Desventuradas Islands Research Articles

Inter-archipelago dispersal, anagenetic evolution, and the origin of a rare, enigmatic plant genus on a remote oceanic archipelago.

Island plants have long interested biologists because of their distinctive morphological features and their isolation on small land areas in vast oceans. Studies of insular endemics may include identifying their ancestors, tracing their dispersal to islands, and describing their evolution on islands, including characters adaptive to island life. Thamnoseris is a monospecific genus endemic to the Desventuradas Islands, Chile. Its origins and relationships are unresolved, given the challenges of getting to the islands and accessing plants there. Sequences from ITS of nrDNA and the complete chloroplast genome were employed to resolve phylogenetic relationships of Thamnoseris. Phylogenetic analyses of nuclear and chloroplast sequences showed Thamnoseris nested within or sister to Dendroseris, the largest endemic genus in the Juan Fernández Islands. Thamnoseris evolved from a common ancestor of all or most species of Dendroseris prior to the diversification of Dendroseris in the Juan Fernández archipelago. The ancestor of Thamnoseris dispersed to the Desventuradas archipelago, which consists of the islands San Ambrosio and San Félix, within the past 3 Ma (the age of San Ambrosio). This is the only known example of possible plant dispersa\l between the Juan Fernández and Desventuradas Islands. We also mention two less likely biogeographic scenarios for the origin of Thamnoseris, which has features not seen in Dendroseris: small capitula with yellow florets; style branches barely divergent; and basally swollen subtending involucral bracts, all features associated with selfing and reduced dispersal. Goats and rabbits (now removed) reduced T. lacerata, once very abundant on the Desventuradas Islands, to several plants, making it of extreme conservation concern and worthy of further study.

Population genomic and biophysical modeling show different patterns of population connectivity in the spiny lobster Jasus frontalis inhabiting oceanic islands

Knowledge about connectivity between populations is essential for the fisheries management of commercial species. The lobster Jasus frontalis inhabits two oceanic island groups, the Juan Fernández Archipelago and the Desventuradas Islands, separated by 800 km. Since this species is primarily exploited in the Juan Fernández Archipelago, knowledge of the connectivity patterns among islands is foundational for species management. Here, we used variability at single-nucleotide polymorphisms (SNPs) and individual-based modeling (IBM) to estimate the genetic structure and connectivity between J. frontalis populations in these island groups. The variability at 9090 SNPs suggests two genetic populations, one in the Juan Fernández Archipelago and one in the Desventuradas Islands. Furthermore, IBM suggests an asymmetric connectivity pattern, with particles moving from the Juan Fernández Archipelago to the Desventuradas Islands but not vice versa. Since the IBM analysis suggests asymmetric larval movement between the islands, and the genetic analysis indicates isolation between the Juan Fernández Archipelago and the Desventuradas Islands, larval retention mechanisms such as small-scale oceanographic processes or behavior could hinder larval movement between islands. This study highlights the importance of using more than one methodology to estimate population connectivity.

Chloeia rozbaczyloi, a new species of polychaete (Archinominae: Amphinomidae) and first record of the family for the Nazca Ridge, southeastern Pacific Ocean

