Publications by authors named "Juan T Timi"

47 Publications

Dendrapta nasicola n. sp. (Copepoda: Siphonostomatoida: Lernaeopodidae) a parasite from the olfactory sacs of Bathyraja scaphiops (Norman, 1937) in the South Western Atlantic.

An Acad Bras Cienc 2020 19;92(suppl 2):e20180933. Epub 2020 Oct 19.

Universidad Nacional de Mar del Plata/UNMdP, Instituto de Investigaciones Marinas y Costeras/IIMyC, Facultad de Ciencias Exactas y Naturales, Laboratorio de Ictioparasitología, Funes 3350 (7600) Mar del Plata, Buenos Aires, Argentina.

During a parasitological survey of the olfactory sacs of 21 species of Rajiformes (Chondrichthyes) from the Southwestern Atlantic Ocean, copepods referable to Dendrapta Kabata (1964) (Siphonostomatoida: Lernaeopodidae) were found parasitizing the cuphead skate Bathyraja scaphiops (Rajiformes: Arhynchobatidae). Morphological analyses using both light and electron microscopy revealed that they belong to a new species. It can be easily distinguished from its congeners by the ratio between lengths of posterior process and trunk (1:0.8), the large to width ratio of trunk (1:0.7) and the armature of the antennule (1, 1, 5 + 1 aesthete). Dendrapta cameroni longiclavata is raised to full specific status, as Dendrapta longiclavata n. comb. Kabata & Gusev, 1966.
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http://dx.doi.org/10.1590/0001-3765202020180933DOI Listing
November 2020

Why ignoring parasites in fish ecology is a mistake.

Int J Parasitol 2020 09 24;50(10-11):755-761. Epub 2020 Jun 24.

Zoology Department, University of Otago, PO Box 56, Dunedin 9054, New Zealand.

Parasites are ubiquitous components of biological systems that have evolved in multiple independent lineages during the history of life, resulting in a diversity of taxa greater than that of their free-living counterparts. Extant host-parasite associations are the result of tight reciprocal adaptations that allow parasites to exploit specific biological features of their hosts to ensure their transmission, survival, and maintenance of viable populations. As a result, parasites may affect host physiology, morphology, reproduction or behaviour, and they are increasingly recognized as having significant impacts on host individuals, populations, communities and even ecosystems. Although this is usually acknowledged by parasite ecologists, fish ecologists often ignore parasitism in their studies, often acting as though their systems are free of parasites. However, the effects of parasites on their hosts can alter variables routinely used in fish ecology, ranging from the level of individual fish (e.g. condition factors) to populations (e.g. estimates of mortality and reproductive success) or communities (e.g. measures of interspecific competition or the structure and functioning of food webs). By affecting fish physiology, parasites can also interfere with measurements of trophic levels by means of stable isotope composition, or have antagonistic or synergistic effects with host parameters normally used as indicators of different sources of pollution. Changes in host behaviour induced by parasites can also modify host distribution patterns, habitat selection, diet composition, sexual behaviour, etc., with implications for the ecology of fish and of their predators and prey. In this review, we summarise and illustrate the likely biases and erroneous conclusions that one may expect from studies of fish ecology that ignore parasites, from the individual to the community level. Given the impact of parasites across all levels of biological organisation, we show that their omission from the design and analyses of ecological studies poses real risks of flawed interpretations for those patterns and processes that ecologists seek to uncover.
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http://dx.doi.org/10.1016/j.ijpara.2020.04.007DOI Listing
September 2020

Rhinoxenus (Dactylogyridae) parasitizing piranhas (Serrasalmidae) at its southernmost limit of distribution (Paraná River, Argentina), with the description of two new species.

An Acad Bras Cienc 2019 2;91(4):e20190711. Epub 2019 Dec 2.

Laboratorio de Ictioparasitología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata/UNMdP, Instituto de Investigaciones Marinas y Costeras/IIMyC-CONICET, Funes 3350, 7600 Mar del Plata, Argentina.

Three piranha species, Serrasalmus maculatus, S. marginatus and Pygocentrus nattereri, living sympatrically in the lower Paraná River (Argentina) were examined searching for nasal monogeneans to know its diversity and distribution. Four species of monogeneans belonging to Rhinoxenus were found parasitizing the nasal cavities. Two new species are described, and new morphological data of 2 previously described species is provided. Rhinoxenus argentinensis n. sp. is characterized by having the male copulatory organ (MCO) as a coiled tube with a reel shaped-base; an elongated accessory piece articulated to base of MCO; a sinistral vagina with a sclerotized vestibule, and a sclerotized cap of the ventral anchor laterally modified forming a triangular expansion. Rhinoxenus paranaensis n. sp. is characterized by having a MCO as a coiled tube with a reel-shaped base; an accessory piece with an elongate proximal portion, a dilated distal portion with digitiform projections articulated to base of MCO; a sinistral vagina with 5-6 cuticular spine-shaped processes, and a sclerotized cap of the ventral anchor modified laterally forming a bilobate expansion. Additionally, multivariate discriminant analyses showed significant morphometric differences in the ventral anchors among Rhinoxenus species parasitizing 'piranhas '.
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http://dx.doi.org/10.1590/0001-3765201920190711DOI Listing
January 2020

Diversity of Empruthotrema Johnston and Tiegs, 1992 parasitizing batoids (Chondrichthyes: Rajiformes and Myliobatiformes) from the Southwest Atlantic Ocean, with description of three new species.

Parasitol Res 2019 Nov 13;118(11):3113-3127. Epub 2019 Sep 13.

Laboratorio de Ictioparasitología, Facultad de Ciencias Exactas y Naturales, Instituto de Investigaciones Marinas y Costeras (IIMyC), Universidad Nacional de Mar del Plata (UNMdP), Funes 3350 (7600) Mar del Plata, Buenos Aires, Argentina.

During an extensive research project involving 519 specimens of batoids, including 13 species of Rajiformes and Myliobatiformes (Chondrichthyes) from the Argentine Sea, three new species of Empruthotrema were found and are described using morphologic characteristics and two molecular markers: LSU rDNA and COI mtDNA. The new species can be distinguished from their congeners by the number and distribution of the marginal loculi, the length and morphology of male copulatory organ, and the presence of eyespots. Additionally, multivariate analysis identified the dimensions of the pharynx and ejaculatory bulb as diagnostic features. Host specificity and previous records of the genus in the region are discussed. This is the first description of new species in this genus for the Southwestern Atlantic Ocean, as well as for arhynchobatid hosts.
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http://dx.doi.org/10.1007/s00436-019-06456-xDOI Listing
November 2019

Distribution patterns of two species of Corynosoma (Acanthocephala: Polymorphidae) in fishes from Southwestern Atlantic.

