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A new ostracod genus, Tuberocandonagen. nov., was collected from Honeycut Hollow Springs, Texas, USA Morphological comparisons and cladistic analyses showed that the new genus displays several different features (e.g. presence of two tubercules on each of the valves, numbers of A1 segments, shape of A2 claws, shape and presence of two claw-like setae on the clasping organs, absence of d2 and dp setae on T2 and T3, absence of alpha and beta setae on Md, shape of hemipenis) from other genera of the tribe. Including the new species, the number of non-marine ostracods known from inland waters of Texas is now 118 species in 45 genera. With the aim of documenting ostracod biodiversity in Texas (USA) by including fossils, we sought documents published from 1927 to 2022 and were able to list 673 ostracod taxa belonging to 142 genera. Among the fossils, 73 ostracods were the oldest records during the Pennsylvanian period (ca. 310 mya), while there were only 42 taxa reported from the Holocene. The Eocene had the highest number of ostracods (126 taxa). In comparison, the living species had only 18 of 673 taxa that were considered nonmarine forms. There are only six species in common with the fossils and recent records. These results suggest the potential for relatively high ostracod species richness and diversity in Texas. This is indeed strongly supported by the present study and the described new genus and its type species (Tuberocandona leonidasisp. nov.).

For many ostracod groups in Korea, published records are missing or are very limited. Loxocaudinae is one such subfamily, with only one named species, Loxocauda orientalis Schornikov, 2011 reported from Korea. Having fewer than 50 species, this subfamily can be considered a small ostracod group, with most of the species known only by their shell morphology. The diagnoses of genera are based on the shell characters that are often homoplastic, and soft body appendages that are difficult to observe, such as the mandibular exopodite. Because of this, the validity of the entire subfamily and some of its genera have been questioned. Here three Loxocaudinae species were collected from the marine macrobenthic assemblages from Korea. Two are new and belong to the genus Glacioloxoconcha Hartmann, 1990, previously known only from Antarctica: Glacioloxoconcha jeongokensissp. nov. and Glacioloxoconcha jisepoensissp. nov.Loxocauda orientalis is briefly redescribed, with some of the populations having unusual morphological features. COI and 18S rRNA sequences of all three species are provided and the latter marker used to assess the position of the subfamily within the family Loxoconchidae and the superfamily Cytheroidea. The resulting tree shows that within the family Loxoconchidae, the genera Glacioloxoconcha and Loxocauda Schornikov, 1969 are the most closely related, with very shallow but well-supported branches. Polyphyletic and paraphyletic natures of several Cytheroidea families are discussed, inferred from the reconstructed phylogeny.

Ilyocypris leptolinea Wang & Zhai, sp. nov. is described from late Quaternary sediments in central-eastern Inner Mongolia, northern China. The new species, which has a carapace shape and pitted surface typical of the genus, is characterised by double rows of fine, densely arranged marginal ripplets, separated by an inner list, along both anterior and posterior calcified inner lamellae in the left valve. Outline analysis and Principal Component Analysis indicate that its morpho-space overlaps with I. bradyi Sars, 1890, I. japonica Okubo, 1990, and I. mongolica Martens, 1991, which have living or fossil representatives in Inner Mongolia, but it is clearly discriminated from I. innermongolica Zhai & Xiao, 2013. Judging from the relatively coarse lithology dominated by silt and sand, and the lack of accompanying brackish-water ostracods, I. leptolinea Wang & Zhai, sp. nov. may have lived in a relatively shallow freshwater lake. It perhaps can be added to the list of species that went extinct during the Quaternary, but the timing and process of extinction await further investigation.

We describe the cypridoidean ostracod Cavernocypris hokkaiensis sp. nov. from riverbed sediments in an alpine stream at an elevation of ca. 1850 m in the Taisetsu Mountains, Hokkaido, Japan. This species differs from congeners in having (1) the outer surface of the carapace smooth, with sparse, tiny setae, but without shallow pits; (2) the carapace elongate rather than triangular in lateral view; (3) the antennula consisting of seven podomeres; (4) first palpal podomere of maxillula with five dorsodistal and one ventro-subdistal setae; (5) the fifth limb lacking setae b and d; and (6) the fifth limb lacking a vibratory plate. We provided the key to the Cavernocypris species. We determined partial sequences for the cytochrome c oxidase subunit I (COI; cox1) and 18S rRNA (18S) genes in C. hokkaiensis. Our sample contained only females, and we obtained a partial 16S rRNA sequence for the endosymbiotic bacterium Cardinium from C. hokkaiensis, indicating the possibility that this ostracod species reproduces parthenogenetically. Our field survey and observations of captive individuals suggested that C. hokkaiensis may be endemic to the Taisetsu Mountains, with a low population density, narrow distributional range, and slow maturation to sexual maturity.

