Status of Corynosoma (Acanthocephala: Polymorphidae) based on anatomical, ecological, and phylogenetic evidence, with the erection of Pseudocorynosoma n. gen

The possession of genital spines has been considered as a key taxonomic trait to differentiate Corynosoma from other genera of the Polymorphidae. However, Corynosoma currently consists of 2 groups of species with clear ecological and morphological divergences: the "marine" group (with ca. 30 species) infects mammals and piscivorous birds in the marine realm, whereas the "freshwater" group (with ca. 7 species) infects waterfowl in continental waters. Species from these groups differ in shape of body and neck, trunk spination, lemnisci length and shape, testes arrangement, and number and shape of cement glands. We tested whether species from these 2 groups formed a monophyletic assemblage based on a phylogenetic analysis by using 15 morphological characters. We also included species of Andracantha, Polymorphus, and Hexaglandula with which potential taxonomic conflicts could most likely arise. We obtained 108 equally most parsimonious trees of 32 steps, with a consistency index (CI) = 0.59, and a retention index (RI) = 0.82. The strict consensus tree indicated that the "freshwater" species of Corynosoma form a monophyletic assemblage closely related to some species of Polymorphus, whereas the "marine" species of Corynosoma are grouped together with Andracantha. Accordingly, Corynosoma is not a monophyletic assemblage, and Pseudocorynosoma n. gen. is proposed for the "freshwater" species of Corynosoma. This decision was strongly supported by (1) a functional comparison of foretrunk muscles between species of Polymophus, Andracantha, and Corynosoma; (2) a multivariate morphometric study of proboscis characters and egg size; and (3) an analysis of ecological patterns of host-parasite relationships.     

Molecular phylogeny of Corynosoma Lühe, 1904 (Acanthocephala), based on 5.8S and internal transcribed spacer sequences

Species of Corynosoma (Acanthocephala) are distributed worldwide as parasites of marine mammals and sea birds. Species diagnosis is based on morphological characters, including the size and number of hooks in the proboscis and the number of spines in the dorsal and ventral regions of the body. We inferred the phylogenetic relationships of 10 nominal species of Corynosoma through analysis of internal transcribed spacers (ITS-1, ITS-2) and 5.8S ribosomal RNA sequences. Nucleotide distances between species of Corynosoma ranged from 0.4 to 11% for ITS sequences. Maximum parsimony and likelihood analyses indicated that species of Corynosoma that inhabit hosts in the marine environment form a monophyletic assemblage, but yielded conflicting hypotheses for the relationship of Corynosoma cetaceum to other members of the genus. However, parsimony and likelihood analyses were consistent for many Corynosoma sister species relationships of (e.g., C. australe plus C. bullosum, C. validum plus C. villosum, C. caspicum plus C. magdaleni, and C. enhydri plus C. strumosum). This phylogenetic framework was used to evaluate taxonomic controversies concerning C. cetaceum and C. caspicum.     

Systematic position of Pseudocorynosoma and Andracantha (Acanthocephala, Polymorphidae) based on nuclear and mitochondrial gene sequences

Species of Pseudocorynosoma are North and South American acanthocephalans that use waterfowl as definitive hosts and amphipods as intermediate hosts, whereas species of Andracantha occur in fish-eating birds with a worldwide distribution. Pseudocorynosoma and Andracantha were originally described as Corynosoma (now restricted to endoparasites of marine mammals). Morphologically, Andracantha is distinct from other genera of Polymorphidae in possessing 2 fields of spines on the trunk, whereas Corynosoma and Pseudocorynosoma have a single field. A recent phylogenetic hypothesis based on morphological characters suggested that Andracantha is closely related to Corynosoma, whereas Pseudocorynosoma was of uncertain phylogenetic position within the Polymorphidae. To test the systematic affinities of these 3 genera, we sequenced 2 nuclear genes (SSU and LSU ribosomal DNA) and 1 mitochondrial gene (cytochrome c oxidase subunit 1; cox 1) of species representing Corynosoma, Andracantha, and Pseudocorynosoma and analyzed the data, including available sequences of other polymorphids. Maximum parsimony (MP), maximum likelihood (ML), and Bayesian analyses of the combined (SSU + LSU) sequences and the concatenated data of 3 genes (SSU + LSU + cox 1) placed Andracantha as the sister taxon to Corynosoma with robust support values. All analyses also showed that Pseudocorynosoma is an independent lineage that does not share a common ancestry with Andracantha and Corynosoma. These phylogenetic hypotheses suggest that birds were the ancestral hosts of polymorphids and that the association of Corynosoma with marine mammals represents a subsequent episode of colonization.     

