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Hexactinellida (glass sponges) are abundant and important components of Antarctic benthic communities. However, the relationships and systematics within the common genus Rossella Carter, 1872 (Lyssacinosida: Rossellidae), are unclear and in need of revision. The species content of this genus has changed dramatically over the years depending on the criteria used by the taxonomic authority consulted. Rossella was formerly regarded as a putatively monophyletic group distributed in the Southern Ocean and the North Atlantic. However, molecular phylogenetic analyses have shown that Rossella is restricted to the Southern Ocean, where it shows a circum-Antarctic and subantarctic distribution. Herein, we provide a molecular phylogenetic analysis of the genus Rossella, based on mitochondrial (16S rDNA and COI) and nuclear (28S rDNA) markers. We corroborate the monophyly of Rossella and provide evidence supporting the existence of one species, namely Rossella antarctica Carter, 1872 and a species flock including specimens determined as Rossella racovitzae Topsent, 1901, Rossella nuda Topsent, 1901, Rossella fibulata Schulze and Kirkpatrick 1910, and Rossella levis (Kirkpatrick 1907).

This paper presents 29 sponges of the family Cladorhizidae Dendy, 1922 sampled at 18 different stations in the Weddell Sea, Antarctic during two expeditions of RV Polarstern, PS61 ANT-XIX/2 ANDEEP 2 in 2002 and PS67 ANT-XXII/3 ANDEEP 3 in 2005. Fourteen species from four genera have been registered – one species of Asbestopluma Topsent, 1901, five species of Chondrocladia Thomson, 1873, three species of Cladorhiza Sars, 1872 and five species of Lycopodina Lundbeck, 1905. Six species are endemics of the Southern Ocean. Four species were previously only known from the areas north of the Antarctic and our records of them are thereby new for this region. Two species of Lycopodina, Lycopodina rhabdostylophora sp. nov. and Lycopodina pediculifera sp. nov., are new to science. Our study has considerably expanded the data on diversity of Cladorhizidae in the Southern Ocean. About 27 cladorhizid species (18–19% of global cladorhizid diversity) are now recorded for this region, of which 56% are endemics.

To assess the trophic relationships of consumers in a sandy lowland brook (Ladberger Muhlenbach, Northrhine-Westphalia, Germany) the fish as well as the benthic communities were sampled monthly over half a year. Analysis of stomach contents of the fishes revealed two different feeding types: detritivores (including only Cyprinidae; foremost roach, Rutilus rutilus and Prussian carp, Carassius auratus gibelio ) and benthivores (mostly stone loach, Barbatula barbatula and three-spined stickleback, Gasterosteus aculeatus ). The detritivores mainly foraged on detritus, but also benthic invertebrates were found in their stomachs. This latter prey (especially some Trichoptera and Coleoptera, which were selected with a high preference) is strongly associated to hard substrates, only present in the brook as coarse detritus. Benthivore fishes only foraged on benthic invertebrates, mostly Gammaridae and Chironomidae, which were the most dominant elements of the macrozoobenthos. Niche overlap between these two foraging groups was very low, while the within-group overlap was rather high. As food could not be shown to be a limiting factor, a direct competition for food between most of these species in this brook seems most unlikely.

The aim of this study is to analyze the community structure, ecology and distribution of deep Weddell Sea sponge faunas. Analysis was performed on the basis of sponges sampled during ANDEEP I–III and SYSTCO I expeditions (2002–2008) by RV Polarstern. The material obtained comprises about 800 sponge specimens, representing 129 species, within these are 95 species of demosponges (including 15 new to science), 25 hexactinellid species (7 new) and 9 calcarean species (5 new). Sponges were sampled at 51 stations in depths between 500 and 5,500 m. At most stations, sponge densities were very low, and many species are represented by one or two specimens only. Community structure by Bray–Curtis similarity was analyzed as well as depth range and spatial distribution of the most common species. Zoogeographic affinities of sampled faunas are analyzed. Three associations of sponges are found in the deep Weddell Sea: (1) The Polymastia/Tentorium community, (including Rossella associations) distributed on the lower shelf and continental slope. (2) The Bathydorus community, distributed on the continental slope and upper abyssal. (3) The Caulophacus community, associated with Cladorhizidae, is characteristic for the abyssal plains. The associations follow each other successively both bathymetrically and geographically, from shallow to deep, from shelf and ridge structures into the open abyssal. A distinct faunistic boundary between shelf and deep sea is not present. In general, the sponge fauna of the deep Weddell Sea is regionally restricted and shows stronger affinities only to the sponge fauna of the subantarctic islands.

