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Two New Taxa of Goniasteridae (Asteroidea, Echinodermata) and Noteworthy Observations of Deep-Sea Asteroidea by the NOAA Ship Okeanos Explorer in the North and Tropical Atlantic
Abstract
Two new species and one new genus, collected by NOAA ship Okeanos Explorer, Bathyceramaster kelliottae n. sp. and Rhianastra isosceles n. gen., n. sp. (Goniasteridae; Asteroidea) are described from deep-sea settings in the North Atlantic. Two potentially undescribed species are observed from imagery and new in situ observations further elucidate life modes and feeding behavior of several species from North Atlantic deep-sea habitats. New occurrences of Atlantic Neomorphaster are presented and Neomorphaster forcipatus is synonymized with Neomorphaster margaritaceus.
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The Avilés Canyon System (ACS) is located at the Southern Bay of Biscay (Northern Spain, Cantabrian Sea). The ACS occupies a total of 339.026 ha and is composed of three canyons, reaching the abyssal plain at 4700 m depth. Water masses that mix in the area form gyres and upwelling that contribute to increasing the nutrients at different depths, which makes it an important place for the settlement of benthic communities. They have been declared Site of Community Importance (SCI: C ESZZ12003) within the Natura 2000 Network and recognized as a Vulnerable Marine Ecosystem where Echinoderms play an important role in these communities and habitats.
The present study tries to inventory and review asteroid fauna collected during the INDEMARES project in the ACS and compare the new findings with previous studies Official Spanish Checklist (IEEM: “Inventario Español de Especies Marinas”, 2017, 2020) to update our knowledge on the diversity and distribution of the asteroid's species.
During the surveys carried out within the project LIFE + INDEMARES-Avilés Canyon System (2010–2012) a total of 445 specimens, belonging to 25 Asteroids species, were collected from 36 stations in a depth range between 266 and 1476 m. The most frequent species were Nymphaster arenatus (Perrier, 1881) (30.55%) and Henricia caudani (Koehler, 1895) (25%). After public datasets, two species should be considered as new records for Spanish waters: Radiaster tizardi (Sladen, 1882) and Henricia sexradiata (Perrier, 1881), and 4 species expand their bathymetric range: Novodinia pandina (Sladen, 1889), H. caudani, H. sexradiata (Perrier, 1881) and Myxaster perrieri Koehler, 1895.
The Easter Island ecoregion (EIE) is one of the most remote marine areas of the world and encompasses a vast and fragile ecosystem including oceanic islands and seamounts. In January 2014 and March 2016, a remotely operated vehicle was used to explore a subsurface peak off Easter Island (27.23°S, 109.48°W) and a seamount (26.92°S, 110.26°W), respectively located 10 km southwest and 98 km west of the island. More than 950 echinoderms were observed in the 5 h of video recorded during the seven dives conducted at depths between ~ 160 and 280 m. The communities of echinoderms observed at these depths markedly differed from those reported for shallower waters near Easter Island. Of the 20 morphospecies reported in the present study, only 5 were previously reported in the EIE. One species, six genera, and three families were reported for the first time in this area, and two new genera were discovered and described. A preliminary biogeographic analysis suggests affinities between the observed echinoderms and those of the West Pacific. These findings highlight the uniqueness of these assemblages and, therefore, the importance of considering them in the establishment of effective management strategies for these communities, which are within the Rapa Nui marine-protected area created in 2017.
“Marine benthic fauna of the Faroe Islands” (BIOFAR) is a large programme with a focus on collecting invertebrate fauna from the Faroes (62°N and 7°W). Cruises were undertaken from 1987 to 1990, and starfish (Asteroidea, Echinodermata) collected during this time were analysed. Asteroidea were sampled at ~50% of all BIOFAR stations. A Detritus sledge and a Triangular dredge proved to be the most efficient equipment, collecting over 60% of the specimens. In total 2473 specimens were collected from 20 to 1500 m depth, including 41 species from 17 families and 31 genera. Henricia pertusa (O. F. Müller, 1776) group, Pontaster tenuispinus (Düben & Koren, 1846), and Leptychaster arcticus (M. Sars, 1851) showed highest relative abundance. Maximum species diversity was found at 500–700 m depth, which coincides with the transition zone of water masses (North Icelandic Winter Water and Arctic Intermediate Water (NI/AI)) at approximately 400–600 m depth. 63% of the species were recorded at an average-weighted depth above 600 m. Two different ordination methods (detrended correspondence analysis (DCA) and nonmetric multidimensional scaling (NMDS)) gave highly consistent representations of the community structure gradients. The first ordination axis scores did not show significant relationships with any environmental variable. Biological covariates like the presence of Lophelia corals were not significantly related to ordination scores on any axis. The second ordination axis scores were significantly correlated with depth. Temperature and salinity were highly correlated (r=0.90), and both negatively correlated with depth (r=−0.69 and r=−0.57, respectively).
