Phylogenetic relationship between Contracaecum spp. (Nematoda, Anisakidae) parasitizing cormorants (Aves, Phalacrocoracidae) in Argentina.

Species of the genus Contracaecum (Family Anisakidae) exhibit a broad host and geographical distribution, parasitizing aquatic organisms such as piscivorous birds and mammals as their definitive hosts. Several Contracaecum species have been reported parasitizing cormorants (Family: Phalacrocoracidae) in South America. The objective of this study was to highlight phylogenetic relationships between Contracaecum species parasitizing cormorants based on both molecular analyses and the papillae arrangement on the male tail. Some Contracaecum species parasitizing Red-legged cormorants from the Ría Deseado (RD), and other nematodes parasitizing eight Neotropic cormorants from San Miguel del Monte lagoon (SMML), Argentina, were collected and analyzed. Both morphological and phylogenetic analyses allowed us to recognize two species: Contracaecum chubutensis parasitizing Phalacrocorax gaimardi, and Contracaecum australe parasitic in Phalacrocorax brasilianus. According to the obtained sequences (mtDNA cox2, ITS1, ITS2, and SSrRNA), Contracaecum sp. parasitizing P. gaimardi exhibited concordance with the previously reported C. chubutensis parasitizing P. atriceps from Bahía Bustamante, Chubut province. Likewise, Contracaecum sp. isolates parasitizing P. brasilianus showed concordance with C. australe from Chile. Besides, the papillae arrangement on the male tail allowed us to understand the interspecific and genetic relationships between the Contracaecum species. The analyses confirm that C. chubutensis specimens parasitizing P. gaimardi from RD present a new host record for the species, whereas, those C. australe specimens parasitizing P. brasilianus from SMML provide a new geographical record for the species and the extension of its distribution range. Present results also confirm the inland and marine distribution of C. australe and C. chubutensis, respectively.

Redescription and molecular characterization of Baruscapillaria spiculata (Nematoda: Capillariidae) parasitizing the Neotropic cormorant Phalacrocorax brasilianus from two Argentinian lagoons.

Two species of intestinal Capillariidae were hitherto known from the Neotropic cormorant Phalacrocorax brasilianus, Baruscapillaria spiculata (Freitas, 1933), and Baruscapillaria appendiculata (Freitas, 1933). The original descriptions are very short and brief, and further reports of both species are scarce and/or confusing. This paper provides a morphological redescription and molecular characterization, based on the partial 18S rDNA gene, of B. spiculata specimens parasitizing the Neotropic cormorant in two continental lagoons from Buenos Aires province, Argentina. Both morphological and morphometrical differences between B. spiculata and B. appendiculata are highlighted on the examination of available type material. Additionally, two previous reports of B. appendiculata from Mexico and Brazil are discussed. A phylogenetic analysis conducted on specimens of B. spiculata and 46 other capillariid isolates available from the GenBank demonstrated a sister-taxon relationship between our specimens and the type species of Baruscapillaria. But, at the same time, significant genetic distances between both taxa showed an interesting variability of the genus Baruscapillaria. The probable division of this genus into multiple genera could probably be confirmed through integrative studies including more species.

The genus Contracaecum Raillet & Henry (Nematoda: Anisakidae): host and geographical distribution on Neotropical and Antarctic species.

Nematodes of the genus Contracaecum Raillet & Henry, 1912 (Anisakidae, Contracaecinae) have a worldwide distribution. The taxonomy of the genus Contracaecum is well-known nowadays due to several morphometric studies, scanning electron microscopy, and molecular biology. The aim of this work was to review, clarify, and summarize the valid species of the genus Contracaecum parasitizing piscivorous sea birds and mammals from both the Neotropical and Antarctic regions reviewing all scientific available papers and electronic searching data up to date. A checklist on Neotropical and Antarctic Contracaecum spp. was organized through a revision of scientific papers and original descriptions. The systematic online search and the most updated papers were obtained through SCOPUS, Google Scholar, PubMed, Medline, World Register of Marine Species, etc. We provide information about hosts, Neotropical and Antarctic localities where worms were collected, references, molecular markers, and Genbank accession numbers. Twenty-five Neotropical and Antarctic Contracaecum species have been recorded up to date and checked out as valid ones according to the most updated data. Twenty-one species parasitize exclusively fish-eating birds, two species were reported only on marine mammals, and the other two parasitize both sea birds and mammals. A total of 20 Contracaecum species are exclusively reported for the Neotropical region, three only for Antarctic hosts, and two species were reported parasitizing both Neotropical and Antarctic hosts. Several Contracaecum species (10) have been corroborated by molecular analysis of different genetic markers. After reviewing all morphological descriptions of the Contracaecum species, and despite most of them have been characterized only by morphometric methods, we are convinced that all species listed in this work correspond to good and valid Contracaecum Neotropical and Antarctic species. Present results indicate that more taxonomic and molecular studies are needed to advance the understanding of the distribution and host specificity of the Contracaecum species.

