Parasitic crustaceans of the family Entoniscidae infest a wide range of decapod hosts worldwide, including swimming crabs (Portunidae). Here, we describe the morphology of multiple life history stages of two new species of Portunion parasitizing the portunids Charybdis (Charybdis) hellerii and Podophthalmus vigil. Morphological differences from other species were observed in both sexes as well as in the epicaridium and cryptoniscus larval stages. Phylogenetic analyses based on 18S rDNA and COI mtDNA sequences, inferred using maximum likelihood and neighbor-joining methods, placed the two new Portunion species together with P. conformis in a sister clade to Cancrion khanhensis, another entoniscid. The prevalence of Portunion infestation was relatively high, with 10.8% in C. (C.) hellerii and 7.7% in P. vigil. In both host species, infestation was significantly more common in females than in males, and in smaller individuals compared to larger ones.

The validity of two overlooked species names in the cymothoid genus Ichthyoxenos Herklots, 1870 (often misspelled Ichthyoxenus) from Chinese freshwater habitats are discussed in the context of the diversity of the genus and validity of the species therein. Ichthyoxenos is problematic as it contains 26 described species from both freshwater and marine habitats and several of the freshwater species were described from the same host in the same general locality in China and are likely synonyms. We briefly review selected species in the genus and discuss their status and the likelihood of the genus being monophyletic. We also replace the junior homonym, Ichthyoxenos yunnanensis Shen, 1940 with Ichthyoxenos sheni nom. nov. and transfer Lironeca enigmatica Fryer, 1968 into Ichthyoxenos.

Two specimens of the munidopsid squat lobster Munidopsis arietina Alcock & Anderson, 1894, collected off New South Wales, Australia (> 2,500 m depth), were parasitized by a thompsoniid rhizocephalan. This is the first record of Thompsoniidae H & oslash;eg & Rybakov, 1992, a family of parasitic barnacles characterized by extreme morphological simplification and extensive character loss, infesting a species of Munidopsidae. A combination of molecular evidence and morphological data obtained by both micro-computed tomography and light microscopy indicates that the parasites represent a new species of Thylacoplethus Couti & egrave;re, 1902. This species is described herein with an assessment of its phylogenetic placement within Rhizocephala. Mitochondrial (COI, 16S) and nuclear (18S) markers reveal instability in the monophyly of both Thylacoplethus and Thompsonia Kossmann, 1872, as well as unresolved relationships among several other rhizocephalan genera and species in various families.

Diagnoses and keys are provided for 15 families, 13 subfamilies and 265 genera of epicaridean isopods. Alaxphryxus Boyko and Williams is diagnosed as a new genus of Hemiarthrinae. The ecology and distribution of each taxon are discussed with citation of literature critical for further investigation and identification of species.

The complex history of Oniscorum squilliformium, Onischi squilliformi, Oniscus squilliformis, and Entoniscus cavolinii is reviewed. Oniscus squilliformis Zimmerman in Cavolini, 1792 is shown to be the senior synonym of Entoniscus cavolinii Giard, 1878, which is the type species of both Entione, Kossmann, 1881 and its junior synonym Grapsion Giard & Bonnier, 1886.

Squat lobsters (Decapoda: Anomura) from New Zealand were previously known to be hosts for approximately 25 species of parasitic isopods (Epicaridea). The present study reports on one new genus and four new species of epicaridean isopods collected from galatheoid squat lobster hosts off New Zealand from depths of ~250-1500 m. Three bopyrids (Munidion radagastisp. nov. on Curtonida endeavourae, Pseudione apoisossp. nov. on C. isos, and Pseudione bourdonisp. nov. on Munidopsis victoriae) and one cryptoniscid (Cryptodanalia australisgen. nov., sp. nov. on Phylladiorhynchus australis) are described. Each new species is compared to its morphologically most closely related species, and a table of comparative female morphology for all cryptoniscid genera is provided. Pseudione fibriata Richardson, 1910, is redescribed and a lectotype designated for that species, Pseudione hayi Nierstrasz & Brender à Brandis, 1931, is confirmed from its type host, Grimothea gregaria, and Pseudione sagamiensis Nierstrasz & Brender à Brandis, 1932, is newly reported from New Zealand. These discoveries underscore that the epicaridean fauna of New Zealand is more diverse than previously recognized and that continued examination of decapod hosts is likely to reveal additional undescribed parasites.

