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Neoheterobothrium chilense Gonzalez, Oliva & Acuna, 2002 is redescribed based on newly collected specimens from the type host, Hippoglossina macrops and type locality (Coquimbo, Northern Chile). Type specimens of Neoheterobothrium hippoglossini Piasecki, Wierzbicka & Kempter, 2000 and Choricotyle exilis Crane, 1972 are also redescribed. These three diclidophorid monogeneans infecting pleuronectiform flatfishes have pre-ovarian seminal receptacle, ootype inside the semicircle of ovary and elongated pharynx, differentiated from the most similar Orbocotyle Euzet & Suriano, 1975 in that members of the latter genus possess post-ovarian seminal receptacle, post-ovarian ootype and cylindrical or pyriform pharynx. Paraheterobothrium n. g. is proposed for P. chilense n. comb. (type), P. hippoglossini n. comb., P. exilis n. comb., P. papillosum n. comb. and P. syacii n. comb. A redescription of Neoheterobothrium affine (Linton, 1898), the type species of the genus, based on voucher specimens confirmed differences from the new genus in the presence of lamellate plate in the anterior jaw of clamps, absence of seminal receptacle and ovoid pharynx. The genus Neoheterobothrium was emended and N. cynoscioni (MacCallum, 1917) and N. mcdonaldi Payne, 1987 were removed from the genus. Neoheterobothrium now comprises N. affine (type), N. insulare Oliva & Luque, 1995, N. hirame Ogawa, 1999, and N. paralichthyi Suriano & Labriola, 1999, all of them parasites of flatfishes of the genus Paralichthys. Molecular analyses with the internal transcribed spacer 1 distinguished the clade for Paraheterobothrium spp. (P. chilense n. comb. and P. papillosum n. comb.) and Neoheterobothrium spp. (N. hirame, N. affine and N. paralichthyi), supporting this taxonomic emendation.

The Chilean jack mackerel Trachurus murphyi support an important fishery in the South-eastern Pacific Ocean and has declined considerably over time. T. murphyi have asynchronous ovarian development with an oceanic spawning (September to January). Despite the economic importance of this resource critical issue such as characteristics and dynamics of atresia, which affect the reproductive output, are unknown. Females of T. murphyi caught in different spawning seasons were analysed to describe patterns of prevalence and intensity of atresia. General linear models (GLM) were performed by using prevalence and intensity atresia as response variables and gonadosomatic index, condition factor, sea surface temperature, postovulatory follicles and month/year as explanatory variables. The batch fecundity and relative fecundity were compared between females showing atresia, postovulatory follicles and non-atretic females. The stages of atresia identified were alpha, beta and gamma. The GLM showed that variations in the prevalence and intensity of atresia were explained for all variables, except condition factor for prevalence, and gonadosomatic index for intensity of atresia. According to our results, the dynamic of alpha and beta atresia could be considered a potential proxy for any disruption of spawning season. The batch fecundity and relative fecundity were lowest compared with other Trachurus spp. This is the first assessment comparing fecundity between atretic and not atretic females for this species.

El Sistema de Afloramiento de la Corriente de Humboldt, definido como “a Large Marine Ecosystem”, se extiende a lo largo de la Costa Occidental de América del Sur, desde la zona Centro Sur de Chile (app. 42°S) hasta el Norte del Perú (4°S). Es uno de los mayores sistemas de afloramiento del mundo y responsable por los extraordinariamente altos niveles de producción. Es considerado un sistema clase 1, altamente productivo (>300 g·C/m2-año). Los altos valores de producción primaria de este sistema soportan las más grandes pesquerías a nivel mundial (Alheit & Bernal, 1993). Alrededor del 18-20% de las capturas mundiales provienen de este sistema, específicamente de pelágicos pequeños como anchoveta (Engraulis ringens Jenyns, 1842), sardina (Sardinops sagax (Jenyns, 1842)) y jurel (Trachurus murphyi Nichols, 1920). De un sistema de estas características deberá esperarse una alta diversidad biológica.

Eurythenes S.I. Smith in Scudder, 1882 (Crustacea: Amphipoda) are prevalent scavengers of the benthopelagic community from bathyal to hadal depths. While a well-studied genus, molecular systematic studies have uncovered cryptic speciation and multiple undescribed lineages. Here, we apply an integrative taxonomic approach and describe the tenth species, Eurythenes atacamensis sp. nov., based on specimens from the 2018 Atacamex and RV Sonne SO261 Expeditions to the southern sector of the Peru-Chile Trench, the Atacama Trench (24–⁠21°S). Eurythenes atacamensis sp. nov. is a large species, max. observed length 83.2 mm, possesses diagnostic features, including a short gnathopod 1 palm and a chelate gnathopod 2 palm, and a distinct genetic lineage based on a 16S rRNA and COI phylogeny. This species is a dominant bait-attending fauna with an extensive bathymetric range, spanning from 4974 to 8081 m. The RV Sonne SO261 specimens were recovered along a 10-station transect from abyssal to hadal depths and further examined for demographic and bathymetric-related patterns. Ontogenetic vertical stratification was evident across the trench axis, with only juveniles present at abyssal depths (4974–6025 m). Total length-depth analysis revealed that the size of females was unrelated to depth, whereas juveniles followed a sigmoidal relationship with a step-up in size at depths >7200 m. Thus, these bathymetric trends suggest that juveniles and females employ differing ecological strategies in subduction trench environments. This study highlights that even dominant and ecologically important species are still being discovered within the abyssal and hadal environments. Continued systematic expeditions will lead to an improved understanding of the eco-evolutionary drivers of speciation in the world’s largest ecosystem.

In the Southern Ocean, many parasites of vertebrates (mainly helminth groups) have been recognized as endemic species, but parasites of marine invertebrates remain almost unknown. It is reasonable to assume that digenean larvae will parasitize gastropods, bivalves, amphipods, and annelids, the usual first and second intermediate hosts for those parasites. Here, using an identification assisted by molecular markers, we report the Digenea species parasitizing the most abundant limpet species inhabiting ice-free rocky intertidal and subtidal zones of the Southern Ocean, viz. Nacella concinna from the Antarctic and Nacella deaurata from the Magellan region. The limpets harbored larval Digenea (two metacercariae and one sporocyst). Phylogenetic analysis based on the multilocus tree supported the hypothesis that N. concinna is parasitized by a species of Gymnophallidae, whereas the limpet N. deaurata is parasitized by Gymnophalloides nacellae and a species of Renicolidae. In addition, differences in prevalence and intensity were also recorded between the two compared host species and also from other congeneric species. This new knowledge in parasite species in marine invertebrates from the Southern Ocean reveals the presence of a particular parasite fauna and confirms the utility of molecular tools to identify biodiversity still scarcely known.

espanolIntroduccion: El virus de inmunodeficiencia humana (VIH) es uno de los problemas de salud mas importante en el mundo. Entre los organos mas afectados en pacientes VIH positivos es la piel, en la cual se pueden observar las primeras manifestaciones de la enfermedad o evolucion de la misma. Objetivos: Determinar las manifestaciones dermatologicas en pacientes con VIH/SIDA acorde a la cuantificacion de CD4 y carga viral; identificar las dermatosis mas frecuentes de acuerdo a la identidad sexual y su correlacion estadistica. Metodo: Diseno epidemiologico analitico retrospectivo. Se revisaron 1,186 historias clinicas, de las cuales 422 presentaron manifestaciones con un total de 544 dermatosis. Resultados: Existe al menos una enfermedad dermatologica en 422 de 1,186 pacientes. La proporcion de pacientes con identidad sexual heterosexual fue el de mayor presencia de dermatosis (n = 287). La prevalencia de manifestaciones infecciosas es predominante en todos los grupos de identidad sexual, pero no muestra relacion estadisticamente significativa (p = 0.61). Las dermatosis que predominaron son de origen infeccioso (n = 332). Conclusiones: Se demostro una relacion estadisticamente significativa entre la prevalencia de dermatosis y el conteo de linfocitos TCD4; por el contrario, la relacion entre la carga viral y las manifestaciones dermatologicas no fue significativa. No se evidencio una relacion estadistica entre las manifestaciones dermatologicas y la identificacion sexual de los pacientes. EnglishIntroduction: The human immunodeficiency virus (HIV) is one of the most important health problems in the world. Among the most affected organs in patients with HIV is the skin, in which the first manifestations of the disease or its evolution can be observed. Objectives: To determine the dermatological manifestations in patients with HIV/ AIDS according to the quantification of CD4 and viral load; identify the most frequent dermatoses according to sexual identity and its statistical correlation. Method: Retrospective analytical epidemiological design. We reviewed 1,186 clinical records, of which 422 presented manifestations with a total of 544 dermatoses. Results: Our results reveal at least one dermatological disease in 422 of 1,186 patients. The proportion of patients with heterosexual sexual identity was the highest presence of dermatosis (n = 287). The prevalence of infectious manifestations is predominant in all sexual identity groups, but it does not show a statistically significant relationship (p = 0.61). The predominant dermatoses are of infectious origin (n = 332). Conclusions: A statistically significant relationship was found between the prevalence of dermatosis and the TCD4 lymphocyte count; on the contrary, the relationship between viral load and dermatological manifestations was not statistically significant. There was no statistical relationship between the dermatological manifestations and the sexual identification of the patients.