Host-parasite relationships between two seal populations and two species of Corynosoma (Acanthocephala) in Finland

Ringed seals ( Phoca hispida botnica ), from the Bothnian Bay, north-eastern Baltic Sea were examined for acanthocephalan parasites in 1977–1982, and specimens from Lake Saimaa in south-eastern Finland ( P. h. saimensis ) were examined in 1980–1981. The two seal stocks have been isolated from Arctic stock for 11,000 years and from each other for 8,000 years. Corynosoma strumosum and C. semerme were found in the Baltic seals, but only C. strumosum in those from the lake.
Eighty two of the ringed seals caught in the Bothnian Bay were infected with both Corynosoma species, one with a single infection of C. strumosum and one with C. semerme in autumn. The total number of C. semerme increased in relation to the number of C. strumosum in each set of seals both in autumn and spring. Corynosoma semerme was dominant in most seals in spring, but in only an average of 60% in autumn. The predominance of C. strumosum in 40% of the autumn material (range 33–80%) is of interest because species ratio favouring C. strumosum is not found in any more heavily infected paratenic fish host of Corynosoma in the Bothnian Bay. The change in the Corynosoma species ratio of seals in autumn may be explained by their exceptional feeding behaviour at this time of the year (total or partial fasting) and the suggested longevity of C. strumosum as compared with C. semerme . The stability of the acanthocephalan populations in ringed seals is documented.     

Charting the course of reed‐warblers across the Pacific islands

Aim Deciphering the complex colonization history of island archipelagos is greatly facilitated by comprehensive phylogenies. In this study we investigate the phylogeny and biogeography of the insular reed‐warblers (genus Acrocephalus) of the tropical Pacific Ocean, from Australia to eastern Polynesia. Location Oceania. Methods We used sequences of mitochondrial DNA (cytochrome b, ND2 and ATP8 genes) to infer the colonization patterns of reed‐warblers endemic to Pacific islands and Australia. We sampled all known taxa of Acrocephalus in the Pacific except A. luscinius nijoi, for which no sample was available. Most taxa were represented by toe‐pad samples from museum specimens collected in the 19th and 20th centuries. With a few exceptions, several specimens per taxon were sequenced independently in two institutions (Smithsonian Institution and Natural History Museum of Geneva). Results Our data indicate that Pacific reed‐warblers do not form a monophyletic group, because A. luscinius luscinius from Guam falls outside the main Pacific radiation. The remaining Pacific taxa are divided into two clades: one clade includes all the reed‐warblers from Micronesia (except Guam) and Australia, and two Polynesian taxa from the Line Islands and the southern Marquesas; the other clade includes all remaining Polynesian taxa. The taxa endemic to three archipelagos (Mariana, Marquesas and Society islands) are polyphyletic, suggesting several independent colonizations. Main conclusions Our results provide evidence for a complex pattern of colonization of the Pacific by reed‐warblers. Calibration analyses suggest that reed‐warbler lineages are much younger than the ages of the islands they occupy. Several remote archipelagos were colonized independently more than once. Consequently, we infer that the colonization of reed‐warblers in the Pacific did not follow a regular, stepping‐stone‐like pattern. The phylogeny also suggests a previously undetected case of reverse colonization (from island to continent) for the Australian lineage and indicates that A. luscinius, as currently defined, is not monophyletic. We discuss the supertramp strategy of reed‐warblers in the Pacific and show that, although Pacific reed‐warblers meet some of the supertramp criteria in their aptitude for colonizing remote archipelagos, their life history characteristics do not fit the model.     