Seamounts in the Ross Sea were surveyed during the New Zealand IPY-CAML research voyage in 2008. Admiralty seamount, and seamounts of the Scott Island Seamount chain (Scott Island, Scott A, Scott B, Scott South) were sampled to examine variability in benthic faunal communities of seamounts. Multivariate analysis of video and still image data showed that benthic community composition was highly variable both within and between seamounts. The distribution patterns of benthic communities varied considerably, with very high densities of certain taxa in some places, sparse fauna in many others, and highly patchy distributions for others. Dissimilarities between seamounts were influenced by differences in population densities of taxa, the proportions of transects in which taxa were present, and by taxa being restricted to only one seamount or group of seamounts. Scott Island seamount was less similar to the others, despite the greater distances between Admiralty and Scott A and B seamounts. The observed variability in community composition was mainly associated with differences in depth, chlorophyll concentration, and seabed rugosity. Results support an earlier hypothesis that the location of seamounts relative to the Ross Sea gyre could be an important factor determining the composition and abundance of benthic invertebrate communities.
The sea pen Ptilosarcus gurneyi Gray provides a major source of food for at least seven predator species in Puget Sound: the asteroids Hippasteria spinosa, Dermasterias imbricata, Crossaster papposus, and Mediaster aequalis, and the nudibranchs Armina californica, Tritonia festiva, and Hermissenda crassicornis. Ptilosarcus is long-lived (15 yr +), takes 5 or 6 yr to reach sexual maturity, and has a spatially clumped pattern of recruitment. It never grows large enough to avoid predation by four of its predators, and the refuges and escape mechanisms of Ptilosarcus are not sufficient to explain its abundance in the face of this predation. Determination of rates of critical life history processes of species involved in this association, e.g., recruitment, growth, and predation, permitted estimates of the effects of the activities of each species on the others in the association. Particular attention was paid to age structure and to the natural history during the periods shortly following metamorphosis of each species. In dense recruitment patches, 97% of Ptilosarcus mortality occurs during the 1st year because of predation by Hermissenda, Tritonia, and Crossaster. Adult pens are eaten by Hippasteria, Dermasterias, Mediaster, and Armina, which together remove 2 pens/m^2@?yr, or 3.1% from the 10 adult year classes combined. The latter four predator species selectively prey upon the largest pens available. The time required for capture and consumption increases at a slower rate with prey size than does prey biomass. Recruitment of the long-lived food specialist Hippasteria seems to be impaired by the spatially unpredictable and clumped nature of Ptilosarcus recruitment. Although the adults have an opulent food supply, the young Hippasteria require small Ptilosarcus to feed on and rarely find enough. The generalists, which are not dependent upon one prey during their recruitment and are able to maintain themselves without Ptilosarcus, could in theory increase until they have reduced the sea pen populations to below the level needed by the specialists and thus outcompete them. However, predation on the generalists by a higher order predator, the asteroid Solaster dawsoni, removes each year at least 9.4% of the adult Mediaster and 38% of the adult Crossaster, a rate at least as great as, and usually greater than, the rate of recruitment into the populations of adult prey. The characteristic organization of the Ptilosarcus association and the existence of Hippasteria may depend upon S. dawsoni.
Ten out of totally 41 species of starfish that were collected around the Faroe Islands during the "BIOFAR" programme extended their previously known distribution area. The species are: Odontaster sp. Verrill, Tremaster mirabilis Verrill, Pseudarchaster gracilis (Sladen), Pteraster (Aptemdon) cf. acicula (Downey), Pteraster obscurus (Perrier), Pteraster pulvillus M. Sars, Neomorphaster margaritaceus (Perrier), Pedicellaster typicus M. Sars, Stephanasterias albula (Stimpson) and Stichastrella rosea (O.F. Müller). P. gracilis, P. (A.) cf. acicula and N. margaritaceus are for the first time reported as far north as to the Faroe Islands. O. obscurus has extended its depth range down to 600 m.
New data on deep-sea starfish from the North Atlantic are presented, based on samples obtained in the Charlie-Gibbs Fracture Zone area on three cruises of the RRS James Cook (years 2007, 2009 and 2010) in the framework of the ECOMAR project. Asteroids were collected at 19 stations at depths between 2272 and 2750 m. The collection includes 30 species, 11 of them recorded for the first time on the northern Mid-Atlantic Ridge. Two new species of Hymenaster are described. For some species geographical and depth ranges were extended. An annotated checklist of asteroids collected on the ECOMAR cruises is provided.
In this second contribution the author refers the equinoids and asteroids of the Oceanographical Institute collection (São Paulo University - Brazil), obtained at the brazilian coast, from Fernando de Noronha island to near Uruguay (Palmas). In this paper there are 14 species pertaining to 9 families. On studying the geographical distribution, the author has observed with special interest, that species like Mellita platensis, Astropecten brasiliensis and A. cingulatus go on to the south in its distribution, reaching the Buenos Aires Provincia.