Against a background of the climate and biodiversity crises, there is an urgent need for robust and citable biodiversity information for policy and management decisions. Species are fundamental units of biodiversity and underpin communication in biology. Delineating, describing, and naming species provide the foundation for tracking biodiversity. Taxonomists recognise over 2 million described species, the scientific names of which follow provisions of codes of nomenclature, providing stability for communication about biodiversity. However, described species represent only a fraction of global biodiversity. Current advances in the fields of molecular biology and the growing use of image-based identifications have resulted in an explosion of informal species names globally, herein referred to as temporary names, increasing the rate of discovery of undescribed species and cryptic species complexes. We define two categories of temporary names: Type 1 names that are delineated in a local context but not further assessed; and Type 2 names that have been taxonomically assessed and recognised as either new or part of an unresolved species complex. We explore the different types and uses of temporary names, indicate how they can be managed in a robust and standardised manner and demonstrate how biodiversity databases, such as WoRMS, can be expanded to allow the tracking of both formal and informal scientific names. We propose a solution for the expanding problem of temporary names by defining and recommending the addition of Type 2 temporary names to nomenclatural databases such as WoRMS. We provide practical recommendations on how such names should be selected for entry and then entered to databases in a standardised way. These recommendations are a small step forward, but their broad adoption would support the robust integration of informal and formal taxonomies.

Squat lobsters (Decapoda: Anomura) harbor a high diversity of symbionts, including many parasitic isopod species (Epicaridea: Bopyridae) that reside in their branchial chambers. We describe the bopyrid Parapleurocryptella poha n. sp., found infesting at least four species of squat lobsters from New Zealand. The new species displays morphological traits characteristic of the genus Parapleurocryptella Bourdon, 1972 but it is distinct from the two other described species, P. minuta Bourdon, 1972 and P. elasmonoti Bourdon, 1972, based on the form of the female head as well as male antennal segmentation, midventral tubercles, and dactyl size. Additionally, the new species is widely separated geographically and occurs on different host species compared to others in the genus. The morphology of mature male and female specimens is described, and we show a significant positive correlation of mature female parasite length with host size. The first description of the epicaridium larva of any species of Parapleurocryptella is provided and illustrated using SEM. Epicaridium larvae of the new species possess posterior external yolk sacs, a feature previously reported for larvae in only two other bopyrid genera: Pleurocryptella Bonnier, 1900 and Paragigantione Barnard, 1920. A discussion of the potential impacts of this structure to our understanding of bopyrid life cycles is provided. Additionally, the genera Pleurocryptina Nierstrasz & Brender à Brandis, 1929 and Pagurocryptella Boyko & Williams, 2010 are transferred to Pleurocryptellinae from Pseudioninae and Pseudione kossmanni is transferred to Pleurocryptella as Pleurocryptella kossmanni (Nierstrasz and Brender à Brendis, 1923) nov. comb. based on examination of the holotype.

Crustaceans have “served” humans as an important protein source since prehistoric times, but they have also assumed a cultural importance that transcends mere seafood, as evidenced by their representation in popular culture. Here, we explore varied ways in which crustaceans have been represented in Eastern and Western popular cultures, how they are perceived, and highlight species that have become popular via social media or through print, film, and videogame subcultures. Although overlapping, cultural perceptions of crustaceans in the East and West broadly differ, in part as a result of familiarity, and perhaps also as a result of different underlying historical conceptions of nature. Even so, we contend that greater popular familiarity with crustaceans can only be beneficial to arthropods and humans alike. The ecological place of crustaceans, and sometimes even their survival, however, is now currently threatened not only by direct overharvesting and habitat destruction, but also the wider impacts of climate change. Therefore, conservation efforts using any and all methods to place crustaceans in the public eye should be pursued, including tapping into human emotional responses (via the “cute and cuddly” factor), gastronomic interest (the plight of overfished species and cost of seafood), and even a renewed emphasis on promoting the basic science of discovery and documentation (taxonomy, systematics) that underlies our understanding of the evolutionary history of this ancient, diverse, and fascinating group.