Multiple origins of the Juan Fernández kelpfish fauna and evidence for frequent and unidirectional dispersal of cirrhitoid fishes across the South Pacific

Phylogenetic relationships were reconstructed among chironemid fishes based on morphological and molecular (lrRNA, NADH4, S7 ribosomal protein) characters. Two sympatric species from Juan Fernández in the southeast Pacific are not sister taxa, but rather exhibit independent relationships to Australian/New Zealand chironemids. The most plausible explanation for these relationships and contemporary distributions is an Australian/New Zealand origin of the family, followed by two trans-Pacific dispersal and colonization events, facilitated by larval entrapment within the West Wind Drift. This study demonstrates that the diversity of taxa on an island can reflect multiple colonizations, rather than in situ diversification, even in the case of very small, isolated, and geologically recent islands. When taken in conjunction with studies of related taxa, our results indicate that transoceanic dispersal of temperate cirrhitoid fishes in the South Pacific has been frequent and unidirectional. Molecular estimates of divergence time between southeast Pacific chironemids and their western relatives predate the emergence of Juan Fernández, consistent with hypotheses that much of the marine nearshore faunas of young southeast Pacific islands may be the product of successive transfer from older, now submerged islands.     

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

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

Changing perspectives on the biogeography of the tropical South Pacific: influences of dispersal, vicariance and extinction

Aim The biogeographical patterns and drivers of diversity on oceanic islands in the tropical South Pacific (TSP) are synthesized. We use published studies to determine present patterns of diversity on TSP islands, the likely sources of the biota on these islands and how the islands were colonized. We also investigate the effect of extinctions. Location We focus on oceanic islands in the TSP. Methods We review available literature and published molecular studies. Results Examples of typical island features (e.g. gigantism, flightlessness, gender dimorphism) are common, as are adaptive radiations. Diversity decreases with increasing isolation from mainland sources and with decreasing size and age of archipelagos, corresponding well with island biogeographical expectations. Molecular studies support New Guinea/Malesia, New Caledonia and Australia as major source areas for the Pacific biota. Numerous studies support dispersal‐based scenarios, either over several 100 km (long‐distance dispersal) or over shorter distances by island‐hopping (stepping stones) and transport by human means (hitch‐hiking). Only one vicariance explanation, the eastward drift of continental fragments (shuttles) that may have contributed biota to Fiji from New Caledonia, is supported by some geological evidence, although there is no evidence for the transport of taxa on shuttle fragments. Another vicariance explanation, the existence of a major continental landmass in the Pacific within the last 100 Myr (Atlantis theory), receives little support and appears unlikely. Extinction of lineages in source areas and persistence in the TSP has probably occurred many times and has resulted in misinterpretation of biogeographical data. Main conclusions Malesia has long been considered the major source region for the biota of oceanic islands in the TSP because of shared taxa and high species diversity. However, recent molecular studies have produced compelling support for New Caledonia and Australia as alternative important source areas. They also show dispersal events, and not vicariance, to have been the major contributors to the current biota of the TSP. Past extinction events can obscure interpretations of diversity patterns.     

Historical biogeography of Melicope (Rutaceae) and its close relatives with a special emphasis on Pacific dispersals

The genus Melicope (Rutaceae) occurs on most Pacific archipelagos and is perfectly suited to study Pacific biogeography. The main goal was to infer the age, geographic origin and colonization patterns of Melicope and its relatives. We sequenced three nuclear and two plastid markers for 332 specimens that represent 164 species in 16 genera of Rutaceae. Phylogenetic reconstruction, molecular dating, ancestral area reconstruction and diversification analyses were carried out. The two main clades (Acronychia‐Melicope and Euodia) originated in Australasia and their crown ages are dated to the Miocene. Diversification rates differed among the subclades and were lowest in the Euodia lineage and highest in the Hawaiian Melicope lineage. The Malagasy and Mascarene species form a clade, which split from its SE Asian relatives in the Pliocene/Pleistocene. At least eight colonizations to the Pacific islands occurred. The timing of all colonizations except for the Hawaiian group is congruent with age of the island ages. Australia, New Guinea and New Caledonia have been the source of colonizations into the Pacific islands in the Melicope clade. Melicope shows high dispersability and has colonized remote archipelagos such as the Austral and Marquesas Islands each twice. Colonization of islands of the Hawaiian‐Emperor seamount chain likely predates the ages of the current main islands, and the initial colonization to Kaua'i occurred after the splitting of the Hawaiian lineage into two subclades. Wider ecological niches and adaptations to bird‐dispersal likely account for the much higher species richness in the Acronychia‐Melicope clade compared to the Euodia clade.     