O’Loughlin, P.M., and Waters, J.M., 2004. A molecular and morphological revision of genera of Asterinidae (Echinodermata: Asteroidea). Memoirs of Museum Victoria 61(1): 1‐40. A molecular phylogeny has inspired a reappraisal of the systematics of the Asterinidae. New morphological characters are defined and illustrated and used to diagnose all genera. A table of the distribution of morphological characters among genera and key for genera of Asterinidae are provided. New genera of Asterinidae are erected: Aquilonastra O’Loughlin, Indianastra O’Loughlin, Parvulastra O’Loughlin and Pseudopatiria O’Loughlin. Patiria is raised out of synonymy with Asterina. Allopatiria is a junior synonym of Asterina, Manasterina is a junior synonym of Disasterina, and Paxillasterina is a junior synonym of Asterinides. The genus Asterinopsis and the genus and species Desmopatiria flexilis are nomina nuda. Patiriella tangribensis is a nomen dubium. Genera reviewed are: Anseropoda, Asterina, Asterinides, Callopatiria, Cryptasterina, Disasterina, Kampylaster, Meridiastra, Nepanthia, Paranepanthia, Patiria, Patiriella, Pseudasterina, Pseudonepanthia, Stegnaster, Tegulaster and Tremaster. Asterina cephea var. iranica is raised to species status. Enoplopatiria siderea is a junior synonym of Asterina stellifera. Disasterina leptalacantha var. africana is no longer recognised as a subspecies. Disasterina spinulifera is a junior synonym of Disasterina praesignis. A synonymy of Tremaster novaecaledoniae with Tremaster mirabilis is formalised. Asterinid species reassigned on the basis of molecular evidence and morphological congruity are new combinations: Aquilonastra anomala, A. batheri, A. burtoni, A. coronata, A. minor, A. scobinata, Meridiastra calcar, M. gunnii, M. medius, M. mortenseni, M. occidens, M. oriens, Paranepanthia aucklandensis, Parvulastra calcarata, P. exigua, P. parvivipara, P. vivipara, Patiria chilensis, P. miniata, P. pectinifera. Species reassigned on the basis of morphological evidence are new combinations: Aquilonastra cepheus, A. corallicola, A. heteractis, A. iranica, A. limboonkengi, A. rosea, Asterina ocellifera, Asterinides hartmeyeri, A. pilosa, A. pompom, Disasterina ceylanica, D. longispina, Indianastra inopinata, I. sarasini, Nepanthia pedicellaris, Parvulastra dyscrita, Pseudonepanthia briareus, P. gracilis, P. grangei, P. nigrobrunnea, P. reinga, P. troughtoni, Pseudopatiria obtusa, Tegulaster alba, T. leptalacantha, T. praesignis. Three species remain incertae sedis: Asterina lorioli, Asterina novaezelandiae and Nepanthia brachiata. A table of asterinid species is provided, with original and current combinations. It is concluded that Asterinidae is a cosmopolitan family, mainly of shallow-water narrow-range genera but including some more widespread in deeper waters of all oceans.
Observations were made with scuba on the diet and behavior of 18 species of undisturbed sea stars in their natural habitats along the shores of Washington state through all seasons. Some sea stars are specialists. Hippasteria spinosa feeds almost exclusively on a sea pen; Solaster stimpsoni eats holothurians; full-sized Orthasterias koehleri consume the venerid clam Humilaria; Solaster dawsoni eats its congener S. stimpsoni. Others show remarkably variable diets. In different habitats, Dermasterias imbricata specializes on either anemones, holothurians or sea pens, but within these habitats its diet is consistent throughout the year. The diet of Mediaster aequalis varies with both habitat and season. Pycnopodia helianthoides feeds on sea urchins on rocky substrata but digs clams from sand and cobble. Many other sea stars, including Luidia foliolata, Pteraster tesselatus, Pisater ochraceus, Evasterias troschelii and Leptasterias hexactis, are quite generalized in their diet and, though often demonstrating preferences in laboratory studies, will feed on a variety of prey determined largely by relative abundance of prey species in the particular habitat. The areal and seasonal variation in the diet of sea stars coupled with the reluctance of some to eat any prey in the laboratory makes extension of laboratory observations to the field diet suspect. Laboratory observations can be used to provide a more detailed understanding of field observations. Several previously undescribed behavioral mechanisms of food capture in asterioids and escape or defense responses or prey are described: Orthasterias pulls chips of shell off Humilaria until an opening is made, thus allowing exploitation of a prey species unavailable to other clam-eating asteroids. A number of sea stars, such as Luidia, Hippasteria, Mediaster, Pisaster brevispinus, Orthasterias and Pycnopodia dig into mud, sand or cobble substrata to obtain infaunal prey. The locomotory patterns of S. dawsoni and Crossaster papposus tend to allow encounter with their prey in such a way as to reduce the effectiveness of the escape response. A "pushing" response by Solaster stimpsoni and autotomy in Pycnopodia and Evasterias are thought to be effective responses to S. dawsoni predation. The similar swimming responses to two anemones, a nudibranch, and a holothurian are discussed in relation to asteroid predation. The avoidance responses that many invertebrates show to asteroids are correlated with predator-prey relationships. Two mechanisms may obscure this correlation. The very success of the response may effectively remove the responding organism from the predator's diet. Thus scallops, although abundant, form a very inconspicuous portion of starfish diet. Also biochemical similarities between the predator and other organisms may make a prey species unable to distinguish only its predator. Thus Pycnopodia will move rapidly away from Crossaster and Solaster stimpsoni as well as from S. dawsoni, although the latter is its only asteroid predator. The similarities may be based either on a close taxonomic relationship with the predator, or on the diet of the other organism including species closely related to the responding prey species.