The amphinomid polychaete Chloeia rozbaczyloi sp. nov., collected from seamounts of the Nazca Ridge (NR), northwest of Desventuradas islands, southeastern Pacific Ocean, is described. The new species was observed on only two of seven seamounts surveyed in the area (25.079°S, 82.006°W, and 25.408°S, 81.769°W, ∼220 m depth), being abundant on one of them.Specimens were observed under optical and scanning electron microscopes, and DNA was sequenced (COI, 16S, 18S, and 28S nucleotide alignment). Chloeia rozbaczyloi sp. nov. belongs to the venusta group of Chloeia and is distinguished mainly by: (i) the chromatic pattern of the dorsum (with a single middorsal dark band) and the caruncle (with 16–20 vertical folds and 12 to 14 black spots posteriorly decreasing in diameter), (ii) by the bi-annulated dorsum of the first ten chaetigers, each with a bean-shaped anterior pseudosegment, (iii) long neuropodial cirri, with a short ceratophore, at chaetiger 2 and reaching chaetiger 6, and (iv) bipinnate branchiae from chaetiger 4, with seven to nine lateral branches arising from the primary axis, each possing five pinnules; branchiae change progressively in size to the posterior end. The ciliated margin of the accessory dorsal cirri suggests a respiratory function that might be relevant considering that both seamounts in which the species was observed could be influenced by low-oxygen waters. DNA results further support that C. rozbaczyloi sp. nov. differs from the other five congeneric taxa (C. bimaculata, C. flava, C. parva, C. pocicola, and C. viridis) for which genetic information is available.This finding constitutes the first report of the genus for Chilean waters, increasing the number of species of Amphinomidae in this area to seven. It also confirms the presence of the family in the NR and increases the number of Chloeia species in the world to 43.The seamounts where the new species have been collected are within the newly created offshore Nazca-Desventuradas Marine Park. Information on potentially unique and endemic species, such as the one discussed here, is of utmost importance to preserve special ecological units, address ecosystem services, and implement management measures in the area.

The relationship between naturalized alien and native plant species: insights from oceanic islands of the south-east Pacific over the last 200 years

Aim: The relationship between native and naturalized alien species has been widely studied, particularly across large geographic scales. However, our knowledge of the spatial and temporal variations of their relationships is still limited, particularly for remote oceanic islands such as those of the south-east Pacific and across islands and archipelagos. In this study, we aim to assess the relationships between native and naturalized alien species by analyzing their current patterns of species-area relationships at different spatial scales, in addition to temporal variations in species richness, over the last 200 years.Area: One island (Rapa Nui) and two archipelagos (Juan Fernandez and Desventuradas Islands) comprising a total of 11 oceanic islands of the south-east Pacific (OISEP).Methods: We assembled the most comprehensive dataset of the vascular flora of the OISEP from currently available island flora checklists and updated with recent publications. Each plant species was classified as being native or naturalized alien. We examined temporal changes by estimating species richness, naturalization rates and naturalized-to-native ratios over time based on the first collection year of each naturalized alien species. Then, we determined the best shape of naturalized alien species richness accumulation over time by contrasting the fit of lineal, exponential, sigmoidal and Weibull regressions. Finally, we analyzed the relationships between native and naturalized species firstly at the inter-archipelagic scale by fitting island species-area relationship models and secondly at the island scale by performing ranged major axis regression analysis on residual values.Results: The OISEP flora dataset contained 674 species of which 282 were native and 392 were naturalized alien. Native island species-area relationships were similar to those of the naturalized alien species. Naturalized alien species richness increased notably through time with two clear peaks in 1950 and 2000. A Weibull regression and an exponential shape over time were the most appropriate fits for naturalized alien species richness accumulations at the inter-archipelagic scale, which further emphasizes the notable increase in naturalized alien species richness experienced in the timeframe examined here.Main conclusions: The relationship between naturalized alien species richness and native species richness was found to be independent of the geographic scale. The number of naturalized alien species clearly exceeded the number of native species on most islands but also for the whole OISEP. The accumulation of newly detected naturalized alien species does not show any sign of saturation and it is likely that new species will arrive in the future. Increased efforts on monitoring, prevention and biosecurity are needed to halt biological invasions on these unique island ecosystems.