Abstract In aquatic environments, the presence of biological relationships occurring in different levels of the trophic chain is widely observed and reported in the literature, especially for invertebrates using other organisms as temporary or definitive hosts. These relationships are types of symbiosis, classified as parasitism, mutualism, or commensalism. The last frequently occurs in Platyhelminthes, including the symbiotic flatworm genus Temnocephala Blanchard, 1849, that are observed living on aquatic invertebrates and vertebrates in Central and South America. However, despite an extensive list of symbiotic relationships recorded for species in this genus, no Temnocephala species has ever been reported as an ectosymbiont of Amazon prawns. Herein we report the first occurrence of Temnocephala sp. adhered to Macrobrachium amazonicum (Heller, 1862) and Macrobrachium surinamicum Holthuis, 1948, collected in the Brazilian Amazon. The prawn species and their ectosymbionts were collected in the Guamá River (01°27’54.2”S 048°26’02.6”W), between May and September 2023, using a local trap called “matapi”. We examined 108 specimens of M. amazonicum and 24 individuals of M. surinamicum; the prevalence for Temnocephala sp. was 12.96% and 16.67%, respectively, covering between one and three symbiotic flatworms per prawn. In addition, we discuss the temnocephalan/host interaction, and provide a list of Brazilian records of Temnocephala spp. on crustacean hosts.

Gebiid mud shrimps host numerous symbionts including nearly 40 described species of parasitic epicaridean isopods as well as rhizocephalan barnacles and bivalve molluscs. Collections of gebiids from the Senckenberg Forschungsinstitut were examined to locate new and previously cited specimens bearing bopyrid, rhizocephalan and mollusc symbionts. We report on material from Japan consisting of four species of bopyrid isopods from three genera (Gyge, Phyllodurus, and Procepon), one rhizocephalan barnacle (Parasacculina shiinoi), and one symbiotic bivalve (Peregrinamor ohshimai). The record of the abdominal bopyrid Phyllodurus sp. is based on a single male specimen but likely represents a new species although more material is needed to make that determination. We also report on an additional two species of Gyge: one from European waters (G. branchialis) and one new species from the Persian Gulf. The new species can be distinguished from its closest congener based on the female uropods being visible in dorsal view and having a straight posterior lobe of the first oostegite plus the male having large midventral tubercles on the posterior five pereomeres and all pleomeres. A key to females of all species of Gyge is provided.

