1,721,254 research outputs found
FIGURE1 in New Sericosura (Pycnogonida: Ammotheidae) from deep-sea hydrothermal vents in the Southern Ocean
No full textFIGURE1. Location of the East Scotia Ridge hydrothermal vents, Southern Ocean. Inset shows the three sites E2, E9 and Kemp Caldera, sampled by ROV Isis where pycnogonids were collected during the ChEsSo expedition JC42 in 2010.Published as part of Arango, Claudia P. & Linse, Katrin, 2015, New Sericosura (Pycnogonida: Ammotheidae) from deep-sea hydrothermal vents in the Southern Ocean, pp. 37-50 in Zootaxa 3995 (1) on page 38, DOI: 10.11646/zootaxa.3995.1.5, http://zenodo.org/record/28917
FIGURE 5 in A new species of Raricirrus (Annelida: Cirratuliformia) from deep-water sunken wood off California
No full textFIGURE 5. Phylogenetic tree from the Bayesian analysis of a combined dataset with 16S and COI using in total 32 cirratuliform polychaetes. Numbers on branches are posterior probability values.Published as part of Magalhães, Wagner F., Linse, Katrin & Wiklund, Helena, 2017, A new species of Raricirrus (Annelida: Cirratuliformia) from deep-water sunken wood off California, pp. 51-68 in Zootaxa 4353 (1) on page 61, DOI: 10.11646/zootaxa.4353.1.3, http://zenodo.org/record/106450
An unusual hermaphrodite reproductive trait in the Antarctic brooding bivalve Lissarca miliaris (Philobryidae) from the Scotia Sea, Southern Ocean
No full textThe Antarctic marine environment is extreme in its low temperatures and short periods of primary productivity. Invertebrates must therefore adapt to maximise reproductive output where low temperature and limited food slows larval development. Brooding is a common reproductive trait in Antarctic marine bivalves; larval development occurs within the mantle cavity, and larvae are released as fully developed young. Lissarca miliaris is a small, short lived, shallow-water brooding bivalve of circum-Antarctic distribution and found most abundant in the sub-Antarctic Magellan Region and islands of the Scotia Arc. Here, an unusual hermaphrodite reproductive trait is described for L. miliaris from King George Island (62?14’S, 58?38’W) and Signy Island (60?42’S, 45?36’W), Antarctica, using histological and dissection techniques. Specimens demonstrate simultaneous and sequential hermaphrodite traits; male and female gonads develop simultaneously but the production of oocytes is reduced while testes are ripe. Functional females are more abundant in specimens above 3mm shell length, although male reproductive tissue persists and functional males are found in all size classes. The number of previtellogenic oocytes produced by far exceeds the number of oocytes extruded and brooded, which may indicate an ancestral link to a planktotrophic past. Hermaphroditism in L. miliaris maximises reproductive efficiency in a short-lived species in which the female’s capacity to brood its young is limited, and demonstrates a specialised adaptation to a cold stenothermal and food limited environment prevailing in the Southern Ocean
A new species of Eualus Thallwitz, 1891 and new record of Lebbeus antarcticus (Hale, 1941) (Crustacea: Decapoda; Caridea; Hippolytidae) from the Scotia Sea
Full text linkEleven specimens representing two hippolytid genera, EualusThallwitz, 1892 and LebbeusWhite, 1847 were sampled recently from the Scotia Sea (1517–2598 m). Seven specimens are described and illustrated as Eualus amandae sp. nov., and its morphology is compared with those of previously described species. Four female specimens, morphologically consistent with Lebbeus antarcticus (Hale, 1941), are described and illustrated to supplement previous descriptions of this rarely collected bathyal species. Partial COI mtDNA and 18S rDNA sequences were generated for both species. Only limited DNA sequences are available for the Hippolytidae. COI phylogenetic trees are presented to illustrate that the new species is genetically distinct from all other species in GenBank. This record enhances existing knowledge of Antarctic invertebrate biodiversity and species richness of decapod crustaceans in the Southern Ocean
Low connectivity between ‘scaly-foot gastropod’ (Mollusca: Peltospiridae) populations at hydrothermal vents on the Southwest Indian Ridge and the Central Indian Ridge