Parasitol Res 2019 Oct 31;118(10):2831-2841. Epub 2019 Aug 31.

Laboratorio de Ictioparasitología, Instituto de Investigaciones Marinas y Costeras (IIMyC), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Funes 3350, 7600, Mar del Plata, Argentina.

Corynosoma australe and C. cetaceum are the most frequently reported acanthocephalans in fish from the Argentine Sea, particularly in central and northern areas. Their definitive hosts are otariids and odontocete cetaceans, respectively. The low specificity of these larvae, in combination with high infective capability and long survival periods in fish, make them potentially good biological markers for stocks and other biological features of their fish hosts. In order to determine the distribution patterns of these species and their determining factors, a large dataset composed by newly collected fish samples, published and unpublished data from previous studies by the authors in the region were analysed in relation to host and environmental variables. The complete dataset comprised a total of 5084 fish, belonging to 29 species distributed in 21 families and 9 orders. Host size and trophic habits arose as the main determinants of abundance for both species of Corynosoma, showing higher abundances on larger fish and on higher trophic levels, as it is usual for trophically transmitted parasites. Biogeographic province and depth (indirectly representing the temperature of water) were the main drivers of the spatial distribution, displaying a latitudinal pattern associated to the temperature clines created by the interaction of Malvinas and Brazil currents, determining a decrease in abundance southwards and towards the deeper areas. No patterns were found regarding the distribution of definitive hosts. The knowledge of these distribution patterns of Corynosoma spp. in fish at regional scale, as well as of their causes, provides useful information to design management and conservation policies thus contributing to maintain the full and sustainable productivity of fisheries.
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http://dx.doi.org/10.1007/s00436-019-06440-5DOI Listing
October 2019

Novel polymorphic microsatellite loci in and (s. s.) (Nematoda: Anisakidae): implications for species recognition and population genetic analysis.

Parasitology 2019 09 28;146(11):1387-1403. Epub 2019 Jun 28.

Department of Ecological and Biological Sciences, Tuscia University, Viale dell'Università s/n 01100 Viterbo, Italy.

The species of Anisakis constitute one of the most widespread groups of ascaridoid nematodes in the marine ecosystem. Three closely related taxa are recognised in the A. simplex (s. l.) complex, i.e. A. pegreffii, A. simplex (s. s.) and A. berlandi. They are distributed in populations of their intermediate/paratenic (fish and squids) and definitive (cetaceans) hosts. A panel of seven microsatellite loci (Anisl 05784, Anisl 08059, Anisl 00875, Anisl 07132, Anisl 00314, Anisl 10535 and Anisl 00185), were developed and validated on a total of N = 943 specimens of A. pegreffii and A. simplex (s. s.), collected in fish and cetacean hosts from allopatric areas within the range of distribution of these parasite species. In addition, the locus Anisl 7, previously detected in those Anisakis spp., was investigated. The parasites were first identified by sequence analysis of the EF1 α-1 nDNA. The panel of the microsatellites loci here developed have allowed to: (i) detect diagnostic microsatellite loci between the two species; (ii) identify specimens of the two species A. pegreffii, A. simplex (s. s.) in a multi-marker nuclear genotyping approach; (iii) discover two sex-linked loci in both Anisakis species and (iv) estimate levels of genetic differentiation at both the inter- and intra-specific level.
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http://dx.doi.org/10.1017/S003118201900074XDOI Listing
September 2019

Influence of confluent marine currents in an ecotonal region of the South-West Atlantic on the distribution of larval anisakids (Nematoda: Anisakidae).

Parasit Vectors 2018 Nov 8;11(1):583. Epub 2018 Nov 8.

Laboratorio de Ictioparasitología, Instituto de Investigaciones Marinas y Costeras (IIMyC), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), (7600) Mar del Plata, 3350, Funes, Argentina.

Background: In the marine environment, transitional zones between major water masses harbour high biodiversity, mostly due to their productivity and by containing representatives of species characteristic of adjacent communities. With the aim of assessing the value of larval Anisakis as zoogeographical indicators in a transitional zone between subtropical and sub-Antarctic marine currents, larvae obtained from Zenopsis conchifer were genetically identified. Larvae from Pagrus pagrus and Merluccius hubbsi from two adjacent zoogeographical provinces were also sequenced.

Results: Four species were genetically identified in the whole sample, including Anisakis typica, A. pegreffii, A. berlandi and a probably new species related to A. paggiae. Anisakis typica and A. pegreffii were identified as indicators of tropical/subtropical and sub-Antarctic waters, respectively, and their presence evidenced the transitional conditions of the region. Multivariate analyses on prevalence and mean abundance of Anisakis spp. of 18 samples represented by 9 fish species caught south of 35°S determined that host trophic level and locality of capture were the main drivers of the distribution of parasites across zoogeographical units in the South-West Atlantic.

Conclusions: Most samples followed a clear zoogeographical pattern, but the sample of Z. conchifer, composed mostly of A. typica, was an exception. This finding suggests that population parameters of A. typica and A. pegreffii could differ enough to be considered as a surrogates of the identity of larvae parasitizing a given host population and, therefore, a step forward the validation of the use of larval Anisakis as biological indicators for studies on host zoogeography.
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http://dx.doi.org/10.1186/s13071-018-3119-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6225687PMC
November 2018

Three-dimensional morphology of rigid structures as a tool for taxonomic studies of Dactylogyridae (Monogenea).

Parasitol Res 2017 Oct 19;116(10):2813-2819. Epub 2017 Aug 19.

Laboratorio de Ictioparasitología, Instituto de Investigaciones Marinas y Costeras (IIMIyC), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Funes 3350, (7600), Mar del Plata, Argentina.