Background:Despite centuries of exploration, marine invertebrate biodiversity remains notably under-described. The majority of species in major marine groups are still unnamed, limiting our ability to understand and conserve ecosystems facing rapid environmental change. The rate of species discovery continues to outpace the formal process of species description. This gap creates an urgent need for streamlined, scalable approaches to taxonomy. The SENCKENBERG OCEAN SPECIES ALLIANCE was founded to help meet this challenge by facilitating global collaboration, offering technical support for species documentation and promoting efficient taxonomic publishing. Within this framework, Ocean Species Discoveries provides a forum for concise, but data-rich descriptions of marine invertebrate taxa. This second collection presents a diverse set of taxonomic contributions, based on recent and historical collections, including newly-described species and a re-description of a previously poorly-known taxon. The integrative documentation of the taxa treated herein was facilitated by the newly-established Discovery Laboratory at the Senckenberg Research Institute, the first service unit dedicated to supporting alpha taxonomists. New information:This article presents 14 new species and one re-description, two new genera, with taxa spanning three phyla. Newly-described taxa comprise two polychaete annelids: Nicon salinus Hernández-Alcántara & Dávila-Jiménez, sp. nov. and Spinther bohnorum Tilic & Rouse, sp. nov. Molluscs span four classes, with three polyplacophorans: Craspedochiton zefranki Vončina, sp. nov., Ferreiraella charazata Sigwart, sp. nov. and a new genus with type species Pycnodontochiton sinensis Sirenko, Zhang & Sigwart, gen. et sp. nov. and Pycnodontochiton tenuidontus (Saito and Okutani, 1990), comb. nov. The new monoplacophoran Veleropilina gretchenae Sigwart & Steger, sp. nov. is one of the first species of this class with a high-quality genome, published from the specimen that is now the holotype. The scaphopod Laevidentalium wiesei Sahlmann, 2012 represents a re-description and range extension and the bivalve Myonera aleutiana Machado & Sigwart, sp. nov. is the second bivalve including an anatomical description with non-invasive methods using micro-CT. Amongst crustaceans, there are two new amphipod species: Apotectonia senckenbergae Momtazi & Riehl, sp. nov. and Metharpinia hirsuta Souza-Filho & Andrade, sp. nov. Three isopod species were described, including the parasitic species Zeaione everta Boyko & Williams, sp. nov. that is the only species in the new genus Zeaione Boyko & Williams, gen. nov. and two free-living isopods: Haploniscus bulbosus Henseler, Knauber & Riehl, sp. nov. and Macrostylis peteri Riehl, sp. nov. Finally, there are two new tanaidaceans: Hoplopolemius olo Jóźwiak & Stępień, sp. nov. and Nesotanais thalassinus Stępień, sp. nov.The data used for the description of ten of the species and one of the new genera treated herein were wholly or partially obtained at the SOSA Discovery Laboratory using integrative methods including light and electron microscopy, confocal imaging, molecular barcoding and micro-CT scanning. Additional novel findings include the first record of the family Macrostylidae and the genus Macrostylis G. O. Sars, 1864 from Australian waters (Macrostylis peteri, sp. nov.) and novel host associations: Ferreiraella charazata, sp. nov. is documented with epibiotic tubeworms on its tail valves that are typical of this genus and the decapod Eucalliaxiopsis aequimana (Baker, 1907) is newly recorded as a host for bopyrid isopods, representing the first such record for the family Eucalliacidae.

The present study provides new records of parasitic crustaceans (Isopoda and Rhizocephala) associated with hermit crabs collected in Venezuela. Over 1,200 hermit crabs (Paguristes tortugae and Clibanarius antillensis) from Isla de Margarita were examined. Of this total, 58 hermit crabs (4.8%) were infested with bopyrid isopod or rhizocephalan barnacle parasites. Three species of parasitic crustaceans were recorded: the bopyrids Parathelges tumidipes and Pseudostegias atlantica, and the rhizocephalan Peltogaster purpurea. Parathelges tumidipes is reported for the first time from Paguristes tortugae (7.3% prevalence), extending its geographic and host range. Pseudostegias atlantica, previously recorded from Brazil and Mexico, is confirmed from Venezuela based on newly examined specimens infesting both Clibanarius antillensis and Paguristes tortugae (0.3% and 6.0% prevalence, respectively). The rhizocephalan Peltogaster purpurea, originally described from Brazil, is documented for the first time in Venezuela, and only the second time ever, in association with both hermit crab hosts (1.7% prevalence in Clibanarius antillensis and 11.3% in Paguristes tortugae). This study provides short redescriptions of each parasite species based on the newly collected specimens and highlights the underexplored diversity of parasitic crustaceans in areas of the Caribbean and the need for continued sampling in the region.

As part of a research project on the taxonomy of the woodlice (Oniscidea) of northern Mexico, isopod collections of Mexican academic institutions were examined. For the first time, the main diagnostic morphological traits of 4 native species are documented using SEM micrographs: Alloniscus mirabilis (Stuxberg, 1875) (Alloniscidae) and Littorophiloscia richardsonae (Holmes & Gay, 1909) (Halophilosciidae) from the northern Pacific coast of Baja California, Venezillo apacheus (Mulaik in Mulaik & Mulaik, 1942) (Armadillidae) from northern central Durango, which is also the first record of this species in Mexico, and Porcellio virgatus (Budde-Lund, 1885) (Porcellionidae) from the northeastern states of Nuevo León and Tamaulipas. The first 2 COI haplotypes (mtDNA) for P. virgatus are reported. Bayesian phylogenetic analysis of COI haplotypes placed P. virgatus in a clade with a Porcellio dilatatus haplotype with high support, forming a group with Porcellio scaber.