No full textHydrothermal vents on mid-oceanic ridges are patchily distributed and host many taxa endemic to deep-sea chemosynthetic environments, whose dispersal may be constrained by geographical barriers. The aim of this study was to investigate the connectivity of three populations of the ‘scaly-foot gastropod’ (Chrysomallon squamiferum Chen et al., 2015), a species endemic to hydrothermal vents in the Indian Ocean, amongst two vent fields on the Central Indian Ridge (CIR) and Longqi field, the first sampled vent field on the Southwest Indian Ridge (SWIR). Connectivity and population structure across the two mid-oceanic ridges were investigated using a 489-bp fragment of the cytochrome oxidase c subunit I (COI) gene. Phylogeographical approaches used include measures of genetic differentiation (F ST), reconstruction of parsimony haplotype network, mismatch analyses and neutrality tests. Relative migrants per generation were estimated between the fields. Significant differentiation (F ST?=?0.28–0.29, P?<?0.001) was revealed between the vent field in SWIR and the two in CIR. Signatures were detected indicating recent bottleneck events followed by demographic expansion in all populations. Estimates of relative number of migrants were relatively low between the SWIR and CIR, compared with values between the CIR vent fields. The present study is the first to investigate connectivity between hydrothermal vents across two mid-ocean ridges in the Indian Ocean. The phylogeography revealed for C. squamiferum indicates low connectivity between SWIR and CIR vent populations, with implications for the future management of environmental impacts for seafloor mining at hydrothermal vents in the region, as proposed for Longqi
On the systematics and ecology of two new species of Provanna (Gastropoda: Provannidae) from deep-sea hydrothermal vents in the Caribbean Sea and Southern Ocean
Full text linkThe recent discovery and exploration of deep-sea hydrothermal vent fields in the Mid-Cayman Spreading Centre, Caribbean Sea (Beebe Vent Field, 4956–4972 m depth) and the East Scotia Ridge, Southern Ocean (E2 and E9 vent fields, 2394–2641 m depth) have yielded extensive collections of two new provannid species, Provanna beebei n. sp. and P. cooki n. sp. Morphological and molecular taxonomy (530 bp of the mitochondrial cytochrome c oxidase subunit I gene) confirm P. beebei n. sp. and P. cooki n. sp. as distinct species; these species are formally described, and details are provided of their distribution, habitat and species associations. Bayesian and maximum likelihood analyses support the placement of P. beebei n. sp. and P. cooki n. sp within the genus Provanna and show that these two new deep-sea species form a well-supported clade with the abyssal West Pacific P. cingulata. Provanna beebei n. sp. and P. cooki n. sp. represent the first records of Provanna from hydrothermal vents in the Caribbean Sea and Southern Ocean, respectively, and extend the known geographic range of the genus. For the first time, intraspecific phenotypic variation in size and sculpture has been reported for Provanna. At the East Scotia Ridge, shell-size frequency distributions and median shell size of P. cooki n. sp. varied significantly between the E2 and E9 vent fields, as well as between diffuse flow and high-temperature venting habitats within each field. The variation in shell sculpture in relation to habitat was also observed in P. cooki n. sp
FIGURE 3 in New Sericosura (Pycnogonida: Ammotheidae) from deep-sea hydrothermal vents in the Southern Ocean
No full textFIGURE 3. SEM images. Sericosura bamberi sp. nov. Paratype male (NHMUK 2015.15). A, palp segments 2-7 (incomplete segmentation line between P3 and P4 indicated by arrow). B, tarsus (ta), propodus (pd), main claw (mc) and auxiliary claws (au); C. oviger segments 8, 9 and 10 showing simple spines (white arrows pointing), spine on O9 with tip broken. D, coxa 3 (C3) with characteristic brush of long ventral setae, distal margin of coxa 2 (C2) and femur (Fe). E, oviger segments 4-10 with spines and tufts of long setae, twisted possibly due to preservation. F, detail of chelate arrangement of spines on oviger segment 10 (O10).Published as part of Arango, Claudia P. & Linse, Katrin, 2015, New Sericosura (Pycnogonida: Ammotheidae) from deep-sea hydrothermal vents in the Southern Ocean, pp. 37-50 in Zootaxa 3995 (1) on page 41, DOI: 10.11646/zootaxa.3995.1.5, http://zenodo.org/record/28917
A Bathymetric Compilation of South Georgia, 1985-2015.
