A new Acanthotetilla sponge from the Southwest Atlantic (Tetillidae, Spirophorina, Tetractinellida, Demospongiae), with an updated discussion on the diversity, distribution and morphologic characters of Acanthotetilla spp.

Acanthotetilla is a genus of tetillid sponges diagnosed by the presence of medium-sized, heavily spined oxeas, which are known as megacanthoxeas (or simply acanthoxeas). Currently, seven species are known worldwide: three from the Western Atlantic (A. gorgonosclera, A. rocasensis and A. walteri), three from the Western Indian (A. hemisphaerica, A. enigmatica and A. seychellensis) and one from the Western Pacific (A. celebensis). A megacanthoxea-bearing specimen was obtained from the Fernando de Noronha Archipelago, Southwest Atlantic, in 2016. It is described here as a new Acanthotetilla, namely, A. noronhensis sp. nov. This new species has two categories of megacanthoxeas, like A. celebensis from Celebes/Sulawesi Sea, Indonesia. However, the former differs from the latter, as well as from other congeners, by the combination of endolithic habit and spiculation. Acanthotetilla noronhensis sp. nov. is known on the basis of a single specimen from a large collection of sponges from Fernando de Noronha. Besides, the species was not found in other sponge collections from different areas of Brazil, including oceanic areas. Thus, the new species has probably a low abundance and restricted distribution, alike all other known Acanthotetilla species, aside A. celebensis, which (regardless its low abundance) occurs in a large sector of the western Pacific. Despite A. noronhensis sp. nov. and A. celebensis being separated by a wide geographic distance, the unique occurrence of two categories of megacanthoxeas might suggest closer phylogenetic relationship and biogeographic history as well. A wider discussion on the diversity, distribution and morphologic characters of Acanthotetilla spp. is supplied in this study. A comparative taxonomic table and a taxonomic identification key to Acanthotetilla spp. is supplied as well.

Testacosides A-D, glycoglycerolipids produced by Microbacterium testaceum isolated from Tedania brasiliensis.

Marine bacteria living in association with marine sponges have proven to be a reliable source of biologically active secondary metabolites. However, no studies have yet reported natural products from Microbacterium testaceum spp. We herein report the isolation of a M. testaceum strain from the sponge Tedania brasiliensis. Molecular networking analysis of bioactive pre-fractionated extracts from culture media of M. testaceum enabled the discovery of testacosides A-D. Analysis of spectroscopic data and chemical derivatizations allowed the identification of testacosides A-D as glycoglycerolipids bearing a 1-[α-glucopyranosyl-(1 → 3)-(α-mannopyranosyl)]-glycerol moiety connected to 12-methyltetradecanoic acid for testacoside A (1), 14-methylpentadecanoic acid for testacoside B (2), and 14-methylhexadecanoic acid for testacosides C (3) and D (4). The absolute configuration of the monosaccharide residues was determined by 1H-NMR analysis of the respective diastereomeric thiazolidine derivatives. This is the first report of natural products isolated from cultures of M. testaceum. KEY POINTS: • The first report of metabolites produced by Microbacterium testaceum. • 1-[α-Glucopyranosyl-(1 → 3)-(α-mannopyranosyl)]-glycerol lipids isolated and identified. • Microbacterium testaceum strain isolated from the sponge Tedania brasiliensis.

Checklist, diversity descriptors and selected descriptions of a highly diverse intertidal sponge (Porifera) assemblage at Costa do Descobrimento (Bahia, Brazil).

