We present the description of a new species of genus Timea and the re-description of T. hechteli from cryptic habitats in the Gulf of Mexico. Timea alcoladoi sp. nov. is an encrusting, pale orange sponge, with megascleres ranging from styles to subtylostyles (185–990 μm long) and a single category of microscleres, spherostrongilaster characterized by a prominent rounded centre (5–15 μm in diameter). Timea hechteli was established by Lehnert & Heimler, based on the description of a very small specimen, previously recorded as Halicometes stellata by Little, and transferred to the genus Timea by Hechtel. However, because the name ‘stellata’ was preoccupied by the type species, T. stellata, the species was renamed T. hechteli, to honour George Hechtel. After the revision of Little's material and new material, we present the re-description of T. hechteli. For both species, partial sequences of COI mtDNA and ITS1-5.8S-ITS2 rDNA region were obtained in order to complement our morphological taxonomy and establish their molecular systematic position among tethyids. Tree topologies for both loci were congruent by grouping together our species as a sister group of the main Tethyida clade, which is according to the current systematics of the group. The COI fragment showed Timea as polyphyletic due to two sequences of Timea (from GenBank) that were clustered with other sponge groups. The species described here are the first record of the genus Timea from the Mexican coast of the Gulf of Mexico. A taxonomic key for West Atlantic Timea species is also presented.

Enigmatic chambered structures have been reported forming reef frames in Cryogenian interglacial carbonates, prior to the commonly acknowledged microbial-metazoan reefs at the terminal Ediacaran, and interpreted as fossils of possible sponge-grade organisms. A better constraint on the affinity of these structures is partly hindered by few analogues in other time periods. This study describes similar structures from peritidal dolostones of the Ediacaran Denying Formation from Yunnan, China. Samples were investigated using optical microscopy and three-dimensional (3-D) reconstruction based on grinding tomography. The Dengying chambered structures are comparable with Cryogenian structures in basic construction, but are not frame building, and show variations in overall shape and inhabiting facies. Two-dimensional (2-D) cross-sections show that thin, homogeneous micritic laminae are the basic building blocks of the chamber walls. Thick walls represent parallel accretion of these laminae, and thin walls developed from the angular growth of a single lamina or merging of multiple laminae. In 3-D space, the laminae primarily correspond to continuous surfaces which sometimes contain sub-circular holes, while a few represent filamentous elements connected to the surfaces. The morphological features and growth pattern of the Dengying chambered structures indicate that they are likely to be calcified microbial constructions rather than skeletal remains of basic metazoans. However, aside from the Cryogenian and Dengying examples, comparable chambered constructions with laminae-based architecture are yet unknown from other fossil or extant microbialites. Further work investigating related structures is needed to determine the microbial consortia and controlling environmental factors that produced these chambered structures.

Biogeographical patterns among deep sea benthic communities in the Drake Passage remain poorly understood as a consequence of poor sampling resolution and the spatial remoteness of many sea floor features. Hard-bottom features, including at least 20 seamounts, remain uncharacterized with respect to their benthic megafaunal community assemblages. Here, we present community assemblage patterns from several locations across the Drake Passage to better understand the faunal relationships between deep sea floor communities in the region. Towed camera surveys were conducted on nine topographical features ranging from shelf environments on the southern Chilean Margin, the western Antarctic Peninsula shelf and seamounts in the central Drake Passage. These are the first quantitative measurements of megafaunal abundance at two seamount complexes in the central Drake Passage and multivariate analyses are used to examine the factors influencing species distributions. Three biogeographical groupings were identified based on species assemblages and environmental variables specific to major water mass boundaries in the region: sub-Antarctic Mode Water (318–523 m), Antarctic Intermediate Water (504–1128 m) and Circumpolar Deep Water (1837–3034 m). Further examination of megafaunal associations between sea floor structures may provide clues as to how sub-Antarctic communities are connected throughout the greater Southern Ocean.