Natural Killer (NK) cells are among the first effectors to directly contact influenza and influenza-infected cells and their activation affects not only their intrinsic functions, but also subsequent CD8+ T cell responses. We utilized a NK cell depletion model to interrogate the contribution of NK cells to the development of anti-influenza CD8+ T cell memory. NK cell ablation increased the number of influenza-specific memory CD8+ T cells in the respiratory tract and lung-draining lymph node. Interestingly, animals depleted of NK cells during primary influenza infection were protected as well as their NK-intact counterparts despite significantly fewer reactivated CD8+ T cells infiltrating the respiratory tract after lethal, heterosubtypic challenge. Instead, protection in NK-deficient animals seems to be conferred by rapid reactivation of an enlarged pool of lung tissue-resident (TRM) memory cells within two days post challenge. Further interrogation of how NK cell ablation enhances respiratory TRM indicated that TRM development is independent of global and NK cell derived IFN-γ. These data suggest that reduction in NK cell activation after vaccination with live, non-lethal influenza virus increases compartmentalized, broadly protective memory CD8+ T cell generation and decreases the risk of CD8+ T cell-mediated pathology following subsequent influenza infections.

espanolAntecedentes: Las enfermedades de transmision sexual (ETS) son un conjunto de enfermedades infecciosas que se transmiten a traves de relaciones sexuales. Las ETS y el VIH mantienen una estrecha relacion; la infeccion por VIH incrementa la probabilidad de contraer una ETS y viceversa. Objetivos: Determinar las prevalencias de las enfermedades de transmision sexual en pacientes con VIH/sida acorde a la identidad sexual, cuantificacion de CD4 y su correlacion estadistica; e identificar la relacion entre las enfermedades de transmision sexual y el contacto con trabajadores sexuales en pacientes con VIH. Materiales y metodos: Estudio epidemiologico analitico retrospectivo en el cual se analizaron todas las historias clinicas de los pacientes positivos a VIH (n = 1,186), de los cuales 164 tuvieron ETS. Resultados: De 1,186 pacientes con VIH, 164 mostraron ETS y la sifilis tuvo la mayor prevalencia en todos los grupos de identidad sexual, sobre todo en hombres que tienen sexo con hombres (HSH). El mayor numero de casos de ETS se observo en el grupo con un conteo de CD4 de 200 a 500 cel/μL, con una relacion estadisticamente significativa. De los pacientes que tuvieron una o mas ETS, 53 indicaron relaciones con trabajadores sexuales y 111 pacientes lo negaron, sin relacion estadisticamente significativa. Conclusiones: Los hombres que tienen sexo con hombres poseen la mayor cantidad de ETS, tal vez debido al mayor riesgo relacionado con las relaciones sexuales anogenitales; se observo que las verrugas anogenitales podian ocurrir con un recuento normal de CD4, en concordancia con otros estudios; la gonorrea se encuentra con cifras elevadas de CD4, pero la prevalencia de casos es insuficiente para evidenciar una generalizacion significativa. EnglishBackground: Sexually transmitted diseases (STDs) are a group of infectious diseases that are transmitted through sexual intercourse. STDs and HIV affect a close relationship, HIV infection increases the probability of contracting an STD and vice versa. Objectives: To determine the prevalence of sexually transmitted diseases in HIV / AIDS patients according to sexual identity, quantification of CD4 and its statistical correlation; identify the relationship between sexually transmitted diseases and contact with sex workers in HIV patients. Materials and methods: Retrospective analytical epidemiological study in the analysis of all the medical records of HIV positive patients (n = 1186), of the analyzes (n = 164) STDs. Results: Of 1186 HIV patients, 164 STD patients, the syphilis being the most prevalent in all sexual identity groups, mainly in men who have sex with men (MSM). The highest number of STD cases was identified in the group with a CD4 content of 200-500 cel / μL, showing a statistically significant relationship. Of the patients considering an STD or more, 53 reported having had relationships with sex workers and 111 patients who denied, with no statistically significant relationship Conclusions: Men who have sex with men have the highest amount of STDs, possibly due to the higher risk associated with anogenital sexual relations; Anogenital warts were found to have a normal CD4 count, consistent with other studies; Gonorrhea is found with high levels of CD4, however, the prevalence of cases is decreased to show significant generalization.

BackgroundCurrently, 24 species of Encotyllabe Diesing, 1850 (Monogenea: Capsalidae) are listed in WoRMS, but the validity of many species has been questioned due to deficient or incomplete descriptions. On the other hand, almost all species in the genus have been described from one host species or closely related host species, suggesting host specificity, but other species, specifically Encotyllabe spari Yamaguti, 1934, have been reported at least from 19 species belonging to nine families in two orders (Perciformes and Scorpaeniformes) from Japan, the Arabian Gulf and Brazil. Concerning Brazilian records of Encotyllabe spari (but also as Encotyllabe cf. spari); seven host species belonging to four families and two orders have been reported as hosts for this species. The aim of this study was to describe two new species of Encotyllabe from Brazil, previously considered as E. spari.MethodsDuring 2016, we examined specimens of Orthophristis ruber (Cuvier) (Haemulidae) and Pagrus pagrus (Linnaeus) (Sparidae) caught off the coast of Cabo Frio, Rio de Janeiro, Brazil by local fishermen. Specimens of Encotyllabe were collected from the pharyngeal plates of the hosts. Morphological and morphometric (multivariate analysis of proportional measurements standardized by total length) and molecular analysis (LSU rRNA and cox1 gene) were performed in order to identify the collected monogenea. ResultsThe presence of two new species of Encotyllabe, Encotyllabe yamagutii n. sp. and Encotyllabe haemuli n. sp., parasitizing the pharyngeal plates of Pagrus pagrus and Orthopristis ruber, respectively, is strongly suggested by the three approaches used in this study. The main morphological differences from the most related species include a combination of body size, shape of the penis, and size and position of the testes.ConclusionsSpecimens of Encotyllabe, hitherto recorded as E. spari or E. cf. spari, belong to two new species. Our results suggest that the host specificity for members of Encotyllabe and specimens registered as E. spari, other than those from the original description, must be revisited.

International audience; In recent years, numerous studies conducted on teleost fish have highlighted the contribution of transcriptomic studies in elucidating the physiological mechanisms underlying the molecular events of oogenesis and follicular atresia, enabling the identification of potential genes and molecular networks that participate in both the reproductive cycle and the process of follicular atresia. Atresia can affect the reproductive potential of females by reducing the healthy eggs that a female can spawn in both aquaculture and wild populations. The substantial diversity of reproductive strategies exhibited by teleost fish has contributed to the difficulty in identifying common genes between species, but a set of core genes has emerged as potential markers for atresia in relation to apoptosis/autophagy, lipid metabolism, oxidative metabolism and other physiological processes similar to those identified in other vertebrates, even mammals. We review the current status of the genes that have been identified in ovaries with atretic oocytes. Our primary goal is to review the current status regarding gene expression during gonadal development and follicular atresia. This information will enable us to understand the factors and expression patterns involved in the follicular atresia of teleost fish.