Costa do Descobrimento is located in southern Bahia, Brazil, and only 22 species of sponges (Porifera) were known from the area until now, despite its important reef formations. In the present study, we report a checklist of the sponges of Costa do Descobrimento and their distribution in the studied reefs, with several species illustrated in life. We also describe nine new sponge records for this region, some of which are new records for Brazil, or new records of species previously only poorly known. We present alpha and beta diversity indices and compare the sponge assemblage of the sampled locations. Four reefs were considered: two fringing reefs (Arraial D'Ajuda-AA and Coroa Vermelha / Mutá-CVM) and two offshore Municipal Marine Park "Parque Municipal Marinho- (P.M.M. Coroa Alta-CA and P.M.M. Recife de Fora-RF). A total of 229 specimens were collected (224 Demospongiae, 2 Homoscleromorpha and 3 Calcarea). These were classified in 101 morphotypes. Studied materials included representatives of 15 orders, 34 families and 48 genera. The richest orders are Haplosclerida (29 spp.), Poecilosclerida (15 spp.) and Tetractinellida (11 spp.). The richest families were Chalinidae (24 spp.), Clionaidae (7 spp.) and Mycalidae and Suberitidae (6 spp. each). The richest genus is, by far, Haliclona (20 spp.). Only 13 species were shared among all four reefs surveyed, namely Amphimedon viridis, Cinachyrella alloclada, C. apion, Cladocroce caelum, Cliona varians, Dysidea robusta, Mycale (Naviculina) diversisigmata, Niphates erecta, Spirastrella hartmani, Tedania (Tedania) ignis, Terpios fugax, Tethya bitylastra and T. maza. The reefs with the highest richness were CA and CVM, and the lowest richness was observed in RF. The most similar reefs in terms of species composition were CA and CVM, while AA and RF were more dissimilar to the previous reefs, but also from each other. While the difference among CA, CVM and AA was mainly explained by species turnover, RF differed from the previous based on its lower richness (nestedness component). Even though CA and CVM were the richest reefs, AA presented the highest number of exclusive species, highlighting the uniqueness of this reef, and urging the inclusion of local beachrock fringing reefs in a more holistic conservation strategy at Costa do Descobrimento.

Shallow Suberitida (Porifera, Demospongiae) from Peru.

This study describes 81 specimens belonging to Suberitida, collected during the projects Esponjas del Perú (ESPER), Esponjas da América do Sul (EsponjAS) and Semilla UCSUR 2019 (Demospongiae) along the coast of Peru, down to 30 m depth. Using morphological analyses, eight species were identified, one of which is new to science: Halichondria (H.) cristata, H. (H.) prostrata, Hymeniacidon perlevis, Johannesia reticulosa, Plicatellopsis expansa, Suberites aff. latus, Terpios cf. granulosus and Suberites inti sp. nov. Halichondria (H.) cristata, originally from Tierra del Fuego (SW Atlantic), was found widely distributed along the coast of Peru (06° S-14° S). The Magellanican H. (H.) prostrata and the formerly Chilean endemic P. expansa are extended up to Central Peru (12° S). Hymeniacidon perlevis, which presents a highly variable morphology (colour, shape, and spicule size), is firstly reported from the SE Pacific and its continuous occurrence in Peru (04° S-17° S) should be monitored given its supposed invasive potential. Johannesia reticulosa, previously known from Chile (20° S) and southern Peru (13° S), was found further north (11° S). Suberites latus and T. granulosus were originally recorded far-off from the Peruvian coast, in British Columbia and Hawaii, respectively. Thus, the occurrences of Suberites aff. latus and Terpios cf. granulosus are unexpected and should receive special attention in future molecular studies assessing their taxonomical status. Suberites inti sp. nov. characterised by its skeleton with ectosomal bouquets and multispicular choanosomal tracts, and two categories of straight tylostyles, is provisionally endemic to Paracas (13° S). With these results, the number of shallow Suberitida from Peru increases from 2 to 9. However, this number might rise as sampling in deeper environments could bring descriptions of new records.

Microbiome diversity from sponges biogeographically distributed between South America and Antarctica.