Genetic diversity and structure of the invasive tree Miconia calvescens in Pacific islands

Aim This study investigates the amount and distribution of genetic variation within and among populations of the highly invasive tree, Miconia calvescens (Melastomataceae; hereafter miconia), in tropical island habitats that are differently impacted (distribution and spread) by this weed. Location Invasive populations were included from northern and southern Pacific islands including the Hawaiian Islands (Hawaii, Kauai and Maui), Marquesas Islands (Nuku Hiva), Society Islands (Tahiti, Tahaa, Moorea, Raiatea) and New Caledonia. Methods We used 9 codominant microsatellite and 77 highly variable dominant intersimple sequence repeat markers (ISSRs) to characterize and compare genetic diversity among and within invasive miconia populations. For the codominant microsatellite data we calculated standard population genetic estimates (heterozygosity, number of alleles, inbreeding coefficients, etc.) and described population genetic structure using AMOVA, Mantel tests (to test for isolation by distance), unweighted pair‐group method with arithmetic averages (UPGMA) cluster analysis and principal components analysis (PCA). We also tested for the presence of a population bottleneck and used a Bayesian analysis of population structure in combination with individual assignment tests. For the dominant ISSR data we used AMOVA, PCA, upgma and a Bayesian approach to investigate population genetic structure. Results Both markers types showed little to no genetic differentiation among miconia populations from northern and southern Pacific hemispheres (AMOVA: microsatellite, 3%; ISSR, 0%). Bayesian and frequency‐based analysis also failed to support geographical genetic structure, confirming considerable low genetic differentiation throughout the Pacific. Molecular data furthermore showed that highly successful miconia populations throughout the Pacific are currently undergoing severe bottlenecks and high levels of inbreeding (f = 0.91, ISSR; F_IS = 0.27, microsatellite). Main conclusions The lack of population genetic structure is indicative of similar geographical sources for both hemispheres and small founding populations. Differences in invasive spread and distribution among Pacific islands are most likely the result of differences in introduction dates to different islands and their accompanying lag phases. Miconia has been introduced to relatively few tropical islands in the Pacific, and the accidental introduction of a few or even a single seed into favourable habitats could lead to high invasive success.     

Corals from an Early Jurassic coral reef in British Columbia: refuge on an oceanic island reef

An Early Jurassic (Sinemurian) reef in the Telkawa Range, British Columbia Canada, yields coral species previously known from Morocco, Great Britain, Italy, Peru, and Chile. The principal constructional coral, Phacelostylophyllum rugosum (Laube), known from the Upper Triassic Dolomite Alps in northern Italy, is a holdover species. This coral survived the mass extinctions of the end-Triassic without leaving any other Jurassic records outside Canada. Other corals from the Telkwa reef include Stylophyllopsis victoriae (Duncan) and Actinastraea minima Beauvais known from Jurassic rocks of the Tethys. Closely related corals, Phacelostylophyllum chocolatensis (Wells) and Actinastraea plana (Duncan), are from southern Peru. The paleogeographic Occurrence of the Canadian reef in the volcanic terrane of Stikinia supports the contention that volcanic islands in distant outposts of the ancient Pacific served as refugia. In the aftermath of the end-Triassic reef decimation affecting the Tethys, corals and reef-building activities continued on ancient islands of the ancestral Pacific. The Hispanic Corridor, connecting the western Tethys with the western Pacific, may have played an important role during Sinemurian time. ***Reef; corals, Triassic, Jurassic, extinctions, paleobiogeography.     

A global review of island endemic birds

Although fewer than one-fifth of the world's bird species are restricted to islands, over 90% of bird extinctions during historic times have occurred on islands. The major identified cause has been the effects of exotic animal species introduced by man; the largest number of documented extinctions has occurred on islands of the Pacific Ocean.
Some 39% (402) of threatened bird species are restricted to islands and more than 907; of these are endemic to a single geopolitical unit. The largest numbers occurring in such units are in Indonesia (91) and the Philippines (34). As a region, the Pacific holds more threatened species (110) than any other, including almost half of those considered Endangered and over 40% of the Vulnerable species.
Most threatened island species are forest-dwelling. A high proportion of the Endangered species use seasonal/temperate forest. While habitat destruction now poses the greatest overall threat to island birds (affecting over half the species restricted to islands), the presence of introduced species threatens 30 of the 66 Endangered species.
Although immediate extinctions of island species can best be averted by mitigating the effects of introductions, the removal of native forests will be a more severe problem in the longer term. There is an urgent need for ecologists to provide detailed information on the habitats of both threatened and endemic species so that more appropriate and effective conservation programmes can be developed.     