A Phylogenetically Informed Reclassification of the Rock Daisies (Perityleae; Compositae)

Abstract— Recent phylogenomic analyses of sequence data from chloroplast and nuclear genomes as well as morphological and cytological analyses resolved long standing phylogenetic uncertainty in the rock daisy tribe (Perityleae; Asteraceae) and support reclassification at the generic level to reflect evolutionary relationships. The previously recognized genera Eutetras and Pericome were upheld as clades and continue to be recognized in the new classification. The large genus Perityle as treated in previous taxonomies was found not to be monophyletic and is thus reclassified in four genera, using the available names Laphamia (in an expanded sense), Galinsogeopsis (in an expanded sense), Nesothamnus, and Perityle (in a newly restricted sense). The type species of Perityle belongs to an early diverging lineage of the rock daisy tribe, in a clade with varied chromosome numbers of x = 11, 12, 13, 16, 18, or 19. In addition to the type (Perityle californica), Perityle now includes six other minimum-rank taxa of Perityle, all three taxa of Amauria, and the Desventuradas Islands endemic Lycapsus tenuifolius. Nesothamnus is reinstated as a monotypic genus for the Guadalupe Island endemic shrub Nesothamnus incana. Laphamia and Galinsogeopsis together constitute a clade of woody and herbaceous perennials or annuals with a stabilized base chromosome number of x = 17 (n = 17, 34, 51, 68) that have diversified throughout the Basin and Range Province and the Sierra Madre Occidental of the southwest US and northern Mexico. Laphamia and Galinsogeopsis have overlapping geographic distributions but can be distinguished by a combination of fruit and flower traits. This new generic classification of Perityleae resolves long standing conflict about the circumscription of Perityle without expanding the genus to encompass the entire subtribe Peritylinae and recognizes two independent evolutionary radiations onto island-like rocky habitats in western North America as taxonomically distinct components of this fascinating tribe of composites. To allow for this revised taxonomy, 46 new combinations in Galinsogeopsis, Laphamia, and Perityle are provided, and one new name, Laphamia sanchezii, is adopted.

Reef Fish Diversity Across the Temperate South Pacific Ocean

Patterns of species richness and their structuring forces at multiple scales provide a critical context for research efforts focusing on ecology, evolution, and conservation. Diversity gradients have been demonstrated in tropical reef fish, but corresponding patterns and mechanisms remain poorly understood in temperate regions. We conducted hierarchical (spatially nested) sampling of temperate reef fish faunas across > 140 degrees of longitude in the eastern and western South Pacific Ocean. Our sampling efforts spanned five distinct provinces: the Southeast Australian Shelf (SAS), Northern and Southern New Zealand (N-SNZ), Juan Fernandez and Desventuradas Islands (JFD), and the Warm Temperate Southeastern Pacific (WTPA). We evaluated (i) spatial variation in patterns of species richness and abundance (using Chao 1 index), and distribution of functional diversity (using several functional attributes: max body size, trophic groups, feeding guilds, trophic level, habitat use, gregariousness, and activity patterns) and (ii) scale-dependencies in these patterns. Species richness declined from west to east across the temperate South Pacific, but this pattern was detectable only across larger spatial scales. A functional redundancy index was significantly higher in the western South Australian Shelf at multiple scales, revealing that species contribute in equivalent ways to an ecosystem function such that one species may substitute for another. We also detected that patterns of variation in functional diversity differed from patterns of variation in species richness, and were also dependent on the spatial scale of analysis. Lastly, we identified that species’ traits are not equally distributed among reef fish assemblages, where some provinces are characterized by a distinct functional component within their reef fish assemblages. Planktivorous and schooling species, for instance, dominated the assemblages in the eastern Pacific, which is characterized by higher primary productivity and steep bathymetric slopes favoring these traits. Demersal and pairing behavior traits dominated the reef fish assemblages in western Pacific provinces (SAS, SNZ). We conclude that combining the identifies and species’ traits allow us to disentangle historical, biogeographic and environmental factors that structure reef fish fauna.

High levels of connectivity over large distances in the diadematid sea urchin Centrostephanus sylviae.

