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Ophiacantha wolfarntzi n. sp., paratype ZMH E 8072. SEM photographs. a Close-up of dorsal disc and arm, in dorsal view; radial shields hidden but their extent can be seen beneath the disc scales, dorsal arm plates separated, and broken arm spines are hollow; b, c disc stumps with thorns at various tiers and trabeculate pedicels;
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A new brittle star attributable to the genus Ophiacantha is described from Antarctic waters, in the diffuse limits of the Antarctic Polar Front at Shag Rocks, South Georgia. The new species can be differentiated from its Southern Ocean congeners by the striations on the arm plates. Several adult individuals were observed brooding their juve-niles,...
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... specimens range from 3 to 9 mm in disc diameter. The thorny stumps range from 0.05 to 0.25 mm in height. The disc stumps have thorns in various tiers and their pedicels have trabeculae at their base (Fig. 4c). As in the holotype, the radial shields are obscured by the presence of stumps, although in some specimens distal tips can be seen. The oral shields in specimens of 3-4-mm disc diameter are rounded rhomboid. In specimens of 6 mm or more disc Fig. 3 Ophiacantha wolfarntzi n. sp., holotype ZMH E 8071. General morphology. a Dorsal view; b ...
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... generally poorly preserved, are up to three times the diameter of the disc. The number of arm spines varies from seven in a specimen of 3.5 mm in disc diameter up to ten in a specimen of 9 mm in disc diameter. Ventral arm plates in some speci- mens are arranged as the holotype, while in others they are clearly separated from each other basally (Fig. 4d). Stria- tions are always present on ventral and lateral arm plates (more variable on the latter ones). The dorsal plates of some specimens have striations near their distal ...
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The case put by Alexei Smirnov in 2012 is accepted and the order name Synaptida Cuénot is adopted in place of Apodida Brandt. Two new Synaptida species are described for the Weddell Sea in Antarctica with single author O’Loughlin: Sigmodota magdarogera sp. nov. and Taeniogyrus bamberi sp. nov.. A specimen of Sigmodota magnibacula (Massin & Hétérier...
Citations
... Ophiosabine rosea consists of numerous clades around Australia/New Zealand and New Caledonia (Christodoulou et al. 2019;O'Hara et al. 2013), which may not be the same species as the type collected from off Chile. COI sequences of O. densispina from South Georgia (Martín-Ledo et al. 2013) are distinct from those around southern Australia (O'Hara et al. 2013). There is a second unnamed species at South Georgia closely related to O. wolfarntzi (Martin-Ledo, 2013). ...
The ophiuroid fauna of the le Amsterdam and le Saint-Paul territories (SPA) is reviewed. Four new species are described: Ophiolebes felli, Ophiolebes paulensis, Ophiocomina arnaudi and Amphiura remota. Recent phylogenetic results required a partial reorganisation of Ophiacanthidae and Amphiuridae genera, including the transfer of some Ophiacantha and Ophiomitrella species to a new genus Ophiosabine (O. rosea, O. anomala, O. aristata, O. cuspidata, O. densispina, O. nodosa, O. notata, O. parcita, O. pentactis, O. vivipara, O. wolfarntzi) and existing genera Ophiosemnotes (O. conferta, O. ingrata, O. corynephora, O. clavigera, O. hamata) and Ophiolebes (O. yaldwyni), Ophiacantha spectabilis to Ophiotreta in the Ophiotomidae, and some Amphioplus species to Amphiura (A, acutus, A. ctenacantha, A. cipus). The combination Ophiophycis nixastrum is restored. The SPA endemic species Ophiocten lymani and Amphiura brevispina, and the southern Australian/New Zealand species Ophiactis cuspidata and Ophiocten australis, are recognised as valid species. The North Atlantic species Ophiura ljungmani, Ophiacantha veterna, Ophiosabine cuspidata, Ophiolimna bairdi and Ophiactis nidarosiensis are recorded from the southern Indian Ocean. Shallow water specimens of Ophiura ljungmani from the Western Atlantic are re-identified as O. fallax and O. acervata. The monotypic Ophiothauma heptactis from northern Australia is synonymised with Ophiocomella sexradia and thus the genus Ophiothauma with Ophiocomella. The biogeography of the ophiuroid fauna reflects the position of the islands near the eastward-flowing currents of the South Indian Ocean gyre. The closest affinities are with faunas in the SW Indian Ocean and SE Atlantic Ocean. Despite its proximity, no species are shared with the Kerguelen Plateau to the south. The large temperature gradient across the subtropical front between le Saint-Paul and Kerguelen appears to be a distribution limit for littoral and upper bathyal invertebrates.
