Meiofauna are frequently overlooked in biodiversity assessments, resulting in a lack of understanding regarding their current status, the potential impact of anthropogenic activities, and climate change. This study on the intertidal zone of the Small Beach of Ostend marks a new effort to characterize meiofaunal communities along the Belgian coast. Sampling was carried out on five separate occasions throughout the year, with abiotic data collected during each event. Collected specimens were sorted according to their taxonomic group, resulting in a retrieval of 1742 organisms. Among these, Platyhelminthes and Nematoda were most abundant. Through metabarcoding of the 18S ribosomal region, a biodiversity assessment was conducted, yielding a total of 106 Amplicon Sequence Variants (ASVs). After filtering out rare reads, 65 metazoan ASVs were retained: 18 representing Platyhelminthes, 16 Nematoda, 15 Copepoda, 12 Polychaeta, and 4 Acoela. Identification of the ASVs through blasting generated 23 unique species-level identifications. The highest species richness was observed among Proseriata and Nematoda, each comprising six different species. Additionally, four different species of Polychaeta and Copepoda, two species of Acoela, and one species of Rhabdocoela were identified. Compared to findings on similar beaches along the Belgian coast from about 40 years ago, the meiofaunal communities on this beach exhibit an overall low species richness. Finding fewer and other species might be linked to the potential impact of beach nourishments, human trampling, and climate change. However, confirming this hypothesis requires future research.

The European Union of Aquarium Curators (EUAC) boasts a membership of 150 dedicated individuals, standing as a vital cornerstone within the European public aquarium community. Since 2004, the EUAC Conservation Fund has granted over a quarter of a million euros to approximately 50 conservation projects spanning the globe. These initiatives, diverse in nature and scale, have yielded tangible impacts on local populations and their focal species. This paper delves into the outcomes of these conservation endeavors and proposes enhancements to ensure that the funding is unequivocally channeled towards conservation efforts. One resounding observation gleaned from the array of projects spotlighted in this study is the profound community engagement that emerges, irrespective of the final project outcomes. These endeavors serve as a catalyst for local communities, shedding light on subjects that would otherwise remain shrouded in obscurity. Furthermore, the EUAC-backed projects illuminate the expansive reach of public aquarium initiatives, transcending the confines of acrylic tank walls and institutional boundaries to resonate globally, heightening local awareness about the imperative to safeguard biodiversity. These findings underscore a prospective trajectory for both the EUAC and the public aquaria it comprises: an intensified advocacy and collaboration with legislative bodies to fortify in situ conservation measures. In essence, it is imperative that the public comprehends the pivotal role played by aquaria in preserving a multitude of species and acknowledges that their visits directly contribute to funding projects aimed at safeguarding species within their natural habitats.

We describe a new genus of dalytyphloplanid rhabdocoels, with seven new species. Orostylis gen. nov. has a unique combination of characters including the presence of a sclerotised stylet, an anteriorly positioned male copulatory organ with the male genital pore in the buccal cavity, and the absence of an oviduct. The ovary empties directly into the intestinal lumen. Orostylis dohae sp. nov., Orostylis asinaraensis sp. nov., Orostylis caecus sp. nov., Orostylis distortus sp. nov., Orostylis donanae sp. nov., Orostylis gallicus sp. nov., and Orostylis timucuorum sp. nov. are distinguished from each other by the structure of the sclerotised parts of the male copulatory organ. Molecular and morphological evidence place the new genus in Neodalyellida Willems et al. 2006, and similarities with other taxa are discussed.

The taxon Koinocystididae is the third most species-rich family within Eukalyptorhynchia. However, its diversity and phylogeny have been largely neglected in former studies. We introduce three new genera and twelve new species of Koinocystididae including Simplexcystis asymmetrica gen. n. sp. n., Galapagetula cubensis sp. n., eight species of Reinhardorhynchus gen. n. and two species of Itaipusa. This raises the total number of species within Koinocystididae from 51 to 63. We also report on new distribution records for six known species: I. divae (Cuba, Panama and New Caledonia), I. karlingi (Sardinia and Lanzarote), Reinhardorhynchus riegeri comb. n. (Cuba), R. ruffinjonesi comb. n. (Cuba and Panama), Utelga heinckei (Cuba and Lanzarote), and U. pseudoheinckei (Sardinia). Simplexcystis asymmetrica gen. n. sp. n. is characterised by a male duct running eccentrically through the copulatory bulb, lack of any hard structures in the male system, lack of a bursa, and the fact that the epithelia of the female, the male, and part of the common atrium are covered by a brush border. Galapagetula cubensis sp. n. has a caudal gonopore, a divisa-type copulatory bulb with an unarmed penis papilla, and a female duct without a sphincter. The new species of Itaipusa and Reinhardorhynchus gen. n. differ from their congeners in the detailed structure of the copulatory bulb and especially the hard structures associated with it. In a molecular phylogenetic analysis based on all available 18S and 28S rDNA sequences of koinocystidids, we found support for the monophyly of the family and the genus Utelga Marcus, 1949. The genus Itaipusa is not monophyletic in that I. sinensis forms a clade with Rhinolasius dillonicus, while other species of Itaipusa that have a copulatory bulb armed with hooks form a clade together with Sekerana stolzi. As the type species of Itaipusa (I. divae) is in neither of these clades, we erected a new genus for I. sinensis (Koinogladius gen. n.) and one for species of Itaipusa having a hook-bearing copulatory bulb (Reinhardorhynchus gen. n.), respectively. Whether the remaining species of Itaipusa form a monophylum remains uncertain.