Most benthic marine invertebrates with sedentary benthic adult phases have planktonic larvae that permit connectivity between geographically isolated populations. Planktonic larval duration and oceanographic processes are vital to connecting populations of species inhabiting remote and distant islands. In the present study, we analyzed the population genetic structure of the sea urchin Centrostephanus sylviae, which inhabits only the Juan Fernández Archipelago and the Desventuradas islands, separated by more than 800 km. For 92 individuals collected from Robinson Crusoe and Selkirk Islands (Juan Fernández Archipelago) and San Ambrosio Island (Desventuradas Islands), 7,067 single nucleotide polymorphisms (SNPs) were obtained. The results did not show a spatial genetic structure for C. sylviae; relative high migration rates were revealed between the islands. An analysis of the water circulation pattern in the area described a predominant northward water flow with periods of inverted flow, suggesting that larvae could move in both directions. Overall, this evidence suggests that C. sylviae comprises a single large population composed of individuals separated by more than 800 km.

Terrestrial invertebrates surviving San Ambrosio island’s ecological catastrophe reinforce biogeographic affinities between the Juan Fernández and Desventuradas Islands

ABSTRACT Islands are hotspots of biodiversity and extinction. It is critical to study their unique island life before it is lost forever. The Desventuradas Islands, comprised of San Félix and San Ambrosio islands, are a volcanic archipelago 850 km off the coast of Chile. They are key to understanding the diversification processes which shaped the flora and fauna of other Chilean oceanic islands such as the Juan Fernández Archipelago. But, the biogeographic affinities between these archipelagos are still poorly known. Over the last century, the plant and animal communities present in the Desventuradas have radically changed due to invasive mammal introductions. Here, focusing on terrestrial invertebrates, we: (1) confirm the presence of described endemic species, (2) detect new species records and (3) assess the biogeographic affinities between the Juan Fernández and Desventuradas archipelagos. In September 2018, San Ambrosio was surveyed using different methods (hand collecting, beating sheet, entomological net, pitfall traps and light traps) at night and during the day. A total of 35 morphospecies were collected. Four endemic species were found, in addition to several previously described higher taxonomic groups with undescribed species. Collecting methods were not successful in detecting another nine previously described endemic species. There was a total of 28 new records, including a new land snail, a new Isopoda and representatives of five spider families. Twelve of all the recorded genera from Desventuradas Islands have known relatives in the Juan Fernández Archipelago. Five of them were not previously known for San Ambrosio, reinforcing the biogeographic affinities between both archipelagos. This research highlights the urgency of surveying islands subject to a multitude of threats, including climate change and invasive species, to generate baseline data and place the island’s fauna in a broader biogeographical context.

Seafloor litter at oceanic islands and seamounts of the southeastern Pacific

Seafloor litter in oceanic islands of the southeastern Pacific Ocean have rarely been described and quantified, mainly due to the associated logistical challenges. In this study, we describe and quantify the different kinds of litter from 60 to 320 m depths in Rapa Nui (RN) and Desventuradas Islands (DI), and evaluated the relationship of this litter with the local population in terms of demographic density and fishing activity. The study compiled data from 84 stations surveyed with a ROV representing a total distance of 22 km. Litter was grouped into six categories. 96 observations of litter and debris were taken around RN, most of which associated with local artisanal fishing activity, especially fishing anchors (56%). No tourism-associated debris were reported. Any kind of seafloor litter was observed at DI. The present study provides baseline information for the local community to improve management by understanding the potential sources of seafloor litter.

Deep-sea biodiversity at the extremes of the Salas y Gómez and Nazca ridges with implications for conservation.