... Astrochlamys sol has been documented as a species which broods its young (Madsen 1967;Martin-Ledo et al. 2013) and has been observed strongly attached to bryozoan colonies, using its multiple arms to attach to the branches (Mortensen 1936 Diagnosis Monotypic genus and species with disc composed of naked, imbricating plates, petaloid in shape. Plates arranged as a primary circlet in a rosette arrangement with a distinct, round to irregularly polygonal centrodorsal plate flanked by five plates, then 10-15, varying with individual size (Fig. 5a, d). ...
Four newly described species, Astrochlamys timoharai sp. nov. (Gorgonocephalidae Ljungman, 1867), Ophiosteira lissopatella sp. nov. (Ophiopyrgidae Perrier, 1893), Ophiophyllum umbonatum sp. nov. (Ophiopyrgidae), and Soliophis bakeri sp. nov. (Ophioscolecidae Lütken, 1869) with a description of Soliophis gen. nov., are reported from the Ross Sea and adjacent regions. New occurrence of Euvondrea floretta Fell, 1961a is also reported. These newly described taxa display unusual morphology with two species showing 10 or more arms. Although no evidence of brooding was present, two of the described species belong to genera with other Antarctic species that show brooding behavior. Collections from these areas remain important for new discoveries relevant to Antarctic biodiversity.
... Species such as Ophioplocus januarii, with distribution in San Matías Gulf, reproduced all along the year and may present a mixed reproductive pattern with transitional tropical/ subtropical continuous reproduction with a temperate reproductive cycle and a clear seasonality of spawning (Brogger et al. 2013b). Moreover, in this area, we can find brooders species, such as Anasterias minuta, Abatus cavernosus, and Ophiacantha vivipara (Gil and Zaixso 2007;Gil et al. 2009;Martín-Ledo et al. 2013). Brooding behavior has been described for many temperate, sub-Antarctic and Antarctic echinoderms (McEuen and Chia 1991;Sewell 1994;Gil and Zaixso 2007;Hamel et al. 2007;Gil et al. 2009;Martinez et al. 2011;Martín-Ledo et al. 2013), in contrast with tropical and subtropical species (Gil and Zaixso 2007). ...
... Moreover, in this area, we can find brooders species, such as Anasterias minuta, Abatus cavernosus, and Ophiacantha vivipara (Gil and Zaixso 2007;Gil et al. 2009;Martín-Ledo et al. 2013). Brooding behavior has been described for many temperate, sub-Antarctic and Antarctic echinoderms (McEuen and Chia 1991;Sewell 1994;Gil and Zaixso 2007;Hamel et al. 2007;Gil et al. 2009;Martinez et al. 2011;Martín-Ledo et al. 2013), in contrast with tropical and subtropical species (Gil and Zaixso 2007). Temperature and photoperiod are important environmental factors that could regulate biological functions (Pearse et al. 1986;Gil et al. 2009;Mercier and Hamel 2009;Pérez et al. 2010;Gil et al. 2011;Martinez et al. 2011;Brogger et al. 2013b). ...