Two new Cypridopsinae ostracods, Potamocypris meissnerisp. nov. and Sarscypridopsis harundinetisp. nov. are described. Both were found only as asexual (all-female) populations in temporary waters of southern Africa. Potamocypris meissneri was collected from a small pan in the North-West Province of South Africa. It is approximately 0.5 mm long and belongs to the species group with long swimming setae on the second antennae. However, the species has a somewhat isolated position in the genus owing to the conspicuously reticulated carapace, which is furthermore densely covered by prominent conuli with normal pores carrying long sensilla, as well as to the wide anterior and posterior flanges on the left valve. To allow identification of the new species in relation to its closest congeners, a key to the species of the genus Potamocypris Brady, 1870 from southern Africa is provided. The genus Sarscypridopsis McKenzie, 1977 mostly has an Afrotropical distribution with only few species occurring in other regions. Sarscypridopsis harundineti was collected from floodplains of the outskirts of the Okavango Delta in Botswana. It is approximately 0.4 mm long and can be distinguished from congeners mainly by the smaller and more oval-shaped valves. We conclude that southern African Cypridopsinae urgently need integrated taxonomic revision, by means of both morphological characters and DNA-sequence data.

The New Caledonian Archipelago is a hot spot for biodiversity and endemism. Whereas popular groups such as birds and plants are well-studied, invertebrate groups such as ostracods remain ill-known. Here, Caledromus robinsmithi gen. et sp. nov. is described from a single locality on 'Grande Terre', the main island of the archipelago. The new genus belongs to the Psychrodromini, one of the four tribes in the subfamily Herpetocypridinae (family Cyprididae). Caledromus gen. nov. can be distinguished from all other herpetocypridinids by a combination of the following factors: the absence of marginal septa in both valves, the mildly developed marginal valve structures, the small Rome organ on the A1, the total reduction of the five natatory setae on the A2, the rectangular second palp segment of the Mx1, the broad and asymmetrical palp on the female T1, the absence of additional postlabyrinthal coils in the Hp and the seta Sp of the CR which is a fixed spine. Because of the close similarity to the genus Psychrodromus, the new genus is thought to have Palaearctic affinities, contrary to other ostracod species in New Caledonia, which are either circumtropical or with Australian zoogeographical connections.

Ostracoda is a diverse group of tiny crustaceans. Although more than 9330 extant species have been described, whole-mitogenomic data were available for only five species. Here we present a complete mitogenomic sequence for an additional species, the parthenogenetic podocopan ostracod Heterocypris spadix. The mitogenome is 15,205 bp long and contains the typical animal mitogenomic complement of 13 protein coding, two ribosomal RNA, and 22 transfer RNA genes. In a mitogenome-based phylogenetic tree, Myodocopa and Podocopa were each monophyletic. Gene order in Podocopa was much more similar to the pancrustacean ground pattern than was gene order in Myodocopa. Gene order was invariant in the three myodocopan species examined, all in the family Cypridinidae. Within Podocopa, two species from different families (Fabaeformiscandona kushiroensis, Candonidae; H. spadix, Cyprididae) were identical in gene order and differed from the pancrustacean ground pattern by only a single recombination. In Cyprididae, however, Cypridopsis vidua differed from H. spadix by five rearrangements. These conflicting patterns—apparent gene-order conservation within (Cypridinidae) and between families (Cyprididae and Candonidae), but marked divergence within a family (Cyprididae)—suggest that the evolution of gene order in ostracods was more complex than that expected from the cypridinid data.

