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The use of integrative taxonomy has confirmed the existence of a new distinct crab species, cryptic, within the group of the former genus Liocarcinus, now Polybius, closely related to P. holsatus, P. vernalis and P. marmoreus. Previous reports have considered it to be the Atlantic form of P. vernalis, or as a species “affinis” or “comparable to” P. holsatus. Diagnostic morphological characters are presented for identification and the morphological variability in these species, mainly within P. vernalis (the most related) is analysed. Furthermore, based on molecular and other previous data, a new combination (genus change) is proposed. This new species, Polybius dioscurus sp. nov., lives on infralittoral sandy bottoms, coexisting with the other species mentioned, in the temperate and subtropical zone of the North Atlantic Ocean, including the Alboran Sea (westernmost Mediterranean).

Taxonomy is a scientific discipline that has provided the universal naming and classification system of biodiversity for centuries and continues effectively to accommodate new knowledge. A recent publication by Garnett and Christidis expressed concerns regarding the difficulty that taxonomic changes represent for conservation efforts and proposed the establishment of a system to govern taxonomic changes. Their proposal to "restrict the freedom of taxonomic action" through governing subcommittees that would "review taxonomic papers for compliance" and their assertion that "the scientific community's failure to govern taxonomy threatens the effectiveness of global efforts to halt biodiversity loss, damages the credibility of science, and is expensive to society" are flawed in many respects. They also assert that the lack of governance of taxonomy damages conservation efforts, harms the credibility of science, and is costly to society. Despite its fairly recent release, Garnett and Christidis' proposition has already been rejected by a number of colleagues. Herein, we contribute to the conversation between taxonomists and conservation biologists aiming to clarify some misunderstandings and issues in the proposition by Garnett and Christidis.

The physical isolation of the Antarctic shelf and extreme life conditions contribute to its high degree of endemism. The shelf fauna would, however, be composed of Gondwanan descendants, but also of more recent colonizers. Extreme temperature changes along the climatic history of this region led to the extinction of some lineages, while others flourished. Using molecular phylogenetic methods, this thesis aims to contribute to the general understanding of the evolutionary processes — extinctions, dispersals and in situ diversifications — shaping the biodiversity and geographical distributions of Antarctic amphipods of the families Epimeriidae (genus Epimeria) and Iphimediidae. The systematics of the superfamily presumably including the latter two model families, Eusiroidea, is first revised. Secondly, species boundaries within Epimeria are investigated by using a combination of DNA-based species delimitation methods and morphological descriptions, to ultimately reassess the geographical distribution of species. Finally, the origin of Antarctic lineages, dispersals in/out of the Antarctic shelf and in situ diversification patterns of both Epimeria and iphimediids are explored, using time-calibrated phylogenies. The systematic study of Eusiroidea indicates that at least species belonging to 14 families, including Epimeriidae and Iphimediidae, should be included in a phylogenetically meaningful delimitation of the superfamily. The species richness within Epimeria is greatly underestimated as most nominal species appear to be complexes of geographically-restricted pseudocryptic species. The monophyly of Antarctic Epimeria and (sub-)Antarctic iphimediids suggests that both lineages evolved in isolation since their origin. Both latter clades likely arose from late Gondwanan ancestors and diversified in a cooling environment., (SC - Sciences) -- UCL, 2017

The Antarctic shelf's marine biodiversity has been greatly influenced by the climatic and glacial history of the region. Extreme temperature changes led to the extinction of some lineages, while others adapted and flourished. The amphipod genus Epimeria is an example of the latter, being particularly diverse in the Antarctic region. By reconstructing a time-calibrated phylogeny based on mitochondrial (COI) and nuclear (28S and H3) markers and including Epimeria species from all oceans, this study provides a temporal and geographical framework for the evolution of Antarctic Epimeria. The monophyly of this genus is not supported by Bayesian Inference, as Antarctic and non-Antarctic Epimeria form two distinct well-supported clades, with Antarctic Epimeria being a sister clade to two stilipedid species. The monophyly of Antarctic Epimeria suggests that this clade evolved in isolation since its origin. While the precise timing of this origin remains unclear, it is inferred that the Antarctic lineage arose from a late Gondwanan ancestor and hence did not colonize the Antarctic region after the continent broke apart from the other fragments of Gondwanaland. The initial diversification of the clade occurred 38.04Ma (95% HPD [48.46Ma; 28.36Ma]) in a cooling environment. Adaptation to cold waters, along with the extinction of cold-intolerant taxa and resulting ecological opportunities, likely led to the successful diversification of Epimeria on the Antarctic shelf. However, there was neither evidence of a rapid lineage diversification early in the clade's history, nor of any shifts in diversification rates induced by glacial cycles. This suggests that a high turnover rate on the repeatedly scoured Antarctic shelf could have masked potential signals of diversification bursts.