Species of Contracaecum Parasitizing the Magellanic Penguin Spheniscus magellanicus (Spheniscidae) from the Argentinean Coast.

Anisakid nematodes have a worldwide distribution and are associated with fishes, birds, and marine mammals from freshwater, brackish, and marine systems. The aims of this work are to report for the first time Contracaecum mirounga parasitizing the Magellanic penguin Spheniscus magellanicus, to report another Contracaecum species in the same host species, and to discuss the validity of Contracaeceum spheniscus. Several dead chicks, juveniles, and adults of S. magellanicus were collected along the Argentinean coast from 2002 to 2009. Nematodes were removed from digestive tracts and studied using both light and scanning electron microscopy. Nematode prevalences were 2.38% for C. mirounga and 12.5% for Contracaecum sp. Contracaecum mirounga was found in 1 penguin from Península Valdés, Chubut. This species is known as a specific parasite of marine mammals such as Pinnipedia, thereby suggesting that this nematode is not as specific as believed. Another species of Contracaecum sp. was found parasitizing 1 penguin from the Río de la Plata coast. It possessed an unusual interlabial morphology and arrangement of male caudal papillae. Despite the low prevalence, the distinct morphological features are convincing and support the presence of a new Contracaecum species. However, a formal description is not presented because sufficient male specimens are lacking. Finally, C. spheniscus is considered a junior synonym of Contracaecum pelagicum. Future molecular studies might be helpful to determine the real diversity of Contracaecum species parasitizing S. magellanicus considering the number of sibling species recognized among the anisakids.

A new anisakid species parasitizing the imperial cormorant Phalacrocorax atriceps from the North Patagonian Coast, Argentina.

The anisakid species Contracaecum chubutensis n. sp. was found parasitizing the imperial cormorant Phalacrocorax atriceps at 2 different localities, Bahía Bustamante (45 degrees 11'S, 66 degrees 30'W) and Puerto Madryn (42 degrees 47'S, 65 degrees 02'W) on the Patagonian coast. Morphometrical analysis and further studies of adult specimens of C. chubutensis n. sp. and fourth-stage larvae of Contracaecum sp. were done using light and scanning electron microscopy. The possession and disposition of 7 pairs of tail papillae differentiate this new species from C. osculatum, C. radiatum, C. plagiaticium, and C. mirounga. Double-sized spicules separate it from C. variegatum and C. pelagicum. Moreover, the paracloacal papillae disposition and tail shape differentiate this new species from C. travassosi. The presence of bifurcated interlabia separate it from C. ogmorhini and C. margolisi. Three well-marked lip notches, a sharp tail shape, and the of the transversal paracloacal papillae disposition distinguishes C. chubutensis n. sp. from C. magnipapillatum and C. septentrionale. The species here described can be differentiated from C. caballeroi by its bifurcated interlabia, longer spicules, and for possessing more precloacal papillae pairs. It can be separated from C. rudolphii by a thinner interlabia at the base, deeper lip notches, a sharper tail, the disposition of transversal paracloacal papillae, and greater distance between both papillae of the first subventral distal papillae pair. In addition, fourth-stage larvae recovered from the same host and localities were identified and described as Contracaecum sp. Prevalence of adult parasites was 66.7 %, mean intensity was 4.0, and mean abundance was 7.1.

Further study of Contracaecum pelagicum (Nematoda: Anisakidae) in Spheniscus magellanicus (Aves: Spheniscidae) from Argentinean coasts.