Sponges from South America and Antarctica are evolutionarily closely related. Specific symbiont signatures that could differentiate these two geographic regions are unknown. This study aimed to investigate the microbiome diversity of sponges from South America and Antarctica. In total 71 sponge specimens were analyzed (Antarctica: N = 59, 13 different species; South America: N = 12, 6 different species). Illumina 16S rRNA sequences were generated (2.88 million sequences; 40K ± 29K/sample). The most abundant symbionts were heterotrophic (94.8 %) and belonged mainly to Proteobacteria and Bacteroidota. EC94 was the most abundant symbiont and dominated the microbiome of some species (70-87 %), comprising at least 10 phylogroups. Each of the EC94 phylogroups was specific to one genus or species of sponge. Furthermore, South America sponges had higher abundance of photosynthetic microorganisms (2.3 %) and sponges from Antarctica, the highest abundance of chemosynthetic (5.5 %). Sponge symbionts may contribute to the function of their hosts. The unique features from each of these two regions (e.g., light, temperature, and nutrients) possibly stimulate distinct microbiome diversity from sponges biogeographically distributed across continents.

Lissodendoryx Topsent, 1892 (Poecilosclerida: Coelosphaeridae) from Brazil: a new species and transfer of Strongylacidon oxychaetum Menegola, Santos, Moraes & Muricy, 2012 to the genus Lissodendoryx.

The genus Lissodendoryx Topsent, 1892 has 118 valid species for the world, with five species records for Brazil. Here, we provide a description of Lissodendoryx (Waldoschmittia) almeidai sp. nov., distinguished from the other species of the subgenus by its spicular dimensions and spicular set, composed of oxeas as choanosomal megascleres, tylotes and arcuate isochelae. Also, we transfer Strongylacidon oxychaetum to Lissodendoryx (Anomodoryx), and record, for the first time, Lissodendoryx (Lissodendoryx) carolinensis from Brazil in addition to Lissodendoryx (Anomodoryx) vulcanus from Pernambuco State.

Three new Hymedesmia Bowerbank, 1864 (Demospongiae, Poecilosclerida, Hymedesmiidae) from the Southeast Pacific (Peru and Chile).

Despite its 2000 km long shoreline, to date less than 50 sponge species have been reported from the entire Peruvian coast. A large collecting effort targeting marine sponges was undertaken between 2007 and 2009, yielding a comprehensive collection of nearly 900 samples, whose taxonomic study is underway. Three new species of Hymedesmiidae are presently described from the Peruvian coast, all belonging in Hymedesmia (Hymedesmia), one of which also found in Chile. Hymedesmia (H.) santarositae sp. nov., from Isla Santa Rosa (Paracas), is characterized by the presence of microstrongyles next to sigmas. Hymedesmia (H.) peruana sp. nov., from Isla Foca (Piura), is diagnosed by its three categories of acanthostyles, and single categories of tornotes and arcuate isochelae. Hymedesmia (H.) humboldti sp. nov., from Moquega and Arequipa regions in Peru, and Antofagasta and Atacama regions in Chile, is diagnosed by its two categories of acanthostyles, and single categories of (aniso)strongyles and arcuate isochelae, the latter abundant at the surface. An identification key for Hymedesmia spp. from the South-eastern Pacific, South-western Atlantic, the Sub-Antarctic and the Antarctic is provided.

Fluxes of the Amazon River plume nutrients and microbes into marine sponges.