Groundwater ecosystems host a rich and unique, but still largely unexplored and undescribed, biodiversity. Several lineages of ostracod crustaceans have subterranean representatives or are exclusively living in groundwaters. The stygobitic genus Pseudolimnocythere Klie, 1938 has a West Palearctic distribution, and includes few living and fossil species of marine origin. Through a comprehensive literature review and the description of the two new living species, Pseudolimnocythere abditasp. nov. and Pseudolimnocythere sofiaesp. nov., from springs in the Northern Apennines, Italy, a morphological analysis was carried out with the aim of comparing the valve morphology of living and fossil species, and to discuss previous hypotheses about time and mode of colonization of inland waters. Pseudolimnocythere species show a low variability in valve morphology, with a remarkable stasis over geological times. The distribution of extant and fossil species is consistent with a scenario of multiple and independent events of colonization of continental habitats linked to sea level variations starting from Middle Miocene in the Paratethys and, later, in the Mediterranean. The most common colonization routes of inland waters have taken place through karst formations along ancient coastlines, although we cannot exclude some minor active migration through the hyporheic zone of streams. Available distribution data suggest a poor dispersal ability of Pseudolimnocythere species after they had colonized continental waters.

We describe the cypridoidean ostracod Heterocypris spadix sp. nov. from brackish water on Okinawa Island, Japan. The species closely resembles Heterocypris salina (Brady, 1868) but differs in that (1) the marginal infolds on valves are less developed, (2) the tubercles on the anterior margin of the right valve are completely covered by the selvage and invisible in inner view, and (3) the calcified inner lamella on the ventral margin of the left and right valves is scarcely evident in inner view, as the ventral margins of the valves bend inwardly. We determined partial sequences for the cytochrome c oxidase subunit I (COI; cox1) and 18S rRNA genes in H. spadix for future DNA barcoding and phylogenetic analyses. Our sample contained only females. A breeding experiment revealed that H. spadix females reproduce parthenogenetically. Another experiment showed that H. spadix has low tolerance to desiccation, with all individuals at 25°C dying between 1–2 hours after removal from water. We amplified and sequenced a partial 16S rRNA sequence for the endosymbiotic bacterium Cardinium from H. spadix. Infection by Cardinium may be related to the parthenogenetic reproductive mode we observed in H. spadix.

We describe Obesostoma crinophilum sp. nov. (Ostracoda: Podocopida: Paradoxostomatidae) obtained from the body surface of the feather star Antedon serrata A. H. Clark, 1908 (Crinoidea: Comatulida: Antedonidae). This is the first report of Ostracoda associated with Crinoidea. None of the highly specialized appendages and/or carapace that are related to a commensal lifestyle were observed in O. crinophilum sp. nov. Therefore, the relationship between O. crinophilum sp. nov. and A. serrata must be transient rather than obligatory. However, O. crinophilum sp. nov. has a more developed hook-like distal claw on the antenna in comparison with four previously known Obesostoma species. The relatively well-developed distal claw of the antenna in O. crinophilum sp. nov. should indicate its intimate association with feather stars, though the feeding habit is still unknown.

The depth distribution of living specimens of deep-sea benthic ostracods (small crustaceans with calcareous shells that are preserved as microfossils) in sediments is poorly understood, despite the importance of this aspect of basic ostracod biology for paleoecologic and paleoceanographic interpretations. Here, we investigated living benthic ostracod specimens from deep-sea multiple core samples, to reveal their depths distributions within sediment cores. The results showed shallow distribution and low population density of living deep-sea benthic ostracods (which are mostly composed of Podocopa). The living specimens are concentrated in the top 1 cm of the sediment, hence deep-sea benthic ostracods are either epifauna or shallow infauna. This observation is consistent with the information from shallow-water species. We also confirmed shallow infaunal (0.5–2 cm) and very shallow infaunal (0–1 cm) habitats of the deep-sea ostracod genera Krithe and Argilloecia, respectively.