Polymastiidae (Porifera: Demospongiae) of the Nordic and Siberian Seas are revised and compared with the related species of the North Atlantic based on the morphological data from the type and comparative material and the molecular data from fresh samples. Twenty species from six polymastiid genera are recorded. Two species, Polymastia svenseni from Western Norway and Spinularia njordi from the Norwegian Sea, are new to science. One species, Polymastia andrica, is new to the Nordic Seas and two species, Polymastia cf. bartletti and P. penicillus, are new to the Scandinavian Coast. Distribution of the polymastiids in the North Atlantic and Arctic is discussed and the allegedly wide distribution of Spinularia sarsii and S. spinularia is questioned.

Despite the ecological relevance of tropical reefs, information on species composition and coverage on sandstone reefs is very scarce. Most studies on reef systems have been conducted for true coral reefs, ecosystems that show calcareous formations with extensive coral cover and diversity. The aim of this study was to analyse the coverage of benthic assemblages in a submerged sandstone reef (22–24 m) in a relatively non-explored region (Tropical South-western Atlantic). In this area, filamentous algae (43.6%) and sponges (19.6%) are the main components of the benthic reef assemblages. Other benthic reef fauna (ascidians, corals and zoanthids) showed lower coverage, although their importance may vary depending on the area. A negative correlation between filamentous algae and slow-growing reef-building organisms (calcareous algae) was observed. High sand coverage (19.6%) over the reef revealed a high rate of silting. A low coral diversity (only two resilient species) was quantified, and most of the coral colonies were small-sized. The results provide a baseline assessment for a poorly known ecosystem with turbid-water benthic communities and higher sea-surface temperatures near the Earth's equator.

All polymastiid sponges displaying ornamented exotyles are reviewed and their morphological affinities are reconsidered. The study embraces all known species of Proteleia, Sphaerotylus, Trachyteleia and Tylexocladus as well as several species of Polymastia. A new genus, Koltunia, is established for the Antarctic species Proteleia burtoni based on the unique shape of distal ornamentations of its giant exotyles and on the absence of a spicule palisade in its cortex, a rare feature among the polymastiids. Three new species of Sphaerotylus are described – S. renoufi from the British Isles, S. strobilis from South Africa and S. tjalfei from West Greenland. Transfer of one New Zealand species from Polymastia to Proteleia and of one Chilean species from Polymastia to Sphaerotylus is proposed. The present study provides a background for future integrative phylogenetic analyses based on comprehensive molecular and morphological datasets which should reveal the natural relationships between the polymastiid taxa.

Suitable genetic markers for population studies in sponges are necessary to further our understanding of biodiversity and dispersal patterns, and contribute to conservation efforts. Due to the slow mitochondrial substitution rates in demosponges, nuclear introns are among the preferable markers for phylogeographic studies, but so far only the second intron of the ATP synthetase beta subunit-gene (ATPSβ) has been successfully established. In the present study, we analyse the intron of the Lysidyl Aminoacyl Transfer RNA Synthetase (LTRS), another potential marker to study demosponge intraspecific relationships, on samples of Neopetrosia chaliniformis from various locations in the Indo-Pacific and compare its variation with a mitochondrial marker (CO2). LTRS recovers several reciprocal monophyletic groups among the Indo-Pacific N. chaliniformis and provides a potential alternative to ATPSβ.

Despite the current global decline in seagrass, sessile epifaunal invertebrates inhabiting seagrass ecosystems, particularly sponges and ascidians, have been poorly studied due to their taxonomic complexity. Understanding patterns of distribution of sessile epifaunal communities in seagrass meadows is an important precursor to determining the processes driving their distribution and species interactions. This study (1) identified the sponge and ascidian assemblage associated with Posidonia australis meadows and (2) determined distributional patterns of these invertebrates at a hierarchy of spatial scales in Jervis Bay, Australia. We used a fully nested design with transects distributed in the seagrass (10s m apart), two sites (100s m apart), and six locations (km apart). Within these transects, we recorded the abundance, volume, diversity and substratum used for attachment by sponges and ascidians. We encountered 20 sponge species and eight ascidian species; they were sporadically distributed in the seagrass meadows with high variability among the transects, sites and locations. A few sponge and ascidian species dominated the assemblage and were widespread across the largest spatial scale sampled. The remaining species were mostly rare and sparsely distributed. Sponges attached to a variety of substrata but most notably shells, P. australis and polychaete tubes. No obligate seagrass species were recorded although three species predominantly used P. australis as a substratum. These sponge species relying heavily on seagrass for their attachment are likely prone to disturbances impacting their host habitat. Examining the response of sessile epifauna to the degradation of their seagrass habitat remains a key challenge for the future.