Sponges have co-evolved with microbes for over 400 myr. Previous studies have demonstrated that sponges can be classified according to the abundance of microbes in their tissues as Low Microbial Abundance (LMA) and High Microbial Abundance (HMA). While LMA sponges rely mainly on water column microbes, HMA appear to rely much more on symbiotic fermentative and autotrophic microbes maintained in their tissues. However, it is unclear if this pattern holds when comparing different species of tropical sponges under extreme nutrient conditions and sediment loads in the water column, such as the Great Amazon Reef System (GARS), which covers an area of ~56,000 km2 off the Amazon River mouth. Sponges are the major GARS benthic components. However, these sponges' microbiome across the GARS is still unknown. Here, we investigated water quality, isotopic values (δ13C and δ15N), metagenomic and lipidomic profiles of sponges obtained from different sectors throughout the GARS. >180 million shotgun metagenomic reads were annotated, covering 22 sponge species. Isotopic and lipidomic analyses suggested LMA sponges rely on the Amazon River Plume for nutrition. HMA sponges (N = 15) had higher Roseiflexus and Nitrospira abundance, whereas LMA sponges (N = 7) had higher Prochlorococcus and Pelagibacter abundance. Functional data revealed that the LMA sponge microbiomes had greater number of sequences related to phages and prophages as well as electron transport and photophosphorylation which may be related to photosynthetic processes associated with the Prochlorococcus and Synechococcus found in the LMA. The higher phages abundance in LMA sponges could be related to these holobionts' reduced defense towards phage infection. Meanwhile, HMA sponge microbiomes had higher Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR abundance, which may be involved in defense against phage infection. This study sheds light on the nutrient fluxes and microbes from the Amazon River plume into the sponge holobionts.

Feature-Based Molecular Networking Discovery of Bromopyrrole Alkaloids from the Marine Sponge Agelas dispar.

Investigation of the marine sponge Agelas dispar MeOH fractions using feature-based molecular networking, dereplication, and isolation led to the discovery of new bromopyrrole-derived metabolites. An in-house library of bromopyrrole alkaloids previously isolated from A. dispar and Dictyonella sp. was utilized, along with the investigation of an MS/MS fragmentation of these compounds. Our strategy led to the isolation and identification of the disparamides A-C (1-3), with a novel carbon skeleton. Additionally, new dispyrins B-F (4-8) and nagelamides H2 and H3 (9 and 10) and known nagelamide H (11), citrinamine B (12), ageliferin (13), bromoageliferin (14), and dibromoageliferin (15) were also isolated and identified by analysis of spectroscopic data. Analysis of MS/MS fragmentation data and molecular networking analysis indicated the presence of hymenidin (16), oroidin (17), dispacamide (18), monobromodispacamide (19), keramadine (20), longamide B (21), methyl ester of longamide B (22), hanishin (23), methyl ester of 3-debromolongamide B (24), and 3-debromohanishin (25). Antibacterial activity of ageliferin (13), bromoageliferin (14), and dibromoageliferin (15) was evaluated against susceptible and multi-drug-resistant ESKAPE pathogenic bacteria Klabsiella pneumoniae, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, and Enterococcus faecalis. Dibromoageliferin (15) displayed the most potent antimicrobial activity against all tested susceptible and MDR strains. Compounds 13-15 presented no significant hemolytic activity up to 100 µM.

Sponges present a core prokaryotic community stable across Tropical Western Atlantic.

Sponges are among the earliest lineages of metazoans, with first fossil records dated back to 890 million years ago. All sponge species present associations with microorganisms to some extension, which influence sponges' survival and adaptation. Sponge species can be divided into two categories, Low Microbial Abundance and High Microbial Abundance, depending on the abundance of the microbial community that they host. Monanchora arbuscula (a Low Microbial Abundance sponge species) and Xestospongia muta (a High Microbial Abundance sponge species) are sponges with widespread distribution in the Tropical Western Atlantic. Despite previous studies on the major features of these species, little is known whether M. arcuscula and X. muta prokaryotic communities are stable across vast geographic regions. We obtained a total of ~9.26 million 16S rRNA gene Illumina sequences for M. arbuscula samples collected at seven locations and for X. muta samples collected at three locations, corresponding to five ecoregions of the Caribbean and the Southwestern Atlantic (N = 105, 39 from M. arcuscula and 66 from X. muta). These samples reflected different ecological strategies for prokaryotic communities assembly, since the core prokaryotic communities of M. arbuscula are more heterotrophic and shared with different sources (corals, sponges, seawater, sediments), while X. muta has more significant photosynthetic prokaryotic communities, mainly outsourced from other sponges. Results of M. arbuscula and X. muta prokaryotic communities analysis demonstrate that both sponge species have core prokaryotic communities stable across a vast geographic area (> 8000 km), and the world's most notable coastal marine biogeographic filter, the Amazon River Mouth, in spite of the significant differences found among transient prokaryotic communities of both sponge species.