The composition, taxonomic structure and distribution patterns of bathyal benthic fauna of the northern Mid-Atlantic Ridge between the Azores and the southern tip of the Reykjanes Ridge were studied from specimens collected on the ECON) and in two areas around the Charlie-Gibbs Fracture Zone (CGFZ) (51N) at depths 1237ECO benthic fauna was dominated by echinoderms (49.5% of the total species sampled), sponges (18.2%) and anthozoans (16.7%). Between-station species similarity was analysed using non-metric multidimensional scaling. Our analysis revealed differences between stations from the CGFZ and the Azorean regions. Stations from the Azores formed one cluster whereas stations from the CGFZ separated into two groups related to depth: stations from depths 1263 m to 1916 m and those from 2350 m to 3512 m. The taxonomic structure of the bathyal fauna was also different in the Azores than in the CGFZ areas. At the CGFZ, taxa with the highest percentage of species present were different above and below the 2000 m bathymetric contour, in contrast close to the Azores taxa with the highest percentage of species were the same shallower and deeper than 2000 m. Our results point at turnover in benthic bathyal fauna between the Charlie-Gibbs Fracture Zone and the Azores, which could be related to the presence of the Sub-Polar Front.
A phylogenetic analysis of 13 taxa and 32 characters resulted in a single most parsimonious tree that supports monophyly of the goniasterid (Echinodermata, Asteroidea) genus Circeaster Koehler, 1909 and supports re-establishment of the genus Lydiaster Koehler, 1909. Th e phylogeny supports monophyly of the ingroup, including 10 species, six of which, C. kristinae n. sp., C. helenae n. sp., C. arandae n. sp., C. loisetteae n. sp., C. sandrae n. sp., and C. pullus n. sp., are new. Phylogenetic results support diversifi cation into the Indian, Pacifi c, and Atlantic ocean basins. Th e phylogeny is constrained by a sister taxon with a Cretaceous fossil occurrence and two geologic events, including the closure of the Indonesian seaway and formation of the Panamanian isthmus. Th ese events formed barriers limiting or preventing larval dispersal between the Indian/Pacifi c and the Pacifi c/Atlantic oceans. Larval dispersal through a deep-sea environment was a signifi cant consideration for estimating timing constraints from paleo- environments. Based on fossil constraints, ancestry for the lineage is suggested as early as the Late Cretaceous with subsequent diversifi cation in the Cenozoic. In situ observations of Circeaster perched on bare deep-sea coral skeletons and morphological similarities with other known corallivorous goniasterids suggest important ecological roles in the deep-sea.
Members of the Asteroidea (phylum Echinodermata), popularly known as starfish or sea stars, are ecologically important and diverse members of marine ecosystems in all of the world's oceans. We present a comprehensive overview of diversity and phylogeny as they have figured into the evolution of the Asteroidea from Paleozoic to the living fauna. Living post-Paleozoic asteroids, the Neoasteroidea, are morphologically separate from those in the Paleozoic. Early Paleozoic asteroid faunas were diverse and displayed morphology that foreshadowed later living taxa. Preservation presents significant difficulties, but fossil occurrence and current accounts suggests a diverse Paleozoic fauna, which underwent extinction around the Permian-Triassic interval was followed by re-diversification of at least one surviving lineage. Ongoing phylogenetic classification debates include the status of the Paxillosida and the Concentricycloidea. Fossil and molecular evidence has been and continues to be part of the ongoing evolution of asteroid phylogenetic research. The modern lineages of asteroids include the Valvatacea, the Forcipulatacea, the Spinlosida, and the Velatida. We present an overview of diversity in these taxa, as well as brief notes on broader significance, ecology, and functional morphology of each. Although much asteroid taxonomy is stable, many new taxa remain to be discovered with many new species currently awaiting description. The Goniasteridae is currently one of the most diverse families within the Asteroidea. New data from molecular phylogenetics and the advent of global biodiversity databases, such as the World Asteroidea Database (http://www.marinespecies.org/Asteroidea/) present important new springboards for understanding the global biodiversity and evolution of asteroids.
Assessment of Antarctic taxonomic diversity for asteroids and other taxa for poorly studied or unknown regions, such as the deep-sea, will be important for our understanding of these understudied habitats. Eleven new species and a new genus are described from three families (Asterinidae, Goniasteridae, Solasteridae) within the Valvatida, nearly all of which were collected from deep-sea settings below 1000 m by the US Antarctic Research Program in the 1960s. A new subfamily, the Kampylasterinae subfam. nov. is designated for Kampylaster and Astrotholus nov. gen. which were supported as sister taxa on a monophyletic clade within the Asterinidae. Astrotholus nov. gen. is described to accommodate “Anseropoda” antarctica and four new bathyal and abyssal species, which are a significant morphological divergence from the typological definition of Anseropoda. New species of the goniasterid Notioceramus and the solasterid Paralophaster are also described from bathyal depths (2000–3000 m). Paralophaster ferax n. sp. is among the deepest asteroids known to brood, is the first brooding species within Paralophaster and the second species in the Solasteridae known to brood. Following examination of the type and molecular data, Lophaster densus is found to be included within Paralophaster. A review of Antarctic Lophaster species shows additional specimens of Lophaster abbreviatus which support it as a distinct species from Lophaster stellans. New occurrence data for bathyal Antarctic Asteroidea as well as unusual-gut content observations of shallower-water species are also included.