Understanding the variables (biotic or abiotic) controlling coastal communities is the main goal of ecology research and it is crucial to predict how communities will evolve under the increasing pressure on coastal systems by human activities. The general aims of this study were to assess the variables affecting the distribution of the fast-growing sponge Hymeniacidon cf. perlevis, and to evaluate if physical stressful conditions have an influence in the relationship between Hymeniacidon and the sea lettuce Ulva lactuca. Specifically, the aims were to evaluate the abundance patterns of Hymeniacidon and Ulva and to assess the relationship of Ulva and physical variables on the abundance of Hymeniacidon at both intertidal and subtidal. Hymeniacidon and Ulva showed opposite abundance patterns. Hymeniacidon was more abundant in sites without Ulva, and negatively correlated with Ulva abundance at both heights. Intertidal Hymeniacidon abundance was not correlated with physical variables, but subtidal Hymeniacidon was.

The main objectives of this study are the establishment of a detailed description of five semi-submerged and shallow-water marine caves from the Tarkhankut Peninsula (Crimea), their biological characteristics with particular attention to species composition, and the distribution of sponge assemblages in these caves. Three semi-submerged and two submerged caves with lengths of 9–131 m and volumes of 61–3060 m3 have been investigated. All of them are karst-abrasive or karst in origin. In the investigated caves, we inventoried seven sponge species. All were recorded species of Porifera belong to the class Demospongiae and have previously been recorded also in adjacent open sea waters. These species are tolerant to different hydrological conditions, mostly temperature and salinity. Some of them have wide geographic distribution. The species composition of sponges from the shallow water caves of Crimea is quite different from the sponge composition in Mediterranean caves. This could be due to the geographic isolation of the Black Sea and the differences in the hydro-chemical parameters of the milieu (water salinity in Tarkhankut is 18–21‰).

Although sponges constitute the dominant animal group in marine caves globally, few studies have investigated quantitatively their diversity patterns in this habitat. Regarding Mediterranean marine caves, data describing the structure and diversity gradients of sponge assemblages are available for the north-western basin, while information for the eastern Mediterranean is almost inexistent. In this study, the sponge assemblages in two Aegean marine caves (eastern Mediterranean Sea) with different topography were examined using a non-destructive method. In each cave, three quadrats (25 × 25 cm) were photographed at 5 m intervals, along three transects: one along the ceiling and two along the opposite walls. Per cent coverage for each sponge species was calculated using advanced image processing software. Our analyses revealed a rich sponge assemblage, which consisted of 50 species assigned to eight growth forms. Resemblance analysis for the surveyed caves revealed two major groups of samples corresponding to the shadowy outer and the darker internal cave sectors. However, differences in species composition as well as divergent spatial patterns of species richness, Shannon–Wiener diversity and morphological diversity were found not only between the caves but also between different transects within each cave. Sponge morphological diversity presented significant positive correlation with species richness and Shannon–Wiener diversity in both caves, suggesting that it could possibly be used as a surrogate measure for describing sponge diversity gradients in Mediterranean caves. Cave topography was found to have a significant effect on the observed diversity patterns and assemblage structure, highlighting the high level of individuality in these unique habitats.

Sponge species are infamously difficult to identify for non-experts due to their high morphological plasticity and the paucity of informative morphological characters. The use of molecular techniques certainly helps with species identification, but unfortunately it requires prior reference sequences. Holotypes constitute the best reference material for species identification, however their usage in molecular systematics and taxonomy is scarce and frequently not even attempted, mostly due to their antiquity and preservation history. Here we provide case studies in which we demonstrate the importance of using holotype material to answer phylogenetic and taxonomic questions. We also demonstrate the possibility of sequencing DNA fragments out of century-old holotypes. Furthermore we propose the deposition of DNA sequences in conjunction with new species descriptions.