Diving into the unknown: fourteen new species of haplosclerid sponges (Demospongiae: Haplosclerida) revealed along the Peruvian coast (Southeastern Pacific).

The Peruvian coast is certainly one of the poorest studied areas in the world for marine sponges biodiversity, with only 20 species registered so far from over 2,400 km coastline. In spite of its great species richness worldwide, there is not a single record of Haplosclerida in Peru. Accordingly, in this study we aimed to describe the species belonging to this order present in the relatively recent collections undertaken along the Peruvian coast by two of us (PhW, EH). Here, we describe fourteen new species, provisionally endemic to the Peruvian coast. This finding represents a major addition to the knowledge of the biodiversity of sponges along the Peruvian coast, increasing the list of species known to occur in this area by about 68%. This is also the largest single proposal of new Haplosclerida in over 37 years of sponge taxonomy worldwide. Niphates is for the first time recorded in the Southeastern Pacific, and an identification key to the Haplosclerida from the Peruvian coast is provided. Regarding the distribution of the described species, most of themexcept for Chalinula chelysa sp. nov.have a narrow geographic range, which might indicate their rarity or that the haplosclerid fauna in Peru is still poorly known.

New species of Crella (Pytheas) Topsent, 1890 and Crellomima Rezvoi, 1925 (Crellidae, Poecilosclerida, Demospongiae) from Chilean shallow and Argentinean deep waters, with a synthesis on the known phylogenetic relationships of crellid sponges.

Here, we describe four new species of Crellidae Dendy, 1922 and discuss characters and relationships from published molecular phylogenies including crellid sponges. New species proposed are Crella (Pytheas) chiloensis Fernandez, Gastaldi, Pardo Hajdu, sp. nov., from southern Chile (15 m depth), C. (P.) desventuradae Fernandez, Gastaldi, Zapata-Herndez Hajdu, sp. nov., from Desventuradas Archipelago (1020 m depth), Crella (P.) santacruzae Fernandez, Gastaldi, Thompson Hajdu, sp. nov., from deep waters off Argentina (750 m depth) and Crellomima sigmatifera Fernandez, Gastaldi Hajdu, sp. nov., from the Chilean fjords region (ca. 20 m depth). These new species are set apart from each other and from known species mainly due to aspects of their spiculation. Chelae microscleres and acanthostyles supply characters that might be used to infer phylogenetic relationships and to verify the monophyly of Crella Gray, 1867 and Crellidae, which has seemingly been contradicted by preliminary molecular data available in the systematics literature. Our own interpretation of phylogenetic affinities, in the light of morphological characters from previous taxonomic studies, argues for a classification reassessment of materials (vouchers) included in these molecular phylogenies, especially in the case of Crella incrustans (Carter, 1885). We argue that currently available molecular phylogenetic outcomes for crellid sponges are not supportive of the polyphyly of Crella and Crellidae.

Taxonomy of Petrosiidae Van Soest, 1980 (Haplosclerida, Porifera) from Brazil.