Dactylogyridae is overwhelmingly the most abundant and diverse taxon among monogeneans in continental waters of South America. Their small body size requires considerable sampling effort and training for collecting and identifying the worms from the gills, skin, nasal cavities, and other microhabitats. Indeed, diagnostic characteristics as sclerites and male copulatory complex are generally less than 100-μm long and are essential for taxonomic description and identification of species. Here, a combination of simple and routine methods for three-dimensional morphological studies on hard structures is proposed for dactylogirids: SDS treatment for clarification of specimens and enzymatic digestion with proteinase K for freeing sclerotized structures, followed by laser confocal microscopy. This method is applicable to fresh or fixed specimens and does not require staining or dehydration. Indeed, stable autofluorescence emission is detectable at 500-530 nm for bars, anchors, and male copulatory complex when excited by argon laser. Advantages of this protocol over previous methodologies for taking laser confocal images are discussed. Open access software for image processing was used for three-dimensional reconstruction of sclerotized structures generating models and full 360° rotation videos.
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http://dx.doi.org/10.1007/s00436-017-5591-yDOI Listing
October 2017

Morphological and molecular evidence for a new species of Pseudanisakis Layman & Borovkova, 1926 (Nematoda: Ascaridida), parasitizing Rajiformes in southern Southwest Atlantic waters.

Parasitol Res 2017 Jul 18;116(7):1989-1999. Epub 2017 May 18.

Laboratorio de Ictioparasitología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata (UNMdP), Instituto de Investigaciones Marinas y Costeras (IIMyC), Funes 3350, 7600, Mar del Plata, Buenos Aires, Argentina.

Pseudanisakis argentinensis n. sp. is proposed to accommodate parasitic nematodes found in six skate species (Rajidae and Arhynchobatidae) examined from southern Southwest Atlantic waters. The new species differs from its congeners by the following combination of characters: a cupola on each lip, males with 8-12 pairs of precloacal genital papillae, a larger size for both males and females, a greater length-to-breadth ratio of the ventriculus and the presence of a small knob on the tip of the tail. Allometric growth was observed for several morphometric features; however, the slopes of the allometric relationships across host species exhibited non-significant differences and were considered as a strong evidence for conspecificity. Congruent results were obtained after the genetic characterization of the mitochondrial cytochrome c oxidase subunit 1 gene of worms obtained from different skate species, whose values of genetic divergence (1.3) lay within the range of intraspecific variation. Previous records of specimens referred to as Pseudanisakis tricupola in skates from South American waters are regarded as conspecific with P. argentinensis n. sp.
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http://dx.doi.org/10.1007/s00436-017-5482-2DOI Listing
July 2017

Parasitic copepods infesting the olfactory sacs of skates from the southwestern Atlantic with the description of a new species of Kroeyerina Wilson, 1932.

Zootaxa 2016 Oct 11;4174(1):137-152. Epub 2016 Oct 11.

Laboratorio de Ictioparasitología, Instituto de Investigaciones Marinas y Costeras (IIMyC-CONICET). Universidad Nacional de Mar del Plata, Funes 3350, (7600) Mar del Plata, Argentina.; Email:

The olfactory sacs of 488 specimens belonging to 18 species of rajid and arhynchobatid skates from the Argentine Sea were sampled for parasites. No parasitic copepods were found in 11 host species, but siphonostomatoid specimens referable to Kroeyerina Wilson, 1932 (Kroyeriidae) and Brianella corniger Wilson, 1915 (Lernaeopodidae) were found on the spotback skate Atlantoraja castelnaui (Miranda Ribeiro, 1907), the smallnose fanskate Sympterygia bonapartii Müller & Henle, 1841, the bignose fanskate Sympterygia acuta Garman, 1877 and the zipper sand skate Psammobatis extenta (Garman, 1913) (Rajiformes: Arhynchobatidae). Additionally, specimens of B. corniger were found in the olfactory sacs of the Rio skate Rioraja agassizii (Müller & Henle, 1841) and attached to the pectoral fins of the Magellan skate Bathyraja magellanica (Philippi, 1902) and the smallthorn sand skate Psammobatis rudis Günther, 1870. A new species, Kroeyerina sudamericana sp. nov., is described and illustrated. The new species most closely resembles Kroeyerina nasuta Wilson, 1932, but can be distinguished from it by the different armature of the antennule, a proportionally shorter genital complex and the chela of the antenna which, when closed, leaves a gap between the corpus and claw, the latter having no spines. The new species represents the first record of Kroeyerina in South American marine waters. The present study also extends the distribution range of B. corniger, previously known only from the Pacific, to include Atlantic waters, and records seven new host species, all of which are members of the Arhynchobatidae.
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http://dx.doi.org/10.11646/zootaxa.4174.1.10DOI Listing
October 2016

Parasites of the Brazilian flathead Percophis brasiliensis reflect West Atlantic biogeographic regions.

Parasitology 2017 02 3;144(2):169-178. Epub 2016 Nov 3.

Laboratorio de Ictioparasitología,Instituto de Investigaciones Marinas y Costeras (IIMyC),Facultad de Ciencias Exactas y Naturales,Universidad Nacional de Mar del Plata- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET),Funes 3350, (7600) Mar del Plata,Argentina.

With the aim of evaluating the utility of marine parasites as indicators of zoogeographical regions in the South West Atlantic, we analyzed data on assemblages of long-lived larval parasites of 488 specimens of Percophis brasiliensis distributed in 11 samples from nine localities covering the entire distribution of the species in the Argentine biogeographical Province. Near half a million long-lived parasite individuals belonging to 17 species present in the whole sample displayed clear latitudinal patterns. Data for parasite assemblages at infracommunity and component community levels were analysed in relation to the geographical distance. Significant similarity decay of parasite assemblages over distance was observed, with those based on abundances and mean abundances showing departures from predicted values of regressions. These departures were represented by higher dissimilarities between samples coming from different zoogeographical regions than between those caught within the same region, independently of the distance separating them. Consequently, zoogeographical regions were identified in a distance-decay context. Multivariate analyses corroborated a close fit of similarity between assemblages to existing zoogeographical classifications. Regressions representing distance decay of similarity, and the identification of their outliers, can therefore shed light on the existence of discontinuities or uniformities in the geographic distribution of parasite assemblages and, in turn, in the zoogeography of their fish hosts.
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http://dx.doi.org/10.1017/S0031182016001050DOI Listing
February 2017

Ecotonal marine regions - ecotonal parasite communities: helminth assemblages in the convergence of masses of water in the southwestern Atlantic Ocean.

Int J Parasitol 2016 Nov 3;46(12):809-818. Epub 2016 Sep 3.

Laboratorio de Ictioparasitología, Instituto de Investigaciones Marinas y Costeras (IIMyC), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Funes 3350, 7600 Mar del Plata, Argentina.