Habitat quality and endoparasitism in the Pacific sanddab Citharichthys sordidus from Santa Monica Bay, southern California

Prevalence, mean abundance and mean intensity of the most common endohelminths infecting Pacific sanddab Citharichthys sordidus were compared among six trawl stations in the Santa Monica Bay. These trawl stations varied in their distance from the 8 km effluent of the Hyperion treatment plant which is situated adjacent to Santa Monica Bay. Juvenile stages of Anisakis sp., Corynosoma sp., Lacistorhynchus dollfusi and Tetraphyllidean plerocercoids were found infecting Pacific sanddabs. Significantly higher prevalence and mean intensity of L . dollfusi and Anisakis sp. were seen at the non-outfall stations compared to outfall stations either immediately surrounding or in the vicinity of the outfall. These differences appeared to be related to changes in invertebrate population densities in response to the presence of contaminants. Canonical analysis of discriminance using parasite abundance data discriminated non-outfall from outfall stations. The cestode L . dollfusi explained most of the variability in discriminant scores generated from the analysis and appears to warrant further investigation as a potential bioindicator of pollution exposure in its fish host.     

The IUCN Red List of Threatened Species: an assessment of coral reef fishes in the US Pacific Islands

Widespread declines among many coral reef fisheries have led scientists and managers to become increasingly concerned over the extinction risk facing some species. To aid in assessing the extinction risks facing coral reef fishes, large-scale censuses of the abundance and distribution of individual species are critically important. We use fisheries-independent data collected as part of the NOAA Pacific Reef Assessment and Monitoring Program from 2000 to 2009 to describe the range and density across the US Pacific of coral reef fishes included on The International Union for the Conservation of Nature’s (IUCN) 2011 Red List of Threatened Species. Forty-five species, including sharks, rays, groupers, humphead wrasse (Cheilinus undulatus), and bumphead parrotfish (Bolbometopon muricatum), included on the IUCN List, were recorded in the US Pacific Islands. Most species were generally rare in the US Pacific with the exception of a few species, principally small groupers and reef sharks. The greatest diversity and densities of IUCN-listed fishes were recorded at remote and uninhabited islands of the Pacific Remote Island Areas; in general, lower densities were observed at reefs of inhabited islands. Our findings complement IUCN assessment efforts, emphasize the efficacy of large-scale assessment and monitoring efforts in providing quantitative data on reef fish assemblages, and highlight the importance of protecting populations at remote and uninhabited islands where some species included on the IUCN Red List of Threatened Species can be observed in abundance.     

Molecular phylogeny and biogeography of the endemic Hawaiian Succineidae (Gastropoda: Pulmonata)

The endemic Hawaiian Succineidae represent an important component of the exceptionally diverse land snail fauna of the Hawaiian Islands, yet they remain largely unstudied. We employed 663-bp fragments of the cytochrome oxidase I (COI) mitochondrial gene to investigate the evolution and biogeography of 13 Hawaiian succineid land snail species, six succineid species from other Pacific islands and Japan, and various outgroup taxa. Results suggest that: (1) species from the island of Hawaii are paraphyletic with species from Tahiti, and this clade may have had a Japanese (or eastern Asian) origin; (2) species from five of the remaining main Hawaiian islands form a monophyletic group, and the progression rule, which states that species from older islands are basal to those from younger islands, is partially supported; no geographic origin could be inferred for this clade; (3) succineids from Samoa are basal to all other succineids sampled (maximum likelihood) or unresolved with respect to the other succineid clades (maximum parsimony); (4) the genera Succinea and Catinella are polyphyletic. These results, while preliminary, represent the first attempt to reconstruct the phylogenetic pattern for this important component of the endemic Hawaiian fauna.     