In this study, we describe a new species of cladorhizid sponge, which shows a very peculiar mode of life: It always occurs in association with the scleractinian cold-water corals Lophelia pertusa and Madrepora oculata. Although the sponge lives in nutrient-rich areas, we document its carnivorous feeding behavior. The identity of the new species was verified using molecular markers: the species is very closely related to the North-Atlantic Cladorhiza abyssicola, but it differs distinctly, and forms a monophyletic clade. The two species might be considered very close relatives, probably sister species deriving from a common ancestor.

The Drake Passage has over 20 seamounts and ridges but it is notorious for large waves, fierce storms and strong currents that make benthic sampling difficult and therefore infrequent. Seamounts often have diverse sponge communities and may have high levels of endemism. Hexactinellida from Sars Seamount, an area in which the sponges had not previously been studied, and the Shackleton fracture zone were collected on a research cruise by the Nathaniel B Palmer in the Drake Passage, Southern Ocean. In total, from all cruise stations, 103 specimens of Hexactinellida were collected, however many appeared to be fragments of dead specimens and could not be identified due to missing microscleres. From Sars Seamount 127 sponge specimens were taken and from the Shackleton Fracture Zone 76 sponge specimens were taken; of these 36 and 16 respectively were Hexactinellida. From these two areas three new species of Hexactinellida are described: Doconesthes robinsoni sp. nov., Sympagella walleri sp. nov. and Caulophacus palmeri sp. nov and new records were made of Aulocalyx irregularis and Rossella antarctica.

Hexactinellida (glass sponges) are abundant and important components of Antarctic benthic communities. However, the relationships and systematics within the common genusRossellaCarter, 1872 (Lyssacinosida: Rossellidae) are unclear and in need of revision. The species content of this genus has changed dramatically over the years depending on the criteria used by the taxonomic authority consulted.Rossellawas formerly regarded as a putatively monophyletic group distributed in the Southern Ocean and the North Atlantic. However, molecular phylogenetic analyses have shown thatRossellais restricted to the Southern Ocean, where it shows a circum-Antarctic and subantarctic distribution. Herein, we provide a molecular phylogenetic analysis of the genusRossella, based on mitochondrial (16S rDNA and COI) and nuclear (28S rDNA) markers. We corroborate the monophyly ofRossellaand provide evidence supporting the existence of one species, namelyRossella antarcticaCarter, 1872 and a species flock including specimens determined asRossella racovitzaeTopsent, 1901,Rossella nudaTopsent, 1901,Rossella fibulataSchulze & Kirkpatrick, 1910, andRossella levis(Kirkpatrick, 1907).

Vargas, S., Erpenbeck, D., Gocke, C., Hall, K. A., Hooper, J. N. A., Janussen, D. & Worheide, G. (2012) Molecular phylogeny of Abyssocladia (Cladorhizidae: Poecilosclerida) and Phelloderma (Phellodermidae: Poecilosclerida) suggests a diversification of chelae microscleres in cladorhizid sponges. Zoologica Scripta, 42, 106116. The taxonomic placement of Abyssocladia Levi, 1964 (Poecilosclerida) is controversial, having been assigned at various times to three different families (Mycalidae, Cladorhizidae and Phellodermidae) in two different suborders (Mycalina and Myxillina, respectively), since its inception in 1964. It shares the general body plan with the carnivorous sponge family Cladorhizidae (Mycalina), including the lack of an aquiferous system. Nevertheless, it also has chela spicules apparently identical to those in PhellodermaRidley & Dendy 1886 (Phellodermidae, Myxillina). The ongoing debate on the position of Abyssocladia ultimately reduces to a discussion on the use of chelae morphology to infer phylogenetic relationships within Poecilosclerida. Here, we infer the phylogenetic relationships of the genera Phelloderma and Abyssocladia using two independent molecular markers (28S rDNA and COI), showing that Abyssocladia is not closely related to Phelloderma and belongs in Cladorhizidae. We suggest that despite their complexity, chelae morphology can evolve independently in different poecilosclerid lineages and as such might be potentially misleading as indicator of the phylogenetic history of the group. We also provide the first phylogenetic analysis of the carnivorous sponge family Cladorhizidae and give first insights into the evolution of this feeding mode in Poecilosclerida and, more generally, in Porifera.