The Salas y Gómez and Nazca ridges are underwater mountain chains that stretch across 2,900 km in the southeastern Pacific and are recognized for their high biodiversity value and unique ecological characteristics. Explorations of deep-water ecosystems have been limited in this region, and elsewhere globally. To characterize community composition of mesophotic and deep-sea demersal fauna at seamounts in the region, we conducted expeditions to Rapa Nui (RN) and Salas y Gómez (SyG) islands in 2011 and Desventuradas Islands in 2013. Remote autonomous baited-cameras were used to conduct stationary video surveys between 150–1,850 m at RN/SyG (N = 20) and 75–2,363 m at Desventuradas (N = 27). Individual organisms were identified to the lowest possible taxonomic level and relative abundance was quantified with the maximum number of individuals per frame. Deployments were attributed with associated environmental variables (temperature, salinity, dissolved oxygen, nitrate, silicate, phosphate, chlorophyll-a, seamount age, and bathymetric position index [BPI]). We identified 55 unique invertebrate taxa and 66 unique fish taxa. Faunal community structure was highly dissimilar between and within subregions both for invertebrate (p < 0.001) and fish taxa (p = 0.022). For fishes, dogfish sharks (Squalidae) accounted for the greatest dissimilarity between subregions (18.27%), with mean abundances of 2.26 ± 2.49 at Desventuradas, an order of magnitude greater than at RN/SyG (0.21 ± 0.54). Depth, seamount age, broad-scale BPI, and nitrate explained most of the variation in both invertebrate (R2 = 0.475) and fish (R2 = 0.419) assemblages. Slightly more than half the deployments at Desventuradas (N = 14) recorded vulnerable marine ecosystem taxa such as corals and sponges. Our study supports mounting evidence that the Salas y Gómez and Nazca ridges are areas of high biodiversity and high conservation value. While Chile and Peru have recently established or proposed marine protected areas in this region, the majority of these ridges lie outside of national jurisdictions and are under threat from overfishing, plastic pollution, climate change, and potential deep-sea mining. Given its intrinsic value, this region should be comprehensively protected using the best available conservation measures to ensure that the Salas y Gómez and Nazca ridges remain a globally unique biodiversity hotspot.

First description of deep benthic habitats and communities of oceanic islands and seamounts of the Nazca Desventuradas Marine Park, Chile

Seamounts and oceanic islands of the Chilean Exclusive Economic Zone at the intersection of the Nazca and Salas y Gómez ridges lie within one of the least explored areas in the world. The sparse information available, mainly for seamounts outside Chilean jurisdiction and shallow-water fauna of the Desventuradas Islands, suggests that the area is a hotspot of endemism. This apparent uniqueness of the fauna motivated the creation of the large Nazca-Desventuradas Marine Park (NDMP, ~ 300,000 km2) around the small islands San Felix and San Ambrosio in 2015. We report for the first time a detailed description of benthic microhabitats (i.e., centimeter to meter scale), macrohabitats (i.e., meter to kilometer-scale) and associated megafauna within the NDMP. Descriptions were based on analysis of fauna collected by trawling and ROV video observations from ~ 50 to 370 m depth. Rocky, coarse sand and silty sediment bottom habitats were observed at island slopes. In contrast, rocky and coarse sandy bottom habitats with a predominance of rhodoliths, thanatocoenosis, and other biogenic components were observed at seamounts. Mobile fauna and predators dominated the oceanic islands and nearby seamounts, whereas seamounts farther from the islands were dominated by sessile and hemisessile fauna that were mainly suspension and deposit feeders. Based on the register of 118 taxonomic units, our results provide an expanded and updated baseline for the benthic biodiversity of NDMP habitats, which seemed pristine, without evidence of trawling or anthropogenic debris.