The taxonomy and ecology of ostracods in the Caribbean remain incomplete, even though they are among the most successful and ubiquitous microcrustaceans of marine ecosystems. In an effort to enhance our knowledge of the biodiversity, abundance, and distribution of benthic ostracods, several sediment samples were collected from mesophotic coral ecosystems (MCEs) of Puerto Rico and U.S. Virgin Islands at different depths (30–102 m) using technical diving. The highest densities of ostracods were found in the deepest samples (≥61 m), and these were the most abundant and diverse assemblages. All ostracods collected belong to the subclasses Myodocopa Sars and Podocopa Sars. Myodocopa was represented by the families Cypridinidae Baird, Polycopidae Sars, Sarsiellidae Brady & Norman, Rutidermatidae Brady & Norman, Cylindroleberididae Muller, and Philomedidae Muller. On the other hand, Podocopa was represented by the following families: Bairdiidae Sars, Pontocyprididae Muller, Candonidae Kaufmann (subfamily Paracypridinae Sars), Macrocyprididae Muller, Loxoconchidae Sars, Xestoleberididae Sars, Cytherellidae Sars and Cytheromatidae Elofson. The subclass Podocopa showed the highest number of individuals and species. There was a ~100 % correspondence between morphologically identified species and genetically defined species through a short region of the nuclear large subunit ribosomal DNA, which was shown to be appropriate for species recognition and discrimination in ostracods. Using a morphological (shell shape and ornamentation) and molecular barcoding approach (28S rDNA), we provide the first report of the biodiversity of ostracods in the mesophotic coral ecosystems of northeastern Caribbean.

Ostracods are a class of small crustaceans that inhabit both saltwater and freshwater environments. There are approximately 8,000 living species of ostracods. Non-marine ostracods belong to the Order Podocopida, which is comprised of the superfamilies Cypridoidea, Darwinuloidea, and Cytheroidea (Thorp 2015). They are commonly known as seed shrimp due to their small size, typically smaller than a poppy seed or up to 1 mm. Their carapace, the upper shell of crustaceans, is bivalved, giving it the common name mussel shrimp.

A total of 15 species of ostracods of 7 genera and 3 families of the suborder Podocopa Sars have been recorded in rockpools of the Kandalaksha Bay in the White Sea. Among them, Potamocypris pallida Alm is a new species for the fauna of Russia. Data on species composition and the dominant complex and ecological features of ostracods which inhabit waters of rockpools are presented.

Two new species of the interstitial ostracod genus Parvocythere, P. gottwaldi sp. n. and P. gracilis sp. n., are herein described. Although these two new species are clearly distinguishable by certain morphological differences in elements of the male copulatory organ, and the carapace, they share the following simplified characters of the appendages and male copulatory organ: antennular fourth podomere with no suture; reduced claws on the distal end of antenna; and asymmetric male copulatory organ. The morphological differences among known and new Parvocythere species suggest that the species of this genus can be classified into two groups by the presence/absence of the suture on the antennular fourth podomere. The “Group S” is characterised by the presence of the antennular suture, and all species of this group have a two-clawed antenna and symmetric male copulatory organ, characters which are generally seen in cytheroid ostracods. The species belonging to “Group N” are characterised by the absence of the suture, regarded as a pedomorphic character, show the following characters: two clawed or one clawed antenna, and symmetric or asymmetric male copulatory organ. The morphological variation within Group N includes reductive characters regarded as an adaptation to the narrow spaces of the interstitial environment of a sandy beach. These intrageneric morphological variations of the exclusively interstitial genus Parvocythere suggest the possibilities that Group N might be derived from Group S, and that some adaptive characters to an interstitial environment could have developed after the colonisation of these environments.

The species composition of ostracods in the zooperiphyton was determined in 45 waterbodies and watercourses of Tyumen oblast. A total of 58 species from seven families and 22 genera of the suborder Podocopa Sars, 1866, have been found: 30 species of the family Candonidae, 13 of Cyprididae, 8 of Cyridopsidae, 3 of Ilyocyprididae, 1 of Darwinulidae, 2 of Cytherideidae, and 1 of Limnocytheridae. Of these 58 species, 32 are recorded for the first time in the region; one of them is a Mediterranean species (Stenocypris sp.) from the cooling reservoir of Tyumen Thermal Power Station 1. The distribution and biogeography of the ostracods are described.

Silicified representatives of the ostracode orders Binodicopa, Palaeocopa and Podocopa have been recovered from the late Ordovician Pin Formation, Spiti, NW Himalaya area. Benthic binodicopes are distinctly more abundant than the palaeocope and podocope ostracodes. The binodicopes show biogeographical relations to Australia at the generic level, which supports the close palaeogeographic position of these continents. By contrast, the palaeocope and podocope taxa show close relations to Baltica and Bohemia even at the species level, which may suggest a pelagic or epipelagic mode of life since these regions are separated from each other by the broad and deep waters of Palaeotethys. New taxa are Vendona crassiplicata nov. sp., Glossomorphites himalayaensis nov. sp., Pilla pinensis nov. sp. and Pinpilla u-formis nov. gen. nov. sp.