Between 2015 and 2018, the NOAA ship Okeanos Explorer embarked on the CAPSTONE expedition, that collected video and specimen data from the Hawaiian Islands region and other American territories in the Central and South Pacific Ocean. Ultimately 20 species, 12 of which are newly described, from 14 genera in 3 families are described herein with one further undescribed species of Pythonaster currently in preparation. Okeanos Explorer collected a total of 17 sea star specimens, of which 9 represent new species and 4 new genera. Additionally, one species imaged by Okeanos Explorer during the campaign was discovered in a museum collection is described herein. Supplementary collections from the tropical Pacific by the R/V Nautilus resulted in a further 11th newly described species which had been originally observed by Okeanos Explorer. A total of 21 specimens were involved as part of this effort. Heligmaster n. gen. is the first new genus of the rarely encountered deep-sea Myxasteridae since Fisher (1906). The Goniasteridae, particularly the corallivorous subfamily Hippasterinae were most heavily represented in the collected material. Video imagery was extensive and provided new occurrence data for rarely seen species as well as several new records that likely represent undescribed species. Many of the new species collected were observed preying on of deep-sea octocorals and sponges.
Recent expeditions to Rapa Nui (also known as Easter Island) and New Caledonia have revealed undescribed species from mesophotic and deeper depths. This includes three new species from Rapa Nui, Hacelia raaraa, Linckia profunda (Ophidiasteridae), Uokeaster ahi (Asterodiscididae) and two new species from New Caledonia, Astroglypha pyramidata n. gen. and Ophidiaster colossus (Ophidiasteridae). The new genus Astroglypha is described for A. pyramidata but the genus also includes the Atlantic Tamaria passiflora, which is reassigned herein. Pauliastra n. gen. is designated as a replacement for the homonym issue with Pauliella. New occurrences and synonymies are addressed for taxa related to New Caledonia, Rapa Nui and adjacent regions. A morphology based phylogenetic analysis agrees with prior work which placed Goniaster among the Asterodiscididae and posits biogeographic relationships among asterodiscidid genera. Implications for the Goniasteridae and placement of Goniaster among asterodiscidid genera are discussed. Biogeography and relationships among taxa from Rapa Nui and New Caledonia are reviewed. In situ observations from species observed from Rapa Nui are included.
Exploratory cruises by the NOAA Ship Okeanos Explorer have resulted in a substantial contribution in our understanding of deep-sea echinoderm biodiversity, biology, and ecology in the North Atlantic. This includes the description and in situ feeding observations of two, new corallivorous goniasterid species, Evoplosoma nizinskiae n. sp. and Sibogaster bathyheuretor n. sp. Significant in situ observations include a synchronous feeding event including multiple goniasterid asteroids and a cidaroid urchin on a large demosponge, providing new data for understanding echinoderm feeding behavior, including agonistic behavior, in deep-sea settings and new, in situ feeding observations for 28 deep-sea species including the myxasterid Pythonaster atlantidis, the korethrasterid Remaster palmatus and the poorly understood hippasterine goniasterids, Gilbertaster caribaea and Sthenaster emmae.
In more than 150 years of research in the waters surrounding the Azores, several publications on the fauna of echinoderms of the archipelago have been produced, in the form of papers, notes, reports, reviews, and monographs. This work attempts to summarize the present knowledge on this marine group in the Azorean exclusive economic zone (i.e., waters within 200 nautical miles of the archipelago’s shores). A short review of the history of the species’ taxonomy is given, with key references, geographical distribution, ecology, additional notes and, when possible, figures. We herein report 172 species of echinoderms (6 crinoids, 55 ophiuroids, 45 asteroids, 36 holothurians, and 30 echinoids) from the Azores Archipelago, most of them inhabiting deep waters (>200 m). Only 29 shallow-water species were recorded locally (≤50 m depth). In general, the echinoderm species present in the Azores are characterized by a wide geographical distribution in the Atlantic Ocean. Only nine taxa (all deep-water species, >840 m) appear to be restricted to the Azorean waters. Overall, the knowledge of the echinoderm fauna of the Azores is out-dated, with many species last collected in the archipelago over 100 years ago. A recent interest in the Azorean Mid-Atlantic waters has brought oceanographic cruises back to the archipelago, thus providing new opportunities for the renewal of 150 years of echinoderm studies in the area.
Modern goniasterids are the most numerous of living asteroids in terms of described genera and species and they have important ecological roles from shallow to deep-water marine habitats. Recent MNHN expeditions and historical collections in the USNM have resulted in the discovery of 18 new species, three new genera and multiple new occurrence records from the western Indian Ocean region including Madagascar, Glorioso and Mayotte islands, Walters Shoal, South Africa, and Somalia. This report provides the first significant contribution to knowledge of deep-sea Asteroidea from the Indian Ocean since the late 20th Century. Several deep-sea species, previously known from the North Pacific are now reported from the western Indian Ocean. Gut contents from Stellaster and Ogmaster indicate deposit feeding. Feeding modes of this and other deep-sea species are discussed. Comments are made on fossil members of included taxa. A checklist of Indian Ocean Goniasteridae is also included.