Echinoderms are often of ecological importance in intertidal and subtidal waters, especially as predators and herbivores but also as prey. Several groups of echinoderms respond in a different way to environmental variables, contributing to some of the biodiversity patterns found along latitudinal gradient. This work listed the echinoderms species of San Matías Gulf surrounding the coast of Río Negro Province and analyzed the current state of knowledge of this group by previous works, collection items of the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia,” and from samples taken since 2009 to the present. A total of 35 species of echinoderms corresponding to four classes were recorded. The 34.29 % corresponds to Asteroidea, 31.43 % to Ophiuroidea, 20 % to Echinoidea, and 14.28 % to Holothuroidea. Crinoidea has not been reported for San Matías Gulf. Asteroidea and Ophiuroidea were the most representative groups followed by Echinoidea and Holothuroidea, with only five species in the last class. About 30 % of the country’s species are present in Río Negro Province. This high number of species may be due to the heterogeneity of environments that are possible to find in San Matías Gulf and a transition zone between the Magellanic and Argentine biogeographic provinces that can provide particular physical and climatic characteristics explaining as consequence the faunal composition.
... They can also display an array of unusual anatomical systems, such as a unique vision system using skeletal elements of the arms as an optical instrument [25]. The taxonomy of the Ophiacanthidae is one of the most problematic among brittle stars [26][27][28][29][30][31]. Numerous genera with uncertain diagnoses and absence of a robust phylogeny are among major challenges to ophiacanthid studies. ...
... Numerous genera with uncertain diagnoses and absence of a robust phylogeny are among major challenges to ophiacanthid studies. New ophacanthid species continue to be described [28,30,31], however they are usually discovered in low numbers within a restricted locality. Here we present a detailed morphological description of a common new species of the genus Ophiacantha from the Pacific side of the Japanese Islands in an ontogenetic framework and provide comparison with two closely related species. ...
Current taxonomy offers numerous approaches and methods for species delimitation and description. However, most of them are based on the adult characters and rarely suggest a dynamic representation of developmental transformations of taxonomically important features. Here we show how the underestimation of ontogenetic changes may result in long term lack of recognition of a new species of one of the most common ophiacanthid brittle stars (Echinodermata: Ophiuroidea) from the North Pacific. Based on vast material collected predominantly by various Japanese expeditions in the course of more than 50 years, and thorough study of appropriate type material, we revise the complex of three common species of the ophiuroid genus Ophiacantha which have been persistently confused with each other. The present study thus reveals the previously unrecognized new species Ophiacantha kokusai sp.nov. which is commonly distributed off the Pacific coast of Japan. The new species shows developmental differentiation from the closely related species Ophiacantha rhachophora H. L. Clark, 1911 and retains clearly expressed early juvenile features in the adult morphology. Another species, Ophiacantha clypeata Kyte, 1977, which had been separated from O. rhachophora, is in turn shown to be just a juvenile stage of another North Pacific species, Ophiacantha trachybactra H.L. Clark, 1911. For every species, detailed morphological data from both adult and juvenile specimens based on scanning electron microscopy are presented. A special grinding method showing complex internal features has been utilized for the first time. For all three species in this complex, a clear bathymetric differentiation is revealed: O. rhachophora predominantly inhabits shallow waters, 0–250 m, the new species O. kokusai lives deeper, at 250–600 m, and the third species, O. trachybactra, is found at 500–2,000 m. The present case clearly highlights the importance of considering developmental transformations, not only for a limited number of model organisms, but as part of the taxonomic process.
... There have been two molecular studies that have shed light on the phylogenetic relationships within the Ophiacantha vivipara complex. Ledo et al. (2013) found several distinct phylogenetic clades from around Shag Rock near South Georgia that they identify as O. vivipara, O. pentactis, the five-armed O. densispina Mortensen, 1936, a new five-armed species O. wolfarntzi, and an undescribed five-armed species (sp. 1). ...
... Clade A included both five and six-armed individuals, the others only six-armed forms. A direct comparison of the COI sequences (O'Hara unpublished data) has revealed that clade A is the same as the clade identified by Ledo et al. (2013) as O. pentactis and B as O. vivipara. In summary, there are at least three clades with six-armed forms (as well as numerous clades with only fivearmed individuals) within this complex. ...