A new concept of the hinge classification in the Podocopa is established based on a comprehensive description of the hinge ultrastructure. Four new types of structure are defined, according to the relative position of their ligaments and hingements (teeth elements): basic type, exterior type, intermediate type and interior type. The new classification reveals that the adont hinge, which is known as a simple structure, shares the fundamental structure (basic or exterior type) found in the Platycopida, Darwinuloidea and Bairdioidea, and that it develops not only as the fundamental structure, but also as the advanced structure (interior type) in the Cypridoidea and Cytheroidea. Additionally, the high level of morphological diversification of cytheroid hingements is explained in terms of the structural plasticity of the intermediate and interior hinge structure types. Most cytheroid hinges can develop complex arrangements of teeth (hingements) by only small changes of calcification because their hingements can develop independently from the particular restricted location of the ligaments. The evolutionary pathway of hinge structures is also examined based on a study of fossil records. The pathway indicates that the complex hinge structures of the derived taxa arose from simpler ones, but that sometimes this trend can be reversed and derived taxa can evolve simple hinge structures as adaptations to new habitats. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92, 41–62.

The present study describes the embryonic developmental process of the bioluminescent ostracod crustacean Vargula hilgendorfii. Optical microscopy, scanning electron microscopy, DAPI staining and video recording were used for observations. This study is the first detailed report of the embryonic development of a myodocopid ostracod. Contrary to previous studies, cleavage occurred in the yolk sphere and no evident cleavage furrow was found. No nauplius stage was found, and five pairs of appendages developed simultaneously. A bivalved carapace developed from two independent buds of the carapace valves. The buds of the left and right valves are enlarged, and become combined. The combined ‘one-piece’ carapace was divided by the formation of a hinge, and the usual bivalved carapace was formed. On the 16th day, embryos hatched as juveniles with six pairs of appendages, a pair of immature appendages, a pair of compound eyes, a median eye and a bivalved carapace. An important suggestion for the classification of Ostracoda is derived from the observed development of appendages and carapace, because the subclass Ostracoda is defined mainly by the similarities of appendages and the bivalved carapace. The present observations clearly show that the developmental process of Myodocopa differs from that of Podocopa, and supports polyphyly of the Ostracoda.

Background So far, 16 species of non-marine ostracods have been reported from Kushiro Marsh, Kushiro Shitsugen National Park, eastern Hokkaido, Japan (Hiruta and Smith 2001, Smith and Hiruta 2004). Nine of these species are in Candonidae, the second-most diverse family of non-marine ostracods. This family contains ca. 550 species, or around 25% of the total number of non-marine ostracod species (Martens et al. 2008). New information We sampled ostracods in Kushiro Marsh on 27 December 2012 and identified an undescribed species in the family Candonidae, herein described as Fabaeformiscandona kushiroensis sp. nov. This species belongs to the F. acuminata species group and is characterized by the shapes of the elongate, dorsally directed medial and outer lobes on the distal end of each hemipenis. We also determined for this species the sequence of the nearly complete mitochondrial genome, the first record from the order Podocopa. The genome (ca. 17 kbp) contains two ribosomal RNA, 22 transfer RNA, and 13 protein-coding genes, as also found in other arthropods for which the mitochondrial genome has been sequenced. The gene arrangement is similar to the pancrustacean ground pattern, except that in the control region there is an approximately 2 kbp tandem repeat region composed of 220-bp motif sequences. We describe the genetic features of the mitochondrial genome, including nucleotide composition and the secondary structures of tRNAs and rRNAs, and compare them with the genome of Vargula hilgendorfii (Myodocopa, Ostracoda).