The Humboldt Current Large Marine Ecosystem (HCLME) is recognised as one of the largest and most productive marine ecosystems. The estimated number of teleost fish species for the Chilean coast influenced by the HCLME reaches c.1,030 but digeneans have been reported for 39 teleost species, i.e. less than 4% of the potential hosts. During a survey of parasites of the Galapagos sheephead wrasse Semicossyphus darwini (Jennyns) (Perciformes: Labridae) from off northern Chile, we obtained representatives of three digenean species, Helicometrina nimia Linton, 1910 (Opecoelidae), Proctoeces humboldti George-Nascimento & Quiroga, 1983 (Fellodistomidae) and Labrifer secundus Manter, 1940 (Lepidapedidae). Labrifer secundus, originally described from Semicossyphus pulcher (Ayres, 1854) off the coast of Baja California, Mexico is re-described. Helicometrina nimia is a common parasite from littoral fishes in the HCLME. Semicossyphus darwini is a new host for these three digenean species.

Little is known about the diversity of parasites of the deep-sea fish of the world's oceans. Here, a new species of monogenean parasite of the deep-sea skate Gurgesiella furvescens is described. Specimens of parasites were obtained from the skin of two specimens of the dusky finless skate, G. furvescens (Rajidae), in the vicinity of Valparaiso (33°S, 72°W), central Chile, from midwater trawl fishing at depths of 350–450 m. Both morphological and molecular analyses were conducted to provide a full description of the new species, named Acanthocotyle gurgesiella. For the molecular analyses, nuclear large subunit (LSU) rDNA and the mitochondrial gene cytochrome c oxidase 1 (COI) were used. From the morphological analysis and a comparison with the known species of the genus, A. gurgesiella can be identified by a combination of morphological characteristics, including the number of testes, number of radial rows of sclerites in the pseudohaptor, aperture of the genital pore and shape of the vitelline follicles. The results from the DNA analysis indicated that A. gurgesiella has a genetic divergence of 3.2–3.7% (LSU rDNA gene) from A. urolophi, the only congener species for which molecular data are available.

The horse mackerels of the genus Trachurus (Pisces: Carangidae) are commercially important pelagic fish resources worldwide. There have been several studies of the parasites infecting fishes of this genus, the first one concerning the occurrence of the coccidian Goussia cruciata Thelohan, 1892. Horse mackerels have been targeted in recent projects, in a number of countries that exploit this fish resource (Argentina, Chile, European and Mediterranean countries, North America), with a view of using parasites to define population structure, in conjunction with other methods and techniques, to achieve a better understanding of fish stocks and to minimize risks of localized extinctions. However, information on the occurrence of parasites in this fish genus is scattered through a substantial number of scientific journals, some of them of difficult access. The present review aims to compile the up-to-date knowledge on the occurrence of parasites of horse mackerels, from protozoans to metazoans, their dis...

The South American subcontinent supports one of the world's most diverse and commercially very important ichthyofauna. In this context, the study of South American fish parasites is of increased relevance in understanding their key roles in ecosystems, regulating the abundance or density of host populations, stabilizing food webs and structuring host communities. It is hard to estimate the number of fish parasites in South America. The number of fish species studied for parasites is still low (less than 10%), although the total number of host-parasite associations (HPAs) found in the present study was 3971. Monogeneans, with 835 species (1123 HPAs, 28.5%), and trematodes, with 662 species (1127 HPAs, 30.9%), are the more diverse groups. Data gathered from the literature are useful to roughly estimate species richness of helminths from South American fish, even though there are some associated problems: the reliability of information depends on accurate species identification; the lack of knowledge about life cycles; the increasing number of discoveries of cryptic species and the geographically biased number of studies. Therefore, the closest true estimations of species diversity and distribution will rely on further studies combining both molecular and morphological approaches with ecological data such as host specificity, geographical distribution and life-cycle data. Research on biodiversity of fish parasites in South America is influenced by problems such as funding, taxonomic impediments and dispersion of research groups. Increasing collaboration, interchange and research networks in the context of globalization will enable a promising future for fish parasitology in South America. Fil: Luque, Jose Luis. Universidade Federal Rural do Rio de Janeiro; Brasil Fil: Pereira, F. B.. Universidade Federal Rural do Rio de Janeiro; Brasil Fil: Alves, P. V.. Universidade Federal Rural do Rio de Janeiro; Brasil Fil: Oliva, M. E.. Universidad de Antofagasta; Chile. Universidad de Concepción; Chile Fil: Timi, Juan Tomas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

Background Parasites of deep-sea fishes from the South-East Pacific (SPO) are poorly known. Of c.1030 species of fish found in this area, 100–150 inhabit the deep-sea (deeper than 200 m). Only six articles concerning metazoan parasites of fish from deep-waters of SOP are known, and nine monogenean species have been reported. Currently, ten species are known in Acanthocotyle Monticelli, 1888 (Monogenea) and when stated, all of them are found in shallow waters (10–100 m). Acanthocotyle gurgesiella Ñacari, Sepulveda, Escribano & Oliva, 2018 is the only known species parasitizing deep-sea skates (350–450 m) in the SPO. The aim of this study was the description of two new species of Acanthocotyle from two Rajiformes. Methods In September 2017, we examined specimens of two species of deep-sea skates (Rajiformes), Amblyraja frerichsi (Krefft) and Bathyraja peruana McEachran & Myyake, caught at c.1500 m depth off Tocopilla, northern Chile, as a by-catch of the Patagonian tooth fish Dissostichus eleginoides Smitt fishery. Specimens of Acanthocotyle were collected from the skin of the skates. Morphometric (including multivariate analysis of proportional measurements, standardized by total length), morphological and molecular analyses (LSU rRNA and cox1 genes) were performed in order to identify the collected specimens. Results The three approaches used in this study strongly suggest the presence of two new species in the genus Acanthocotyle: Acanthocotyle imo n. sp. and Acanthocotyle atacamensis n. sp. parasitizing the skin of the thickbody skate Amblyraja frerichsi and the Peruvian skate Bathyraja peruana, respectively. The main morphological differences from the closely related species Acanthocotyle verrilli Goto, 1899 include the number of radial rows of sclerites, the non-discrete vitelline follicles and the number of testes. Conclusions The two species of monogeneans described here are the only recorded parasites from their respective host species in the SPO. Assessing host specificity for members of Acanthocotyle requires clarifying the systematics of Rajiformes.

Parasite communities are similar to free-living communities; decay of similarity over geographic distance, theory of island biogeography, species-area relationships and nestedness have been documented in both communities. Ecological succession has been studied in free-living communities but has rarely been examined in parasite communities. We use seriation with replication to test the hypothesis that succession of parasite community structure is deterministic, thus developing throughout consecutive changes along the fish ontogeny, via a seriated pattern. 12 306 marine fishes (95 species) were studied. In 40 species, a seriated pattern was detected; 25 had a tendency towards a seriated pattern, and for 31 species, succession was at random. Age-classes for each host species explained deterministic successional patterns for whole parasite communities and ectoparasites. Richness and number of age-classes explained this pattern for endoparasites. Seriated successional pattern was evident for parasite communities of long-lived marine fish, indicating that parasite communities follow sequential changes over time, like many free-living communities.

We studied the parasite fauna of five deep-sea fish species (>1000 m depth), Three members of Macrouridae ( Macrourus holotrachys , Coryphaenoides ariommus and Coelorhynchus sp.), the Morid Antimora rostrata and the Synaphobranchidae Diaptobranchus capensis caught as by-catch of the Patagonian toothfish ( Dissostichus eleginoides ) from central and northern Chile at depths between 1000 and 2000 m. The parasite fauna of M. holotrachys was the most diverse, with 32 species (The higher reported for Macrourus spp.) and the lower occur in the basketwork eel D. capensis (one species). Trophically transmitted parasites, mainly Digenea and Nematoda explain 59.1% of the total number of species obtained (44 species) and the 81.1% of the 1020 specimens collected. Similarity analysis based on prevalence as well as a Correspondence analysis shows that higher similitude in parasite fauna occurs in members of Macrouridae. The importance of diet and phylogeny is discussed as forces behind the characteristics of the endoparasite and ectoparasite communities found in the studied fish species.

