Sponges are an integral part of marine benthic communities with a high-impact role in benthic–pelagic coupling processes, as an important source of food for demersal grazers and predators, as hosts of a highly diverse microbial biomass, and as bio-eroders. Sponges provide age-old (hygienic) services to humans and continue to be of interest in modern times as sources of an unprecedented array of useful substances.

A new sponge species Coelocarteria agglomerans sp. nov. (Isodictyidae: Mycalina: Poecilosclerida) is described from the reef slopes of Bunaken National Marine Park, North Sulawesi, Indonesia. The new species can be separated from the other two congeneric species: C. singaporensis and C. spatulosa by several characters concerning sponge surface, fistule shape, form and size of the spicules and habitat. In detail it differs from C. singaporensis in the presence of strongyles instead of oxeas as main megascleres and of spines in the shaft of palmate isochelae. It differs from C. spatulosa in the absence of characteristic fistules with spatula shaped hoods and in spicule size, because both categories of strongyles and palmate isochelae are remarkably larger in the latter.

Three new species of the boring genus Aka, A. coralliirubri, A. microterebrans and A. ruetzleri are described respectively from the Mediterranean Sea, Celebes Sea and Caribbean Sea. The Indo-Pacific A. maldiviensis, known only for the structure of its epilithic fistules, is here described in more detail. The new species confirm that the sponges comprising the genus Aka are able to bore in biogenic substrata only, in particular coral rock, bivalve shells and the scleraxis of the precious coral Corallium. The study of the macroscopic excavation shows that three different patterns can be described: producing discrete boring chambers, large undivided cavities and interconnecting microtunnels giving rise to a spongious aspect of the substratum.

Three new species of Crambe are described from the upper and middle-southern coast of Chile, south-east Pacific. Crambe chilensis sp. nov. and C. amarilla sp. nov. are astroclone bearing species, while C. maldonadoi sp. nov. has sphaeroclones as asterose desmas. Morphological characters of Crambe were re-evaluated to consider this unsuspected high diversity of Crambe in the south-east Pacific. The main characters for the distinction of Chilean species as well as of other Crambe species were the live-colour; the shape and size of asterose desmas and (sub)(tylo)styles; the shape, number of categories and size-range of anchorate isochelae; and the presence/absence and dimensions of spined microxeas. An identification key for the Crambe of the world is provided. If astroclone and sphaeroclone desma-bearing species groups would represent two distinct evolutionary lineages, then the south-eastern/eastern Pacific Region would have been occupied by two evolutionary lineages with distinct life histories. The relatively high diversity of Crambe in the Chilean temperate coast, together with its occurrence in New Zealand's Oligocene, is suggestive of a likely wide distribution in Panthalassa, which contrasts to earlier suggestions of wide distribution in the Tethyan Realm only.

Esperiopsis koltuni, a new species of the sponge family Esperiopsidae, is described from deep water of the Sea of Okhotsk. The new species has a unique growth form: there is a basal plate with radiating cylindrical branches, whose oval flat distal parts bear filament-like outgrowths. Megascleres are arranged differently in the main part of branches and in their distal flat parts. The dermal membrane contains isochelae with protruding alae and abundant sigmancistras. Microscleres are represented by large anchorate spatuliferous isochelae, small isochelae, sigmas and sigmancistras. Esperiopsis koltuni sp. nov. is hermaphroditic, with parenchymella larva. The larval skeleton consists only of sigmas and sigmancistras. Esperiopsis koltuni sp. nov. can be easily distinguished from other Esperiopsis species by dimensions and combination of spicule types. In particular, it is the only species in the genus with three different size categories of styles. The new species lacks the aquiferous system, has a characteristic body plan with symmetrical lateral expansions, an unusual arrangement of microscleres in the dermal membrane and true sigmancistras. Moreover, prey capture by a filament-like outgrowth of the flat distal part was observed. All of these characteristics indicate that Esperiopsis koltuni sp. nov. is a carnivorous sponge.