Multi-locus phylogenetic studies of echinoderms based on Sanger and RNA-seq technologies and the fossil record have provided evidence for the Asterozoa-Echinozoa hypothesis. This hypothesis posits a sister relationship between asterozoan classes (Asteroidea and Ophiuroidea) and a similar relationship between echinozoan classes (Echinoidea and Holothuroidea). Despite this consensus around Asterozoa-Echinozoa, phylogenetic relationships within the class Asteroidea (sea stars or starfish) have been controversial for over a century. Open questions include relationships within asteroids and the status of the enigmatic taxon Xyloplax. Xyloplax is thought by some to represent a newly discovered sixth class of echinoderms – and by others to be an asteroid. To address these questions, we applied a novel workflow to a large RNA-seq dataset that encompassed a broad taxonomic and genomic sample. This study included 15 species sampled from all extant orders and 13 families, plus four ophiuroid species as an outgroup. To expand the taxonomic coverage, the study also incorporated five previously published transcriptomes and one previously published expressed sequence tags (EST) dataset. We developed and applied methods that used a range of alignment parameters with increasing permissiveness in terms of gap characters present within an alignment. This procedure facilitated the selection of phylogenomic data subsets from large amounts of transcriptome data. The results included 19 nested data subsets that ranged from 37 to 4281 loci. Tree searches on all data subsets reconstructed Xyloplax as a velatid asteroid rather than a new class. This result implies that asteroid morphology remains labile well beyond the establishment of the body plan of the group. In the phylogenetic tree with the highest average asteroid nodal support several monophyletic groups were recovered. In this tree, Forcipulatida and Velatida are monophyletic and form a clade that includes Brisingida as sister to Forcipulatida. Xyloplax is consistently recovered as sister to Pteraster. Paxillosida and Spinulosida are each monophyletic, with Notomyotida as sister to the Paxillosida. Valvatida is recovered as paraphyletic. The results from other data subsets are largely consistent with these results. Our results support the hypothesis that the earliest divergence event among extant asteroids separated Velatida and Forcipulatacea from Valvatacea and Spinulosida.
Research cruises by the Monterey Bay Aquarium Research Institute (MBARI) have resulted in the discovery of three new species of asteroids from the lower bathyal/abyssal regions of the North Pacific. A new genus, Bathyceramaster is described to accommodate "Mediaster" elegans Ludwig 1905 and related species. New records and in situ observations are also presented. An identification key and taxonomic account of the deep-sea Goniasteridae known from this region including one new genus and two new species is included. An overview of the genus Sibogaster, including a new widely occurring species, is also included.
A review of high-latitude Goniasteridae south of 50°S is presented, including a key to species, figures and taxonomic descriptions of all species with a brief taxonomic summary for all genera. Nineteen species in 11 genera are reviewed. Era-tosaster jenae nov. gen and sp., Chitonaster trangae nov. sp., and Pillsburiaster calvus nov. sp. are described. Several taxa, including Chitonaster, have not been reviewed since their initial description and revision of the group has clarified taxonomic boundaries between species. The genus Pentoplia is a junior synonym of Chitonaster. Rarely encountered species, synonyms, and range extensions are reported for multiple species.
A new species of corallivorous goniasterid, Evoplosoma watlingi n. sp., from Bear Seamount in the North Atlantic is described in conjunction with an overview of other species within the genus Evoplosoma. Hippasteria tasmanica McKnight, 2006 is re-classified within Evoplosoma. In situ images of Atlantic deep-sea Goniasteridae, including Evoplosoma spp., Hippasteria phrygiana and Circeaster americanus, are presented herein. Observations of several Evoplosoma species and the Atlantic C. americanus are documented for the first time, recorded by the R/V Okeanos Explorer. The feeding duration of C. americanus is also documented for the first time.
New molecular phylogenetic data and new specimens provide the basis for a revision of the family Poraniidae. We present molecular phylogenetic data for five out of 11 genera in the Poraniidae including a newly discovered taxon from the North Pacific. Bathyporania ascendens nov. gen., nov. sp., is described from Davidson Seamount (35º43'N, 122º43'W). Another newly discovered poraniid taxon, Clavaporania fitchorum nov. gen., nov. sp. is described from south of Macquarie Island (56º21'S, 158º 28'E) but was not included in the analysis. Revision of the Poraniidae has been undertaken. We present two new genera and reinstate the previously synonymized genus Glabraster and return Culcitopsis to genus level. The genus Porania sensu Clark (1993) and Clark and Downey (1992) is not monophyletic. Porania, Poraniomorpha and Poraniopsis are revised. In situ feeding observations of Bathyporania are described and compared with other poraniid feeding accounts.
Asteroids (sea stars) can be important predators in benthic communities and are often present in ecologically important and vulnerable deep-sea coral and sponge habitats. However, explicit studies on the trophic ecology of deep-sea asteroids are rare. We investigated the diets of seven species of deep-sea asteroid from the bathyal zone of Newfoundland and Labrador, eastern Canada. A multifaceted approach including live animal observations, stomach content analysis, and stable isotope analysis revealed the asteroids to be either top predators of megafauna or secondary consumers (mud ingesters, infaunal predators, and suspension feeders). The stable isotope signatures of Ceramaster granularis, Hippasteria phrygiana, and Mediaster bairdi are characteristic of high-level predators, having δ15N values 4.4‰ (more than one trophic level) above Ctenodiscus crispatus, Leptychaster arcticus, Novodinia americana, and Zoroaster fulgens. We present strong evidence that corals and sponges are common food items for two of the predatory species, C. granularis and H. phrygiana. During laboratory feeding trials, live H. phrygiana fed on several species of soft coral and C. granularis fed on sponges. Stomach content analysis of wild-caught individuals revealed sclerites from sea pens (e.g. Pennatula sp.) in the stomachs of both asteroid species; H. phrygiana also contained sclerites from at least two other species of octocoral and siliceous sponge spicules were present in the stomachs of C. granularis. The stomach contents of the secondary consumers contained a range of invertebrate material. Leptychaster arcticus and Ctenodiscus crispatus feed infaunally on bulk sediment and molluscs, Zoroaster fulgens is a generalist infaunal predator, and the brisingid Novodinia americana is a specialist suspension feeder on benthopelagic crustaceans. This study provides a foundation for understanding the ecological roles of bathyal asteroids, and suggests that some species may have the potential to be important modulators of deep-sea benthic communities.