There are Cambrian fossils attributed to the Ostracoda but the extant subclasses Podocopa and Myodocopa do not appear until the Ordovician. At this time the morphologically similar, free-living ancestors of the now sedentary Thecostraca (Ascothoracida, Acrothoracica and Cirripedia) may have still been extant, and from an ecological point of view it seems likely that, by and large, ostracods replaced them. However, living ostracods have an abbreviated, direct development, and some key aspects of their morphology, such as the nature of the maxillary segment and abdomen, are conjectural. Thus the affinities between these and related taxa remain uncertain; e.g., while some contemporary carcinologists place Ostracoda as a taxon coordinate with the Branchiopoda, Remipedia, Cephalocarida, Maxillopoda, Malacostraca, others tentatively or unequivocally ally them with the Maxillopoda (generally Mystacocarida, Copepoda, Tantulocarida and Thecostraca, and sometimes Branchiura and Pentastomida). Others, largely involved with fossils, have stretched the definition of the Maxillopoda even further, to the point where it seems even less likely a monophyletic taxon. Until recently cladistic analyses utilizing genetic (largely 18S rDNA) as well traditional morphological characteristics have given confusing results regarding the affinities between these taxa, and an important one suggested the Ostracoda might even be diphyletic. Furthermore, a very recent genetic study utilizing protein encoding genes places a podocopine ostracod among the most primitive of the extant crustaceans (Branchiopoda, Cephalocarida Remipedia and Mystacocarida), and then generally at the base of a lineage leading to the Malacostraca, a lineage giving rise to copepods and cirripeds along the way. This indicates these so-called maxillopodan taxa evolved independently from a malacostracan-like ancestor, and if so they are convergent. And finally, from genetic studies it is not only becoming well documented the Crustacea rather than Myriapoda gave rise to the Hexapoda, but it appears the Hexapoda stem from among the lower rather than the higher crustaceans, possibly even from the Ostracoda. Whether there were terrestrial ostracods at the time hexapods appeared in the Lower Ordovician is unknown, but the modest diversity of terrestrial ostracods today are podocopines which also first appeared in the Lower Ordovician. Thus, if current interpretations of living ostracodan and fossil hexapodan body plans are largely correct, it can be hypothesized the Ostracoda are close to the ancestor of the Hexapoda.

The ontogeny of the musculature and segments of the antennule of Heterocypris incongruens (Ramdohr, 1808) is documented. The musculature of the antennule of the juveniles indicates that during ontogeny the additional segments originate by existing segments dividing. Previously presented hypotheses are tested with these new data. Smith & Martens' (2000) hypothesis on the development of the antennule of Eucypris virens (Jurine, 1820) is supported and is expanded to cover other groups. There are five segments in the early juveniles of most species and some of these divide to form new segments during ontogeny. Additionally, some segments fuse together, and some segments divide and then fuse together again. Most divisions of segments produce two true segments, rather than annulations or secondary joints, but one species shows evidence of an annulation in the antennule.

A broad array of the highly variable morphological characters available in Ostracoda were used (1) to construct a new tabular key to the families of the subclass Myodocopa (and to differentiate the Myodocopa from the Podocopa), and (2) to explore the evolution of bioluminescence in the myodocopid family Cypridinidae. Results of a cladistic analysis of the Cypridinidae strongly support a single origin of bioluminescence within the family; a single clade contains at least 64 species known to luminesce (not all described). Furthermore, within that large clade, complex bioluminescent mating displays were confined by the analysis to a single clade of exclusively Caribbean cypridinids, though that result was unresolved by bootstrap analysis.Chemically different bioluminescence occurs convergently in two ostracode groups; it is produced within carapace glands of certain Halocypridina, but it is produced and extruded from the upper lips of many cypridinid Myodocopida and serves as an antipredatory behavior in both groups. Additionally at least 60 cypridinid species also produce spectacular and complex species-specific male mating displays nightly in the Caribbean Sea. The cladistic analysis using 58 morphological characters of 44 taxonomic units (24 described genera of Cypridinidae, 11 individual species assigned to the genus Vargula, six groups of bioluminescent signalling Caribbean species (many undescribed), the Cylindroleberididae, and the Philomedidae) was performed using PAUP with the parsimony criterion. Twenty-five of the characters were previously underutilized characters of the complex upper lip and large male copulatory limbs discovered through dissection and SEM. These proved especially valuable, but characters of all other limbs were also included.The Cypridinidae was confirmed as a monophyletic taxon with several well-supported subclades in addition to the large bioluminescent one. Skogsbergia, which apparently uses an antennular fan of iridescent blue filaments in courtship (Parker, 1997) belongs to a clade with five other cypridinid genera, including the four that have a similar fan. The genus Vargula was determined to be a polyphyletic assemblage. New genera will be established for former Vargula species including: “V.” tubulata, “V.” hilgendorfii, “V.” tsujii and all bioluminescent signaling species. Similar problems may exist for other large cypridinid genera, and clearer resolution of generic definitions might possibly reveal more significant patterns of geographic distribution within the family.Most characters of the carapace were found to be too convergent to be useful. Though carapace characters are diagnostic for some ostracode taxa, most should not be used by themselves to identify ostracodes with certainty. General aspects of reproduction are also reviewed.

