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Phelloderma oxychaetoides sp. nov. is a remarkable new species from the deep Weddell Sea, bearing abundant oxychaetes (onychaete-like microxeas), morphologically distinct from the onychaetes of Tedania spp. collected in the same area. We give a redescription of the holotype of P. radiatum Ridley & Dendy, 1886, the type species of Phelloderma. We recognize three and a possible fourth species in Phelloderma: P. flava (Lévi, 1993); P. oxychaetoides sp. nov.; P. polypoides Whitelegge, 1906; and P. radiatum Ridley & Dendy, 1886. An identification key for the species of Phelloderma is proposed. A discussion on the affinities of Phelloderma to both Mycalina and Myxillina is offered, and the current preference for the latter is further supported by the marked similarity between the oxychaetes of Phelloderma oxychaetoides sp. nov. and those of Chaetodoryx spp. (Coelosphaeridae, Myxillina). [ABSTRACT FROM PUBLISHER]

Amongst the Hexactinellida, Hexasterophora is the most important taxon in terms of number of species as well as concerning the variability in morphological characters. In this study the first comprehensive analysis of phylogenetic relations between hexactinellid families and genera of the subclass Hexasterophora based on morphological features is presented. Therefore, 157 morphological characters of the Hexasterophora were compiled into a matrix by presence/absence data. The resulting phylogenetic trees are compared with conclusions based on molecular data and classical systematics. So far, we find the main hexasterophoran taxa (Hexactinosida, Rossellidae and Euplectellidae) well established as monophyletic and in rather good correspondence with classical systematics and molecular results. Our phylogenetic trees largely support the systematic classification proposed by Schulze (1886) and Mehl (2002). However, some families (e.g. Euretidae) are not corroborated. For others (Euplectellidae), our cladistics approach is at odds with the system proposed by Tabachnick (2002a). Morphological phylogeny becomes problematic for those taxa, in which many of the diagnostic characters are either symplesiomorphic, or multiple homoplastic. Our results indicated the need for revision of the classification features used. [ABSTRACT FROM PUBLISHER]

Deep-sea research utilizing hyperbenthic sampling devices has revealed unexpected high densities and diversity of sponges, and many of the recently collected deep-sea sponges are new species. Selected case studies in the Antarctic, North Atlantic and Mediterranean Sea show that this is true not only in hydrothermal environments but is a general feature of bathyal and abyssal areas in our oceans. Some groups of siliceous sponges are known to be a significant part of benthic life in the deep-sea, but the large populations of extremely small sponges and especially the documentation of rich associations of calcareans are new to science. So far, only five species of calcareous sponges have been described from depths below 2000 m, and the Calcarea were considered as a group of primarily shallow water animals. Organic sheats that cover the spicules of calcarean sponges, probably offers some protection and enables them to mineralize in spite of the high CO2 pressure. Special adaptations to soft bottom environments and alternative feeding strategies allow the sponges to thrive in deep-sea environments. The fossil resord of sponges goes back to the Late Proterozoic and also molecular data confirm that the Porifera are the oldest known metazoans. Palaeontological investigations have shown that sponges have been living in deep water at least since the Early Cambrian. The radiative success of sponges, particularly after extinction events in Earth's history, may be linked with their ability to survive in the deep-sea.

Histological investigations of animals with hard skeletons represent a challenging problem in histotechnology. Siliceous and calcareous sponges commonly are treated with acid to remove the spicules prior to embedding and cutting. Methods for the investigation of spiculated sponge tissue are poorly known. Furthermore, fluorescence in situ hybridization (FISH), a key method to study symbiotic microbes, is not possible after acid treatment. For a broad range of siliceous sponge species, we developed and evaluated methods for embedding in paraffin, methylmetacrylat resins, LR White resin and cryomatrix. Different methods for cutting of tissue blocks as well as mounting and staining of the sections also were tested. Our aim was to enable histological investigations and FISH without prior removal of the spicules. To obtain an overview of tissue and skeleton arrangement, we recommend embedding of tissue blocks with LR White resin combined with en bloc staining techniques for large specimens with thick and numerous spicules, but paraffin embedding and subsequent staining for whole small specimens. For FISH on siliceous sponges, we recommend Histocryl embedding if the spicule content is high, but paraffin embedding if it is low. Until now, a standard method suitable for all histological attempts is not available.