Environmental Drivers of Mesophotic Echinoderm Assemblages of the Southeastern Pacific Ocean

Mesophotic ecosystems (50–400 m depth) of the southeastern Pacific have rarely been studied because of the logistical challenges in sampling across this remote zone. This study assessed how oxygen concentrations and other environmental predictors explain variation in echinoderm assemblages at these mesophotic systems, where this group is among the predominant fauna. We compiled data on echinoderm taxa at 91 sampling stations, from historical and recent surveys (between 1950 and 2019), covering a longitudinal gradient of approximately 3,700 km along with the Nazca, Salas y Gómez, and Juan Fernández ridges. Uni- and multivariate model-based tools were applied to analyze the patterns of benthic fauna in relation to environmental factors. Our results indicate a significant positive relationship between echinoderm species richness and depth, oxygen, and salinity. Changes in echinoderm community composition were significantly explained by oxygen, longitude, and chlorophyll-a. We observed notable species turnovers at ∼101 and ∼86°W, where assemblages tend to be more variable across stations. This turnover possibly reflects the effects of physical barriers to dispersion (e.g., currents) and habitat changes. Echinoderm assemblages observed around Easter and Desventuradas Islands presented a high occurrence of potentially endemic taxa and distinct species assemblages. This study is the first to assess the structure of mesophotic echinoderm assemblages of the southeastern Pacific Ocean along a large spatial scale. The information reported here could help design appropriate management tools for the vast, recently created, marine protected areas in the southeastern Pacific.

Understanding the impact of climate change on the oceanic circulation in the Chilean island ecoregions

Abstract The largest changes in the circulation of the South‐eastern Pacific resulting from global warming are associated with the southward shift and intensification of the anticyclone and with coastal surface warming. Coastal upwelling is projected to be increase off central Chile, due to an increase in equatorward winds, although increased oceanic stratification and associated enhanced nearshore turbulence will yield an onshore deepening/flattening of the thermocline. The overall increase in south‐easterly trade winds of the South‐eastern Pacific in a warmer climate are likely to increase the connectivity pattern between Juan Fernandez and Desventuradas islands, and along the Sala y Gomez ridge, through increasing wind‐driven mean ocean currents. Deoxygenation associated with the warmer temperatures and changes in ventilation are likely to modify marine habitat and the respiratory barriers of species in the seamounts located in the vicinity of the limits of the minimum oxygen zone. In the South‐eastern Pacific, the prevailing 2D understanding of the responses of marine life to climate change needs to be expanded to 3D approaches, integrating the vertical habitat compression of marine organisms as a result of ocean warming and deoxygenation, as climate velocities for temperature and oxygen have contrasting vertical and horizontal patterns. There is a need for regional biogeochemical‐coupled modelling studies dedicated to the Chilean islands in order to provide an integrated view of the impact of anthropogenic stressors (e.g. deoxygenation, increased stratification, and climate shift) at the scale required for addressing socio‐ecological interactions. A refined understanding of the large‐scale biogeography and spatial dynamics of marine populations through experimentation with high‐resolution regional ocean models is a prerequisite for scaling‐up regional management planning and optimizing the conservation of interconnected marine ecosystems across large scales.

A new species of Munida Leach, 1820 (Crustacea: Decapoda: Anomura: Munididae) from seamounts of the Nazca-Desventuradas Marine Park.

Munida diritas sp. nov. is described for the seamounts near Desventuradas Islands, in the intersection of the Salas & Gómez and Nazca Ridges, Chile. Specimens of the new species were collected in the summit (∼200 m depth) of one seamount and observed by ROV at two nearby ones. This species is characterized by the presence of distinct carinae on the thoracic sternites 6 and 7. Furthermore, it is not related with any species from the continental shelf nor the slope of America, while it is closely related to species of Munida from French Polynesia and the West-Pacific Ocean (i.e., M. ommata, M. psylla and M. rufiantennulata). In situ observations indicate that the species lives among the tentacles of ceriantarid anemones and preys on small crustaceans. The discovery of this new species adds to the knowledge of the highly endemic benthic fauna of seamounts of the newly created Nazca-Desventuradas Marine Park, emphasizing the relevance of this area for marine conservation.

A new species of Eunice Cuvier, 1817 (Polychaeta: Eunicidae) from the slope of the Desventuradas Islands and seamounts of the Nazca Ridge, southeastern Pacific Ocean.