The genus Stoeba has 11 recognized species. Herein we describe a new species of Stoeba endemic from two oceanic archipelagoes off north-eastern Brazil (Fernando de Noronha and São Pedro e São Paulo), constituting the first record of this genus for the western Atlantic. Stoeba latex sp. nov. is characterized by its thickly encrusting to massive shape, stretched surface, brownish-red colour, and spiculation of calthrops and sanidasters with well developed spines; dichotriaenes and oxeas are absent. Stoeba and Dercitus are very closely related genera, and should probably be merged. The genus Stoeba now contains the following valid species: S. dissimilis, S. exostotica, S. extensa, S. lesinensis, S. natalensis, S. occulta, S. pauper, S. plicata, S. reptans, S. simplex, S. syrmatita and S. latex sp. nov. Several other species still await description. A key to the valid species of Stoeba is given.

A new sponge genus and species, Astrotylus astrotylus, is described from the Antarctic abyssal zone. Its peculiar microscleres, herein referred to as astrotylostyles, combine the features of asterose spicules and tylostyles. Similar spicules are observed in Hymeraphia and Discorhabdella (order Poecilosclerida). But this similarity is convergent as far as a radial choanosomal skeleton composed by principal tylostyles and a cortical palisade of small tylostyles in Astrotylus undoubtedly confirm its allocation to the order Hadromerida and most likely to the family Polymastiidae. Atergia, Acanthopolymastia and Tylexocladus have the closest affinities with Astrotylus that calls for the phylogenetic analysis of their relations. Meanwhile astrotylostyles of Astrotylus, cladotylostyles of Tylexocladus and grapnel-like exotyles of Proteleia may be the remnants of non-monaxonic ancestral spicule type in Polymastiidae that calls for reconsideration of the relations between hadromerid families.

The genus Asconema, widely distributed in the North Atlantic and Arctic, was for some time considered to be monospecific. Its revision shows that it contains five species including the previously known A. setubalense, reinstated A. foliata and three new species (two of which are subdivided into three and four subspecies). The generic diagnosis is changed to encompass the specific characters of the new species.

A new species of the clionaid genus Pione is described from the south-western Atlantic in Argentine waters. Pione angelae sp. nov. is the first record of the genus from southern South America. It occurs on shells of Olivancillaria urceus and Buccinanops monilifer, two common gastropods living off Mar del Plata, Buenos Aires, Argentina (38°01′41″S 57°31′07″W) that are inhabited by the hermit crab Loxopagurus loxochelis. Pione angelae sp. nov. is visible on the shell surfaces as circular papillar perforations of 312 μm on average with regular diameters. They lead directly into interconnected chambers from both sides of the shell. The chambers form well-defined galleries in dense substratum. Straight tylostyles in two size-classes (defined by their length: width ratio) occur: 158.6 μm length×2.1 μm width and 185.0×4.5 μm, with spherical heads. Microscleres are more common than tylostyles, with microspined acanthoxeas of 91 μm length, slightly bent in the centre, as well as spirasters of 12 μm length with spines more concentrated on the crests of the spirals; rarely they are straight (microrhabd like). The present samples are compared to similar valid species of the same genus and it is concluded that they represent a new species.

Sponges from Rathlin Island, Northern Ireland were sampled during a six week SCUBA diving expedition. One hundred and twenty-eight species were recorded, 29 of which were previously undescribed. With previous records a total of 134 species are now known from Rathlin, the richness of its sponge community makes it a key site for sponges in Europe. Eight new species are described: Axinella parva, Spongosorites calcicola, Crella plana, Phorbas punctata, Lissodendoryx (Ectyodoryx) jenjonesae, Antho (Antho) granditoxa, Hymeraphia breeni and Hymeraphia elongata and information is given on the poorly known species Axinella pyramidata, Myxilla (Styloptilon) ancoratum, Antho (Antho) brattegardi, Clathria (Microciona) laevis and Plocamionida tylotata. Extension of the range of Hexadella racovitzai is discussed. A small bay of particularly high nature conservation importance for sponges was identified, many of the rarer species were limited to this area. Sponge populations on the east coast of Rathlin seem to have been damaged by dredging.