In this paper we report on recently collected specimens of glass sponges belonging to Farreidae Gray, 1872, and Tretodictyidae Schulze, 1886 (Porifera: Hexactinellida: Hexactinosida). All specimens represent new geographical records for their genera: Coral Sea for Aspidoscopulia Reiswig, 2002 (Farreidae) and Psilocalyx Ijima, 1927 (Tretodictyidae); north-west Atlantic for Sarostegia Topsent, 1904 (Farreidae). Two new species, Aspidoscopulia australia Dohrmann, Gocke & Janussen sp. nov. and Aspidoscopulia ospreya Dohrmann, Gocke & Janussen sp. nov., are described. To investigate further the evolution of hexactinosidan sponges, we sequenced two nuclear (18S and 28S rDNA) and two mitochondrial [16S ribosomal rDNA, cytochrome oxidase subunit I (COI)] genes from these specimens, as well as from a recently described new species of Lonchiphora Ijima, 1927 (Farreidae). Besides corroborating the monophyly of Tretodictyidae, our molecular phylogenetic analyses support a clade of clavule-bearing sponges with a farreoid dictyonal framework (i.e. Farreidae sensu stricto). In contrast, Sarostegia, which lacks these features, appears unrelated to this clade – instead our data are consistent with an earlier placement of this genus in Euretidae Zittel, 1877. We introduce formally the taxon Sceptrulophora Mehl 1992, and emend the classification of Hexactinosida to reflect this move and our new findings regarding the position of Sarostegia. Finally, we discuss implications of the molecular phylogeny for the evolution of sceptrules, the defining autapomorphy of Sceptrulophora. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163, 1003–1025.

In this study, we present the hexactinellid sponges sampled in the Weddell-Sea during the ANT 24-2 SYSTCO expedition (30.10.2007–31.01.2008) on the RV Polarstern. All deep-sea stations sampled during this expedition showed comparably modest sponge colonization, with Hexactinellida and Demospongiae occurring in similar numbers of species and individuals. The hexactinellids sampled represent three abyssal species and six species from the deep shelf. Among the deep-sea glass sponges one species new to science was found, Lonchiphora antartica sp. nov., belonging to a poorly known genus, so far represented by only a single specimen known from the Sagami Bay, Japan. Herein we give the first detailed emended diagnosis of the genus and a description of the new species representing the genus as its first well-known specimen. Ecological analysis shows three clearly differentiated associations of hexactinellid sponges in the Antarctic Ocean, which replace each other with increasing depths. Sponge communities on the shelf are dominated by Rossella spp., those on the continental slope and in the lower bathyal mostly by Bathydorus spinosus, and the abyssal associations by Caulophacus spp. No distinct geographical distribution pattern of the Weddell-Sea Hexactinellida could be observed, apart from those caused by their bathyal ranges.