The present monograph includes general systematic considerations on the family Epimeriidae, a revision of the genus Epimeria Costa in Hope, 1851 in the Southern Ocean, and a shorter account on putatively related eusiroid taxa occurring in Antarctic and sub-Antarctic seas. The former epimeriid genera Actinacanthus Stebbing, 1888 and Paramphithoe Bruzelius, 1859 are transferred to other families, respectively to the Acanthonotozomellidae Coleman & J.L. Barnard, 1991 and the herein re-established Paramphithoidae G.O. Sars, 1883, so that only Epimeria and Uschakoviella Gurjanova, 1955 are retained within the Epimeriidae Boeck, 1871. The genera Apherusa Walker, 1891 and Halirages Boeck, 1891, which are phylogenetically close to Paramphithoe, are also transferred to the Paramphithoidae. The validity of the suborder Senticaudata Lowry & Myers, 2013, which conflicts with traditional and recent concepts of Eusiroidea Stebbing, 1888, is questioned. Eight subgenera are recognized for Antarctic and sub-Antarctic species of the genus Epimeria: Drakepimeria subgen. nov., Epimeriella K.H. Barnard, 1930, Hoplepimeria subgen. nov., Laevepimeria subgen. nov., Metepimeria Schellenberg, 1931, Pseudepimeria Chevreux, 1912, Subepimeria Bellan-Santini, 1972 and Urepimeria subgen. nov. The type subgenus Epimeria, as currently defined, does not occur in the Southern Ocean. Drakepimeria species are superficially similar to the type species of the genus Epimeria: E. cornigera (Fabricius, 1779), but they are phylogenetically unrelated and substantial morphological differences are obvious at a finer level. Twenty-seven new Antarctic Epimeria species are described herein: Epimeria (Drakepimeria) acanthochelon subgen. et sp. nov., E. (D.) anguloce subgen. et sp. nov., E. (D.) colemani subgen. et sp. nov., E. (D.) corbariae subgen. et sp. nov., E. (D.) cyrano subgen. et sp. nov., E. (D.) havermansiana subgen. et sp. nov., E. (D.) leukhoplites subgen. et sp. nov., E. (D.) loerzae subgen. et sp. nov

The present monograph includes general systematic considerations on the family Epimeriidae, a revision of the genus Epimeria Costa in Hope, 1851 in the Southern Ocean, and a shorter account on putatively related eusiroid taxa occurring in Antarctic and sub-Antarctic seas. The former epimeriid genera Actinacanthus Stebbing, 1888 and Paramphithoe Bruzelius, 1859 are transferred to other families, respectively to the Acanthonotozomellidae Coleman & J.L. Barnard, 1991 and the herein re-established Paramphithoidae G.O. Sars, 1883, so that only Epimeria and Uschakoviella Gurjanova, 1955 are retained within the Epimeriidae Boeck, 1871. The genera Apherusa Walker, 1891 and Halirages Boeck, 1891, which are phylogenetically close to Paramphithoe, are also transferred to the Paramphithoidae. The validity of the suborder Senticaudata Lowry & Myers, 2013, which conflicts with traditional and recent concepts of Eusiroidea Stebbing, 1888, is questioned. Eight subgenera are recognized for Antarctic and sub-Antarctic species of the genus Epimeria: Drakepimeria subgen. nov., Epimeriella K.H. Barnard, 1930, Hoplepimeria subgen. nov., Laevepimeria subgen. nov., Metepimeria Schellenberg, 1931, Pseudepimeria Chevreux, 1912, Subepimeria Bellan-Santini, 1972 and Urepimeria subgen. nov. The type subgenus Epimeria, as currently defined, does not occur in the Southern Ocean. Drakepimeria species are superficially similar to the type species of the genus Epimeria: E. cornigera (Fabricius, 1779), but they are phylogenetically unrelated and substantial morphological differences are obvious at a finer level. Twenty-seven new Antarctic Epimeria species are described herein: Epimeria (Drakepimeria) acanthochelon subgen. et sp. nov., E. (D.) anguloce subgen. et sp. nov., E. (D.) colemani subgen. et sp. nov., E. (D.) corbariae subgen. et sp. nov., E. (D.) cyrano subgen. et sp. nov., E. (D.) havermansiana subgen. et sp. nov., E. (D.) leukhoplites subgen. et sp. nov., E. (D.) loerzae subgen. et sp. nov