The epicaridean isopods previously known to have epicaridium larvae with posterior yolk sacs were species of Pleurocryptella Bonnier, 1900 and a new subfamily, Pleurocryptellinae, was recently erected for this genus. Epicaridium larvae bearing posterior yolk sacs are newly reported from two species of the genus Paragigantione Barnard, 1920 which is transferred from Pseudioninae to Pleurocryptelline on the basis of this and other shared characters of adult males and females with species of Pleurocryptella. Two new species of Paragigantione are described, one from the northeast Atlantic based on type material that was misidentified as belonging to the type species of the genus, P. papillosa Barnard, 1920 and a second from off New Zealand. One specimen of the New Zealand species had a cryptoniscus larva of a new species of hyperparasite of the genus Bourdonia Rybakov, 1990 in the marsupium while another had a species of Duplorbis (Rhizocephala); the former is described based on this material as well as a specimen from a specimen of Pseudione cf. fibriata Richardson, 1910 from New Zealand. Keys to species of Paragigantione for both males and females are provided.

External yolk sacs in free-living larvae of marine invertebrates are extremely rare, with all reported cases exhibiting yolk that is taken up through connection with the anterior alimentary canal. Herein, we confirm a novel yolk sac connected to the posterior end of the alimentary canal in the first larval stage of species in the bopyrid isopod genus Pleurocryptella, all known as ectoparasites in the branchial chambers of squat lobsters. Pleurocryptella poseidon Williams & Boyko sp. nov. infesting the munidopsid Galacantha bellis in the Arabian Sea, is described on the basis of adults and larvae. In common with conspecifics, the new species exhibits a suite of putative "primitive" characters including the presence of oostegites on the sixth and seventh pereomeres of females and maxillipeds and articulated uropods in males. Pleurocryptella poseidon Williams & Boyko sp. nov. differs from other species of Pleurocryptella by characters of body shape, antennae, oostegite 1, pleon, and uropods of females and midventral tubercles, pleomeres, and pleopods of males. The epicaridium larvae have a large posterior, external yolk sac and segmented maxillipeds, a unique set of characters within Epicaridea. In addition to larval and adult characters, molecular data (COI) indicate that the genus is distinct from other members of Bopyridae, so we erect the new subfamily Pleurocryptellinae for it. Pleurocryptella poseidon Williams & Boyko sp. nov. bears a new genus and species of hyperparasitic isopod that is herein described based on its cryptoniscus stage. A review of epicaridium larval morphology and a key to the species of Pleurocryptella are provided.

In the American Museum of Natural History, New York, there is an old specimen labelled as “Holodromia harrisonwilliamsi Boone, MS name” that was collected from Cocos Island in 1925. This name has never been published. An examination of the specimen shows that it is a juvenile specimen of Homolodromia robertsi Garth, 1973, a species described from Peru, which has since been reported from Chile and off the coast of Ecuador. This paper reports on the specimen Homolodromia robertsi Garth found in Costa Rica for the first time, a discovery that extends the known range of this species northwards.

The World Register of Marine Species (WoRMS) started in 2007 with the question “how many species live in our oceans?”. Now, a little over 15 years later, WoRMS is able to answer several questions related to marine species discovery rates and provides a dynamic number of existing marine species, based on the information provided by hundreds of taxonomic experts worldwide, who have proven to be diverse and dynamic. We present basic statistics on marine species discovery rates based on the currently available content of WoRMS, as well as insights in the day-to-day activities and dynamics of our editorial board and the progress made so far on the content priorities as defined by the WoRMS Steering Committee. As for all dynamic systems, WoRMS is not complete and faces challenges. As an endorsed project of the UN Ocean Decade, WoRMS aims to tackle a number of these challenges and knowledge-gaps by 2030, including detailed documentation of authorships and original descriptions, and will provide continuous support to all marine initiatives, programs and projects that rely on WoRMS as an authoritative classification and catalogue of marine names.