The metazoan parasites of 403 specimens of the southern ray's bream Brama australis from three localities in southern Chile (Lebu 36° 70' S; 73° 40' W, Calbuco 41° 50' S; 73° 08' W and Punta Arenas 53° 10' S; 70° 50' W) were recorded. More than 23 400 parasite specimens belonging to 12 taxa were registered. Metazoan parasites were dominated by the copepod Hatschekia conifera, constituting 97% of the total number of parasites; the larval cestode Hepatoxylon trichiuri was the second most important parasite (2·1% of the total number of parasites). The remaining 10 species constituted

We describe Calicotyle hydrolagi n. sp. (Monogenea: Monocotylidae) infecting the cloaca of deep-water Eastern Pacific black ghost sharks, Hydrolagus melanophasma captured as bycatch at a local fishery for Patagonian toothfish Dissostichus eleginoides, (Nototheniidae) in the Atacama Trench using morphological and nucleotide (LSU rRNA and SSU rRNA) data. This new species is differentiated from its congeners by a number of characters, including the absence of a cecal diverticula, the size and shape of the male copulatory organ and the shape of the vagina, as well as by differences in molecular data (SSU rRNA and LSU rRNA). The suitability of some sclerotized structures such as the male copulatory organ (MCO) as a taxonomic character is discussed; specifically, we found that the relationship between MCO and total length exhibit different trends in members of Calicotyle isolated from sharks, skates and chimaeras. Additional efforts to obtain sample of Calicotyle species and further molecular studies based on ribosomal and mitochondrial genes are necessary to clarify the degree of host specificity in this genus. Additionally, this is the first report of a member of Calicotyle to be reported in the Southeastern Pacific Ocean.

Recent studies have demonstrated that the oviductal environment plays an active role in modulating the epigenetic marks of the preimplantation embryo genome, but the molecular factors that mediate this epigenetic effect are unknown. Folate is a well-known epi-nutrient that can impact on cell epigenetic machinery during embryonic and fetal development. However, the study of this epi-nutrient in the oviduct is still limited. The present study was conducted to confirm the presence and physiological concentration of folate in bovine oviductal fluid (OF) and to determine if bovine oviduct epithelial cells (BOECs) are able to regulate the uptake of this micronutrient. Samples of OF from ipsi- and contralateral oviducts were collected at different stages of the estrous cycle and folate levels were determined using a competitive receptor binding immunoassay. In addition, gene expression of folate receptors (FOLR1, FOLR2) and transporters (SLC19A1, SLC46A1) were analyzed in BOECs from ampulla and isthmus regions during different stages of the estrous cycle using RT-qPCR. In vitro culture assays were also performed to evaluate whether expression of these genes responds to hormonal stimulation. Our results demonstrated presence of folate in the OF, showing changes of its concentration in the ipsilateral oviduct during the estrous cycle and significantly lower levels at the postovulatory stage. Moreover, gene expression of folate receptors and transporters was detected in BOECs, showing regional and cycle-dependent changes. In particular, differential expression of FOLR1 mRNA was observed in BOECs from the isthmus region, reaching significantly higher levels during the postovulatory stage. Under in vitro culture conditions, gene expression of folate receptors and transporters was maintained in BOEC explants and a particular susceptibility to steroid hormone stimulation was observed. In conclusion, the present study confirms the presence of folate in the bovine oviduct and proves the existence of a fine-tuned regulation of the expression of its receptors and transporters, highlighting the importance to expand the knowledge about this epi-nutrient in the oviductal context. Fil: García, Elina V.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán; Argentina Fil: Oliva, María E.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina Fil: Leblanc, Jean Guy Joseph. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina Fil: Barrera, Antonio Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina

Parapedocotylinae, a new subfamily, is proposed to accommodate the gen. n. et sp. n. Parapedocotyle prolatili (Monogenea: Diclidophoridae), a gill parasite of the Pacific sandperch, Prolatilus jugularis (Valenciennes) (Pinguipedidae) from northern Chile (30 degrees 56'S; 71 degrees 20'W). Among the Diclidophoridae Cerfontaine, 1895, the species of the Pedocotylinae Yamaguti, 1963 are unique by bearing the first pair of clamps (most posteriorly) in a haptoral projection. Pedocotyle MacCallum, 1913, the only genus in the Pedocotylinae, is characterised by the first pair of clamps non-pedunculate, modified and non-functional, without accessory suckers, and clamps of pairs 2-4 being pedunculate and functional. In contrast, the first pair of clamps in Parapedocotyle is well developed and functional at the terminal end of a long haptoral appendix and having clamp pairs 2-4 pedunculated, modified and apparently not functional. Seminal receptacle is preovarian in Parapedocotyle in opposition to its postovarian position in Pedocotyle. These differences justified the erection of the new subfamily Parapedocotylinae. The new subfamily is also supported by genetic analyses (18S rDNA, 28S rDNA and cox1 sequences) demonstrating that the Pedocotylinae and Parapedocotylinae belong to different clades in the Diclidophoridae.

The most studied digenean of marine organisms in Chile is by far Proctoeces humboldti , a parasite of the intestine of the clingfish Sicyases sanguineus and gonad of the keyhole limpet Fissurella spp. (progenetic metacercariae). The mussel Perumytilus purpuratus has been suggested as the first intermediate host for this digenean. In a study examining the parasites of S . sanguineus from central Chile, we found specimens of Proctoeces showing significant morphological differences with P . humboldti . To assist in the resolution of the taxonomic identification of these specimens, as well sporocysts obtained from the mussel P . purpuratus from central and northern Chile, phylogenetic studies using DNA sequences from the SSU rRNA, as well the LSU rRNA and Cox 1 gene were performed. Results showed that the clingfish S . sanguineus is a host for two species of Proctoeces ( P . humboldti and P . syciases n. sp.) along the northern and central Chilean coast, without geographic separation; the mussel P . purpuratus is the first intermediate host for P . syciases n. sp. but not for P . humboldti in central and northern Chile. Fissurellids (Archaeogastropoda) along the Chilean coast harbor only progenetic stages of P . humboldti , but there is no evidence of progenesis for P . syciases . The reinstatement of Proctoeces humboldti is strongly suggested.

SUMMARYResearch using parasites in fish population studies in the South Eastern Pacific (SEP) is summarized. There are 27 such studies (snapshots mainly) in single host species sampled at different geographic localities and at somewhat similar times. They have been devoted mainly to economically important species, though others on coastal and intertidal fish or on less- or non-commercial species provide insights on scales of temporal and spatial variation of parasite infracommunities. Later, we assess whether the probability of harbouring parasites depends on the host species body size. Our results indicate that a stronger tool for fish population studies may be developed under regular (long term) scrutiny of parasite communities, especially of small fish host species, due to their larger variability in richness, abundance and total biomass, than in large fish species. Finally, it might also be necessary to consider the effects of fishing on parasite communities as well as the natural oscillations (coupled or not) of host and parasite populations.

Two new species, Encotyllabe cheilodactyli and Encotyllabe antofagastensis (Monogenea: Capsalidae), have been found in the pharyngeal plates of Cheilodactylus variegatus and Anisotremus scapularis, respectively, in northern Chile (23°38′N, 70°24′W). Descriptions of the new species were based on morphometric and molecular evidence. Both species differ from previously described species of the genus by a combination of characteristics, including the size and relative position of the testes and the shapes of the major and small hamulus. In addition, E. cheilodactyli is unique among the known species of Encotyllabe due to the testes crossing the equatorial line of the body proper, and E. antofagastensis is unique among the known species of Encotyllabe due to its penis structure and anatomy leading to the genital pore. The analysis of the cytochrome c oxidase I gene as well as morphometric analyses demonstrated that the specimens belonged to 2 different species.

The absence of the larval Anisakis simplex s. l . in samples from central Chile but heavy infections in fish from southern localities suggest the existence of two stocks of Strangomera bentincki , one closely associated with the central coast of Chile (landing port San Antonio and Talcahuano, c. 33 ◦ 30 � S–36 ◦ 40 � S) and the other associated with southern Chile (landing port Puerto Montt, c. 41 ◦ 30 � S). Results confirm the usefulness of metazoan parasites, like A. simplex s. l . as biological markers.