Eusiroidea is one of the 20 amphipod superfamilies that were erected to subdivide the very large and controversial suborder Gammaridea. Yet, the definition of the superfamily is not based on synapomorphies, but on a combination of diagnostic phenetic similarities that hold more or less consistently across families. Moreover, many of the characters used to define eusiroid families are suspected to show convergent evolution. The current classification of the Eusiroidea may therefore not reflect evolutionary relationships accurately. Here, we present a molecular phylogenetic re-analysis of the Eusiroidea based on a comparison of 18S and 28S rDNA sequences of 73 species, representing 47 genera and 16 families that potentially belong to the superfamily. The results suggest that at least species belonging to 14 of these traditional families would be part of a eusiroid clade, increasing by more than twofold the species and generic richness of the group. However, most of the eusiroid families surveyed do not appear monophyletic. Finally, the analyses show that several important morphological characteristics, traditionally used in eusiroid taxonomy, are homoplastic.

There has been a significant body of literature on species flock definition but not so much about practical means to appraise them. We here apply the five criteria of Eastman and McCune for detecting species flocks in four taxonomic components of the benthic fauna of the Antarctic shelf: teleost fishes, crinoids (feather stars), echinoids (sea urchins) and crustacean arthropods. Practical limitations led us to prioritize the three historical criteria (endemicity, monophyly, species richness) over the two ecological ones (ecological diversity and habitat dominance). We propose a new protocol which includes an iterative fine-tuning of the monophyly and endemicity criteria in order to discover unsuspected flocks. As a result nine « full » species flocks (fulfilling the five criteria) are briefly described. Eight other flocks fit the three historical criteria but need to be further investigated from the ecological point of view (here called « core flocks »). The approach also shows that some candidate taxonomic components are no species flocks at all. The present study contradicts the paradigm that marine species flocks are rare. The hypothesis according to which the Antarctic shelf acts as a species flocks generator is supported, and the approach indicates paths for further ecological studies and may serve as a starting point to investigate the processes leading to flock-like patterning of biodiversity.

Eurythenes gryllus is one of the most widespread amphipod species, occurring in every ocean with a depth range covering the bathyal, abyssal and hadal zones. Previous studies, however, indicated the existence of several genetically and morphologically divergent lineages, questioning the assumption of its cosmopolitan and eurybathic distribution. For the first time, its genetic diversity was explored at the global scale (Arctic, Atlantic, Pacific and Southern oceans) by analyzing nuclear (28S rDNA) and mitochondrial (COI, 16S rDNA) sequence data using various species delimitation methods in a phylogeographic context. Nine putative species-level clades were identified within E. gryllus. A clear distinction was observed between samples collected at bathyal versus abyssal depths, with a genetic break occurring around 3,000 m. Two bathyal and two abyssal lineages showed a widespread distribution, while five other abyssal lineages each seemed to be restricted to a single ocean basin. The observed higher diversity in the abyss compared to the bathyal zone stands in contrast to the depth-differentiation hypothesis. Our results indicate that, despite the more uniform environment of the abyss and its presumed lack of obvious isolating barriers, abyssal populations might be more likely to show population differentiation and undergo speciation events than previously assumed. Potential factors influencing species’ origins and distributions, such as hydrostatic pressure, are discussed. In addition, morphological findings coincided with the molecular clades. Of all specimens available for examination, those of the bipolar bathyal clade seemed the most similar to the ‘true’ E. gryllus. We present the first molecular evidence for a bipolar distribution in a macro-benthic deep-sea organism.