The anisakid species Contracaecum pelagicum Johnston and Mawson, 1942, is reported for first time at 2 different sites on the Argentine coast (Peninsula Valdés, 42 degrees 04'S, 63 degrees 38'W and Mar del Plata, 38 degrees 05'S, 57 degrees 38'W), parasitizing the Magellanic penguin, Spheniscus magellanicus Foster. Morphometric analysis and further studies of adult specimens of C. pelagicum were done using light and scanning electron microscopy. The presence of bifurcated interlabia differentiates the present species from most others in the genus, except (1) from Contracaecum travassosi, which possesses higher interlabia and longer spicules, and a blunt, more constrained tail; (2) from Contracaecum rudolphii, which has longer spicules, blunter spicule tips, postparacloacal papillae with oblique disposition, and a blunter constrained tail; (3) from Contracaecum eudyptulae, which has a blunter tail and longer spicules; and (4) from Contracaecum variegatum, which possesses smaller-diameter, hooklike extensions on auricle lips, and a less robust interlabium with a more marked furrow. In this paper we present the first detailed description of C. pelagicum adults from S. magellanicus. Morphometric data between adult specimens of C. pelagicum from S. magellanicus and those from the black-browed albatross, Diomedea melanophris Temminck, from Argentinean coasts were compared. In addition, fourth-stage larvae that parasitized both hosts were assigned to a nondeterminated Contracaecum species. Ecological parameters for adults and larvae nematodes were calculated.

Molecular identification and larval morphological description of Contracaecum pelagicum (Nematoda: Anisakidae) from the anchovy Engraulis anchoita (Engraulidae) and fish-eating birds from the Argentine North Patagonian Sea.

Anisakids use invertebrates as paratenic and/or intermediate hosts as a basic feature of larval transmission. The third-stage larva usually develops in invertebrates which are prey items of finfish paratenic hosts. Contracaecum larvae molt twice inside the egg and hatch as free third-stage larvae ensheathed in the second-stage larval cuticle. Copepods act as paratenic or obligatory hosts, usually ingesting these free L3 larvae, and fish act as intermediate/paratenic or metaparatenic hosts preying on infected copepods. Fish-eating birds acquire L3 larvae by ingesting infected fish where they develop into the fourth-stage larvae and adults. Objectives of this work were to establish the specific correspondence between Contracaecum pelagicum L3 larvae parasitizing the anchovy Engraulis anchoita, and the adults parasitizing the Magellanic penguin Spheniscus magellanicus and the Imperial shag Phalacrocorax atriceps through the use of molecular markers; and, to evaluate the anisakid L3 larval recruitment and infection caused by ingestion of anchovy by S. magellanicus. Sixteen specimens of Contracaecum L3 larvae were analyzed from E. anchoita from Bahía Engaño, Chubut, eight adult nematodes from S. magellanicus and six adult specimens from P. atriceps both from the Valdés Peninsula, Chubut. All nematodes were sequenced for three genes: mitochondrial cytochrome oxidase 2 (mtDNA cox2), mitochondrial ribosomal RNA (rrnS), and the internal transcribed spacers (ITS-1 and ITS-2) of the nuclear ribosomal DNA region. Phylogenetic analyses were performed by using Maximum Parsimony (MP) analysis by PAUP. In addition, studies under SEM and LM were carried out on L3 larvae. All L3 individuals from E. anchoita, adults from S. magellanicus, and P. atriceps clustered in the same clade, well supported in the MP tree inferred from the mtDNA cox2, and rrnS gene sequences analyses. Further, the sequence alignments of L3 larvae and adults of C. pelagicum here obtained at the ITS-1 and ITS-2 regions of the rDNA matched the sequences of C. pelagicum previously deposited by us in GenBank. Nematode recruitment (Ro) was equal to 33.07 (7.20-91.14) L3 larvae for C. pelagicum in each penguin's meal of anchovy. The MP tree topologies obtained from mtDNA cox2 and rrnS genes demonstrated that specimens of Contracaecum L3 larvae from E. anchoita and C. pelagicum from S. magellanicus as well as from P. atriceps constitute a unique clade, well-distinct and supported from all the others formed by the Contracaecum spp. sequenced so far for these genes. Molecular markers are considered to be an effective tool to elucidate larval transmission. The Contracaecum L3 larval recruitment value showed that many worms fail to establish in the bird digestive tract, probably because they are below a critical size. Further work is needed to elucidate other factors (e.g., physiological, immunological) that control nematode populations in the penguin digestive tract.