The benthic fauna was investigated during the expedition ANT-XXIV/2 (2007/08) in relation to oceanographic features, biogeochemical properties and sediment characteristics, as well as the pelagic, benthic pelagic and air-breathing fauna. The results document that Maud Rise (MR) differs distinctly from surrounding deep-sea basins investigated during previous Southern Ocean expeditions (ANDEEP 2002, 2005). Considering all taxa, the overall similarity between MR and adjacent stations was low (20% Bray-Curtis-Similarity), and analyses of single taxa show obvious differences in species composition, abundances and densities. The composition and diversity of bivalves of MR are characterised by extremely high abundances of three species, especially the small sized Vesicomya spp. Exceptionally high gastropod abundance at MR is due to the single species Onoba subantarctica wilkesiana, a small brooder that may prey upon abundant benthic foraminiferas. The abundance and diversity of isopods also show that one family, Haplomunnidae, occurs with a surprisingly high number of individuals at MR while this family was not found at any of the 40 bathyal and abyssal ANDEEP stations. Similarly, polychaetes, especially the tube-dwelling, suspension-feeder fraction, are represented by species not found at the comparison stations. Sponges comprise almost exclusively small specimens in relatively high numbers, especially a few species of Polymastiidae. Water-column sampling from the surface to the seafloor, including observations of top predators, indicate the existence of a prospering pelagic food web. Local concentrations of top predators and zooplankton are associated with a rich ice-edge bloom located over the northern slope of MR. There the sea ice melts, which is probably accelerated by the advection of warm water at intermediate depth. Over the southern slope, high concentrations of Antarctic krill (Euphausia superba) occur under dense sea ice and attract Antarctic Minke Whales (Balaenoptera bonaerensis) and several seabird species. These findings suggest that biological prosperity over MR is related to both oceanographic and sea-ice processes. Downward transport of the organic matter produced in the pelagic realm may be more constant than elsewhere due to low lateral drift over MR

In this study we provide evidence that the species Rossella podagrosa Kirkpatrick, 1907, commonly considered a synonym of Rossella racovitzae Topsent, 1901, is truly a valid species. We show that it can be clearly distinguished from other species especially when taking into consideration the in situ habitus of the sponge in combination with the spicules. Furthermore we demonstrate the weaknesses in the so far published synonymy concept for the very complicated genus Rossella Carter, 1872. From this we conclude that the best strategy for further analysis of Rossella and establishment of acceptable synonymies will need to be based on detailed examination of the spicules, the holotypes, and in situ habitus. When possible it will be useful to analyze specimens from all Antarctic oceanographic regions.

Due to their high abundance and large body size sponges have a central position in Antarctic zoobenthos, where they form the most extensive sponge grounds of the world. Though research on Antarctic benthos communities is quite established, research on sponge-associated infauna communities is scarce. We analyzed associated infauna of fifteen individuals of the sponge species Mycale (Oxymycale) acerata Kirkpatrick, 1907 (Demospongiae: Mycalina), Rossella antarctica Carter, 1872 and R. racovitzae Topsent, 1901 (both Hexactinellida: Lyssacinosida). Samples were collected from the deep Ekstrom Shelf at 602 m in the South-Eastern Weddell Sea, Antarctica, during the ANT XXIV-2 (SYSTCO I) expedition of RV Polarstern. The number of species, α- and β-diversity and the significantly different species composition of infauna communities related to sponge species were calculated, the latter via cluster analysis. The sponge-associated infauna consisted of five phyla: Foraminifera, Nematoda, Polychaeta, Mollusca and Arthropoda. In total 11,463 infaunal specimens were extracted and we found at least 76 associated species. Highest values of α-diversity were calculated for a sample of R. antarctica with a Shannon-Index of 1.84 and Simpson-Index of 0.72 respectively. Our results of the cluster-analysis show significant differences between infauna communities and a unique species composition for single sponge species. Polychaetes of the genus Syllis Lamarck, 1818 were numerous in M. acerata and genera like Pionosyllis Malmgren, 1867 and Cirratulus Lamarck, 1801 were numerous in R. antarctica. Individuals of the amphipod species Seba cf. dubia Schellenberg, 1926 were often found in R. antarctica and R. racovitzae while Colomastix fissilingua Schellenberg, 1926 was frequent in samples of M. acerata. Molluscs were present in M. acerata and R. antarctica but absent in R. racovitzae.

The Drake Passage has over 20 seamounts and ridges but it is notorious for large waves, fierce storms and strong currents that make benthic sampling difficult and therefore infrequent. Seamounts often have diverse sponge communities and may have high levels of endemism. Hexactinellida from Sars Seamount, an area in which the sponges had not previously been studied, and the Shackleton fracture zone were collected on a research cruise by the Nathaniel B Palmer in the Drake Passage, Southern Ocean. In total, from all cruise stations, 103 specimens of Hexactinellida were collected, however many appeared to be fragments of dead specimens and could not be identified due to missing microscleres. From Sars Seamount 127 sponge specimens were taken and from the Shackleton Fracture Zone 76 sponge specimens were taken; of these 36 and 16 respectively were Hexactinellida. From these two areas three new species of Hexactinellida are described: Doconesthes robinsoni sp. nov., Sympagella walleri sp. nov. and Caulophacus palmeri sp. nov and new records were made of Aulocalyx irregularis and Rossella antarctica .