Parasites in stranded cetaceans of Patagonia

There is an increasing interest in parasites of marine mammals of Argentina. Here, we examined several poorly known cetaceans, i.e., 2 spectacled porpoises and 1 Burmeister's porpoise (Phocoenidae), and 1 Gray's beaked whale and 1 Cuvier's beaked whale (Ziphidae); we also updated the parasite information for 1 sperm whale (Physeteridae). These hosts strand only occasionally. We found Anisakis simplex s.l. in 2 spectacled porpoises and the Burmeister's porpoise, and recorded its distribution among the stomach chambers. Anisakis physeteris infected the sperm whale; Corynosoma cetaceum occurred in the duodenal ampulla of the Burmeister's porpoise; Corynosoma australe was found in the posterior-most region of the intestine of 1 spectacled porpoise, while another one had Tetrabothrius sp. in the anal crypts; Corynosoma bullosum and Corynosoma sp. were found in the sperm whale. The only digenean found was Pholeter gastrophilus in the Burmeister's porpoise. Merocercoids of Phyllobothrium delphini were present in the blubber of 1 spectacled porpoise, the sperm whale, and the Gray's beaked whale, while Scolex pleuronectis infected the Gray's beaked whale and 1 spectacled porpoise. No parasites were recovered from the Cuvier's beaked whale. Poor parasite-species assemblages are consistent in marine mammals of Patagonia. Given the conservation status of these hosts, the limited parasitological information gathered is valuable for conservation or management of these hosts in Patagonia.     

The age and origin of the Pacific islands: a geological overview

The Pacific Ocean evolved from the Panthalassic Ocean that was first formed ca 750 Ma with the rifting apart of Rodinia. By 160 Ma, the first ocean floor ascribed to the current Pacific plate was produced to the west of a spreading centre in the central Pacific, ultimately growing to become the largest oceanic plate on the Earth. The current Nazca, Cocos and Juan de Fuca (Gorda) plates were initially one plate, produced to the east of the original spreading centre before becoming split into three. The islands of the Pacific have originated as: linear chains of volcanic islands on the above plates either by mantle plume or propagating fracture origin, atolls, uplifted coralline reefs, fragments of continental crust, obducted portions of adjoining lithospheric plates and islands resulting from subduction along convergent plate margins. Out of the 11 linear volcanic chains identified, each is briefly described and its history summarized. The geology of 10 exemplar archipelagos (Japan, Izu-Bonin, Palau, Solomons, Fiji, New Caledonia, New Zealand, Society, Galápagos and Hawaii) is then discussed in detail.     

Indo-Pacific echinoids in the tropical eastern Pacific

The existing literature reports that only one species of Indo-Pacific echinoid (Echinometra oblonga), occurs in the eastern Pacific. In this study we confirm the presence of this species at Islas Revillagigedo and also report the presence of two species ofEchinothrix (a genus hitherto unknown outside the Indo-Pacific) at Isla del Coco and at Clipperton Island. We also present evidence from isozymes and from mitochondrial DNA sequences indicating that at least one individual ofDiadema at Clipperton may belong to a maternal lineage characteristic of the west Pacific speciesD. savignyi. These data are consistent with the hypothesis that the observed populations of Indo-Pacific echinoid species are recent arrivals to the eastern Pacific, as opposed to the view that they are relicts of Tethyan pan-tropical distributions.Echinothrix diadema, in particular, may have arrived at Isla del Coco during the 1982-1983 El Nifio. In addition to Indo-Pacific species, Clipperton, Isla del Coco and the Revillagigedos contain a complement of eastern Pacific echinoids. The echinoid faunas of these islands should, therefore, be regarded as mixtures of two biogeographic provinces. Though none of the Indo-Pacific species are known to have reached the coast of the American mainland, their presence at the offshore islands of the eastern Pacific suggests that, for some echinoids, the East Pacific Barrier is not as formidable an obstacle to migration as was previously thought.     

Metazoan parasites of the thumb grenadier Nezumia pulchella, from the south-eastern Pacific, off Chile, and their use for discrimination of host populations

The parasite communities of Nezumia pulchella across its geographical range in the south-eastern Pacific were described, from 217 fish captured from four localities in northern and central Chile (24° S to 33° S). Five ectoparasites and 13 endoparasites were recorded and the highest prevalence and intensity of infection was found for the copepods Jusheyhoea macrura and Clavella sp. 1, for the monogenean Diclidophora sp. and for the larval acanthocephalan Corynosoma australe . Parasite species richness decreased with latitude. Multivariate discriminant analysis and correspondence analysis supported the use of parasites of N. pulchella to discriminate populations of this host, suggesting the existence of three well-defined host populations in the geographical range examined. Jusheyhoea macrura , C. australe , Lophoura sp., Diclidophora sp., Capillaria sp. and Proleptus sp. were the most important species for discriminant analysis.