Early descriptions for species of Aka were poor in detail, and the only spicule type that occurs in this genus does not vary much between species, which led to taxonomic confusion. Moreover, the type specimens of five species of Aka are lost, causing considerable problems. Mediterranean specimens of Aka were identified as Aka labyrinthica (Hancock, 1849) by Topsent (1900), even though this species was originally described from the Indo-Pacific. All following publications on Mediterranean Aka accepted Topsent's decision. We assessed this problem with new samples from the Ionian Sea. Our material consisted of only one specimen of Aka, and we had to rely mainly on spicule characters for comparison with other species. We developed a system for species recognition solely based on spicular characters and biometry, involving a combination of the parameters oxea length, width, tip form and angle of curvature. This approach was surprisingly accurate. Forming ratios of the above parameters was less helpful, but can sometimes provide additional information. We identified our sample as Aka infesta (Johnson, 1899), and describe it as a minute-fistulate species with large, multicamerate erosion traces and stout, smooth oxeas. Our data further imply that A. labyrinthica sensu Hancock has not yet been found in the Mediterranean. Aka labyrinthica sensu Topsent is a collection of different species not including A. labyrinthica sensu Hancock.

This paper focuses on Aka species boring coral of the East Pacific Ocean and the Caribbean Sea (Mexico). The new species Aka cryptica sp. nov. is described from Mexican Pacific coral reefs, which constitutes the first time that a species of the genus Aka is reported from the East Pacific Ocean. The new species lives cryptically boring coral species of the genus Pocillopora. It is characterized by the small size of their papillae (from 1 to 4.5 mm high and from 0.8 to 1.8 mm in diameter), and oxeas (from 67 to 120 μm), and their exposed parts blend in well with background colours which tend to be overlooked during benthic marine surveys. In addition, Aka coralliphaga and Aka brevitubulata from Mexican Caribbean coral reefs are redescribed. The latter species is reported for the first time in Mexico.

Phorbas is a common genus with cosmopolitan distribution. A new species of sponge, Phorbas megasigma sp. nov. (Porifera: Poecilosclerida: Hymedesmiidae) is described from material collected during the third Spanish expedition on the study of the Antarctic benthos, ‘Bentart 03’. Phorbas megasigma is closely related to P. nexus but differs in the possession of arcuate chelae and very big sigmata as microscleres.

Seven syntypes of Halichondria isodictyalis, type species of Lissodendoryx, were rediscovered and studied. By choosing a lectotype and studying it along with the paralectotypes, we find that L. isodictyalis, subgenus Lissodendoryx, is a Caribbean sponge characterized by smooth megascleres, ectosomal tylotes and choanosomal styles, and one size-class of microscleres comprising arcuate isochelae and sigmas. Having determined these characteristics, we re-erect Lissodendoryx (Lissodendoryx) carolinensis (previously synonymized with L. isodictyalis), with the same smooth megascleres but two distinct size categories of microscleres, isochelae and sigmas; and we add a new western Atlantic species, Lissodendoryx (L.) spinosa sp. nov., with coarse spines on the megasclere terminals and with two size-classes of isochelae and sigmas. Other species in the region are Lissodendoryx (L.) colombiensis, with smooth tylotes and robust strongyles, and two categories of microscleres (isochelae and sigmas) accompanied by conspicuous raphids arranged in trichodragmas; Lissodendoryx (L.) strongylata, with smooth tylotes and slim strongyles, one size-class each of isochelae and sigmas, rare and very thin raphids. Lissodendoryx sigmata is here assigned to the subgenus Anomodoryx, with smooth tylotes exclusively as megascleres, two size-classes of isochelae, and one or two sizes of sigmas; it may represent a species complex far more diverse than previously thought. To this subgenus we add another species, Lissodendoryx (A.) amphispinulata sp. nov., characterized by fine spines ornamenting both tyles of part of the tylotes. A third subgenus, Ectyodoryx, is represented by Lissodendoryx (E.) acanthostylota sp. nov., with smooth tylotes and finely spined acanthostyles in two size-classes, as well as two size-classes each of isochelae and sigmas as microscleres. All species studied alive occur in shallow lagoon habitats with mangroves and sea grass (Thalassia) but museum specimen records show that some may reach a depth of 60 m.