Coelogynopora schockaerti n. sp. (Proseriata: Coelogynoporidae) is described from the northwestern Gulf of Lion, Mediterranean. Only a few representatives of this genus are reported from Mediterranean marine sandy shores and only from the northwestern to central Mediterranean, but all of these species also occur outside the Mediterranean. So far, C. schockaerti n. sp. is the only species exclusively known from the Mediterranean. The species is solely encountered in the Gulf of Lion, a coldwater pocket in the Mediterranean and can, therefore, be considered as a remnant of an ancient coldwater platyhelminth fauna. C. schockaerti n. sp. is characterized by the shape and size of the spines of the male copulatory organ and the presence, orientation, shape and size of the two accessory spines. An identification key is given for the entire genus.

An overview is given of all representatives of the genus Typhlopolycystis Karling, 1956: the five known species (T. coeca Karling, 1956; T. mediterranea Brunet, 1965; T. coomansi Schockaert and Karling, 1975; T. schockaerti Karling, 1978 and T rubra Noldt and Reise, 1985) and eleven new species: T. microphthalma n. sp. from S. France, T. fonsecai n. sp. and T. maikoni n. sp. from Brazil, T. norenburgi n. sp. and T. leasiae n.sp from the Pacific coast of Panama, T. pluvialiae n. sp. from Lanzarote (Canary Islands, Spain), T. riegeri n. sp. from Tanzania, T. tahitienis n. sp. from French Polynesia, T. australiensis n. sp. from South Australia, T. sardan. sp. from Sardinia (Italy), the S. of France and from Lanzarote, and T. errata n. sp. from Sardinia (Italy). We consider T. limicola Schilke, 1970 as a species inquirenda of which no type material exists. Finally, some comments are given on the distribution of the genus of which representatives have been found in almost all places that have been sampled world wide.

The long snout of pipefishes and seahorses (Syngnathidae, Gasterosteiformes) is formed as an elongation of the ethmoid region. This is in contrast to many other teleosts with elongate snouts (e.g., butterflyfishes) in which the snout is formed as an extension of the jaws. Syngnathid fishes perform very fast suction feeding, accomplished by powerful neurocranial elevation and hyoid retraction. Clearly, suction through a long and narrow tube and its hydrodynamic implications can be expected to require certain adaptations in the cranium, especially in musculoskeletal elements of the feeding apparatus. Not much is known about which skeletal elements actually support the snout and what the effect of elongation is on related structures. Here, we give a detailed morphological description of the cartilaginous and bony feeding apparatus in both juvenile and adult Syngnathus rostellatus and Hippocampus capensis. Our results are compared with previous morphological studies of a generalized teleost, Gasterosteus aculeatus. We found that the ethmoid region is elongated early during development, with the ethmoid plate, the hyosymplectic, and the basihyal cartilage being extended in the chondrocranium. In the juveniles of both species almost all bones are forming, although only as a very thin layer. The elongation of the vomeral, mesethmoid, quadrate, metapterygoid, symplectic, and preopercular bones is already present. Probably, because of the long and specialized parental care which releases advanced developmental stages from the brooding pouch, morphology of the feeding apparatus of juveniles is already very similar to that of the adults. We describe morphological features related to snout elongation that may be considered adaptations for suction feeding; e.g. the peculiar shape of the interhyal bone and its saddle‐shaped articulation with the posterior ceratohyal bone might aid in explosive hyoid retraction by reducing the risk of hyoid dislocation. J. Morphol., 2010. © 2009 Wiley‐Liss, Inc.

Cirrifera genitoductus sp.n. (Platyhelminthes, Proseriata, Coelogynoporidae) is described from sandy beaches at the Belgian and Northern French coasts. The species is characterised by a cirrus with small spines, all of the same size, a prostate vesicle far behind the copulatory bulb, a long genito-intestinal duct and a pair of large gland complexes behind the genital pore. An identification key for the Cirrifera-species is given as are some data on the ultrastructure. A brief discussion on the character distribution within the Coelogynoporidae shows that the discovery of a species of Cirrifera with a genito-intestinal duct makes the demarcation of the genera even more blurred than it already is.