... It may also occur on other subantarctic islands. The second clade (clade A of O'Hara et al. 2013 and pentactis of Ledo et al. 2013) is circumpolar Antarctic as well as occurring around South Georgia (Martin-Ledo et al. 2013), South Orkney and Bouvet Islands, and on the southern Macquarie Ridge (O'Hara et al. 2013). It appears to include both five and six-armed individuals, although this should be confirmed with a study using faster evolving genetic loci than COI which is known to be unable to discriminate some echinoderm species pairs (Williams 2000). ...
The taxonomy of some ophiuroids reported from off Argentina, western Antarctica and the SW Atlantic Ocean is reviewed. The species Amphilepis sanmatiensis, known only from the small holotype, is a synonym of Amphioplus lucyae. This synonymy removes the only reported endemic ophiuroid from Argentina. The species name " Ophiacantha ingrata Koehler, 1923 " used for specimens from South Georgia is invalid; the specimens are likely to belong to one of two cryptic species within the O. vivipara complex. Specimens of Amphiura joubini reported from Argentina are re-identified as Amphiura princeps, and specimens of Ophiactis amator from the Antarctic Peninsula are re-identified as Ophiactis asperula.
... All of them led to the publication of the most important papers on SO ophiuroids: Studer (1876), Lyman (1875Lyman ( , 1882, Koehler (1901Koehler ( , 1908Koehler ( , 1912Koehler ( , 1922, Hertz (1927) and Mortensen (1936). The last species that has been described is Ophiacantha wolfarntzi Martín-Ledo, Sands and López-González, 2013 in the waters of the South Georgia Islands (Martín-Ledo et al. 2013). ...
... All of them led to the publication of the most important papers on SO ophiuroids: Studer (1876), Lyman (1875Lyman ( , 1882, Koehler (1901Koehler ( , 1908Koehler ( , 1912Koehler ( , 1922, Hertz (1927) and Mortensen (1936). The last species that has been described is Ophiacantha wolfarntzi Martín-Ledo, Sands and López-González, 2013 in the waters of the South Georgia Islands (Martín-Ledo et al. 2013). ...
The present biogeographic study on the ophiuroid fauna from the Southern Ocean (SO) contains an updated checklist, based on a compilation of all the published information provided for the Antarctic and sub-Antarctic regions as well as the information available in SCAR-MarBIN database. Faunal composition and geographical and bathymetric distribution are included. So far, 219 species have been recorded, of which 126 are endemic to the SO, 76 are exclusive to Antarctic waters, and 30 are exclusive to sub-Antarctic waters. This study corroborated the circumpolar and eurybathic character of the ophiuroid fauna of the SO, but some differences are discussed when considering shelf and deep-sea fauna in the whole SO, or in the Antarctic and sub-Antarctic regions separately. The biogeographic affinities of 17 areas considered in the SO are revised, based on a presence/absence datamatrix of the 219 species. This similarity analysis shows three main groups, two of them including sub-Antarctic areas and one for Antarctic areas. The faunal movement patterns between the main geographical connections have been based on historical site records of each species. These movements have a level of faunal exchange that exceeds that of other Antarctic benthic groups. Such movements are mainly from Antarctic and sub-Antarctic regions to the subtropical waters of South America, and from New Zealand and southern Australian waters to sub-Antarctic areas. In this context, the origin of the ophiuroid Antarctic fauna is discussed.
Ophiothrix angulata (Say, 1825) is one of the most common and well-known ophiuroids in the Western Atlantic, with a wide geographic and bathymetric range. The taxonomy of this species has been controversial for a century because of its high morphological variability. Here we integrate information from DNA sequence data, color patterns, and geometric morphometrics to assess species delimitation and geographic differentiation in O. angulata. We found three deeply divergent mtDNA-COI clades (K2P 17.0-27.9%). ITS2 nuclear gene and geometric morphometrics of dorsal and ventral arm plates differentiate one of these lineages, as do integrative species delineation analyses, making this a confirmed candidate species.