Petrosiidae (Haplosclerida, Demospongiae) is characterized by the hard and friable consistency, and an isotropic reticulated skeleton of oxeas/ strongyles. The Brazilian coast and oceanic islands harbor three out of four known genera of Petrosiidae: Neopetrosia de Laubenfels, 1949; Petrosia (Petrosia) Vosmaer, 1885 and Xestospongia de Laubenfels, 1932. A taxonomic survey of samples from several expeditions housed at the Porifera Collection of Museu Nacional, Universidade Federal do Rio de Janeiro, with additional comparative materials obtained from the Museu de Cincias Naturais, Fundao Zoobotnica do Rio Grande do Sul, and Universidade Federal de Pernambuco enabled the description of two new species: P. (P.) revizee sp. nov. and X. dorigo sp. nov. We also recorded a range extention for Neopetrosia proxima and Xestospongia muta, and Xestospongia grayi was synonymized with X. muta. Other species reported from the country are diagnosed, and an identification key for Petrosiidae from Brazil is provided.

Zootaxa 20 years: Phylum Porifera.

The peer-reviewed journal Zootaxa has accelerated the rate of sponge (Porifera) species discoveries in 289 peer-reviewed papers published between 2002 up until the end of 2020, describing 725 new species, six new subspecies, 27 new genera, four new subgenera, and 123 new species and genus names needed to resolve existing homonyms. Zootaxa has been the most prolific of all taxonomic journals in its contributions to describing new taxa of Porifera in modern times. This present article analyses these taxonomic contributions over the past 20 years of Zootaxa, including their trends and highlights pertaining to sponge publications.

Anxiolytic-like effect of brominated compounds from the marine sponge Aplysina fulva on adult zebrafish (Danio rerio): Involvement of the GABAergic system.

Benzodiazepines are commonly used to treat disorders of the central nervous system, including anxiety. However, due to their adverse effects, there is a continuing interest in discovering new safe and effective drugs. Marine natural products have emerged as a prolific source of bioactive nitrogenated compounds. Aiming to discover new biologically active natural compounds, the marine sponge Aplysina fulva, a nitrogen-bearing heterocyst producer, was investigated. The main isolated compounds (4, 6, and 9) were evaluated on adult zebrafish (Danio rerio). A group of fishes (n = 6) was preliminarily subjected to acute toxicity, and open field tests using 0.1, 0.5, and 1.0 mg/mL (v. o.) of those compounds was performed. The anxiolytic effect was further investigated in the light/dark assay based on the locomotor response at zebrafish. Interactions through the GABAergic system were investigated using flumazenil, a silent modulator of GABA receptors. To improve the results, a study of molecular docking using the GABAA receptor also was performed. Based on the results, the bromotyrosine derivative compounds 4, 6, and 9 exhibited anxiolytic-like effects mediated by the GABAergic system.

New records of Demospongiae (Porifera) from Reserva Marina El Pelado (Santa Elena, Ecuador), with description of Tedania (Tedania) ecuadoriensis sp. nov.

The first taxonomic descriptions of the sponge diversity at El Pelado Marine Protected Area in the province of Santa Elena, Ecuador is reported. Tedania (Tedania) ecuadoriensis Jaramillo & Hajdu, sp. nov. is described from its shallow waters. In addition, Callyspongia (Callyspongia) aff. californica (sensuCruz-Barraza and Carballo 2008; non sensuDickinson 1945) and Cliona aff. euryphylle are reported for the first time. The former species is likely distributed over 4,000 km along the Tropical Eastern Pacific, whereas the latter might be an example of a trans-isthmian lineage. An amended diagnosis for Callyspongia (Callyspongia) and an updated identification key for the subgenera of Callyspongia are provided.

Three new Raspailiidae Hentschel, 1923 (Axinellida, Demospongiae) from Peru.