International audience; Candoninae is by far the most diverse ostracod group in subterranean habitats, with many genera which today have no surface water representatives. This subfamily is also peculiar because species tend to have restricted distributions regardless of habitat type, and, unlike other non-marine ostracod lineages, extremely rarely reproduce parthenogenetically. Nannocandona faba Ekman, 1914 is an exception, being originally described from Sweden, but then reported throughout the Holarctic. We study morphological vari- ability of this species here, both based on old museum specimens and on freshly collected material. We propose that the name should only be restricted to the Swedish population, and we describe two new subterranean species: Nannocandona danielopoli n. sp. from Austria, and Nannocandona schornikovi n. sp. from South Korea and the Russian Far East. These descriptions allow us to evaluate records of N. faba in other parts of the Holarctic. A new map of the genus distribution is proposed, as well as a key to species identification. Parthenogenetic reproduction of Candoninae and their general ecology is also discussed.

Unambiguously biramous appendages with a proximal precoxa, well-defined coxa and basis, setose plate-like epipod originating on the precoxa, and both an endopod and exopod attached to the terminal end of the basis are described from several living Ostracoda of the order Halo-cyprida (Myodocopa). These limbs are proposed as the best choice for comparison of ostracode limbs with those of other crustaceans and fossil arthropods with preserved limbs, such as the Cambrian superficially ostracode-like Kunmingella and Hesslandona. The 2nd maxilla of Metapolycope (Cladocopina) and 1st trunk limb of Spelaeoecia, Deeveya and Thaumatoconcha (all Halocypridina) are illustrated, and clear homologies are shown between the parts of these limbs and those of some general crustacean models as well as some of the remarkable crustacean s.s. Orsten fossils. No living ostracodes exhibit only primitive morphology; all have at least some (usually many) derived characters. Few have the probably primitive attribute of trunk segmentation (two genera of halocyprid Myodocopa, one order plus one genus of Podocopa, and the problematic Manawa); unambiguously biramous limbs are limited to a few halo-cyprids. Homologies between podocopid limbs and those of the illustrated primitive myodocopid limbs are tentatively suggested. A setose plate-like extension, often attached basally to a podocopid protopod, is probably homologous to the myodocopid epipod, which was present at least as early as the Triassic. Somewhat more distal, less setose, and plate-like extensions, present on some podocopid limbs (e.g., mandible), may be homologous instead to the exopod (clearly present on myodocopid mandibles). The coxa (or precoxa) is by definition the most basal part of the limb. A molar-like tooth is present proximally on the mandibular protopod of many ostracodes; it is the coxal endite and projects medially from the coxa (or proximal protopod). The Ostracoda is probably a monophyletic crustacean group composed of Myodocopa and Podocopa. All have a unique juvenile (not a larva) initially with three or more limbs. Except that juveniles lack some setae and limbs, they are morphologially similar to the adult. Thus the following suite of characters in all instars may be considered a synapomorphy uniting all Ostracoda: (1) Each pair of limbs is uniquely different from the others. (2) The whole body is completely enclosed within a bivalved carapace that lacks growth lines. (3) No more than nine pairs of limbs are present in any instar. (4) The body shows little or no segmentation, with no more than ten dorsally defined trunk segments. No other crustaceans have this suite of characters. A probable synapomorphy uniting the Podocopa is a 2nd antenna with exopod reduced relative to the endopod.