The ability of stony corals to thrive in the oligotrophic (low-nutrient, low-productivity) surface waters of the tropical ocean is commonly attributed to their symbiotic relationship with photosynthetic dinoflagellates 1,2 . The evolutionary history of this symbiosis might clarify its organismal and environmental roles 3 , but its prevalence through time, and across taxa, morphologies and oceanic settings, is currently unclear 4-6 . Here we report measurements of the nitrogen isotope ( 15 N/ 14 N) ratio of coral-bound organic matter (CB-δ 15 N) in samples from Mid-Devonian reefs (Givetian, around 385 million years ago), which represent a constraint on the evolution of coral photosymbiosis. Colonial tabulate and fasciculate (dendroid) rugose corals have low CB-δ 15 N values (2.51 ± 0.97‰) in comparison with co-occurring solitary and (pseudo)colonial (cerioid or phaceloid) rugose corals (5.52 ± 1.63‰). The average of the isotopic difference per deposit (3.01 ± 0.58‰) is statistically indistinguishable from that observed between modern symbiont-barren and symbiont-bearing corals (3.38 ± 1.05‰). On the basis of this evidence, we infer that Mid-Devonian tabulate and some fasciculate (dendroid) rugose corals hosted active photosymbionts, while solitary and some (pseudo)colonial (cerioid or phaceloid) rugose corals did not. The low CB-δ 15 N values of the Devonian tabulate and fasciculate rugose corals relative to the modern range suggest that Mid-Devonian reefs formed in biogeochemical regimes analogous to the modern oligotrophic subtropical gyres. Widespread oligotrophy during the Devonian may have promoted coral photosymbiosis, the occurrence of which may explain why Devonian reefs were the most productive reef ecosystems of the Phanerozoic., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Guided by LC-MS/MS molecular networking-based metabolomics and cytotoxic activity, two new discorhabdin-type alkaloids, tridiscorhabdin ( 1 ) and didiscorhabdin ( 2 ), were isolated from the sponge Latrunculia biformis , collected from the Weddell Sea (Antarctica) at -291 m depth. Their structures were established by HRESIMS, NMR, [α] D , and ECD data coupled with DFT calculations. Both compounds bear a novel C-N bridge (C-1/N-13) between discorhabdin monomers, and 1 represents the first trimeric discorhabdin molecule isolated from Nature. Tridiscorhabdin ( 1 ) exhibited strong cytotoxic activity against the human colon cancer cell line HCT-116 (IC 50 value 0.31 μM).

Latrunculia sponges represent a rich source of discorhabdin-type pyrroloiminoquinone alkaloids, a few of which comprise a dimeric structure. The anticancer-activity-guided isolation of the n -hexane subextract of the Antarctic deep-sea sponge Latrunculia biformis yielded the known compound (-)-(1R,2R,6R,8S,6'S)-discorhabdin B dimer ( 1 ) and two new derivatives, (-)-(1S,2R,6R,8S,6'S)-discorhabdin B dimer (2) and (-)-(1R,2R,6R,8S,6'S)-16',17'-dehydrodiscorhabdin B dimer (3). The chemical structures of compounds 1 - 3 were elucidated by means of HR-ESIMS, NMR, [], ECD spectroscopy, and a comparison with the previously reported discorhabdin analogs. Compounds 1 and 2 showed significant in vitro anticancer activity against the human colon cancer cell line (HCT-116), with IC 50 values of 0.16 and 2.01 µM, respectively. Compared to monomeric discorhabdins, dimeric discorhabdins are very rare in Nature. This study adds two new discorhabdin dimers ( 2 and 3 ) to this small pyrroloiminoquinone subfamily. This is also the first report of compound 1 as a natural product and the first assessment of its in vitro anticancer activity., Competing Interests: The authors declare no conflict of interest.

The sponge genus Latrunculia is a prolific source of discorhabdin type pyrroloiminoquinone alkaloids. In the continuation of our research interest into this genus, we studied the Antarctic deep-sea sponge Latrunculia biformis that showed potent in vitro anticancer activity. A targeted isolation process guided by bioactivity and molecular networking-based metabolomics yielded three known discorhabdins, (-)-discorhabdin L ( 1 ), (+)-discorhabdin A ( 2 ), (+)-discorhabdin Q ( 3 ), and three new discorhabdin analogs (-)-2-bromo-discorhabdin D ( 4 ), (-)-1-acetyl-discorhabdin L ( 5 ), and (+)-1-octacosatrienoyl-discorhabdin L ( 6 ) from the MeOH-soluble portion of the organic extract. The chemical structures of 1 - 6 were elucidated by extensive NMR, HR-ESIMS, FT-IR, [α] D , and ECD (Electronic Circular Dichroism) spectroscopy analyses. Compounds 1 , 5 , and 6 showed promising anticancer activity with IC 50 values of 0.94, 2.71, and 34.0 µM, respectively. Compounds 1 - 6 and the enantiomer of 1 ((+)-discorhabdin L, 1e ) were docked to the active sites of two anticancer targets, topoisomerase I-II and indoleamine 2,3-dioxygenase (IDO1), to reveal, for the first time, the binding potential of discorhabdins to these proteins. Compounds 5 and 6 are the first discorhabdin analogs with an ester function at C-1 and 6 is the first discorhabdin bearing a long-chain fatty acid at this position. This study confirms Latrunculia sponges to be excellent sources of chemically diverse discorhabdin alkaloids.