In this study we provide evidence that the species Rossella podagrosa Kirkpatrick, 1907, commonly considered a synonym of Rossella racovitzae Topsent, 1901, is truly a valid species. We show that it can be clearly distinguished from other species especially when taking into consideration the in situ habitus of the sponge in combination with the spicules. Furthermore we demonstrate the weaknesses in the so far published synonymy concept for the very complicated genus Rossella Carter, 1872. From this we conclude that the best strategy for further analysis of Rossella and establishment of acceptable synonymies will need to be based on detailed examination of the spicules, the holotypes, and in situ habitus. When possible it will be useful to analyze specimens from all Antarctic oceanographic regions.

The paper reports on two new species of calcareous sponges (Porifera, Calcarea) from the Antarctic Weddell Sea, Clathrina brandtae sp. nov. and Leucetta delicata sp. nov., collected at 600 m depth during the ANT XXIV/2-SYSTCO expedition in January 2008. The new species are described based on a combination of morphological and molecular data. With these new additions the number of species of calcareous sponges reported from south of 50°S (~south of the Polar Front) reaches 50 species. We report an exceptionally high degree of endemism within the group, and as many as 44 out of the 50 species of calcareous sponges are solely confined to Antarctic waters. An updated list of species of calcareous sponges from the area is provided.

In this study, we present the demosponges sampled in the Antarctic Weddell Sea during the ANT-XXIV/2 (SYSTCO I) expedition (28.11.2007–04.02.2008) by the RV Polarstern. This collection comprises 43 species of Demospongiae of which four species are new to science, three of which are described herein, Cornulum antarcticum sp. nov., Cladorhiza penniformis sp. nov., and Desmacella koltuni sp. nov. We furthermore provide short descriptions and remarks for all species found, and in cases of rare or badly characterized species we also provide detailed documentation and descriptions of our material. In conclusion, we discuss the comparative faunistic and ecological aspects of our collection with respect to the Weddell Sea sponge fauna.

The genus Rossella Carter, 1872 comprises a group of very abundant and large sponges, which often dominate and even define the benthic habitats of the Antarctic shelf. While the ecological role and importance of the genus is unquestionable, the taxonomy of Rossella has been in a state of flux since its erection in 1872. Several species have been described, many of which have proven to be individual representatives of species with high variation in diagnostic characters, thus many published species are actually synonyms and a valid concept is still lacking. Here, we present the Rossella -fauna of one station sampled during the SYSTCO-I expedition in winter 2007/08 at 600 m depth on the lower Ekstrom-shelf near Kapp Norvegia, Eastern Weddell Sea, Antarctica. This sponge fauna showed some remarkable peculiarities in its characters, especially an unusually large growth of many microscleres, which will broaden the diagnoses of many Rossella spp. significantly. Implications for the definitions of these species are discussed.

Molecular systematic studies have indicated that the hexactinellid sponge species Rossella nodastrella Topsent (Lyssacinosida, Rossellidae), previously only known from the NE Atlantic, is only distantly related to its congeners, which are restricted to the Southern Ocean, representing the only case thus far reported of a diphyletic genus in the class Hexactinellida. Here we describe new material of "Rossella" nodastrella from cold-water coral reefs in the NW Atlantic (Florida). Morphological comparison with the holotype from the Azores and specimens recently reported from off Ireland reveal at least two distinct species, which we corroborate with molecular data. Because the diphyletic nature of "Rossella" is further supported with inclusion of the new specimens in the molecular phylogeny, we erect a new genus, Nodastrella gen. nov., for these two species. The Irish specimens are synonymized with our new species Nodastrella asconemaoida sp. nov. Subtle morphological and molecular differences between the E and W Atlantic specimens are for the time being ascribed to intraspecific geographic variation, but indicate that Nodastrella might contain more (sub) species, pending investigation of additional specimens, especially from intermediate locations.