Introduction ... 3 List of the stations, where Asteroidea were collected ... 4 Taxonomic report ... 11 Survey of the species ... 18 Literature cited ... 82 Explanation of the plates ... 88 Index ... 90 INTRODUCTION The present paper deals with the Asteroidea (Echinodermata), collected during two surveys of the continental shelf of Surinam (O. C. P. S. I & II) carried out in the spring of 1966 and 1969 by H . N L . M . S. Snellius and H. N L . M . S. Luymes, respectively. During my studies I have identified and classified the sea-stars of the bottom-samples. I have also tried to solve nomenclatural problems and to correct some nomenclatural conceptions, with which I did not agree. For each species I have composed the distributional pattern from records in the literature. During the surveys "it proved to be possible to correlate the zoological work with the geomorphological and sedimentological survey of the shelf bottom" (Vervoort, 1967, 1971, these papers can be considered as an introduction to this report).
In all previous studies involving the behavior of the cushion star Pteraster tesselatus Ives, the possibility that this asteroid's copious secretions of mucus are defensive in nature has been suggested, but never studied to any degree. Our research shows that discharge of mucus from Pteraster was triggered not only by physical stimulation, but also from contact with the asteroid-consuming sea stars Solaster dawsoni Verrill and Pycnopodia helianthoides (Brandt). It was also found that mucus repelled these two asteroids so effectively that it provided Pteraster tesselatus with protection from predation for essentially 100% of the time. Pteraster specimens were easily and harmlessly rendered defenseless by removing their mucous-cell-containing supradorsal membranes by dissection. Without the mucous secretions available for discharge, it was shown that P. tesselatus was easily preyed upon by both Solaster dawsoni and Pycnopodia helianthoides.
Benthic organisms in marine ecosystems modify the environment on different spatial and temporal scales. These modifications, many of which are initially at a microscale, are likely to have large scale effects on benthic seascapes. This is especially so if the species are ecosystem engineers. Most species of infaunal and epifaunal invertebrates and macrophytes contribute at a geophysical or geochemical level. Microorganisms also play a key but currently neglected role. In the intertidal and immediately sublittoral zone, algae and seagrasses, and mussels in mussel beds have received considerable attention. A substantial fossil record also exists. Mathematical modelling of these systems is still in its infancy, although several sophisticated mathematical tools have been applied. The effects of bioturbation and of microorganisms have been less studied, and little is known about the activities of benthic organisms in the deep sea. This paper addresses all these effects, and places them in the context of large scale benthic seascapes and of the extensive literature on species defined as ecosystem engineers in the sea.
In the course of this work over 3000 specimens were examined and recorded. These came from the two largest collections in New Zealand, NIWA (incorporating the New Zealand Oceanographic Institute) and the Museum of New Zealand. Collections at the Auckland Museum were also reviewed. The order Paxillosida is represented by four families-Luidiidae (1 genus, 5 species), Astropectinidae (8 genera, 24 species), Radiasteridae (1 genus, 2 species), and Porcellanasteridae (5 genera, 7 species). There are eight new species. The order Notomyotida is represented by one family-Benthopectinidae (3 genera, 12 species, none new). Specimens were collected from very shallow tidal areas to nearly 5000 m. A typical specimen is described in detail for each species, and geographic distribution and variations in depth are also discussed. Photographs and drawings of relevant parts are included. In three very common species with many individuals (Astromesites primigenius, Astropecten polyacanthus, and Psilaster acuminatus), a number of specimens were dissected and stomach contents listed. No parasites were observed. Dissected specimens appeared to be in good condition with generally well-developed gonads. Notes on internal anatomy and other features of interest are included where applicable.
CONTENTS Introduction.......... 3 Acknowledgements........ 4 List of the stations where Asteroidea were collected........ 4 Taxonomic report......... 7 Identification.......... 9 Survey of the species........ 11 Literature cited......... 88 Index............ 95 INTRODUCTION In a previous paper (Walenkamp, 1976) a revision was given of the Asteroidea of the coastal waters of Surinam. Since the preparation of that paper new material, collected in 1970 by the "Luymes" Guyana Shelf Expedition, became available. The present report is based on this new material. The 1970 expedition not only explored the waters off Surinam, but also the continental shelf off Guyana and French Guyana, and, moreover, investigated deeper waters than the O.C.P.S. expeditions dealt with in my 1976 paper. As a result fourteen species were taken, which were not represented in the collections of the previous expeditions. The present report, which can be considered a supplement to the 1976 report, has the same set-up. Of the newly found species synonymy and full descriptions are given. For the other species I may refer to the 1976 descriptions. In addition to the material mentioned above, a small collection of Asteroidea, property of the Surinaams Museum, Paramaribo, is included. These
Eleven species of goniasterid sea stars collected by the R/V Gerda during a biological survey of the Straits of Florida were studied. Each is fully described and illustrated. A key to all the goniasterid genera in the tropical western Atlantic is provided.Wide variations occur within many of the species, and as a result, many invalid nominal species have been described. Thus, a good deal of taxonomic revision is made. Ceramaster affinis is made a junior synonym of C. grenadensis. The genus Peltaster is delimited and placenta placed in it. Peltaster planus is made a junior synonym of P. placenta. Plinthaster perrieri, P. nitidus, and P. comptus are made junior synonyms of P. dentatus. Lydiaster is made a junior synonym of Circeaster, and Circeaster occidentalis is made a junior synonym of C. americanus.