A new species of Eunicidae, Eunice decolorhami sp. n., from the southeastern Pacific Ocean, is described. The species was collected at the slope of the Desventuradas Islands (San Félix and San Ambrosio) and in three nearby seamounts of the Nazca Ridge, in dead coral rubble bottoms from 180 to 340 m depth and inhabiting inside parchment-like branched tubes. Eunice decolorhami sp. n. can be distinguished from other species of the genus, mainly by the coloration pattern of the subacicular hooded hooks along the body segments, the beginning of the subacicular hooded hooks, the beginning of the branchiae, the maximum number of branchial filaments, and the maxillary formula. A key for the seven Eunice species recorded off the coast of Chile and Peru, including the new species described herein, is provided.

Paralarval and juvenile stages as a proxy for cephalopod diversity in the Juan Fernández and Desventuradas ecoregion, southeast Paific Ocean

Southeast Pacific (SEP) oceanic islands are characterized by their extreme isolation and high degree of endemism. To date, most research has focused on species composition and distributions, with little information available on early life stages. In this study, we provide new records of early life stages of cephalopods based on planktonic collections carried out during October and November 2016 around three oceanic islands: San Félix, San Ambrosio (Desventuradas Islands; 26.3°S, 79.8°W), and Alejandro Selkirk (Juan Fernández Archipelago; 33.7°S, 80.7°W), which are part of the Nazca-Desventuradas Marine Park, the largest marine park in the Americas. Twenty-four paralarvae and juveniles were obtained and identified based on morphological characteristics [i.e., mantle length (ML), chromatophore patterns, number and shape of suckers on arms and tentacles] and DNA barcoding [i.e., mitochondrial Cytochrome c Oxidase subunit I (COI) sequences]. Six families were recorded, including Brachioteuthidae, Onychoteuthidae, Tremoctopodidae, Octopodidae, Octopoteuthidae, and Lycoteuthidae. Most individuals (92%) corresponded to larger stages of 4–12 mm ML (Brachioteuthidae, Onychoteuthidae, Tremoctopodidae, and Lycoteuthidae), and 8% were newly hatched paralarvae of around 1 mm ML (Octopodidae and Octopoteuthidae). The DNA barcoding approach validated the identity of Brachioteuthis sp., Onykia aff. robsoni , Octopus mimus, and Tremoctopus sp., with two specific identities (Octopoteuthidae and Lycoteuthis sp.) remaining to be evaluated. ese records provide new information on cephalopod diversity and distribution around SEP islands, adding to the current knowledge about zoogeographic patterns of this group and evidencing their potential relationships with continental or nearby habitats.

Larval development and osteology of Callanthias platei (Teleostei: Callanthiidae) from Desventuradas Islands, South Pacific

Larvae of the Juan Fernández Splendid Perch, Callanthias platei Steindachner, 1898 (Teleostei: Callanthiidae), are described for the first time. The five available specimens, ranging from 3 mm notochord length (NL) to 6.1 mm standard length (SL), were collected with plankton nets near Desventuradas Islands, Southeast Pacific, during the austral spring of 2015 and 2016. The larvae are deep bodied with a narrow caudal peduncle, a large head and a triangular, coiled gut. The pigmentation is scarce in preflexion larvae but increases after flexion. All individuals have several groups of head spines: anterior and posterior preopercular, interopercular, subopercular, opercular and supracleithral. The formation of all fins occurs early in development, with the pectoral fins appearing first and the pelvic fins last. The osteological development of the skull, vertebral column, fins, and scales are described.

A new species of Atrimitra Dall, 1918 (Gastropoda: Mitridae) from seamounts of the recently created Nazca-Desventuradas Marine Park, Chile.