No full textWe present a new bathymetric compilation of the greater South Georgia region, here defined by a bounding box of ~900km (45W to 19W) by ~580km (63S to 50S) and covering an area of 530,000 km2. The region includes the South Georgia shelf, the Shag Rock shelf (to the west of South Georgia), the surrounding continental slopes and adjacent deep sea. This bathymetry grid was compiled from a variety of different data sources including multibeam swath bathymetry collected from scientific cruises undertaken by British Antarctic Survey (BAS), Alfred Wegener Institute (AWI) and the Institute of Geophysics, University of Texas. The grid has been constructed using a layered hierarchy dependent on accuracy of each dataset. The data is available as a 100m resolution GeoTIFF, ESRI ascii grid or KMZ file of elevation data along with a shapefile indicating the spatial coverage of all the contributing datasets. This work was supported by the National Environmental Research Council (grant number NE/L002531/1). For further information regarding the creation of this dataset please refer to doi:10.1038/srep33163.</span
Iheyaspira bathycodon new species (Vetigastropoda: Trochoidea: Turbinidae: Skeneinae) from the Von Damm Vent Field, Mid-Cayman Spreading Centre, Caribbean
Full text linkIheyaspira bathycodon sp. nov. is described from the Von Damm Vent Field on the world's deepest spreading centre, the Mid-Cayman Spreading Centre (MCSC), Caribbean, at 2300 m depth. The new species is defined and illustrated from 11 specimens, with brief notes on habitat and known distribution. Molecular phylogenetic data from partial COI mDNA, 16S rDNA and nuclear 18S rDNA regions are used to analyse the species’ phylogenetic position and its morphology is compared with previously described skeneid and vent taxa. The new species is distinguished from the most closely allied vent species, Iheyaspira lequios Okutani, Sasaki & Tsuchida, 2000 by morphological differences in radula diagnosis and appendage structure of the head-foot. Iheyaspira bathycodon sp. nov. is the tenth turbinid to be described from a hydrothermal-vent environment and the second species to be named from recently discovered hydrothermal vents on the MCSC. Determining the faunal composition of assemblages at the vent fields of the MCSC will help to elucidate the vent biogeography of the region
The ‘scaly-foot gastropod’: a new genus and species of hydrothermal vent-endemic gastropod (Neomphalina: Peltospiridae) from the Indian Ocean
No full textThe ‘scaly-foot gastropod’ is widely recognized as an iconic species of deep-sea hydrothermal vent ecosystems in the Indian Ocean. Uniquely among gastropods, this species carries hundreds of dermal sclerites on its foot and these scales can be covered in iron sulphide that also covers its shell, making it the only extant metazoan known to utilize iron sulphide as part of its skeleton. It has not been formally named, despite attracting great attention from both scientists and the general public alike, although a manuscript name has occasionally been used in various sources. The RRS James Cook JC67 expedition in 2011 sampled the biota of the Longqi vent field (37°47.027?S, 49°38.963?E), Southwest Indian Ridge, for the first time, revealing a previously unknown population of the ‘scaly-foot gastropod’. The present study gives a formal name to the ‘scaly-foot gastropod’, Chrysomallon squamiferum n. gen., n. sp. with Longqi vent field as the type locality. The erection of the new monotypic genus is supported by both morphological and molecular characterization, differentiating it from existing genera of the family Peltospiridae. Analysis of the cytochrome c oxidase subunit I gene reveals a 24–26% pairwise distance between Chrysomallon and five other genera of Peltospiridae, while the range among those five genera is 14–25%. The new genus is placed in the family Peltospiridae based on morphological characteristics, including lack of sexual dimorphism, no copulatory organ, the distal end of marginal teeth being subdivided into many denticles and the ventral margin of the gill leaflets carrying a series of bulges. A five-gene Bayesian phylogenetic reconstruction does not contradict the placement within Peltospiridae
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