An increasing number of cryptic species are being discovered within sponges with assumed wide geographical distribution. Pachymatisma johnstonia (Bowerbank in Johnston, 1842) (Astrophorida: Geodiidae) is one of the most common and known sponges throughout the north-east Atlantic coasts. Pachymatisma normani Sollas, 1888 is a northern species previously synonymized with P. johnstonia by Topsent. It is here redescribed on the basis of fresh material from the type locality, the Korsfjord in the Bergen area (Norway). Spicules are shown to be reliable characters to distinguish the species investigated. Pachymatisma normani is characterized by larger spicules, most markedly in the sterrasters. Our observations also suggest that habitat and gross morphology distinguish P. johnstonia from P. normani. Furthermore, using a partial sequence of the cytochrome c oxidase subunit I (COI) and an ITS1-5.8-ITS2 nuclear fragment, we show that consistent genetic differences exist between the two species. A brief overview of the genus and a key to the known species are also given.

A systematic survey of the sponge fauna of the Aegean Sea has been carried out. Twenty-eight stations located in the Aegean Sea were explored and 59 species of Demospongiae were collected from this particular area, which covers a broader geographical area of the Aegean and Cretan Seas. Some of the species found are poorly known for the Mediterranean fauna, like Cerbaris curvispiculifera and Spongosorites flavens, which are reported for the first time in the Aegean Sea and generally in the eastern Mediterranean. The species Axinyssa michaelis sp. nov. (Halichondriidae: Halichondrida) is new to science. In this paper, a description of the new species is presented along with the description of the first recorded species in the Aegean Sea. In addition to the taxonomic description of the species, some ecological data and a distribution pattern are also presented.

Five new species of sponges are described from the coast of Lebanon in the eastern Mediterranean, Levantine Basin. Euryspongia raouchensis (Dysideidae), Liosina blastifera (Dictyonellidae) and Niphates toxifera (Niphatidae) belong to genera that are new for the Mediterranean but widely distributed in the tropics. Cinachyrella levantinensis (Tetillidae) and Ciocalypta carballoi (Halichondriidae) are described in genera with a restricted distribution in the Mediterranean, which have affinities with species from the Atlantic West African coast. These species do not appear to be lessepsian migrants, but are interpreted as remnants of an ancient thermophilous fauna that survived in the easternmost part of the Mediterranean.

Calcareous sponges (Calcarea: Calcinea) are being described, for the first time, from São Paulo State, Brazil. A total of five species are described, two of which are new to science (Clathrina alcatraziensis sp. nov. and Leucascus roseus sp. nov.). The remaining three species have their distribution widened (Clathrina aurea, C. conifera and C. tetractina).

We present the most comprehensive cytochrome oxidase subunit 1 gene tree published to date for demosponges based on new sequences. The CO1 barcoding fragment is sequenced for 65 species from the Caribbean Sea, and its gene tree reconstructed. Although its deeper nodes are not particularly well-supported, the gene tree provides a variety of information for new phylogenetic patterns, as well as support for previously published 28S rDNA gene trees. In our analysis Halichondriidae cluster with Suberitidae, supporting previous 28S rDNA data. Chelae-bearing Poecilosclerida are monophyletic but most taxa lacking chelae in this dataset cluster more distantly. Haplosclerida are not resolved monophyletically under this fragment. While some species exhibit distinct barcodes, some genera contain species that share CO1 haplotypes.

We present a 28S rDNA gene tree of selected Raspailiidae, Axinellidae and other demosponges to obtain insight into raspailiid phylogeny and character evolution. The Raspailiidae in our data set cluster in a well-supported clade, distinguished from Axinellidae, Agelasida and Hadromerida. Raspailia (s.s.), Eurypon, Sollasella, Aulospongus and Ectyoplasia form a Raspailiidae clade. Some Raspailia subgenera, in particular R. (Parasyringella), are not retrieved monophyletically. Trikentrion falls into the Thrinacophorinae, and not the Cyamoninae as earlier hypothesized. The axinellid genera Ptilocaulis and Reniochalina also cluster with Raspailiidae, distant from the other Axinellidae. The suitability of particular morphological characters for raspailiid phylogeny is discussed.