RESUMO
Pomacea canaliculata is one of the most dangerous invasive species. Morphological and molecular analyses have revealed that a digenean species belonging to the family Echinostomatidae parasitizes this snail at two sites in Buenos Aires Province, Argentina, South America. Molecular results confirmed that the species belongs to a genus closely related to Patagifer. Analysis of the 28S rDNA showed that the sequences of the rediae and metacercariae are identical, indicating that the apple snail acts as the first and second intermediate host. The cercariae may encyst as metacercaria inside the redia and also emerge and re-infect the same snail or another snail. The prevalence of digeneans was higher in one of the sampling locations (15.1% vs. 0.72%), probably because the bird species that acts as the definitive host is more abundant in that area. Histopathological examination showed that the parasite quickly invades multiple host organs (gills, intestines, albumen gland, lung, kidney, and mantle border) besides the gonad and digestive gland, as is usual in digeneans. In addition, the partial or total castration of snails was observed in cases of moderate and high infection intensity. In males, there was loss of integrity in testicular tubules, while in females, the replacement of ovarian tissue by rediae was found.
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Ecto and endoparasites of four species of coastal birds, Haematopus ater, Larus dominicanus, Leucophaeus scoresbii (Charadriiformes), and Lophonetta specularioides (Anseriformes), are reported from Puerto Deseado on the Patagonian coast, Argentina. Only H. ater was infested with lice (Phthiraptera), belonging to 2 species (Ischnocera, Amblycera). A total of 19 helminth species were found parasitizing the coastal birds studied: 4 cestodes (1 Tetrabothriidae, 3 Cyclophyllidea); 11 trematodes (2 Gymnophallidae, 3 Microphallidae, 2 Notocotylidae, 1 Philophthalmidae, 2 Renicolidae, 1 Schistosomatidae); 3 nematodes (1 Anisakidae, 2 Acuariidae); and 1 acanthocephalan (Polymorphidae). Although some isolated records have been previously reported for these birds, the present work provides a parasitofauna study for H. ater, L. scoresbii, and L. specularioides for the first time. Endoparasites reflected the feeding habits of the birds; the parasite assemblage of L. dominicanus was the richest, indicating their wide prey spectrum and the diversity of the habitats frequented. A great species richness of trematodes, whose life cycles are partially known, suggests that L. specularioides feeds upon crustaceans and small bivalves. The blackish oystercatcher H. ater preys upon the limpet Nacella magellanica which hosts two larval trematodes corresponding to the adults found parasitizing it.
Assuntos
Charadriiformes , Iscnóceros , Nematoides , Trematódeos , Animais , Aves/parasitologia , Charadriiformes/parasitologia , Oceano AtlânticoRESUMO
By way of morphological and molecular analysis we describe a new species of notocotylid, Paramonostomum deseado n. sp., parasitizing Haematopus ater from Argentina and we contribute to elucidate its life cycle. Within this genus, 4 groups can be morphologically distinguished according to body shape: 'Oval', 'Pyriform', 'Elongate', 'Overlong'. The new species belongs to the 'Elongate group', which presents a wide variation in body length (5974500 µm). The new species, Paramonostomum caeci from Australia, Paramonostomum actitidis from the Caribbean and Paramonostomum alveoelongatum from Russia share the smallest range of body size in this group (<1130 µm). The new species more closely resembles P. actitidis but differs from it by cirrus-sac length, which is shorter in the new species (97146 vs 280430 µm in P. actitidis), and egg size which is larger in the new species (2533 vs 1820 µm in P. actitidis). Paramonostomum deseado n. sp. uses the limpet Nacella magellanica as both first and second intermediate hosts in which metacercariae encyst inside the redia. This is the first abbreviated cycle described for notocotylid species. Ribosomal RNA sequences provided for adults (ITS1, ITS2 and 28S) and metacercariae inside the rediae (ITS1) support the species identification and the correspondence among stages. Phylogenetic analysis based on 28S placed P. deseado n. sp. close to other Notocotylus spp. and Paramonostomum anatis. Molecular results demonstrate that the hosts involved in the life cycles and the habitat more than morphological differences are determining the phylogenetic relationships in members of Notocotylidae.