Limatula chilensis sp. nov. is described on the basis of shell morphology and soft tissue anatomy. Studied individuals were obtained periodically between June 2008 and January 2009 from sublittoral soft-sediments off Punta Coloso in northern Chile at depths of 22 to 33 m. Shell morphology of the new species differs from the 4 described species of Limatula from the Pacific coast of South America and Antarctic Peninsula (5°-65°S). Main characteristics of L. chilensis include an average height of 3.50 mm (range 2.36-4.42, SD ± 0.60, n = 34), number of radial ribs 16-21 (mode = 20, SD= 1.69, n = 8) and greater shell obliqueness. L. chilensis is the only known species of the genus found off northern Chile.

Lopez-Escribano H, Parera MM, Guix P, Serra JM, Gutierrez A, Balsells D, Oliva-Berini E, Castro JA, Ramon MM, Picornell A. Balearic archipelago: three islands, three beta-thalassemia population patterns. The mutation spectrum of 175 β-thalassemia (β-thal) carriers, identified in pilot carrier screening on 22,713 individuals from Balearic Islands (Spain), is reported. The β0 CD39 (C>T) mutation is the most frequent (61.1%), followed by β+ IVS-I-110 (G>A) (12.0%), β+ IVS-I-6 (T>C) and β0 IVS-1-1 (G>A) (3.4% both) and eight other rare mutations (2.9–0.6%); with a distinct prevalence and distribution between islands. Minorca shows the highest prevalence in Iberian populations, with a single mutation, CD39 (C>T), present in most β-thal carriers. Ibiza is the only Western Mediterranean population where the most frequent β-thal mutation is IVS-I-110 (G>A). These results can be explained by a combination of historical–demographic characteristics together with evolutionary forces such as founder effect, genetic drift and probably selection by malaria. Knowledge of the mutational spectrum in the Balearic Islands will enable to optimize mutation detection strategy for genetic diagnosis of β-thal in these islands.

Early macrobenthos succession in small, disturbed patches on subtidal soft bottoms is facilitated by the arrival of post-larval colonizers, in particular by active and passive dispersers along the seafloor or through the water column. Using a field experiment at two contrasting sites (protected vs. exposed to wave action), we evaluated the role of (a) active and passive dispersal through the water column and (b) the influence of small-scale spatial variability during succession of subtidal macrobenthic communities in northern Chile. Containers of two sizes (surface area: small—0.12 m2 and large—0.28 m2) at two positions above the natural substratum (height: low—3 cm and high—26 cm) were filled with defaunated sediment, installed at two sandy sublittoral sites (7–9 m water depth) and sampled after 7, 15, 30, 60 and 90 days, together with the natural bottom sediment. The experiment took place during austral fall (from late March to early July 2010), when both larval and post-larval stages are abundant. At the exposed site, early succession was driven by similar proportions of active and passive dispersers. A sequence from early, late and reference communities was also evident, but container position and size affected the proportional abundance of dispersal types. At the protected site, the successional process started with abundant colonization of active dispersers, but toward the end of the experiment, the proportion of swimmer/crawlers increased, thus resembling the dispersal types found in the natural community. At this site, the position above the sediment affected the proportional abundance of dispersal types, but patch size had no effect. This study highlights that macrobenthic post-larvae can reach at least 26 cm high above the bottom (actively or passively, depending on site exposure), thus playing an important role during early succession of sublittoral soft bottoms. The active or passive use of the sediment–water interphase may also play an important role in the connectivity of benthic populations and in the recovery after large-scale disturbances of sublittoral habitats.

Amphioxi represent the evolutionary link between vertebrates and invertebrates. For this reason, research dealing with these animals has been focused mainly on embryological and anatomical studies. Out of 30 described species, only one, Branchiostoma elongatum, is known to inhabit shallow sandy bottoms along the Humboldt Current System (HCS) of Chile and Peru. The population dynamics of B. elongatum from northern Chile was studied between February 2008 and January 2009, and the results were compared with other species within the genus Branchiostoma inhabiting distinct ecosystems. Mean abundance of B. elongatum was low (158.6 ind m−2) in comparison with the abundance of other species within Branchiostoma. Although the gametogenic activity was continuous, a clear spawning event was observed between August and October, which seemingly produced a recruitment pulse during the summer and consequently a simultaneous increase in population density and decrease of mean length during that period. Growth of B. elongatum was best fitted to the seasonalized von Bertalanffy growth function (K = 0.45 year−1 and L∞ = 64.6 mm), with faster growth during summer–autumn. Growth performance (Ф′ = 3.273) was high in comparison with other species within the genus. Mortality of B. elongatum (Z = 1.075 year−1) was well fitted to the single exponential model (r2 = 0.92). The annual total production of B. elongatum reached 0.68 g ash-free dry mass (AFDM) m−2 and the annual mean biomass was 0.56 g AFDM m−2, which determined a production to biomass ratio of 1.22. The huge productivity of the HCS was not reflected in a high abundance and biomass of B. elongatum. However, this species displayed a high growth efficiency and P/B ratio that are comparable to those of other Branchiostoma inhabiting highly productive ecosystems.

Riascos, J. M., Heilmayer, O., Oliva, M. E., and Laudien, J. 2011. Environmental stress and parasitism as drivers of population dynamics of Mesodesma donacium at its northern biogeographic range. – ICES Journal of Marine Science, 68: 823–833. Mesodesma donacium is a commercially important bivalve in Chile and Peru. During strong El Niño events, populations at the northern end of its geographic distribution are wiped out, so to understand its threshold responses to biotic and abiotic factors, the population dynamics of one of the northernmost population remnants was analysed between 2005 and 2007. Strong interannual differences were found in abundance, body mass, growth rate, somatic production, and the prevalence of the parasite Polydora bioccipitalis. A Spearman rank correlation analysis showed that changes in beach slope, seemingly linked to repeated storm surges, negatively affected the clam's abundance and seemingly also affected growth, mortality, body mass somatic production, and parasite prevalence. Infestation by P. bioccipitalis was restricted to adult clams. Juvenile clams suffered high mortality because they inhabit the intertidal zone, where wave action is strong. Larger clams also showed high mortality, which seemed best explained by a synergistic effect of parasite load and environmental stress. This parasite-climate-driven mortality of larger clams had a strong impact on somatic production and implied a dramatic loss of fecundity (82%), which may significantly affect the ability of the species to recover its former abundance and distribution.

The aims of the present study were to compare, using multivariate analyses, the degree of similarity of the endoparasite fauna of five fish species belonging to the order Gadiformes: Merluccius gayi, Merluccius australis, Macruronus magellanicus (Gadoidei) and Micromesistius australis and Nezumia pulchella (Macrouroidei), from the southern and central Chilean coast, and to evaluate whether the composition of the endoparasite fauna was determined by phylogenetic or ecological relationships. We employed our database of Merluccius australis, M. magellanicus and Micromesistius australis, which was complemented with published information for M. magellanicus, Merluccius australis, Micromesistius australis, M. gayi and N. pulchella. A higher number of endoparasite species was recorded for Merluccius australis, Micromesistius australis and M. magellanicus, namely Anisakis sp. and Hepatoxylon trichiuri, which is the most prevalent parasite among these hosts. Aporocotyle wilhelmi and Hysterothylacium sp. were detected only in M. gayi, whereas Lepidapedon sp. was found exclusively in N. pulchella. These results suggest that fish ecology rather than host phylogeny was the most important factor for the determination of similarity in parasite composition. This result could be explained by the similar trophic patterns of hosts and by the predominance of generalist larval species among these fish parasite communities.

Benthic communities show changes in com- position and structure across different environmental characteristics and habitats. However, incorporating spe- cies biological traits into the analysis can provide a better understanding of system functioning within habitats. We compare the functional diversity of macrobenthic com- munities from a contrasting shallow (15 m) and deep (50 m) sublittoral soft-sediment habitats in northern Chile, using biological traits analysis. Our aim was to highlight the biological characteristics responsible for differences between habitats and the implications for ecosystem functioning. Trait analysis showed that the deep habitat was restricted in providing functionally important biogenic structure and bioturbation and supports less diverse feed- ing-related energy pathways. The shallow habitat is char- acterized by more diverse energy pathways and a higher potential for matter exchange through bioturbation. We provide support to the predictions of transfer of energy from the benthos to upper trophic levels in the shallow, which is characterized mainly by normoxia and little organic matter content in the sediment. In the deep habitat, characterized by hypoxia and more organic matter, energy appears to be transferred to microbial components. We suggest that trait analysis should be added to the traditional approaches based on species diversity, because it provides indicators of ecosystem stress.

