sp. and Hysterothylacium sp. in the visceral cavity, mesentery and serosa of the stomach and intestines and on the liver and spleen; the trematodes Austrodiplostomum compactum in the eye (metacercariae) and Genarchella genarchella in the stomach; and the cestodes Proteocephalus macrophallus, Proteocephalus microscopicus, and Sciadocephalus megalodiscus in the intestines. Hysterothylacium sp. larvae (P = 86%) and P. microscopicus (P = 74%) were the most prevalent parasites. Anisakids were more prevalent and abundant in the dry season. A negative correlation between the abundances of Hysterothylacium sp. and P. microscopicus was observed, suggesting a competitive/antagonistic relationship between these parasites. Cichla piquiti represents a new host for four parasite species. These new records significantly increase the list of parasites of C. piquiti, contributing to the knowledge of the host-parasite relationship and the geographical distribution of these helminths.

Redescription of Gymnorhynchus isuri (Cestoda: Trypanorhyncha) from Isurus oxyrinchus (Elasmobranchii: Lamnidae)

Specimens of the elasmobranch, Isurus oxyrinchus Rafinesque, captured in 1999 in the state of Santa Catarina, Brazil, were parasitized with the poecilacanthoid trypanorhynch cestode Gymnorhynchus isuri Robinson, 1959, that is redescribed here. New details of scolex and proglottid morphology are given. These details are mainly related to tentacle armature, terminal genitalia and observations of external morphology of proglottids.

Larval Contracaecum sp. (Nematoda: Anisakidae) in Hoplias malabaricus and Hoplerythrinus unitaeniatus (Osteichthyes: Erythrinidae) of economic importance in occidental marshlands of Maranhão, Brazil

This work describes the presence of Contracaecum sp. larvae (Nematoda: Anisakidae) found in food fish of economic importance captured in occidental marshlands in the State of Maranhão, Brazil. Hoplias malabaricus (Erythrinidae) and Hoplerythrinus unitaeniatus (Erythrinidae), commonly called "traíra" and "jejú", respectively, were examined. All H. malabaricus were infected with a mean intensity of 24.6+/-38.3 (1-137 parasites per host) while eighty percent of H. unitaeniatus showed a mean intensity of 10.4+/-9.2 (2-31) parasites. Nematodes were most similar to larvae of a type 2 described by Moravec, Kohn and Fernandes [Moravec, F., Kohn, A., Fernandes, B.M.M., 1993. Nematode parasites of fishes of the Parana River, Brazil. Part 2. Seuratoidea, Ascaridoidea, Habronematoidea and Acuarioidea. Folia Parasitol. 40, 115-134], but differed in having a longer intestinal caecum and greater caecum/ventricular appendix ratio. Larval measurements and a description of their Brazilian fish hosts are presented.

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.

Digenea and acanthocephala of elasmobranch fishes from the southern coast of Brazil

New records for helminth species recovered from elasmobranch fishes in Brazil are established. Digenean and acanthocephalan parasites of elasmobranch fishes are reported from the southern coast of Brazil: Otodistomum veliporum (Creplin, 1837) Stafford, 1904 (Digenea: Azygiidae) in the stomach and spiral valve of Dipturus trachydermus and in the spiral valve of Squatina sp. Cystacanths and juveniles of the acanthocephalans Corynosoma australe Johnston, 1937 and Corynosoma sp., in the spiral valve of Squatina sp., Galeorhinus galeus and Hexanchus griseus and in the stomach of Squalus megalops; a juvenile of Gorgorhynchus sp., in the spiral valve of Sphyrna zygaena. Dipturus trachydermus and Squatina sp. are new host records for O. veliporum. Digeneans and acanthocephalans are reported for the first time parasitizing elasmobranch fishes in Brazil.