Glass sponge reefs on the continental shelf of western Canada and south-east Alaska are considered stable deep-sea habitats that do not change significantly over time. Research cruises using a remotely operated vehicle equipped with accurate GPS positioning have allowed us to observe the same sponges at two reefs in the Strait of Georgia, British Columbia to document recruitment, growth and response to damage over time. Spermatocysts and putative embryos found in winter suggest annual, asynchronous reproduction. Juvenile sponges (2–10 cm in osculum diameter) in densities up to 1 m−2 were more concentrated near live sponges and sponge skeletons than away (Spearman rank correlations, P < 0.0001 for live cover and for skeletons), suggesting that recruitment occurs in particular regions using sponge skeletons as substrate. Most sponges showed no change in shape or size over 2–3 years, but some had died while others showed growth of 1–9 cm year−1. Deposition rates of reef-cementing sediments were 97 mm year−1 at Galiano Reef and 137 mm year−1 at Fraser Reef, but sediments eroded so that there was no net gain or loss over time. Sponges recovered within 1 year from small-scale damage that mimicked bites by fish or nudibranchs; however sponges did not recover from crushing of a large area (1.5 × 2 m2) even 3 years later. These observations and experiments show that while recruitment and growth of sponge reefs is more dynamic than previously thought, the reefs are not resilient in the face of larger-scale disturbances such as might be inflicted by trawling.

Didiscus gladius sp. nov. is described from Bahia State (Brazil). The sponge is thinly encrusting to lump-shaped and has a glassy, translucent appearance, through which the spiculation is clearly visible. The megascleres are styles and two categories of oxeas. The microscleres are discorhabds. Colour is beige or brown in ethanol. Didiscus verdensis is the nearest relative in the Atlantic which differs from the new species in a series of traits (e.g. absence of true styles and presence of strongyles). A key to species of Didiscus is given.

Sponge-related research in Taiwan has primarily focused on natural product exploration. This research has, however, been hampered by a lack of fundamental work on sponge taxonomy and ecology. In the present study, subtidal sponges were photo-recorded in situ and collected by scuba diving at a depth range of 2–20 m from 2009 to 2012 in 16 different sites surrounding the Penghu Archipelago, Taiwan. Sponge samples were identified to the lowest taxonomic level based on skeletal morphology and spicules. A total of 53 species belonging to 24 families and 10 orders were identified in this study. The number of sponge species per site ranged from 0 to 24. The most widely distributed sponge species was Callyspongia (Euplacella) cf. communis (Carter, 1881) followed by Haliclona (Gellius) cymaeformis (Esper, 1794), and Aaptos suberitoides (Brøndsted, 1934). At one location, Chipeiyu, no sponges were observed. Non-metric multidimensional scaling (NMDS) ordination revealed relatively low similarity among most sampling sites. Large- and small-scale hydrological and habitat features are probably responsible for compositional variation of sponge assemblages among groups of sampling sites. Our richness analyses suggest that many more sponge species remain to be discovered in the Penghu Archipelago.

Experimental removals of the dominant canopy-forming kelp Ecklonia radiata were conducted at two sites on rocky walls in New Zealand and monitored for approximately 1.5 years. We hypothesized that the removal of the E. radiata canopy would affect the structure of subcanopy assemblages, such that there would be a reduction in sponge species richness and abundance. Furthermore, we investigated the biological and physical (predictor) variables that best explained variability in sponge assemblages after canopy removal. Canopy removal led to a community dominated by turf algae, which corresponded with a decrease in sponge abundance and richness. Our results suggest that the Ecklonia canopy may positively influence the presence of sponge species such as Crella incrustans; we propose that the canopy may allow its coexistence with turf algae underneath the canopy by altering the light regime and other environmental factors, which may be detrimental for some species. Our results highlight how any loss of canopy-forming species might have negative effects on sponge assemblages, which could affect the energy flow and the overall biodiversity found in these habitats.