With the aim of evaluating the utility of marine parasites as indicators of ecotonal regions in the marine environment, we analysed data on assemblages of long-lived larval parasites of Zenopsis conchifer inhabiting the region of convergence of three masses of water in the southwestern Atlantic Oceans. These masses of water with different origins are expected to affect the structure of parasite communities by acting as sources of infective stages of helminth species typical of adjacent zoogeographical regions. Multivariate analyses at both infracommunity and component community levels, including data of four other species recognised as harbouring parasite assemblages representatives of these zoogeographical regions, were carried out to corroborate the existence of repeatable distribution patterns and to provide further evidence of the utility of parasites as zoogeographic indicators in the region. Results showed a tight correspondence with the existing zoogeographical classification in the study region, namely two zoogeographical provinces, one of which is subdivided into two districts demonstrating the ecotonal nature of parasite assemblages from the convergence region, which were characterised by a species rich component community but depauperate and heterogeneous infracommunities. The borders of biological communities have been suggested as priority areas for conservation where a fully functioning ecosystem can be protected and parasite communities can be considered as reliable indicators to define such transitional regions.
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http://dx.doi.org/10.1016/j.ijpara.2016.07.004DOI Listing
November 2016

A new species of Dendromonocotyle Hargis, 1955 (Monogenea: Monocotylidae) from the skin of Zearaja chilensis (Guichenot) (Rajiformes: Rajidae) from the Argentine Sea.

Syst Parasitol 2016 May 18;93(4):367-74. Epub 2016 Apr 18.

Laboratorio de Parasitología, Facultad de Ciencias Exactas y Naturales, Instituto de Investigaciones Marinas y Costeras (IIMyC), Universidad Nacional de Mar del Plata (UNMdP), Funes, 3350, Mar del Plata, Buenos Aires, Argentina.

Dendromonocotyle rajidicola n. sp. is described from the dorsal surface of the yellownose skate Zearaja chilensis (Guichenot) (Rajiformes) caught on the Argentine shelf. Dendromonocotyle rajidicola n. sp. can be distinguished from the other 17 species in the genus by the morphology of the distal portion of the male copulatory organ and by the unique morphology of the sclerotised proximal portion of the vagina. This is the first species of Dendromonocotyle to be described from a host in the Rajiformes and also the first record of this genus in the southwestern Atlantic Ocean.
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http://dx.doi.org/10.1007/s11230-016-9624-1DOI Listing
May 2016

A survey of nematodes of the genus Cucullanus Müller, 1777 (Nematoda, Seuratoidea) parasitic in marine fishes off Brazil, including description of three new species.

Zootaxa 2015 Nov 5;4039(2):289-311. Epub 2015 Nov 5.

Departamento de Parasitologia Animal, Universidade Federal Rural do Rio de Janeiro (UFRRJ), Caixa Postal 74.540, Seropédica, RJ, 23851-970, Brazil Programa de Pós-Graduação em Ciências Veterinárias, UFRRJ, CEP 23851-970, Seropédica, RJ, Brazil; Email:

A taxonomic survey of six nematode species (including three new taxa) from the genus Cucullanus Müller, 1777, parasites of marine fishes off the Brazilian coast, is provided. Nematodes were studied using light and scanning electron microscopy (SEM). Cucullanus gastrophysi n. sp. parasitic in Lophius gastrophysus Miranda Ribeiro differs from its congeners by the combination of the following features: shape and number of sclerotized structures in the oesophastome (a pair of lateral elongate structures and a single small reniform one), position of deirids and excretory pore (both anterior to oesophagus base), spicule length and spicule/body length ratio (0.97-1.29 mm and 6.5-10.5%, respectively), morphology and length of gubernaculum (V-shaped, 107-135 µm long). Cucullanus protrudens n. sp. from Pagrus pagrus (Linnaeus) has the cloacal lips broadly protruded, which differentiates it from several species of Cucullanus; other features, e.g., the length of spicules and gubernaculum (400-415 µm and 91-103 µm, respectively), arrangement of caudal papillae and position of excretory pore (slightly posterior to oesophagus-intestine junction) also characterize this species. Cucullanus pseudopercis n. sp. from Pseudopercis semifasciata (Cuvier) has deirids and excretory pore posterior to the oesophagus-intestine junction, which distinguishes the species from most of the congeners; furthermore, the arrangement of caudal papillae in combination with the length of spicules and gubernaculum (1.0-1.5 mm and 178-196 µm, respectively) separate this species from other taxa. Newly collected specimens of C. cirratus Müller, 1777 (type species of the genus) from Urophycis brasiliensis (Kaup), C. pedroi from Conger orbignianus Valenciennes (type host of the species) and C. genypteri Sardella, Navone & Timi, 1997 from Genypterus brasiliensis Regan, were studied as well. Comparisons between newly collected samples and the taxonomic data available for each respective species revealed features that were not previously mentioned (e.g. presence of unpaired cloacal papilla, detailed morphology of cloacal lips), as well as negligible differences in morphometry and caudal papillae arrangement. Observations on the type material of C. carioca suggested affinities with the genus Dichelyne Jägerskiöld, 1902; however, the poor preservation of these specimens does not allow further conclusions. Cucullanus rougetae is considered to be a species inquirenda.
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http://dx.doi.org/10.11646/zootaxa.4039.2.5DOI Listing
November 2015

Parasites of Urophycis brasiliensis (Gadiformes: Phycidae) as indicators of marine ecoregions in coastal areas of the South American Atlantic.

Parasitol Res 2014 Nov 24;113(11):4281-92. Epub 2014 Sep 24.

Curso de Pós-Graduação em Ciências Veterinárias and Departamento de Parasitologia Animal, Universidade Federal Rural do Rio de Janeiro, Caixa Postal 74.540, CEP 23851-970, Seropédica, RJ, Brasil.