We describe Atrimitra isolata sp. n. (Gastropoda: Mitridae), collected on the summit of seamounts (~200 m water depth) in the vicinity of Desventuradas Islands, Chile insular territory. Additionally, we provide some insight into the habitat of this new species based on underwater imagery taken with a remotely operated vehicle. A. isolata sp. n. is characterized by its small size (up to 26 mm), elongate-ovate shape, solid shell and smooth appearance. It has a base brown color, with some specimens being tan or yellow. It is morphologically related to counterparts from shallow depths on the west coast of North, Central and South America (i.e., Atrimitra idae, Atrimitra orientalis and Atrimitra semigranosa), but has no affinities with species of the family reported from around Easter Island, on the far western side of the Salas y Gómez ridge (e.g., Strigatella flavocingulata, Imbricariopsis punctata and Neocancilla takiisaoi), or with other Indo-Pacific species. The present contribution adds to the knowledge of the poorly studied fauna of the seamounts in the southern portion of the Nazca ridge and easternmost section of the Sala y Gómez ridge, an area characterized by the high degree of endemism of its benthic fauna, and now protected within the large and newly created Nazca-Desventuradas Marine Park.

Record of stomatopods and decapods, including descriptions of the species of commercial interest from the submarine rises and surrounding waters of the Chilean oceanic islands (southeastern Pacific Ocean)

The Chilean oceanic islands are located in the southeastern Pacific Ocean and include Easter Island, Salas y Gomez Island, Desventuradas Islands (San Felix Island and San Ambrosio Island), and the Juan Fernandez Archipelago. They are of volcanic origin and are the emerged peaks of seamounts that form part of the Salas y Gomez and Nazca ranges that rise up from the Nazca tectonic plate. The islands are at a great distance from each other and from the South American continent, and their surrounding areas have depths around 4000 m to the ocean floor. The objective of this study is to update stomatopods and decapods records from these islands, from their surrounding waters and from the seamount ranges of which they are part of. Given that there is little information on some of these sites, and the records are disperse, a literature review is carried out, analysing different sources including both published reports and reports with limited circulation. To date, three families of Stomatopoda with five species and 57 families of Decapoda with 194 species have been recorded. Of this total, three species represent potential resources to develop fisheries and only another three are exploited to differing degrees ( Jasus frontalis , Panulirus pascuensis and Chaceon chilensis ). Their more relevant aspects, including their exploitation status, are described.

Marine Biodiversity in Juan Fernández and Desventuradas Islands, Chile: Global Endemism Hotspots.

The Juan Fernández and Desventuradas islands are among the few oceanic islands belonging to Chile. They possess a unique mix of tropical, subtropical, and temperate marine species, and although close to continental South America, elements of the biota have greater affinities with the central and south Pacific owing to the Humboldt Current, which creates a strong biogeographic barrier between these islands and the continent. The Juan Fernández Archipelago has ~700 people, with the major industry being the fishery for the endemic lobster, Jasus frontalis. The Desventuradas Islands are uninhabited except for a small Chilean military garrison on San Félix Island. We compared the marine biodiversity of these islands across multiple taxonomic groups. At San Ambrosio Island (SA), in Desventuradas, the laminarian kelp (Eisenia cokeri), which is limited to Desventuradas in Chile, accounted for >50% of the benthic cover at wave exposed areas, while more sheltered sites were dominated by sea urchin barrens. The benthos at Robinson Crusoe Island (RC), in the Juan Fernández Archipelago, comprised a diverse mix of macroalgae and invertebrates, a number of which are endemic to the region. The biomass of commercially targeted fishes was >2 times higher in remote sites around RC compared to sheltered locations closest to port, and overall biomass was 35% higher around SA compared to RC, likely reflecting fishing effects around RC. The number of endemic fish species was extremely high at both islands, with 87.5% of the species surveyed at RC and 72% at SA consisting of regional endemics. Remarkably, endemics accounted for 99% of the numerical abundance of fishes surveyed at RC and 96% at SA, which is the highest assemblage-level endemism known for any individual marine ecosystem on earth. Our results highlight the uniqueness and global significance of these biodiversity hotspots exposed to very different fishing pressures.