Dercitus (Stoeba) pseudodiscorhabda sp. nov. is described from the tropical western Atlantic. It is the only Dercitus (Stoeba) with four-rayed calthrops and discorhabds-like sanidasters. This is the 16th species of the genus to be recognized worldwide, the sixth from the Atlantic. The new species is compared with all its congeners worldwide.

Jia De Laubenfels, 1930 was erected to accommodate Californian Jia jia, a microcionid sponge possessing a unique J-shaped microsclere, subsequently named croca (crook, shepherd's staff). In later revisions, the genus was assigned to the synonymy of Antho Gray, 1867 because of similarity in skeletal and spicular characters with that large worldwide genus. Over the years, two additional species, one Atlantic, one from the Tropical East Pacific, were found to possess the crocae, and here four additional species with these intriguing spicules are described from Indo-West and East Pacific localities. It appears that now seven species, all Antho-like, are known to possess crocae, together distributed over all three oceans. This leads us to hypothesize that crocae are a shared character of a monophyletic group of Antho species and accordingly we propose to revive Jia as a subgenus of Antho. The four new species are Antho (Jia) galapagosensis sp. nov., Antho (Jia) lithisticola sp. nov., Antho (Jia) wunschorum sp. nov. and Antho (Jia) ramosa sp. nov.

A comparison is made of sponge diversity and abundance in nine cold-water coral reef locations situated in four regions of the north-east Atlantic, Rockall Bank (two reef locations, both deep, oceanic), Porcupine Bank (two locations, both deep, oceanic), Mingulay (two reef locations, both shallow, near-shore), Skagerrak (three reef locations, all shallow, near-shore). Literature data from two reefs were used to supplement our own data from seven reef locations. Geographical distance between the regions may be summarized as Rockall Bank < Porcupine << Mingulay <<< Skagerrak. The first three regions are all situated west of the British Isles, and prevailing current patterns and bottom conditions would make direct larval transport between all three a distinct possibility. The fourth region, Skagerrak, is situated away from the Atlantic regions, with larval contact hampered by long distances over predominantly shallow sedimented sea bottoms. Accordingly, we expected the largest taxon turnover to be between the three Atlantic regions and the Skagerrak localities. However, cluster analysis and multidimensional scaling clearly show, that shelf reefs at Mingulay were faunistically closer to the geographically- distant shelf reefs at Skagerrak than to the geographically closer bathyal reefs of the Porcupine–Rockall area. Further research is necessary to determine whether depth is a proxy for other abiotic factors such as oceanic circulation or trophic conditions.

Sponges (phylum Porifera) are important components of the benthic marine fauna known for their interactions with vertebrates and a large sort of invertebrates seeking for food, shelter or substrate for attachment. Studies on this subject, however, were restricted only to the macrofauna inhabiting sponges of the class Demospongiae. In the present work, we describe the macrofauna associated with a calcareous sponge in Brazil, Paraleucilla magna. Individuals of this allegedly non-native species were monthly collected during one year in Rio de Janeiro (Brazil). Fifty taxa representing 10 animal phyla were found associated with P. magna. The most frequent and abundant taxa were Crustacea, Mollusca, Polychaeta and Bryozoa, while echinoderms, cnidarians, ascidians, nemerteans, platyhelminthes and sponges were less frequent or even rare and less abundant. Juveniles of several taxa and pregnant females of Crustacea were found associated with P. magna, but these associations were not exclusive. The macrofauna associated with P. magna did not present a clear seasonality, although it was possible to observe a change in the community composition alongside the year. The volume of the sponges was significantly related to the diversity index (H′) and number of taxa, but not with evenness (J′) and number of individuals. Our results show that P. magna is used as a substrate for attachment and/or shelter by its associates and that most of these associations are just opportunistic. The data presented here reiterate a previous proposal that sponges are important biodiversity reservoirs and that they should be seriously considered in conservation programmes.