Ecological studies that enhance our understanding of the structure and function of the natural world rely heavily on accurate species identification. With rapid sample accumulation and declining taxonomic expertise, cladistics, phylogenetics and coalescent-based analyses have become key tools for identification or discrimination of species. These tools differ in effectiveness and interpretation depending on researcher perspective and the unique evolutionary histories of the taxa. Given the cost and time required for taxonomic assessment of ambiguous species groups, we advocate a pragmatic approach to clarify species assignment. We carried out a case-study on species from the diverse ophiuroid genus Ophiacantha common in shelf habitats around the Southern Ocean. Although several of the species are formally described with clear and distinctive morphological characters and reproductive strategies (O. vivipara, O. pentactis, O. densispina, O. antarctica, and O. wolfarntzi), recent molecular data has highlighted issues with these morphospecies, the characters that formally define them and their evolutionary histories. Here we provide evidence that key morphological features of species can be deceptive and show that six-armed O. vivipara, for example, is not a widely distributed Southern Ocean species as currently accepted, rather, three disparate clades. Ophiacantha pentactis, described as having five arms, frequently has six arms and the six-armed form is mistakenly classified as O. vivipara. All six-armed specimens collected from the Antarctic continental shelf fall into the O. pentactis species clade. Molecular tools designed for species delimitation appear to fail to reflect the “true” species composition. Rather than rely on a single tool for species recognition, we advocate an integrated approach using traditional detailed taxonomic morphology, summary statistics of molecular sequence data from populations, robust phylogenies, sufficient geographical sampling and local biological knowledge to ensure that species hypotheses can be built on mutually supporting lines of evidence.
Species inventories are essential to the implementation of conservation policies to mitigate biodiversity loss and maintain ecosystem services and their value to society. This is particularly topical with respect to climate change and direct anthropogenic effects on Antarctic biodiversity, with the identification of the most at-risk taxa and geographical areas becoming a priority. Identification tools are often neglected and considered helpful only for taxonomists. However, the development of new online information technologies and computer-aided identification tools provides an opportunity to promote them to a wider audience, especially considering the emerging generation of scientists who apply an integrative approach to taxonomy. This paper aims to clarify essential concepts and provide convenient and accessible tools, tips and suggested systems to use and develop knowledge bases (KBs). The software Xper3 was selected as an example of a user-friendly KB management system to give a general overview of existing tools and functionalities through two applications: the ‘Antarctic Echinoids’ and ‘Odontasteridae Southern Ocean (Asteroids)’ KBs. We highlight the advantages provided by KBs over more classical tools, and future potential uses are highlighted, including the production of field guides to aid in the compilation of species inventories for biodiversity conservation purposes.
Poecilogony, or multiple developmental modes in a single species, is exceedingly rare. Several species described as poecilogenous were later demonstrated to be multiple (cryptic) species with a different developmental mode. The Southern Ocean is known to harbor a high proportion of brooders (Thorson’s Rule) but with an increasing number of counter examples over recent years. Here we evaluated poecilogony vs. crypticism in the brittle star Astrotoma agassizii across the Southern Ocean. This species was initially described from South America as a brooder before some pelagic stages were identified in Antarctica. Reproductive and mitochondrial data were combined to unravel geographic and genetic variation of developmental modes. Our results indicate that A. agassizii is composed of seven well-supported and deeply divergent clades (I: Antarctica and South Georgia; II: South Georgia and Sub-Antarctic locations including Kerguelen, Patagonian shelf, and New Zealand; III-VI-VII: Patagonian shelf, IV-V: South Georgia). Two of these clades demonstrated strong size dimorphism when in sympatry and can be linked to differing developmental modes (Clade V: dwarf brooder vs. Clade I: giant broadcaster). Based on their restricted geographic distributions and on previous studies, it is likely that Clades III-VI-VII are brooders. Clade II is composed of different morphological species, A. agassizii and A. drachi, the latter originally used as the outgroup. By integrating morphology, reproductive, and molecular data we conclude that the variation identified in A. agassizii is best described as crypticism rather than poecilogony.