Although there is extensive information concerning the colonization sequences of benthic communities, little is known about the successional development of subtidal hard-bottom habitats in highly productive coastal upwelling areas. In these systems, succession is predicted to be fast due to high growth rate of the later dominant colonizers. Using artificial hard substrata a field experiment was conducted in a rocky subtidal area off Northern Chile (Humboldt Current System) and monitored at 3-month intervals to test the following hypotheses: (i) epibenthic succession may proceed through consecutive replacement of species, (ii) there is a fast convergence rate towards natural communities, and (iii) different seasonal starting points for the colonization will produce different community structure over a 1-year period of exposure. Panels were installed on a vertical wall at 17 m water depth. Three replicate panels were sampled every 3 months over a period of 27 months. As a reference, six haphazardly selected plots from the surrounding natural community were surveyed at each sampling date. To evaluate how seasonally varying substratum availability affects community development, further panels were exposed for a 12-month period, starting in four different seasons (n = 3 replicates per season). Community succession was slow and occurred through progressive changes, between early encrusting red corallines, middle Balanus flosculus and late Lagenicella variabilis. After 27 months, the community composition, but not its structure, was similar between experimental and reference communities on surrounding rocky bottoms. Seasonality had no effects and after 1 year of exposure the experimental communities converged towards a common structure. This study indicates that succession of subtidal epibenthic communities follows a slow and predictable pattern with a dominant late colonial species. In addition, aseasonal variability might be more relevant during colonization and succession in this upwelling ecosystem.

A new nematode species, Philometra genyp- teri sp. n. (Philometridae), is described from male and female specimens found in the ovary of red cusk-eel, Genypterus chilensis (Guichenot) (Ophidiidae, Ophidii- formes), from the eastern South Pacific Ocean off the coast of northern Chile. Based on light and scanning electron microscopy examination, the new species differs from most other gonad-infecting Philometra spp. in the length of spicules (126-135 μm), a gubernaculum with dorsal lamella-like structures on its distal end, and the number and arrangement of genital papillae in the male. From a few congeneric, gonad-infecting species with unknown males, it can be distinguished by some morphological and biometrical features found in gravid female (absence of caudal projections, length of first- stage larvae or oesophagus, moderately developed ante- rior oesophageal inflation) and by the host type (fish family) and geographical distribution. P. genypteri is the first philometrid species reported from a fish belonging to the order Ophidiiformes and the second nominal species of Philometra recorded from marine fishes of the eastern South Pacific.

The biodiversity of hard-bottom substrata comprises species growing on exposed rock and in hidden microhabitats, such as cracks and crevices. This study examines the succession of epibenthic organisms colonizing an artificial substratum with one surface exposed and one surface hidden on a vertical wall off northern Chile. On each sampling date species coverage of three replicate panels on both surfaces was assessed. The hidden surface was dominated in terms of coverage by the bryozoans Membranipora isabelleana and Lagenicella variabilis, while algae were absent. In contrast, the exposed surface was dominated by encrusting red corallines and the red alga Rhodymenia corallina. At the end of the experimental period both surfaces were dominated by colonial suspension feeders, but showed a different community structure and successional pattern. On the exposed surface, competitive exclusion was identified as an important aspect of succession, whereas on the hidden surface this pattern was not observed. These findings have implications for overall biodiversity, because pioneer species that are not able to survive long periods on exposed surfaces become restricted to hidden surfaces, from where they spread laterally. Thus, hidden microhabitats provide refuges for certain species, and may play an important role in the overall succession on rock faces. We conclude that examination of hidden microhabitats is necessary in order to fully understand succession in hard-bottom habitats. La biodiversidad en sustratos de fondo duro está compuesta por especies que crecen en las superficies expuestas de las rocas así como también aquellas presentes en microhábitats ocultos como grietas y cavidades. Este estudio examina el proceso de sucesión de organismos epibentónicos que colonizan un sustrato artificial presentando una superficie expuesta y una oculta en una pared vertical en la península de Mejillones en el norte de Chile. Cada tres meses, tres paneles fueron colectados y en el laboratorio se cuantificó la cobertura de especies en ambas superficies. Durante la sucesión en las superficies ocultas los briozoos Membranipora isabelleana y Lagenicella variabilis dominaron la comunidad en términos de cobertura notándose una ausencia total de algas. En contraste, las algas coralinas custrosas y Rhodymenia corallina fueron componentes importantes de las comunidades que colonizaron las superficies expuestas. La estructura comunitaria y los patrones de sucesión fueron diferentes en ambas superficies, observándose una tendencia a la dominancia de los animales coloniales suspensívoros. En las superficies expuestas se identificó la exclusión competitiva como un proceso importante durante la sucesión, mientras que en las superficies ocultas este patrón no se observó. Esto tiene implicaciones en la biodiversidad general, debido a que las especies pioneras que no pudieron sobrevivir periodos largos en las superficies expuestas, se restringen a los hábitats ocultos desde donde pueden crecer lateralmente. Los microhábitats ocultos proporcionan refugios para algunas especies, lo que puede afectar la sucesión en hábitats rocosos. Concluimos que es necesario examinar los microhábitats ocultos para poder tener un total entendimiento de la sucesión en hábitats de fondos duros.

Examination of 248 adult specimens of whitemouth croaker Micropogonias furnieri from five localities along the Brazilian coast revealed 8735 parasites belonging to 41 metazoan species. Samples from Ceará to Bahia and Rio de Janeiro to Santa Catarina showed a high level of correct assignation (92 and 87%, respectively) and cross assignation (i.e. almost all specimens misidentified in Ceará were assigned to Bahia and almost all specimens misidentified in Bahia were classified as Ceará), so samples were pooled in the northern and south-eastern samples, and Rio Grande do Sul was considered a southern area. Eight parasite species were characteristic of the northern localities, five species were found just in the area associated with south-eastern localities and two species were characteristic of the southern area providing first evidence of stock discreteness. The multivariate discriminant analysis successfully discriminated three groups of localities associated with three stocks of M. furnieri in Brazil: a northern stock associated with Ceará and Bahia, a south-eastern stock related to Rio de Janeiro and Santa Catarina and a southern stock in the area of Rio Grande do Sul, which could be considered as the northern limit of the stock associated with the Common Fishing Zone of Uruguay and Argentina.

Two deep-sea shark species were obtained as by-catch of the local fishery of the Patagonian toothfish, Dissostichus eleginoides, at depths ranging from 1000 to 2200 m off central and northern Chile. A total of 19 parasite taxa were found in 133 specimens of the southern lanternshark, Etmopterus granulosus, (n = 120) and largenose catshark, Apristurus nasutus, (n = 13). Fourteen taxa (four Monogenea, one Digenea, four Cestoda, one Nematoda, two Copepoda, one Annelida and one Thecostraca) were found in E. granulosus, whereas five taxa (one Monogenea, two Cestoda and two Nematoda) were found in A. nasutus. Representatives of Cestoda showed higher values of prevalence and a greater intensity of infection; this pattern is consistent with reports for elasmobranchs, but the monogenean richness was higher than that previously reported for related deep-sea sharks. Regarding E. granulosus, a positive and significant correlation between host length and abundance was found for six (four ectoparasites, one mesoparasite, and one endoparasite) of the 14 taxa recorded, but prevalence was significantly correlated with host length only for the monogenean Asthenocotyle sp. Although the sample size for A. nasutus was limited, we compared richness, abundance, diversity and evenness at the infracommunity and component community levels. All of these variables were higher for E. granulosus, but at the infracommunity level, abundance was higher for A. nasutus. All the parasite taxa (except two) represent new host and geographical records.

Two new species, Choricotyle scapularis and Choricotyle isaciencis (Monogenea: Diclidophoridae), are described from the gills of haemulid fishes, Anisotremus scapularis and Isacia conceptionis, respectively, in San Jorge Bay, northern Chile (23 degrees 42'S, 70 degrees 24'W); they are compared with the known species in the genus. Diagnostic characters for C. scapularis includes the number of hooks in the male copulatory organ, a developed isthmus, the shape of the haptor, and the number of testes. The diagnostic characters for C. isaciensis include the presence of an oval accesory sclerite in the clamps, the number of testes, the number of hooks in the male copulatory organ, and the relative clamp peduncle size.