Two new lysianassoid amphipods of the genus Pseudorchomene Schellenberg, 1926 from the Southern Ocean are described: P. debroyeri sp. n. collected in baited traps deployed around the Falkland Islands, Burdwood Bank and Îles Kerguelen between 55 and 470 m, and P. lophorachis sp. n. collected in baited traps and Agassiz trawls deployed in the Scotia and Weddell Seas at depths between 847 and 1943 m. P. lophorachis sp. n. is characterized by an strongly elongated first gnathopod and by the occurrence of low posterodorsal humps on the body segments. P. debroyeri sp. n. is very similar to P. coatsi (Chilton, 1912) but exhibits slight differences of proportions in the articles of gnathopods 1 and 2, more spines on pereopods and more acute spines on the propodus of pereopods 3-7. Molecular data indicate the existence of a welldefined clade comprising P. lophorachis sp. n., P. debroyeri sp. n., P. coatsi (Chilton, 1912), Abyssorchomene plebs (Hurley, 1965) and A. rossi (Walker, 1903). On the other hand, A. plebs and A. rossi do not form a clade with A. chevreuxi (Stebbing, 1906), which is the type species of the genus Abyssorchomene De Broyer, 1984. The definition of Pseudorchomene is amended, so that it now includes P. coatsi, P. debroyeri, P. lophorachis, P. plebs and P. rossi. The triangular coxa 1 in these 5 species is unique for 'orchomenid' lysianassoids, thus considered as a putative synapomorphy. P. coatsi (Antarctic species) is morphologically extremely similar to P. debroyeri (sub-Antarctic species) but it is genetically closer to the morphologically distinct P. lophorachis (Antarctic species). Hypotheses for these recent speciations and the mor phological evolution within Pseudorchomene are discussed. The type species and the nomenclatural history of the genus Tryphosa Boeck, 1871, which is the type genus of the subfamily Tryphosinae, are discussed. Copyright © 2012 · Magnolia Press.

Eurythenes gryllus (Lichtenstein, 1822) is a presumed cosmopolitan eurybathic bentho-pelagic giant deep-sea amphipod. However, previous studies already highlighted genetically divergent lineages in the Atlantic and Pacific Oceans, which appeared to be vertically stratified, and minor morphological differences between populations were also recorded. With an aim to quantify the geographic and bathymetric patterns of genetic variations, the genetic diversity in Eurythenes gryllus was investigated at the global scale (Arctic, Atlantic, Pacific and Southern Oceans) using three different genes (COI, 16S rRNA, 28S rRNA). This genetic analysis was followed by a thorough morphological study. Phylogenetic and phylogeographic analyses revealed the existence of at least seven well-supported clades, two bathyal and five abyssal, which were separated by genetic distances at the level of usual interspecific divergences. Furthermore, a clear genetic break was observed between specimens sampled above and below 3000 m. One clade comprised specimens from several bathyal sites in the Arctic and Southern Oceans. A subsequent morphological analysis confirmed the genetic findings and revealed small but consistent differences between the different clades, which will be described as separate species. This bathymetric break below 3000 m has already been reported for several organisms and regions, suggesting its role as a ubiquitous phylogeographic barrier for barophysical tolerance. The widely distributed Eurythenes clade, which is presumably the true E. gryllus, is, to our knowledge, the first molecular evidence for a bipolar distribution in a macro-benthic deep-sea organism. The present results clearly highlight the difficult nature of research on the systematics of deep-sea crustaceans and shows that the abyss is a more complex environment than previously assumed, which is likely to harbour an important hidden diversity.

Eurythenes gryllus (Lichtenstein, 1822) is a presumed cosmopolitan eurybathic bentho-pelagic giant deep-sea amphipod. However, previous studies already highlighted genetically divergent lineages in the Atlantic and Pacific Oceans, which appeared to be vertically stratified, and minor morphological differences between populations were also recorded. With an aim to quantify the geographic and bathymetric patterns of genetic variations, the genetic diversity in Eurythenes gryllus was investigated at the global scale (Arctic, Atlantic, Pacific and Southern Oceans) using three different genes (COI, 16S rRNA, 28S rRNA). This genetic analysis was accompanied by a thorough morphological study. Phylogenetic and phylogeographic analyses revealed the existence of at least eight well-supported clades, two bathyal and six abyssal, which were separated by genetic distances at the level of usual interspecific divergences. A subsequent morphological analysis confirmed the genetic findings and revealed small but consistent differences between the different clades, which will be described as separate species. Furthermore, a clear genetic break was observed between specimens sampled above and below 3000 m. This bathymetric break below 3000 m has already been reported for several organisms and regions, suggesting its role as a ubiquitous phylogeographic barrier for barophysical tolerance. The Eurythenes clade, comprising specimens sampled at bathyal sites in the Arctic and Southern Oceans, is presumably the true E. gryllus. This represents, to our knowledge, the first molecular evidence for a bipolar distribution in a macro-benthic deep-sea organism. The present results clearly highlight the difficult nature of research on the systematics of deep-sea crustaceans and shows that the abyss is a more complex environment than previously assumed, likely to harbour an important hidden diversity.