Currently 26 sponge species are known for the Peruvian coast, but so far no raspailiids had been recorded from this region. Raspailiidae are distributed worldwide and its species are characterized by encrusting, massive, lobate, fan-shaped or branching growth forms, usually with a very hispid surface. In the present study, three new species of Raspailiidae are described from the Peruvian coast. Two new Eurypon spp. were collected at Islas Lobos de Afuera (Lambayeque). Eurypon lacertus sp. nov. is a thinly encrusting orange sponge with choanosomal skeleton composed of large tylostyles and small acanthostyles, and ectosomal skeleton with anisoxeas. Eurypon hookeri sp. nov. is a crustose, ruby red sponge, with choanosomal skeleton composed of large (subtylo)styles and acanthostyles, and ectosomal skeleton pierced by acanthostyles and (subtylo)styles, often surrounded by bouquets of smaller styles. The third new species, Plocamione matarani sp. nov., was collected at Matarani (Arequipa). It is a thinly encrusting orange sponge, the only Plocamione with two categories of choanosomal styles, and a single category of ectosomal styles, acanthostyles and anisoacanthostrongyles. These are the first records of Eurypon and Plocamione for the Peruvian coast, and the entire Southeastern Pacific, in the case of the latter.

First record of Ciocalypta Bowerbank, 1862 (Demospongiae, Suberitida, Halichondriidae) in the Eastern Pacific, with description of a new species from Peru.

Ciocalypta includes species with finger-shaped fistules emerging from a basal mass and skeleton composed by a central axis and secondary tracts supporting the ectosome. Although worldwide distributed, no species of this genus has been reported from the Eastern Pacific. In this study, a new Ciocalypta is described from shallow waters of the southern coast of Peru. Ciocalypta magnastyla sp. nov. is greenish white, possesses the typical fistules with oscula located at their tips, and it is characterized by the presence of large styles (370-1000/5.0-32.5 µm) in combination with oxeas of intermediate size (160-500/5.0-12.5 µm). This new species constitutes the first record of the genus for the Peruvian coast as well as for the entire Eastern Pacific.

A collection of hexactinellids (Porifera) from the deep South Atlantic and North Pacific: new genus, new species and new records.

This article describes or redescribes four hexactinellid sponges, namely Poliopogon amadou, Euplectella sanctipauli sp. nov., Bolosoma perezi sp. nov. and Advhena magnifica gen. et sp. nov. P. amadou, E. sanctipauli sp. nov. and B. perezi sp. nov. represent new findings for the South Atlantic deep-sea fauna, including the first record of Bolosoma for this ocean. Advhena magnifica gen. et sp. nov., on the other hand, was collected by NOAA oceanographic expeditions in the North Pacific (Pigafetta Guyot).

Sponges from Doumer Island, Antarctic Peninsula, with description of new species of Clathria (Axosuberites) Topsent, 1893 and Hymeniacidon Bowerbank, 1858, and a re-description of H. torquata Topsent, 1916.

Antarctic sponges were mainly studied from trawling or dredging (shallow and deep water) during pioneering oceanographic expeditions carried out since the late 19th century. More recently, sponge collections by SCUBA diving have allowed the detection of species in more cryptic habitats such as rocky walls. In this study, we analyzed Antarctic sponges collected by SCUBA (in 2016 to 2018; shallower than 25 m) around Doumer Island (Palmer Archipelago, Western Antarctic Peninsula-WAP), where only five sponge species have been known. We gathered over 215 specimens, most part identified; 18 known species and one new species. Clathria (Axosuberites) retamalesi sp. nov., is set apart from its congeners on account of the combination of its habit, categories and dimensions of spicules. The East Antarctic material named as Hymeniacidon spec. (3397 m depth) from the Gauss scientific collection has been related to the shallow species H. torquata Topsent, 1916. We described H. torquata based in several specimens (n= 51) from Doumer Island (WAP), only ca. 41 km from Petermann Island (the type locality). Spicules of H. torquata are smaller than the ones present in the Hymeniacidon spec. material, which is here named Hymeniacidon hentscheli sp. nov., since it does not fit into any known cold water species of Hymeniacidon from Antarctica or the Southern Hemisphere, due to a combination of habit, oscula shape, and spicule dimensions. Only five sponge species were previously known from Doumer Island, also collected by SCUBA. Our findings suggest that the ongoing study of collections of sponges assembled at Doumer Island will still yield new taxonomic findings.