SUMMARYNested structure is a pattern originally described in island biogeography to characterize how a set of species is distributed among a set of islands. In parasite communities, nestedness has been intensively studied among individual fish from a locality. However, nested patterns among parasite assemblages from different host populations (localities) have scarcely been investigated. We recorded the occurrence of parasites in 9 fish species widely distributed along the southeastern Pacific coast to determine whether the ecto- and endoparasite assemblages of marine fishes show a nested structure associated with host distributional range. Nestedness was tested using Brualdi-Sanderson index of discrepancy (BR); and 5 null models incorporated in a‘Nestedness’programme (Ulrich, 2006). The ecto- and endoparasite richness do not show similar patterns of latitudinal gradients among fish hosts, with 33–66% of analysed ectoparasite assemblages, and 25–75% of endoparasite assemblages showing nested structures through the host distributional range. For ectoparasites, species richness gradients and nested structure (when present) might be associated with decreased host densities or could reflect negative environmental conditions in the distributional border of the host species, whereas for endoparasites might be caused by geographical breaks of prey or changes in prey availability (intermediate hosts). The sampled extension of the distributional range of the host species, as well as the lack of specificity of some parasites, could influence the detection of nestedness.

The surf clam Mesodesma donacium is an economically important species for Chilean and Peruvian shellfisheries. This clam is often infested by Polydora bioccipitalis, a species belonging to the Spionidae, the most common parasitic polychaete group. To study this association, clams were sampled monthly over a one-year period in northern Chile. Collected clams covered the entire available size range and were classified into four infestation levels in order to study: (1) the relationship between prevalence of infestation (PI) and host size, (2) the temporal pattern of infestation events related to seasonal temperature changes, and (3) the relationship between infestation, body condition index (BCI) and gonado-somatic index (GSI). Additionally, growth rate and digging ability of clams with different infestation levels was studied. A logistic regression model best explained the relationship between PI and host size, with the smallest infested clam being 34 mm long and PI increasing steeply thereafter. Ontogenetic shifts in the habitat of the clam and ontogenetic changes, mainly in shell morphology, seem to explain the sigmoid pattern. Periods of increased shell blistering after infestation by P. bioccipitalis showed a similar seasonal pattern with GSI and BCI of non-infested clams, suggesting either an association between infestation ability and low condition of the clam or common environmental triggers for those factors. Heavily infested clams showed a significant lower BCI, growth rate and digging ability; however, given its low number, they are unlikely to be significant in terms of the local population survival. However, the infestation could play a key role in explaining mass mortality of northern populations during El Nino events, given the latitudinal differences in PI and the fact that infestation ability could be enhanced by increased temperature and facilitated in stressed clams.

The taxonomic composition of the metazoan parasites found in the stomach of 629 specimens of the “Patagonian toothfish” Dissostichus eleginoides Smitt, 1898, from two localities in southern Chile (Lebu 36°00′S; Quellon 48°49′S), is recorded. More than 58,000 parasite specimens belonging to 9 taxa were registered. Adult worms were represented by the hemiurids Gonocerca phycidis Manter 1925, Lecithochirium genypteri Luhe 1905, Brachyphallus crenatus (Rudolphi 1802), and Derogenes varicus (Muller 1784) and the nematode Hysterothylacium sp. Ward & Magath 1917. Larval forms of anisakid nematodes, an acanthocephalan ( Corynosoma sp.), a trypanorhynch cestode ( Hepatoxylon trichiuri (Holten 1802)) and an unidentified pseudophyllidean cestode were also obtained. Parasitological evidence, based on univariate and multivariate analys i s, does not support either the existence of discrete stocks, migratory movements between areas or seasonality in pattern of infection.

Parasites have been used successfully as biological tags in population studies, mainly in marine fishes, but also in marine mammals, crustaceans and molluscs. Almost all published information dealing with parasites as biological tags evaluates differences between localities. However, local variability in the component community has not been assessed. In this work, we examined whether local variation of the metazoan parasite fauna of Engraulis ringens, extracted from five independent samples from two nearby localities in northern Chile, can be a factor causing bias in stock identification. Our results show that local variability, as estimated by a single sample, may suffice to represent component community variability with no need for replicated data.

Keywords: macrozoobenthos ◊ community analyses ◊ feeding modes ◊ Mejillones Bay ◊ El NiñoThe macrozoobenthos of Mejillones Bay (23ºS; Humboldt Current) was quantitatively investigated over a seven years period from austral summer 1995/96 to winter 2002. 78 single van Veen grab samples taken at six stations (5, 10, 20 m depth) provided the basis for the analysis of the distribution of 60 species and 28 families as well as their abundance and biomass. Mean abundance (2119 ind. m-2) was consistent with previous estimates by Zúñiga et al (1983) (2762 ind. m-2). Mean biomass was 966 g formalin wet mass m-2 and ranged between 72 g m-2 (5 m) and 1521 g m-2, (10m). Thus, the mean value exceeds prior estimations (396 g alcohol wet mass m-2) mainly due to the dominance of the bivalve Aulacomya ater, which reached a maximum abundance of up to 2400 ind. m-2 at the 10 m stations in summer 2000 and occurred along the whole depth range sampled. This bivalve was not a dominant faunistic element in earlier investigations (e.g., Zúñiga et al 1983). A possible explanation is that the regime shift to warmer conditions in the 80ies and 90ies (Arntz et al. 2006) created more favourable conditions for this bivalve off northern Chile. 43% of the taxa sampled inhabited the complete depth range. Mean taxonomic Shannon diversity (HŽ, Log e) was 1.54 ± 0.58 with a maximum at 20 m (1.95 ± 0.33), evenness increased with depth (Fig. 1). The fauna was numerically dominated by carnivorous gastropods, polychaetes and crustaceans (48%). Echinoderms occurred only in low numbers, 15% of the species were suspensivorous, 13% sedimentivorous, 11% detritivorous, 7% omnivorous and 6% herbivorous. Cluster analyses showed a significant difference between the shallow and the deeper stations. Gammarids and the polychaete family Nephtyidae characterized the 5-m-zone, the molluscs Aulacomya ater, Mitrella unifasciata and gammarids the intermittent zone, while the gastropod Nassarius gayi, Nassarius gayi and Mitrella unifasciata and the polychaete family Nereidae were most prominent at the deeper stations.The communities of the three depths did not appear to be limited by hypoxia during non-El Niño conditions. From Figure 1 it is obvious that although oxygen concentrations rose at all depth the signal was by far not as clear for the fauna of Mejillones Bay as off Peru and in observations of deeper living communities of Concepción Bay (Chile). Therefore, no typical change in community structure occurred during El Niño 1997/98. This suggests that EN-induced enhanced oxygen levels significantly increase diversity only in those communities, where abundances and species richness are normally limited due to oxygen stress and thus, unfavourable settling conditions for larvae (Arntz et al. 2006). Oxygen limitation explains the low diversity during non-EN years at deeper bottoms throughout the Humboldt Current Ecosystem. When physiological tolerance limits are no longer exceeded due to improved oxygen concentrations in the bottom water (Arntz et al. 2006) previously excluded species may extend their distribution to lower and greater depths or proliferate strongly (opportunists). This is in line with observations of Tarazona et al. (1996) who state that very strong or very prolonged EN events may produce favourable conditions only in hypoxic study areas, reflected in considerable community changes but never reaching the species numbers of comparable bays favoured generally by better oxygenation. Although the 1997-98 EN might be one of the strongest on record, according to some physical indices, the biological impact off northern Chile was not as catastrophic as generally expected. This does not only hold true for the analysed soft-bottom community, but also for the pelagic ecosystem of the same area. Differences in the impact compared with previous events may furthermore be attributed to the distinct seasonal onset (Arntz et al. 2006): while EN 1982-83 started in austral spring, just before the reproductive season, EN 1987-98 commenced in late austral autumn (and thus in the northern hemisphere reproductive season).

