Online biogeographic databases are increasingly being used as data sources for scientific papers and reports, for example, to characterize global patterns and predictors of marine biodiversity and to identify areas of ecological significance in the open oceans and deep seas. However, the utility of such databases is entirely dependent on the quality of the data they contain. We present a case study that evaluated online biogeographic information available for a hydrozoan narcomedusan jellyfish, Aegina citrea. This medusa is considered one of the easiest to identify because it is one of very few species with only four large tentacles protruding from midway up the exumbrella and it is the only recognized species in its genus. Online resources such as the Global Biodiversity Information Facility (GBIF) and the Ocean Biogeographic Information System (OBIS) suggest that A. citrea is broadly distributed throughout the world's oceans. However, lack of traceability to information from original providers made it impossible to validate the great majority of records in online resources, casting doubt on species identification. Thus, we conducted a new systematic investigation of A. citrea, integrating morphological and genetic observations of specimens obtained from a variety of different localities. Contrary to the status quo, our molecular phylogenetic analysis shows that the genus Aegina and the family Aeginidae are polyphyletic. In conjunction with our phylogenetic framework, we clarify the morphological characters distinguishing different clades of 'Aegina'. To accommodate for the previously unrecognized diversity in this group, we describe two new families, three new genera, and one new species. In addition, we clarify the identities of found species by providing updated descriptions. Specifically, we redescribe A. citrea, and resurrect and redescribe A. rosea, A. brunnea (as Aeginona brunnea gen. nov.), A. rhodina and A. pentanema, erecting a new family and genus for the latter two species (Pseudaeginidae, Pseudaegina). A new genus and species, Solmundaegina nematophora, is also described, with the erection of a new family Solmundaeginidae to contain it and the genera Solmundella, Aeginopsis and Solmundus. In light of our integrative systematic study, we find that many past conclusions about the biology of 'Aegina citrea', from life history to ecology to distributions, are compromised because observations of more than one species were applied to a single name, highlighting how systematics and taxonomy provide the foundation upon which all other biological science is built.http://zoobank.org/urn:lsid:zoobank.org:pub:AF6B533C-8110-44A0-A7E5-B71F878DAC4A ARTICLE HISTORY

The majority of calycophoran siphonophores release cormidia from the end of the polygastric colony to form a free-living sexual unit, called the eudoxid stage. Despite having a very different morphology from that of the polygastric colony, nearly all calycophoran species have had their eudoxid stages described, through a combination of morphological and distributional similarities with the polygastric stages. However, in the catch-all genus Lensia, less than half of the small, rocket-shaped polygastric stages have had eudoxid stages assigned to them. In this work, DNA barcoding of the mitochondrial 16S gene allowed two new Lensia eudoxid stages to be reliably linked with their polygastric stages: L. havock and L. leloupi. A re-examination of the latter species has indicated that L. nagabhushanami is a junior synonym. A review of all known Lensia eudoxid bracts is given, with some notes on five as-yet unassigned eudoxid stages.http//zoobank.org/urn:lsid:zoobank.org:pub:0C7F3376-B07C-481D-8F2F-367E2B7152CC

Acantharians (supergroup Rhizaria) can be important contributors to surface primary production and to carbon flux to the deep sea, but are often underestimated because their delicate structures are destroyed by plankton nets or dissolved by chemical fixatives. As they are also uncultured, relatively little is known about acantharian biology, especially regarding their life cycles. Here, we take a paired approach, bringing together high‐throughput, in situ imaging and metabarcode sequencing, to investigate acantharian abundance, vertical distribution, and life history in the western North Pacific. Concentrations of imaged acantharian cells correlated well with relative abundances of 18S rRNA gene sequences from acantharians with known, recognizable morphologies, but not to sequences corresponding to acantharians with unknown morphology. These results suggest that morphologically undescribed clades may lack the characteristic star‐shaped acantharian skeleton or are much smaller than described acantharians. The smaller size of acantharians imaged at depth supports current hypotheses regarding nonsymbiotic acantharian life cycles: cysts or vegetative cells release reproductive swarmer cells in deep water and juvenile cells grow as they ascend toward the surface. Moreover, sequencing data present the possibility that some photosymbiotic acantharians may also reproduce at depth, like their nonsymbiotic, encysting relatives, which is counter to previous hypotheses. Finally, in situ imaging captured a new acantharian behavior that may be a previously undescribed predation strategy.

A series of dives around the Hatoma Knoll, Okinawa Trough, have revealed a diverse community of gelatinous midwater animals. Many of these animals are potential predators of the larvae of hydrothermal vent-associated organisms. Due to the lack of published information on the midwater fauna of the Okinawa Trough, this paper endeavours to present a synopsis of the macroplanktonic gelatinous faunal elements present in and around the vent site at all depths where vent larvae may occur-from the surface to the benthopelagic layer. Three pelagic tunicates, eight ctenophores, seven siphonophores, eight hydrozoan medusae and two syphozoan medusae were recognized. Taxonomic treatments and comments on distribution and ecology are provided where such information exists. Keywords