The Zoroasteridae comprise a small but widespread family of asteroids distributed throughout the deep sea. Although poorly understood, they are often collected in the hundreds, suggesting that they occupy important ecological roles. A phylogenetic analysis including 24 terminal taxa and 70 morphological characters was performed, resulting in a single most-parsimonious tree. The tree separated zoroasterids with open, reticulate skeletons (e.g. Myxoderma) as more basal than those with more heavily armored, imbricate skeletons (e.g. Zoroaster), which were more derived. In addition to agreement with established genera, a new genus is supported by the phylogeny as the sister taxon to Myxoderma. The cladistic analysis was performed in conjunction with a revisionary survey of zoroasterid species, resulting in taxonomic changes to species in nearly every genus. Bathymetric and physiographic shifts were observed between the reticulate and imbricate zoroasterid clades. Zoroasterids possess a single marginal plate series, which occurs in basal sister-group neoasteroids (crown-group asteroids). Phylogenetic results suggest that the morphololgical resemblance between zoroasterids and Palaeozoic taxa, such as Calliasterella, is convergent but a paraphyletic Zoroasteride cannot be rejected and remains consistent with basal crown-group affinities. Although the phylogenetic position of the Eocene Zoroaster aff. fulgens was not strongly supported, its presence within a derived cluster of Zoroaster spp. suggests a relatively recent (i.e. Cenozoic) diversification into the deep sea. Taxonomic revisions, and geographical and bathymetric range extensions are also included. © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society, 2007, 150, 177–210.
Zoroaster fulgens is a slope-dwelling seastar species that is distributed throughout the Atlantic Ocean. Studies into the population structure and systematics of marine animals have increasingly found that species with a reported cosmopolitan distribution are, in fact, collections of closely related cryptic or sibling species. In the Porcupine Seabight, three morphotypes of Z. fulgens can be found that have a distribution that is stratified by depth. This study investigates the genetic divergence between these morphotypes using sections of the cytochrome oxidase 1 (COI) and 16S regions of the mitochondrial genome. Bathymetrically separated morphotypes of Z. fulgens are reproductively isolated over distances of approximately 1km while gene flow occurs among morphotypes, along isobaths, over distances of approximately 900km. Reproductive isolation on the continental slope may have occurred as a result of selection exerted by gradients of depth-correlated physical factors, such as pressure and temperature. However, allopatric speciation with subsequent range expansion may also explain the observed patterns of genetic divergence. Further investigation of radiation within this group may provide important information on the evolution of slope species. Taxonomic revision of the genus is required.
The Valvatacea is one the most ecologically important, taxonomically diverse, and widespread groups of post-Palaeozoic (i.e. modern) Asteroidea. Classification within the group has been historically problematic. We present a comprehensively sampled, three-gene (12S, 16S, early-stage histone H3) molecular phylogenetic analysis of the Valvatacea. We include five of the six families within the Paxillosida, the monotypic Notomyotida, and 13 of the 16 families of the living Valvatida. The Solasteridae is removed from the Velatida (Spinulosacea) and joins the Ganeriidae and the Leilasteridae as members of the clade containing the Asterinidae. The Poraniidae is supported as the sister group to the large cluster of Valvatacea. Asteropseids and poraniids are phylogenetically distant, contrary to morphological evidence. Several goniasterid-like ophidiasterids, such as Fromia and Neoferdina are supported as derived goniasterids rather than as Ophidiasteridae. The Benthopectinidae (Notomyotida) are supported as members of the Paxillosida as are two members of the Pseudarchasterinae that have traditionally been considered members of the Goniasteridae. Our data suggest that Antarctic valvataceans may be derived from sister taxa in adjacent regions.
© 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 161, 769–788.
The Hippasterinae is a subfamily within the Goniasteridae, consisting of five genera and 26 species, which occur in cold-water settings ranging from subtidal to abyssal depths. All known genera were included in a cladistic analysis resulting in two most parsimonious trees, supporting the Hippasterinae as monophyletic. Our review supports Sthenaster emmae gen. etsp. nov. as a new genus and species from the tropical Atlantic and two new Evoplosoma species, Evoplosoma claguei sp. nov. and Evoplosoma voratus sp. nov. from seamounts in the North Pacific. Hippasteria caribaea is reassigned to the genus Gilbertaster, which previously contained a single Pacific species. Our analysis supports Evoplosoma as a derived deep water lineage relative to its continental-shelf, shallow water sister taxa. The genus Hippasteria contains approximately 15 widely distributed, but similar-looking species, which occur in the northern and southern hemispheres. Except for Gilbertaster, at least one species in each genus has been observed or is inferred to prey on deep-sea corals, suggesting that this lineage is important to the conservation of deep-sea coral habitats. The Hippasterinae shares several morphological similarities with Circeaster and Calliaster, suggesting that they may be related.
© 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160, 266–301.