The potential value of parasites as ecosystem markers was tested by analyzing the metazoan assemblages of Urophycis brasiliensis caught in four locations distributed in three ecoregions of the Warm Temperate Southwestern Atlantic. A total of 5,001 metazoan parasites belonging to 33 species were found. The identified parasites varied across locations in terms of presence, prevalence, and abundance, and their multivariate analyses resulted in clear similarity patterns. No differences were observed between two locations of the same ecoregion, whereas an evident separation of samples was observed across ecoregions in support of the existing hypotheses regarding the ecoregional division of the southwestern Atlantic. We proposed that parasite assemblages, which are composed of several metazoan phyla, are potentially useful as ecosystem indicators. This suggestion is derived from the combined evidence of the evolutionary history and biogeography of multiple lineages, which is expected to be more efficient in capturing recurrent patterns in overall biodiversity than individual lineages. Furthermore, as many parasites have complex life cycles, their distribution patterns are dependent not only on environmental conditions but also on the distribution and population density of all hosts involved in their life cycles, adding further sources of distributional variability that act synergistically to define robust geographical patterns. The selection of long-lived parasites and their comparative analysis provided evidence supporting the existence of three different stocks in the four sampled areas. The best parasite tags were those with low specificity in fish hosts, constituting promising biological tags for the stock discrimination of other fish species in the region.
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http://dx.doi.org/10.1007/s00436-014-4106-3DOI Listing
November 2014

Genetic and morphological evidence reveals the existence of a new family, genus and species of Echinorhynchida (Acanthocephala).

Folia Parasitol (Praha) 2014 Aug;61(4):377-84

Gymnorhadinorhynchus gen. n. is proposed to accommodate its type species, G. decapteri sp. n., a parasite of the marine fish Decapterus punctatus (Cuvier), caught from the coastal waters of Brazil. Gymnorhadinorhynchus decapteri sp. n. was morphologically most similar to species of two echinorhynchid families, the Rhadinorhynchidae and the Cavisomidae, particularly in the structure of the proboscis and the absence of somatic spines, respectively. This combination of morphological features made it difficult to assign our specimen to an extant family of the Acanthocephala. Therefore, in order to clarify the systematic placement of G. decapteri, a molecular phylogenetic analysis was performed based on the SSU and LSU rDNA and the mitochondrial cox1 gene sequences obtained for the new taxon and other 26 acanthocephalan species. The results of parsimony and maximum likelihood analyses, using individual, combined and concatenated sequence data, consistently indicate that the specimens do not belong to any known family of the Echinorhynchida. Rather, G. decapteri represents a distinct lineage that is closely related to the Transvenidae, but distantly related to both the Rhadinorhynchidae and the Cavisomidae. Gymnorhadinorhynchidae fam. n. is therefore erected. This newly described family can be distinguished from other families of Echinorhynchida by the combination of the following morphological characters: a proboscis cylindrical with 10 rows of 22-26 hooks, dorsoventral differences in proboscis hooks, basal hooks forming a ring and being abruptly larger than anterior hooks, absence of trunk spines and presence of four tubular cement glands. This combination, in addition to several molecular autapomorphies, justifies the erection of a new genus, Gymnorhadinorhynchus gen. n., in order to accommodate this new species.
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August 2014

Merizocotyle euzeti sp. n. (Monogenea: Monocotylidae) from the nasal tissue of three deep sea skates (Rajidae) in the southwestern Atlantic Ocean.

Folia Parasitol (Praha) 2014 Jun;61(3):206-12

A new species of Merizocotyle Cerfontaine, 1894 (Monogenea: Monocotylidae) is described from the nasal tissues of three deep sea rajid skates: the southern thorny skate, Amblyraja doellojuradoi (Pozzi), broadnose skate, Bathyraja brachyurops (Fowler), and yellownose skate, Zearaja chilensis (Guichenot), collected off Buenos Aires Province, Argentina, southwest Atlantic Ocean. Two additional species of sympatric rajid, the white-dotted skate, Bathyraja albomaculata (Norman), and the Patagonian skate, Bathyraja macloviana (Norman), were also examined but no merizocotylines were found. The taxonomy of the Merizocotylinae is not widely accepted and, as a result, the status of Thaumatocotyle and Mycteronastes, and their proposed synonymy with Merizocotyle are currently under discussion. The new species differs from its congeners by having a unique haptoral structure, 6 peripheral loculi that are asymmetrically arranged (one much smaller, indistinctly located in the left or right side of the haptor). The presence of the new species in three sympatric species of Rajidae belonging to distinct genera and subfamilies, as well as its absence in sympatric congenerics indicates the lack of phylogenetic host specificity. Host ecology and geographical distribution appear to be more important than host phylogeny in determining the distribution of this parasite across potential hosts in the region. This constitutes the first record of Merizocotyle in the southwestern Atlantic Ocean.
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http://dx.doi.org/10.14411/fp.2014.031DOI Listing
June 2014

Chondracanthid copepod parasites of dories (Zeiformes: Zeidae) with the description of a new species of Chondracanthus from waters off northern Argentina.

Folia Parasitol (Praha) 2013 Sep;60(4):359-64

Laboratorio de Parasitología, Instituto de Investigaciones Marinas y Costeras, Universidad Nacional de Mar del Plata-CONICET, Mar del Plata, Argentina.

A new species of parasitic copepod, Chondracanthus hoi sp. n. (Copepoda: Chondracanthidae), is described based on specimens of both sexes collected from the buccal cavity and gill arches of the silvery john dory, Zenopsis conchifer (Lowe) (Zeiformes: Zeidae), from waters off northern Argentina (35-36 degrees S, 53-54 degrees W). Female of C. hoi differs from its congeners by the following combination of characters: presence of five pairs of trunk processes, antennule with four knobs tipped with small setae and absence of denticles on the terminal process of maxilla. Chondracanthids and zeiform fishes have been proposed as an example of co-speciation; this assumption is derived from a series of analyses based on incomplete records of both geographical distribution and host range of some parasite species, as well as misidentification offish hosts. These inconsistences observed during our bibliographical analyses are also discussed.
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http://dx.doi.org/10.14411/fp.2013.037DOI Listing
September 2013

Molecular identification, morphological characterization and new insights into the ecology of larval Pseudoterranova cattani in fishes from the Argentine coast with its differentiation from the Antarctic species, P. decipiens sp. E (Nematoda: Anisakidae).

Vet Parasitol 2014 Jan 4;199(1-2):59-72. Epub 2013 Oct 4.