Two new Hexactinellida species from the Clarion-Clipperton Zone (CCZ) in the East Pacific Ocean are described. They are the first described representatives of the genus Sympagella in this region. The new sponges were collected in 2013 during the ABYSSLINE Project´s first cruise, AB01, on board the RV Melville. The CCZ is known for its polymetallic nodules but megafaunal biodiversity is still poorly understood. Our findings suggest that the poriferan fauna of the eastern CCZ is both species rich and inadequately known, and that substantially more sampling and taxonomic studies of the CCZ sponge fauna are required to establish a megafaunal biogeography and evaluate potential extinction risks resulting from polymetallic-nodule mining.

The Antarctic deep-sea sponge Latrunculia ( Latrunculia ) biformis Kirkpatrick, 1908 (Class Demospongiae Sollas, Order Poecilosclerida Topsent, Latrunculiidae Topsent) was selected for chemical analyses due to its potent anticancer activity. Metabolomic analysis of its crude extract by HRMS/MS-based molecular networking showed the presence of several clusters of pyrroloiminoquinone alkaloids, i.e., discorhabdin and epinardin-type brominated pyridopyrroloquinolines and tsitsikammamines, the non-brominated bis-pyrroloiminoquinones. Molecular networking approach combined with a bioactivity-guided isolation led to the targeted isolation of the known pyrroloiminoquinone tsitsikammamine A ( 1 ) and its new analog 16,17-dehydrotsitsikammamine A ( 2 ). The chemical structures of the compounds 1 and 2 were elucidated by spectroscopic analysis (one-dimensional (1D) and two-dimensional (2D) NMR, HR-ESIMS). Due to minute amounts, molecular modeling and docking was used to assess potential affinities to potential targets of the isolated compounds, including DNA intercalation, topoisomerase I-II, and indoleamine 2,3-dioxygenase enzymes. Tsitsikammamines represent a small class of pyrroloiminoquinone alkaloids that have only previously been reported from the South African sponge genus Tsitsikamma Samaai & Kelly and an Australian species of the sponge genus Zyzzya de Laubenfels. This is the first report of tsitsikammamines from the genus Latrunculia du Bocage and the successful application of molecular networking in the identification of comprehensive chemical inventory of L. biformis followed by targeted isolation of new molecules. This study highlights the high productivity of secondary metabolites of Latrunculia sponges and may shed new light on their biosynthetic origin and chemotaxonomy., Competing Interests: The authors declare no conflict of interest.

The brominated pyrroloiminoquinone alkaloids discorhabdins B, L and G and 3-dihydro-7,8- dehydrodiscorhabdin C, isolated from methanol extracts of two specimens of Latrunculia sp. sponges collected near the Antarctic Peninsula, are here demonstrated for the first time to be reversible competitive inhibitors of cholinesterases. They showed K i for electric eel acetylcholinesterase of 1.6-15.0 μM, for recombinant human acetylcholinesterase of 22.8-98.0 μM, and for horse serum butyrylcholinesterase of 5.0-76.0 μM. These values are promising when compared to the current cholinesterase inhibitors used for treatment of patients with Alzheimer's disease, to counteract the acetylcholine deficiency in the brain. Good correlation was obtained between IC 50 data and results by molecular docking calculation on the binding interactions within the acetylcholinesterase active site, which also indicated the moieties in discorhabdin structures involved. To avoid unwanted peripheral side effects that can appear in patients using some acetylcholinesterase inhibitors, electrophysiological experiments were carried out on one of the most active of these compounds, discorhabdin G, which confirmed that it had no detectable undesirable effects on neuromuscular transmission and skeletal muscle function. These findings are promising for development of cholinesterase inhibitors based on the scaffold of discorhabdins, as potential new agents for treatment of patients with Alzheimer's disease., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Sponges (Porifera) are abundant and diverse members of benthic filter feeding communities in most marine ecosystems, from the deep sea to tropical reefs. A characteristic feature is the associated dense and diverse prokaryotic community present within the sponge mesohyl. Previous molecular genetic studies revealed the importance of host identity for the community composition of the sponge-associated microbiota. However, little is known whether sponge host-specific prokaryotic community patterns observed at 97% 16S rRNA gene sequence similarity are consistent at high taxonomic ranks (from genus to phylum level). In the present study, we investigated the prokaryotic community structure and variation of 24 sponge specimens (seven taxa) and three seawater samples from Sweden. Results show that the resemblance of prokaryotic communities at different taxonomic ranks is consistent with patterns present at 97% operational taxonomic unit level.

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.