The opecoelid Helicometrina nimia Linton, 1910 has been reported from numerous marine fishes along the Pacific and Atlantic coasts of the Americas. Along the Chilean coast, H. nimia is found in fishes belonging to at least 9 families. This surprisingly low host specificity of H. nimia raises question about the correct identification of specimens assigned to this species. Here we evaluate whether H. nimia specimens isolated from sympatric fish species in northern Chile but with different diets and found in different habitats (water column and demersal) are the same species. Our results demonstrate that specimens from the shallow benthic fish Labrisomus philippii (Steindachner) do not correspond to H. nimia but instead belong to a new species of Helicometrina. This species is described and distinguished from H. nimia using morphological descriptions and 2 molecular markers (the cytochrome c oxidase subunit 1 gene and the V4 region of the SSU rRNA gene). The new species Helicometrina labrisomi (Digenea: Opecoelidae), is found in the intestine of L. philippii (Steindachner, 1866) (Pisces: Labrisomidae), a shallow benthic fish that inhabits the northern coast of Chile. We also studied the related Helicometrina nimia Linton, 1910 from the benthopelagic fishes Paralabrax humeralis (Valenciennes, 1828) and Acanthistius pictus (Tschudi, 1846) (Serranidae). The new species differs from H. nimia by a combination of characters that include ovary shape, number of uterine loops, and position of the genital pore. Our results indicate that morphological characteristics, such as body size, extent of the vitellarium, shape of the testes, and cirrus sac size and extent, traditionally used in the taxonomy of Helicometrina are highly variable. In contrast, meristic and morphological characteristics, such as a lobed ovary, the number of uterine loops, dimensions of the pharynx, and the opening of the genital pore, are highly constant.

The uptake of polybrominated diphenyl ethers (PBDEs) by carrot and lettuce was investigated. Degradation of PBDEs in soil in the absence of the plants was discarded. Different carrot (Nantesa and Chantenay) and lettuce (Batavia Golden Spring and Summer Queen) varieties were grown in fortified or contaminated compost-amended soil mixtures under greenhouse conditions. After plant harvesting, roots (core and peel) and leaves were analyzed separately for carrot, while for lettuce, leaves and hearts were analyzed together. The corresponding bioconcentration factors (BCFs) were calculated. In carrots, a concentration gradient of 2,2',3,4,4',5'-hexabromodiphenyl ether (BDE-138) became evident that decreased from the root peel via root core to the leaves. For decabromodiphenyl ether (BDE-209) at the low concentration level (7 and 20 ng g(-1)), the leaves incorporated the highest concentration of the target substance. For lettuce, a decrease in the BCF value (from 0.24 to 0.02) was observed the higher the octanol-water partition coefficient, except in the case of BDE-183 (BCF = 0.51) and BDE-209 (BCF values from 0.41 to 0.74). Significant influence of the soils and crop varieties on the uptake could not be supported. Metabolic debromination, hydroxylation or methylation of the target PBDEs in the soil-plant system was not observed.

Aim We evaluate, for the first time, the decay of similarity over distance in four species of marine fishes with different vagility: Trachurus murphyi (pelagic, highly vagile), Merluccius gayi (demersal, highly vagile), Sebastes capensis (demersal, low vagility) and Hippoglossina macrops (benthic, non-vagile). Location We use our own data of the species composition of parasite communities in four host species: T. murphyi (Perciformes), M. gayi (Gadiformes), H. macrops (Pleuronectiformes) and S. capensis (Scorpaeniformes), from the coast of Chile and southern Argentina. Trachurus murphyi, M. gayi and H. macrops in the area studied live closely associated with the cold waters of the Humboldt Current System, while S. capensis in southern Chile is associated with the fjord areas south of c. 43° S, and in Argentina this species lives in close association with the cold water of the Malvinas Current, which mixes with the warm water of the Brazilian Current in the sampled area. Thus, for all four host species there are no known geographical (oceanographic) barriers that interrupt their continuous distributions. Methods Fish were collected and frozen (−18 °C) until examination in the laboratory. After thawing, each visceral organ was dissected separately, washed in running water, filtered using a mesh of 0.25 mm, and examined under a stereomicroscope (20×). For S. capensis, only ectoparasites were included in this study because data on endoparasites for some locations are not available. The approach of Poulin [Journal of Biogeography30 (2003) 1609] was used. For each host species, we computed similarity in parasite composition using the Bray–Curtis distance on a presence/absence matrix. Similarity between each pair of localities was correlated (linear regression on raw and transformed data) with the distance (in nautical miles) among those sites. Results Among conspecific populations of host fish, there was no correlation between sample size and parasite species richness. The same pattern was evident when all host populations were pooled and treated as a single sample. Except for H. macrops, an important proportion of the geographical ranges of the host species was covered. The decay in similarity of parasite communities over distance was recorded in three of the four hosts analysed. For H. macrops, no relationship between distances and decay of similarity was evident. A linear regression on non-transformed data provided a good fit, and the regression on log(n + 1) does not change significantly for both r2 and probability, but slopes are smaller for log-transformed than for non-transformed data. Main conclusions Three of the four fish parasite systems studied fit well with the expected decay of similarity over distance. The slopes of the relationship between distance and similarity in the marine fishes studied are lower, but significant (three orders of magnitude) than those recorded in freshwater fishes by Poulin (2003). In our case, Hippoglossina macrops (benthic, non-vagile host) does not show any relationship, suggesting homogeneity over the geographical area studied for this species.

The value of parasites and commensals of the northern scallops Argopecten purpuratus as biological tags for stock discrimination is assessed. Six-hundred and eighty-six specimens obtained from four wild populations in northern Chile (El Fraile, La Rinconada, Caldera and Tongoy) were analyzed. Eleven species (four parasites and seven commensals) were obtained. A canonical multivariate analysis suggests that scallops from northern Chile comprise four stocks. Identification of stocks is largely based on significant differences in the mean intensity of infection of Rhinebothrium sp. (Cestoda) and Dodecaceria sp. and Polydora sp. (Polychaeta)

We have previously observed a significant reduction of ceftriaxone resistance in Proteus mirabilis associated with an increase in the use of cefepime, along with a decrease in the consumption of broad-spectrum cephalosporins (CEP). However, we did not observe such a reduction with Klebsiella pneumoniae . Therefore, we sought to determine whether replacement of CEP by piperacillin-tazobactam might be useful in reducing sustained high rates of CEP resistance by this organism. We used a 6-month “before and after model”; during the second (intervention) period, most prescriptions of CEP were changed to piperacillin-tazobactam at the pharmacy. No additional barrier precautions were undertaken. During intervention, consumption of ceftazidime decreased from 17.73 to 1.14 defined daily doses (DDD) per 1,000 patient-days ( P < 0.0001), whereas that of piperacillin-tazobactam increased from 0 to 30.57 DDD per 1,000 patient-days ( P < 0.0001). The levels of resistance to CEP by K. pneumoniae and P. mirabilis decreased from 68.4 and 57.9% to 37.5 and 29.4%, respectively ( P < 0.05). We conclude that replacement of ceftazidime by piperacillin-tazobactam might be a suitable strategy to decrease endemic CEP resistance by K. pneumoniae and P. mirabilis , even where there are high bacterial resistance rates and irrespective of any additional precautions for controlling nosocomial infection.

Examination of 290 red rockfish Sebustes capensis from two fishing grounds in northern Chile (Coquimbo 71°30'W; 30°0'S and Antofagasta 70°40'W; 23°30'S) revealed 8770 metazoan parasites, belonging to 18 taxa: Udonella caligorum (Udonellidae); Interniloculus chilensis, Paramicrocotyle sp. and Neobenedenia melleni (Monogenea); larval Gnathia sp., Cirolana sp. and Rocinela sp. (Isopoda); Helicometrina nimia, Diphtherostomum sp., Lecithochirium sp. and Pseudopecoclus sp. (Digenea); Ascarophis sebastodis, Anisakis sp. and larval Hysterothylacium sp. (Nematoda); Caligus cheilodactylus, Lepeophtheirus chilensis and Trifur tortuosus (Copepoda); larval Corynosoma australe (Acanthocephala). Ten species were found only in Coquimbo and three were found only in Antofagasta, species common to both localities were Pseudopecoelus sp., C. australe, Anisakis sp. and A. sebastodis, Evidence, based on qualitative differences between the parasite faunas of the red rock fish, suggests the existence of two discrete stocks.