Laboratorio de Parasitología, Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, 7600 Mar del Plata, Buenos Aires, Argentina. Electronic address:

Larvae of the genus Pseudoterranova constitute a risk for human health when ingested through raw or undercooked fish. They can provoke pseudoterranovosis in humans, a fish-borne zoonotic disease whose pathogenicity varies with the species involved, making their correct specific identification a necessary step in the knowledge of this zoonosis. Larvae of Pseudoterranova decipiens s.l. have been reported in several fish species from off the Argentine coasts; however, there are no studies dealing with their specific identification in this region. Here, a genetic identification and morphological characterization of larval Pseudoterranova spp. from three fish species sampled from Argentine waters and from Notothenia coriiceps from Antarctic waters was carried out. Larvae were sequenced for their genetic/molecular identification, including the mitochondrial cytochrome c oxidase subunit II (mtDNA cox2), the first (ITS-1) and the second (ITS-2) internal transcribed spacers of the nuclear ribosomal DNA, and compared with all species of the P. decipiens (sensu lato) species complex (sequences available in GenBank). Further, adults of Pseudoterranova spp. from the definitive host, the southern sea lion, Otaria flavescens, from Argentine and Chilean coasts were sequenced at the same genes. The sequences obtained at the ITS-1 and ITS-2 genes from all the larvae examined from fish of Argentine waters, as well as the adult worms, matched 100% the sequences for the species P. cattani. The sequences obtained at mtDNA cox2 gene for Antarctic larvae matched 99% those available in GenBank for the sibling P. decipiens sp. E. Both MP and BI phylogenetic trees strongly supported P. cattani and P. decipiens sp. E as two distinct phylogenetic lineages and depicted the species P. decipiens sp. E as sister taxon to the remaining taxa of the P. decipiens complex. Larval morphometry was similar between specimens of P. cattani from Argentina, but significantly different from those of P. decipiens sp. E, indicating that larval forms can be distinguished based on their morphology. Pseudoterranova cattani is common and abundant in a variety of fish species from Chile, whereas few host species harbour these larvae in Argentina where they show low levels of parasitism. This pattern could arise from a combination of factors, including environmental conditions, density and dietary preferences of definitive hosts and life-cycle pathways of the parasite. Finally, this study revealed that the life-cycle of P. cattani involves mainly demersal and benthic organisms, with a marked preference by large-sized benthophagous fish.
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http://dx.doi.org/10.1016/j.vetpar.2013.09.033DOI Listing
January 2014

A new species of Colobomatus (Copepoda, Phylichthyidae) parasitic on Mullus argentinae (Perciformes, Mullidae) from South American Atlantic coast.

Acta Parasitol 2012 Sep 9;57(3):323-8. Epub 2012 Aug 9.

Curso de Pós-Graduação em Ciências Veterinárias and Departamento de Parasitologia Animal, Universidade Federal Rural do Rio de Janeiro, Seropédica, Brasil.

A new species of Colobomatus Hesse, 1873 is described from pores of the cephalic sensory system and nostrils of Argentine goatfish, Mullus argentinae Hubbs et Marini, 1933 (Perciformes: Mullidae), living along the southwestern Atlantic coast. The fish were collected at different latitudes, stretching from the State of Rio de Janeiro in the north, through Santa Catarina, Rio Grande do Sul (Brazil) to of Mar del Plata (Argentina) in the south. The prevalence of the infection ranged from 42% through 84%. The new species look alike to two other species, parasites of mullids (C. steenstrupi and C. mulli) particularly in the body shape and the number, shape, and ornamentation of cephalic, thoracic, and genital processes. The new species, however, can be readily distinguished by having the central cephalic process shorter than lateral ones, the later being bilobed at tip forked, and a relatively larger abdomen. Furthermore, C. steenstrupi possesses relatively wider trunk processes with rounded tips, a short abdominal dorsal process, and attains a larger size (up to 3.6 mm). C. mulli also differs by having all body processes with forked tips, and relatively shorter sixth thoracic somite and abdominal segments 1-3. This is the third record of a species of Colobomatus in South American Atlantic waters.
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http://dx.doi.org/10.2478/s11686-012-0032-7DOI Listing
September 2012

A new species of Neoascarophis (Nematoda: Cystidicolidae) parasitic in Macrourus carinatus (Macrouridae) from Argentinean waters.

J Parasitol 2012 Jun;98(3):643-7

Laboratorio de Parasitología, Instituto de Investigaciones Marinas y Costeras (IIMyC), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Funes 3350, (7600) Mar del Plata, Argentina.

Nematodes of the cystidicolid Neoascarophis Machida, 1976 , are all parasites of macrourid fishes, making up at present 5 species. Several other unidentified species have also been reported in several fish species from the northern and southern Atlantic Ocean, including 1 from Macrourus carinatus (Günther) (Macrouridae) in the southwest Atlantic Ocean. During a parasitological survey carried out on samples of M. carinatus from Patagonian waters, nematodes referable to Neascarophis were found in ulcers in the gastric mucosa. These nematodes Neascarophis sphaerocaudata n. sp. closely resemble N. macrouri by the posterior position of the vulva and the dilated posterior extremity in females. However, the new species differs from N. macrouri mainly by its larger size, a larger muscular esophagus, and a widely globose posterior extremity in females. SEM study of cephalic structures also showed morphological differences between both species, especially in the morphology of the submedian labia and lateral pseudolabia. In view of these differences a new species is proposed.
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http://dx.doi.org/10.1645/JP-GE-2947.1DOI Listing
June 2012

A new species of Neoascarophis (Nematoda: Cystidicolidae) parasitic in Mullus argentinae (Perciformes: Mullidae) from the Atlantic coast of South America.

Folia Parasitol (Praha) 2012 Feb;59(1):64-70

Curso de Pós-Graduação em Ciências Veterinárias and Departamento de Parasitologia Animal, Universidade Federal Rural do Rio de Janeiro, Caixa Postal 74.508, CEP 23851-970, Seropédica, RJ, Brasil.