Eurythenes gryllus (Lichtenstein, 1822) is a presumed cosmopolitan eurybathic bentho-pelagic giant deep-sea amphipod. However, previous studies already highlighted genetically divergent lineages in the Atlantic and Pacific Oceans, which appeared to be vertically stratified, and minor morphological differences between populations were also recorded. With an aim to quantify the geographic and bathymetric patterns of genetic variations, the genetic diversity in Eurythenes gryllus was investigated at the global scale (Arctic, Atlantic, Pacific and Southern Oceans) using three different genes (COI, 16S rRNA, 28S rRNA). This genetic analysis was accompanied by a thorough morphological study. Phylogenetic and phylogeographic analyses revealed the existence of at least eight well-supported clades, two bathyal and six abyssal, which were separated by genetic distances at the level of usual interspecific divergences. A subsequent morphological analysis confirmed the genetic findings and revealed small but consistent differences between the different clades, which will be described as separate species. Furthermore, a clear genetic break was observed between specimens sampled above and below 3000 m. This bathymetric break below 3000 m has already been reported for several organisms and regions, suggesting its role as a ubiquitous phylogeographic barrier for barophysical tolerance. The Eurythenes clade, comprising specimens sampled at bathyal sites in the Arctic and Southern Oceans, is presumably the true E. gryllus. This represents, to our knowledge, the first molecular evidence for a bipolar distribution in a macro-benthic deep-sea organism. The present results clearly highlight the difficult nature of research on the systematics of deep-sea crustaceans and shows that the abyss is a more complex environment than previously assumed, likely to harbour an important hidden diversity.

A new common deep-sea species of Halirages Boeck, 1871 closely related to H.qvadridentatus G.O. Sars, 1877, H.cainae sp. nov., is described after specimens collected in the Norwegian Sea during the MAREANO 2009-111 cruise. Examination of the syntypes of H. elegans Norman, 1882 demonstrates that Norman's species is a junior synonym of H.qvadridentatus G.O. Sars, 1877 and that the species usually named H.elegans in literature was actually undescribed. The name H.stappersi sp. nov. is proposed for that species. A key to and a checklist of Halirages species is given.

With over 850 described species, amphipods are by far the most speciose animal group in the Southern Ocean, being present at all depths and occupying a wide range of habitats and trophic niches. At the RBINS, an integrative approach combining morphological and genetic studies is used for studying their species diversity, present-day distributions and for understanding the underlying processes structuring the diversity and the mechanisms of speciation. Both morphological and molecular studies revealed a large number of inadequately or undescribed species in several amphipod groups. DNA taxonomy and phylogeographic studies were conducted to detect possible cryptic diversity and to test the circumpolarity and/or eurybathy of some taxa. These studies demonstrated that several morphospecies are genetically heterogeneous species complexes with allo- and sympatric distributions. Furthermore, molecular phylogenies are applied to test the hypotheses concerning the colonization of the abyssal basins from the shelf and vice versa (the submergence and emergence hypotheses). To expand our knowledge on the processes structuring the Southern Ocean benthos and on predicting their response to environmental changes, future projects will include molecular studies at a microevolutionary scale and the modeling of the spatial distribution of amphipod taxa.

Polar regions experience greater rates of climate change than any other region in the world. Their biota are highly adapted to the extreme environment they are living in and appear vulnerable to shifts in climate conditions. Antarctic marine species are especially sensitive to temperature variation as their physiology is set to a narrow range of temperatures. Because of the key‐role of the Southern Ocean in the global system and the growing impact of global environmental change, it is crucial to establish comprehensive baseline information on Antarctic marine biodiversity as a sound benchmark against which future change can reliably be assessed. It is equally important to better understand the ecological role of biodiversity in the functioning of the Southern Ocean ecosystem and to assess how its structural and functional characteristics might be affected by a changing climate. These aspects are addressed in the BIANZO II project, by focusing on benthic organisms and communities, specifically representatives from three different size classes of the zoobenthos: Nematoda (meiobenthos), Amphipoda (macrobenthos) and Echinoidea (megabenthos). BIANZO II has been accepted as an IPY activity (# 391) linked to CAML (IPY core activity). Its aims fully contribute to the objectives of the SCAR EBA programme. The BIANZO II consortium is also involved in the development of SCAR‐MarBIN, which was initiated by the BIANZO I project, and is currently implemented by the Belgian Biodiversity Platform. All partners are contributing to the IPY ANDEEP‐SYSTCO project, which is the continuation of the very successful ANDEEP collaboration. Additionally, UGent is involved in ClicOpen, also an IPY project (# 34).