Assuntos
Gastrópodes , Trematódeos , Infecções por Trematódeos , Animais , Filogenia , RNA Ribossômico 28S/genética , Estágios do Ciclo de Vida , Metacercárias , América do Sul , Infecções por Trematódeos/veterináriaRESUMO
Via morphological and molecular analysis, we describe a new species of taeniid from Patagonia (Argentina): Versteria cuja n. sp., parasitizing the Lesser grison Galictis cuja (Molina) (Carnivora: Mustelidae). This is the first report of a species of Versteria in Argentina and for a native mustelid. The new species (the third in the genus Versteria) is proposed using an integrative taxonomic approach, based on traditional morphology (distinctive morphological and morphometric diagnostic characters), genetic distances and phylogeny based on molecular data, the distinct geographical distribution, and the different definitive host species. Versteria cuja n. sp. mainly differs from Versteria mustelae (Gmelin, 1790) (from Europe) in the number of testes (54-85 vs. 83-127 in V. mustelae), the rostellum size (39-75 vs. 85-180 µm in V. mustelae), the genital atrium size (170-420 vs. 68-91 µm in V. mustelae) and in the hooks' shape. It also differs from the African species Versteria brachyacantha (Baer and Fain, 1951) by having smaller measurements regarding the main diagnostic characters, i.e. size of scolex, rostellum and suckers, number, size and shape of rostellar hooks, number of testes, and by having smooth cirrus (vs. cirrus covered with hair-like bristles in V. brachyacantha). Phylogenetical analysis using cox1 showed our specimens clustering with North American isolates of Versteria sp. in a well-supported American clade (mean genetic divergence 0.024), separated from another clade composed of different isolates of V. mustelae (0.093). The close relationship between the new species and the North American species, known as "zoonotic" Versteria sp., and responsible for fatal infections by metacestodes in free-ranging wildlife (rodents), captive primates and immunosuppressed people, lead us to think that the zoonotic potential of Versteria cuja n. sp. should not be discarded.
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The study reports a previously unknown apicomplexan (APXSc) parasite infecting wild scallops Aequipecten tehuelchus (d'Orbigny, 1842) from two separate areas (La Tapera and Punta Conos) of the San José gulf, in Patagonia Argentina. Histology, transmission electron microscope, molecular analyses and in situ hybridization were performed to describe the morphology of APXSc, and confirm its phylogenetic status. The prevalence of APXSc infection was 24% and 72% in scallops from La Tapera and Punta Conos, respectively. Seasonal variation was observed for scallops from La Tapera, recording highest prevalence in summer. A positive relationship between the presence of the APXSc and the size of the scallops was observed. A SSU rDNA consensus sequence of 1758 base pairs was generated which has a 94.8% identity to sequences obtained from a pathogenic apicomplexan parasite infecting Ostrea chilensis in New Zealand, but not closely related to other apicomplexans. The asexual reproduction, i.e. merogony, occurs in the Tehuelche scallop whilst the gamogonic and sporogonic stages were absent, suggesting a yet unknown definitive host. Severe host inflammation response involving fibroblast-like hemocytes surrounding the APXSc in the form of granuloma-like "swirls" is characteristic for this apicomplexan infection. Further studies are needed to reveal the life cycle, and presumable pathogenicity of APXSc.
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Auriculostoma is a genus of digenean (Trematoda) whose adults are parasites of Neotropical freshwater fishes. We describe Auriculostoma ocloya n. sp. using morphological and molecular tools, and we elucidated its life cycle, the first known of a species of this genus. The first intermediate host is the bivalve Pisidium ocloya, the second intermediate host is the amphipod Hyalella sp., and the definite hosts are siluriform fishes. The adult presents a single pair of muscular lobes on either side of the oral sucker with a broad base, stretching from ventrolateral to dorsolateral side, a structure also present in the rest of species of the genus. Nevertheless, the new species differs from all congeners by the combination of several traits, and mainly because on the dorsal side "free" ends of the lobes are absent because they are fused. This is the first study to provide sequence data on larval and adult stages of a species of Auriculostoma. Our phylogenetic analysis demonstrated its basal position among species of the genus. Therefore, integrative morphological, molecular, and life cycle data on other South American species of the genus, would contribute to reveal more patterns in the allocreadiid systematics.
Assuntos
Doenças dos Peixes , Trematódeos , Infecções por Trematódeos , Animais , Estágios do Ciclo de Vida , Filogenia , RNA Ribossômico 28S , Trematódeos/genéticaRESUMO
Diphterostomum brusinae (Zoogonidae) is a digenean species that has been recorded worldwide parasitizing marine fishes. Several species have been synonymized with D. brusinae because they lack conspicuous morphological differences. However, due to the breadth of its geographic distribution and the variety of hosts involved in the life cycles, it is likely to be an assemblage of cryptic species. Diphterostomum flavum n. sp. is described here as a morphologically cryptic relative of D. brusinae, in the fish Pinguipes brasilianus (Pinguipedidae) off the Patagonian coast, Southwestern Atlantic Ocean, and its life cycle is elucidated through morphology and molecular analysis. This species uses the gastropod Buccinanops deformis (Nassariidae) as first and second intermediate host with metacercariae encysting within sporocysts. They also, however, use the polychaete Kinbergonuphis dorsalis (Onuphidae) as second intermediate host. No morphological differences were found between adults of D. flavum n. sp. and D. brusinae; however, the number of penetration glands of the cercariae, a diagnostic feature, differed (9 vs. 3 pairs), as well as the ITS2 sequences for the two species. This work provides morphological and molecular evidence of cryptic diversification among species described as D. brusinae, in which the only clear differences are in larval morphology and host spectrum. The strict specificity to the snail acting as the first intermediate host and the variety of fishes with different feeding habits acting as definitive hosts support the likely existence of multiple cryptic species around the world.
