Annotated catalogue of Porifera type specimens in the Belgian national collections

The national zoological collections of Belgium house 161 type specimens representing a total of 64 nominal species of Porifera. A list of extant and lost specimens is provided, presenting their original name, synonyms, museum characteristics and bibliography

A new deep sea coralline sponge from Turks and Caicos Islands: <i>Willardia caicosensis</i> gen. <i>et</i> sp. nov. (Demospongiae: Hadromerida)

A new coralline sponge, Willardia caicosensis, assigned to the family Timeidae, is described from the deep fore reef off the Turks & Caicos Islands, tropical western Atlantic Ocean, where it is common at depths ranging from 100 to 119 m. Individuals vary up to 15-20 cm in width. The relatively thin aragonitic skeleton is covered with delicate pillars up to + 1 mm. The living tissue is restricted to the spaces between pillars and a thin sheet lying above the calcareous skeleton. Exhalant canals converge upon regularly spaced central oscules on the sponge surface. Siliceous spicules include tylostyles and amphiasters which are secondarily embedded in the aragonitic moiety of the skeleton. In addition, ultrastructural characters of thechoanocytes, such as periflagellar sleeves are typical of the Order Hadromerida. Two types of cells with dense spherules are abundant in the mesohyl: sperulous cells packed with large heterogeneous inclusions, protruding at the surface of the sponge, and glycocytes with smaller ovoid corpuscles, mainly grouped along the basal calcareous skeleton. Rough collagen fibrils extend in tracts from the base of the sponge to the ectosome. Sparse bacteria are scattered in the mesohyl

<i>Esperiopsis koltuni</i> sp. nov. (Demospongiae: Poecilosclerida: Esperiopsidae), a carnivorous sponge from deep water of the Sea of Okhotsk (North Pacific)

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

<i>Clathria (Cornulotrocha) rosetafiordica</i> sp. nov. from a south-east Pacific fjord (Chilean Patagonia) (Microcionidae: Poecilosclerida: Demospongiae: Porifera)

This article reports on a new species originating from the northern Chilean fjord region, which argued for the resurrection of Cornulotrocha, here classified as a new subgenus of Clathria, for sponges with choanosomal acanthostyles, ectosomal quasidiactinal monactines and rosettes of palmate (an)isochelae. Clathria (Cornulotrocha) rosetafiordica sp. nov. was collected at 23 m depth at Quintupeu fjord (~42°S), and is unique within this very large genus, in possessing rosettes of palmate anisochelae. The new species is compared to the only other known Clathria (Cornulotrocha), viz. C. (Cornulotrocha) cheliradians n. comb.; to the single other Clathria known with anisochelae, viz C. (Thalysias) dubia; to other crustose Clathria from southern South America, the subantarctic and Antarctic areas; and also to other sponges bearing rosettes; and is considered clearly distinct from all. The phylogenetic significance of rosettes is discussed, a likely adaptive value being discarded in view of the variable location of such structures in the distinct poecilosclerid taxa in which they occur

Growth rate and chemical features of the massive calcium carbonate skeleton of <i>Petrobiona massiliana</i> (Baeriida: Calaronea: Calcispongiae)

In addition to the spicules typically produced by sponges, about twenty hypercalcified species belonging to both classes Demospongiae and Calcispongiae secrete a massive basal calcareous skeleton composed of calcite or aragonite. Skeletal growth rates and growth mechanisms are still poorly known in those hypercalcified Calcispongiae. In situ calcein staining experimentation on the Mediterranean calcisponge Petrobiona massiliana revealed a mean annual growth rate of the massive skeleton of 236 µm/y (+/-90). Scanning electron microscopy (SEM) revealed that some spicules are entrapped within the massive skeleton (a solid mass forming apical crests with multidirectional growth axes) during its formation. Whole actines were observed within the massive skeleton of fractured specimens, indicating that they do not dissolve after entrapping Calcein incorporation bands seen through epifluorescence microscopy and SEM morphological observations of the skeletal surface revealed cone shaped protuberances corresponding to active growth areas A spatially discontinuous growth was highlighted, but the annual growth rates were similar at the tip of crests and at the bottom of depressions separating them The skeleton of P. massiliana is composed of magnesium calcite with strontium as the main trace element Significant differences in skeletal chemistry of specimens collected in different Mediterranean locations revealed a possible temperature dependence of Mg/Ca Although such temperature signature exists in the massive skeleton of P. massiliana, its use as an accurate environmental recorder is limited by several factors including multidirectional and spatially discontinuous growth

Stable carbon isotopic composition of <i>Mytilus edulis</i> shells: relation to metabolism, salinity, d¹³C_DIC and phytoplankton

Bivalve shells can potentially record the carbon isotopic signature of dissolved inorganic carbon (d13CDIC) in estuarine waters, thereby providing information about past estuarine biogeochemical cycles. However, the fluid from which these animals calcify is a ‘pool’ of metabolic CO2 and external dissolved inorganic carbon (DIC). The incorporation of respired 13C-depleted carbon into the skeletons of aquatic invertebrates is well documented, and may affect the d13C record of the skeleton. Typically, less than 10% of the carbon in the skeleton is metabolic in origin, although higher amounts have been reported. If this small offset is more or less constant, large biogeochemical gradients in estuaries may be recorded in the d13C value of bivalve shells. In this study, it is assessed if the d13C values of Mytilus edulis shells can be used as a proxy of d13CDIC as well as providing an indication of salinity. First, the d13C values of respired CO2 (d13CR) were considered using the d13C values of soft tissues as a proxy for d13CR. Along the strong biogeochemical gradient of the Scheldt estuary (The Netherlands–Belgium), d13CR was linearly related to d13CDIC (r2 = 0.87), which in turn was linearly related to salinity (r2 = 0.94). The mussels were highly selective, assimilating most of their carbon from phytoplankton out of the total particulate organic carbon (POC) pool. However, on a seasonal basis, tissue d13C varied differently than d13CDIC and d13CPOC, most likely due to lipid content of the tissue. All shells contained less than 10% metabolic carbon, but ranged from near zero to 10%, thus excluding the use of d13C in these shells as a robust d13CDIC or salinity proxy. As an example, an error in salinity of about 5 would have been made at one site. Nevertheless, large changes in d13CDIC (>2‰) can be determined using M. edulis shell d13C