A new nematode species (Neoascarophis mariae n. sp.) is described based on specimens collected from the Argentine goatfish Mullus argentinae (Hubbs et Marini) from coastal waters off the state of Rio de Janeiro, Brazil. In the genus, the new species belongs to the group of species with females that have the vulva near the posterior end of the body. Only males of Neoascarophis longispicula Moravec et Klimpel, 2009 are known and can be distinguished from those of the new species by their larger body, developed and somewhat dorsoventrally expanded flat inner part of the pseudolabia, bifurcate deirids and larger spicules (the left one with a rounded tip) with a different length ratio. Other species with females that have the vulva near the equatorial region are N. yarihige Machida, 1976 and N. bathygadi Machida, 1976. Both males and females of N. yarihige are longer than those of the new species and have a shorter vestibule; males have shorter spicules with a different length ratio. Neoascarophis bathygadi is the only member of the genus that shares the presence of a cephalic vesicle with the new species, which, however, is shorter and arises at 40 microm from the anterior end instead from the deirids, as in the new species. Both males and females of N. bathygadi are also longer than those of the new species and have a shorter vestibule; males have a larger left spicule, but shorter right spicule and a different length ratio. Ascarophis upeneichthys Johnston et Mawson, 1945, a parasite ofa mullid host, is transferred to Neoascarophis Machida, 1976 and is distinguished from the new species by having a shorter vestibule in females and shorter spicules (left spicule with a pointed tip) with a different length ratio in males.
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http://dx.doi.org/10.14411/fp.2012.010DOI Listing
February 2012

Geographical patterns of parasite infracommunities in the rough scad, Trachurus lathami Nichols, in the Southwestern Atlantic ocean.

J Parasitol 2012 Aug 23;98(4):768-77. Epub 2012 Feb 23.

Laboratorio de Parasitología, Instituto de Investigaciones Marinas y Costeras (IIMyC), FCEyN, Universidad Nacional de Mar del Plata-CONICET, Funes 3350, (7600) Mar del Plata, Argentina.

We assessed temporal variability in parasite infections of rough scad (Trachurus lathami) in 3 samples from Miramar (MI) in 2008, separated by periods of 1 mo, and 2 samples from Villa Gesell (VG), 1 each in 2008 and 2009 (Buenos Aires Province, Argentina), respectively. A sample was also obtained from Cabo Frio (CF) (Brazil) in 2009 to compare differences in parasite communities between fish from this locality and each Argentinean locality. All rough scad were parasitized by at least 1 of 27 parasite species. Similarity-based multivariate analysis revealed significant differences between localities, but temporal homogeneity in each Argentinean locality. Overall, prevalence and abundance of parasite species were most similar between samples from MI and VG, while the greatest differences occurred between samples from MI and CF. A canonical analysis of principal coordinates showed significant differences among samples. Grillotia carvajalregorum was the most important species in determining the position of Argentinean samples, especially those from MI, while Ectenurus virgulus , Raphidascaris sp., and Hysterothylacium sp. were the most important species related to fish from CF. The parasite assemblage of T. lathami showed a notable temporal persistence within the same locality and a high variability at the spatial scale, suggesting the existence of 3 independent stocks of T. lathami in South Atlantic waters.
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http://dx.doi.org/10.1645/GE-2950.1DOI Listing
August 2012

Patterns of trunk spine growth in two congeneric species of acanthocephalan: investment in attachment may differ between sexes and species.

Parasitology 2012 Jun 6;139(7):945-55. Epub 2012 Feb 6.

Cavanilles Institute of Biology and Evolutionary Biology, University of Valencia, Calle Catedrático José Beltrán 2, E-46980, Paterna, Valencia, Spain.

Acanthocephalans have evolved a hooked proboscis and some taxa have trunk spines to attach to their definitive hosts. These structures are generated before being used, thus a key question is how investment in attachment could optimally be allocated through the ontogeny. The number and arrangement of hooks and spines are never modified in the definitive host, but it is unclear whether these structures grow during adult development. A comparison of the size of trunk spines between cystacanths and adults of Corynosoma cetaceum and C. australe indicated that spines grow in both species, but only in females, which also had significantly larger spines than males. This sexual dimorphism did not result from pure allometry because the body of females was smaller, and did not grow more than that of males. However, having a longer lifespan, females would need to withstand the extreme flow conditions prevailing in marine mammals for longer, inducing different investment and development schedules for spines. Patterns of spine growth also differed between species: fore-trunk spines grew in both species, but hind-trunk spines did only in C. cetaceum. In conclusion, investment strategies on attachment may differ, not only between congeneric species of acanthocephalan, but also between sexes of the same species.
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http://dx.doi.org/10.1017/S0031182012000078DOI Listing
June 2012

Parasite communities in three sympatric flounder species (Pleuronectiformes: Paralichthyidae): similar ecological filters driving toward repeatable assemblages.

Parasitol Res 2012 Jun 14;110(6):2155-66. Epub 2011 Dec 14.

Laboratorio de Parasitología, Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, 7600, Mar del Plata, Argentina.

The relative role of host phylogeny and ecology on parasite community structure is analyzed in three sympatric paralichthyids from Argentine waters: the carcinophagous Xystreurys rasile and the piscivorous Paralichthys isosceles and P. patagonicus. Their relatedness, inherited ecological and physiological traits and shared past histories should result in certain similarities in their parasite assemblages. With this as our null hypothesis, we focused on the effects of measurable traits (size, age and diet) across fish species, with departures from a general pattern being interpreted as a consequence of ecological filters preventing homogeneous infections. The percentage of individuals/species that host-specific parasites contributed to each component community, as well as their effect on similarity of assemblages within/across host species, showed that they were not important contributors to abundance, richness and similarity, being irrelevant for the repeatability within component communities and across fish species as a phylogenetically related group. To minimize the effect of variables other than diet or trophic level only trophically transmitted nonspecific parasites were included in further analyses. After controlling for fish size, the congeneric host species harboured assemblages significantly different from those found in X. rasile, but were similar to each other because of their shared high trophic levels. Assemblages of equivalent structure harboured by fish with different age-size relationships showed that these variables seem to act at dissimilar rates on different features of the parasites assemblages. Indeed, age affected mainly the parasite abundance, whereas body size influenced mostly species richness. In conclusion, similar ecological filters produce analogous infections across host species driving towards homogeneous parasite communities.
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http://dx.doi.org/10.1007/s00436-011-2741-5DOI Listing
June 2012

Pauciconfibula patagonensis sp. nov. (Monogenea: Microcotylidae) parasitizing the horsefish, Congiopodus peruvianus (Pisces: Congiopodidae), from the Patagonian Shelf, Argentina.

Mem Inst Oswaldo Cruz 2011 May;106(3):335-8

Laboratorio de Parasitología, Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Mar del Plata, Argentina.