TITLE: Spéciation cryptique du Digène Zoogonidae Diphterostomum flavum n. sp. démontrée par des données morphologiques et moléculaires. ABSTRACT: Diphterostomum brusinae (Zoogonidae) est une espèce de digène, parasite des poissons marins, qui a été signalée dans le monde entier. Plusieurs espèces ont été synonymisées avec D. brusinae parce qu'elles ne montrent pas de différences morphologiques visibles. Cependant, en raison de l'étendue de sa répartition géographique et de la variété d'hôtes impliqués dans les cycles de vie, il est probable qu'il s'agisse d'un assemblage d'espèces cryptiques. Diphterostomum flavum n. sp. est décrit ici comme une espèce morphologiquement cryptique de D. brusinae, chez le poisson Pinguipes brasilianus (Pinguipedidae) au large de la côte de la Patagonie, dans le sud-ouest de l'océan Atlantique, et son cycle de vie est élucidé par la morphologie et l'analyse moléculaire. Cette espèce utilise le gastéropode Buccinanops deformis (Nassariidae) comme premier et deuxième hôte intermédiaire avec des métacercaires s'enkystant dans les sporocystes. Cependant, elle utilise également le polychète Kinbergonuphis dorsalis (Onuphidae) comme deuxième hôte intermédiaire. Aucune différence morphologique n'a été trouvée entre les adultes de D. flavum n. sp. et D. brusinae, mais le nombre de glandes de pénétration des cercaires, une caractéristique diagnostique, diffère (9 paires contre 3), ainsi que les séquences ITS2 pour les deux espèces. Ce travail fournit des preuves morphologiques et moléculaires de la diversification cryptique parmi les espèces décrites comme D. brusinae, dans lesquelles les seules différences claires sont dans la morphologie des larves et le spectre de l'hôte. La spécificité stricte au mollusque servant de premier hôte intermédiaire et la variété de poissons avec différentes habitudes alimentaires servant d'hôtes définitifs soutiennent l'existence probable de plusieurs espèces cryptiques dans le monde.
Assuntos
Estágios do Ciclo de Vida , Trematódeos , Animais , Oceano Atlântico , Cercárias/anatomia & histologia , Cercárias/genética , DNA Espaçador Ribossômico/genética , Metacercárias/anatomia & histologia , Metacercárias/genética , Especificidade da Espécie , Trematódeos/anatomia & histologia , Trematódeos/classificação , Trematódeos/genéticaRESUMO
There are increasing global concerns of the alarming pollution impacts on marine life, thus it is becoming essential to generate reliable tools to monitor and understand the effects of these impacts on aquatic organisms. We performed a field study assessing how exposure to anthropogenic pollution impacts immunological and health-state parameters and parasite infection of a wild marine fish, the Brazilian sandperch Pinguipes brasilianus. Then we compared this information to previously published data of a sympatric species, the Patagonian rockfish Sebastes oculatus inhabiting the same polluted and pristine areas. The field study revealed that exposed P. brasilianus showed chronic stress, poor immune condition and higher prevalence and abundance of acanthocephalan parasites. By comparing these former results with already published in S. oculatus, we concluded that, although both species exhibited physiological alterations associate to inhabiting sites exposed to pollution, their specific immunological and health-state responses differed. Our results demonstrate that Patagonian reef-fish assemblages inhabiting sites exposed to pollutant are being affected in their immune and heath condition, which could potentially result in higher susceptibility to disease and in turn population decline. These findings highlight the necessity of more studies incorporating interspecific comparisons to assess variation in fish susceptibility in an ecoimmunotoxicological context and get a more profound understanding of anthropogenic impacts on wildlife.
Assuntos
Bass , Parasitos , Perciformes , Animais , Brasil , Poluição Ambiental , PeixesRESUMO
This study documents the lesions caused by 9 digenean larvae parasitizing 6 marine gastropod species from Patagonia, Argentina. Most digeneans produce a lesion where the parthenitae replace the gonadal tissues and also occupy part of the digestive gland. Three atypical lesions and tropism were observed in (1) Trophon geversianus (Muricidae) infected by Renicolidae gen. et sp. 1, where the sporocysts occur inside the gonad acini which retain their general structure due to the persistence of the acinus wall, (2) Nacella magellanica (Nacellidae) infected by Renicolidae gen. et sp. 2, where the gonad is not affected and the sporocysts are located only among the digestive gland tubules, and (3) Siphonaria lessonii (Siphonariidae) infected by Schistosomatidae gen. et sp., where fully developed cercariae occur inside the digestive tubules. At high infection intensities or in double infections, larvae can invade other organs (mantle, foot or gill) and, on occasion, may elicit hemocytic encapsulation.