Pauciconfibula patagonensis sp. nov. (Monogenea: Microcotylidae), parasite of gill filaments of the horsefish, Congiopodus peruvianus (Congiopodidae) collected in the Patagonian Shelf, Argentina, is described and illustrated. The new species is characterized by having intestinal caeca not confluent and entering into the haptor, vitelline follicles extending from the genital pore to near the posterior portion of haptor, two parallel rows each comprised of 16-20 microcotylid clamps in the haptor, 25-43 testes and a fusiform egg with one very long tangled polar filament. P. patagonensis is the only member of the genus known to parasitize a scorpaeniform host and represents the first record of a representative of this genus in the southern Atlantic Ocean.
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http://dx.doi.org/10.1590/s0074-02762011000300013DOI Listing
May 2011

A new species of Heterosentis Van Cleave, 1931 (Acanthocephala, Arhythmacanthidae), a parasite of pinguipedid fishes in the southwest Atlantic.

J Parasitol 2011 Feb 22;97(1):111-5. Epub 2010 Sep 22.

Laboratorio de Parasitología, Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Funes 3350, 7600 Mar del Plata, Argentina.

A new species of arhythmacanthid acanthocephalan, Heterosentis martini n. sp., parasitic in the Argentinean sandperch Pseudopercis semifasciata (Cuvier) (Perciformes, Pinguipedidae) from the coasts of Argentina is described. Heterosentis martini n. sp. differs from all congeneric species by having 10 longitudinal rows of hooks in the proboscis, each with 7-8 hooks, consisting of 1 medium apical and 3 larger sub-apical hooks with root, and 3-4 smaller, basal, curved hooks with rudimentary roots and spines in both ventral and dorsal regions of the body. The most similar species, Heterosentis heteracanthus (Linstow, 1896) Van Cleave, 1931, and Heterosentis brasiliensis Vieira, Felizardo and Luque, 2009, also have 10 longitudinal rows of hooks, but H. heteracanthus differs from the new species by having only 3-5 (more frequently 4) hooks in each row, with only the anterior hook large and bearing a developed root. Heterosentis brasiliensis differs from the new species by possessing 2 sub-apical hooks in each row (instead of 3), similar body length but shorter proboscis, and trunk spines restricted to the ventral surface of body.
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http://dx.doi.org/10.1645/GE-2507.1DOI Listing
February 2011

Males of Ichthyofilaria argentinensis Incorvaia, 1999 and I. bergensis (Wülker, 1930) (Dracunculoidea:Guyanemidae): new morphological aspects and emendation of the generic diagnosis.

Folia Parasitol (Praha) 2010 Nov;57(4):289-94

Laboratorio de Parasitología, Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, Mar del Plata (7600), Argentina.

Abstract: The adult male of dracunculoid nematode Ichthyofilaria argentinensis Incorvaia, 1999 (Guyanemidae) is described for the first time based on specimens found in the swimbladder of its type host, Merluccius hubbsi Marini (Merlucciidae), caught off the coast of Buenos Aires, Argentina (western Atlantic Ocean). In addition, the males of Ichthyofilaria bergensis (Wülker, 1930) Køie, 1993 are redescribed from specimens collected from the body cavity and visceral surface of Molva macrophthalma (Rafinesque) (Lotidae) caught in the western Mediterranean Sea, off the coast of Sardinia. Light and scanning electron microscopy examinations revealed some new morphological features for the genus, such as a pair of deirids located near the end of muscular oesophagus, the body wall conspicuously twisted immediately anterior to the cloaca, the presence of a copulatory plate, one pair of adcloacal papillae and a pair of phasmids situated on the posterior half of the tail. On the basis of this material, the generic diagnosis of Ichthyofilaria is modified to include some of these newly observed features, as well as to indicate the absence of spicules. The diagnosis of Guyanemidae is extended to include that a copulatory plate and/or two spicules may be present as characteristics for this family.
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http://dx.doi.org/10.14411/fp.2010.035DOI Listing
November 2010

Seasonal stability in parasite assemblages of the Brazilian flathead, Percophis brasiliensis (Perciformes: Percophidae): predictable tools for stock identification.

Folia Parasitol (Praha) 2010 Sep;57(3):206-12

Laboratorio de Parasitologia, Departamento de Biologia, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, (7600) Mar del Plata, Argentina.

A comparison of the composition and structure of parasite communities of the Brazilian flathead, Percophis brasiliensis Quoy et Gaimard (Perciformes: Percophidae) among seasons during one year was carried out in the Argentine Sea. A total of 195 fish specimens were examined and 25 parasite species were found. Parasite communities in seasonal samples showed a high degree of homogeneity in taxonomic composition and infection levels. Similarity analysis showed that the seasonal stability within and between samples was constant in both the composition and community structure throughout the year. Parasites can, therefore, be considered predictable markers for fish stock identification, independently of the season of capture, at least on an annual scale.
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http://dx.doi.org/10.14411/fp.2010.027DOI Listing
September 2010

Host ontogeny and the temporal decay of similarity in parasite communities of marine fish.

Int J Parasitol 2010 Jul 24;40(8):963-8. Epub 2010 Feb 24.

Laboratorio de Parasitología, Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, 7600 Mar del Plata, Argentina.

Geographical distances between host populations are key determinants of how many parasite species they share. In principle, decay in similarity should also occur with increasing distance along any other dimension that characterizes some form of separation between communities. Here, we apply the biogeographical concept of distance decay in similarity to ontogenetic changes in the metazoan parasite communities of three species of marine fish from the Atlantic coast of South America. Using differences in body length between all possible pairs of size classes as measures of ontogenetic distances, we find that, using an index of similarity (Bray-Curtis) that takes into account the abundance of each parasite species, the similarity in parasite communities showed a very clear decay pattern; using an index (Jaccard) based on presence/absence of species only, we obtained slightly weaker but nevertheless similar patterns. As we predicted, the slope of the decay relationship was significantly steeper in the fish Cynoscion guatucupa, which goes through clear ontogenetic changes in diet and therefore in exposure to parasites, than in the other species, Engraulis anchoita and Micropogonias furnieri, which maintain a roughly similar diet throughout their lives. In addition, we found that for any given ontogenetic distance, i.e. for a given length difference between two size classes, the similarity in parasite communities was almost always higher if they were adult size classes, and almost always lower if they were juvenile size classes. This, combined with comparisons among individual fish within size classes, shows that parasite communities in juvenile fish are variable and subject to stochastic effects. We propose the distance decay approach as a rigorous and quantitative method to measure rates of community change as a function of host age, and for comparisons across host species to elucidate the role of host ecology in the development of parasite assemblages.
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http://dx.doi.org/10.1016/j.ijpara.2010.02.005DOI Listing
July 2010