Combined high-resolution video-recordings of live specimens, SEM and serial microtome sections were used to document the morphofunctional aspects of blood (hemolymph) circulation in Ostracoda, exemplified by the nektobenthic myodocopid Vargula hilgendorfii from Japan. The circulatory system is comprised of a single-chambered dorsal heart (pericardium, myocardium with two ostia), efferent vessels (aorta and secondary arteries) and an integumental afferent network of sinuses radiating from the adductor muscle area to a peripheral channel leading to heart. The heartbeat and the linear velocity of hemolymph in sinuses range from 0.5 to 6 times s-1 and 200 to 1000 μm s-1, respectively. Hemocytes (10 to 17 μm) of irregular shapes occur within the circulating hemolymph. This typical open circulatory system is found in most myodocope ostracodes and other crustaceans. It is totally absent in small (mostly

Ostracodes are described from the “Cerro del Fuerte Section” and neighboring localities, all in the Precordillera de San Juan (northern Argentina, San Juan Province), and from sparse faunas in Bolivia (Chuquisaca, Tarabuco Province). Additional material comes from the collection of Thomas (1905). This preliminary study gives the first detailed description of ostracode assemblages in the Upper Silurian and Lower Devonian of the South American continent. Records of other abundant lower Paleozoic (Lower Ordovician to Lower Devonian) ostracodes in Argentina, Bolivia, Brazil, Peru, and Venezuela are also reviewed. Twelve different species, belonging to Palaeocopa (Beyrichiacea and Primitiopsacea) and to Binodicopa and Podocopa (Healdiacea, Thlip-suracea, Cypridacea) are described and a new genus is established (Australobollian. gen.). Ostracode distribution at Cerro del Fuerte attests to the presence of the Siluro-Devonian boundary within the upper Los Espejos Formation and confirms recent stratigraphical attributions mainly based on conodonts and brachiopods (Benedetto et al., 1992). The beyrichiaceanHemsiellaindicates a late Ludlow to Pridolian age for the lower part of upper Los Espejos Formation. The non-palaeocope“Thlipsurella-Phanasymmetria-Ranapeltis”assemblage found in the uppermost part of the formation indicates an Early Devonian (Lochkovian) age. The present study reveals the existence of faunal links at genus (Silurian) and probably species (Early Devonian) level between South America (Argentina, Bolivia), Laurentia, Avalonia-Baltica, and northern Gondwana. For example, close affinities (e.g.,Ranapeltissp. aff.rowlandiandThlipsurellasp. aff.ellipsoclefta)exist between the uppermost Los Espejos Formation (Argentina) and contemporaneous horizons in the North American Mid-Continent (e.g., Haragan Formation, Oklahoma; Shriver Formation, Pennsylvania). Two types of ostracode assemblages, “beyrichiacean-dominated” and “thlipsuracean-bairdiacean-cypridacean dominated,” are recognized in the Late Silurian–Early Devonian of Argentina and discussed relative to other assemblages known in Laurentia, Avalonia-Baltica, and northern Gondwana. Their paleoecological significance in relation to marine bathymetry is addressed.

The Miocene Termina Formation of the northern Apennines (Italy) contains thin marly limestone or marly sandstone bodies rich in macrofauna mainly consisting of large lucinid clams. Modern representatives of this fauna occur in cold seep settings where they house chemosymbiotic bacteria. Moreover, these rocks record a δ13C-depletion confirming their origin influenced by a cold seep. The Miocene sections of Sasso delle Streghe and Sarsetta (near Modena) represent classic examples of cold seeps. These sections consist of marls and marly sandstones, respectively, with lucinids (Sasso delle Streghe) or bioclastic sands with lucinids (Sarsetta); both sections are capped by the Sandstones of Montebaranzone. They yield ostracodes that are mainly represented by deep-water filter-feeder species (Platycopa, i.e. Cytherella sp.) and numerous deposit-feeders (Podocopa: i.e. Neonesidea and Krithe), together with species frequently occurring in shallow water environments. These assemblages are able to colonize disaerobic environments such as cold seeps. Although some authors consider the filter-feeders as dominant taxa in disaerobic settings, our data do not provide evidence of significant differences in the ostracode assemblage composition between the deposits originated in seafloors with or without seepage influence. However, the number of specimens is greater in seafloors devoid of seepage influence.

Four interstitial cobanocytherid species are described from central Japan: Cobanocythere ikeyai sp. nov., Cobanocythere lata sp. nov., Paracobanocythere watanabei sp. nov. and Paracobanocythere grandis sp. nov. The reports of the two new Paracobanocythere species are the second and third for this genus since the original description of P. hawaiiensis Gottwald, 1983. Cobanocythere ikeyai sp. nov., and C. lata sp. nov., from Japan are morphologically more similar to the species of the “lanceolata group” by Gottwald (1983) and C. guttaeformis Gottwald, 1983 from the Galapagos Islands, respectively, rather than to other Cobanocythere species from Japan. The Japanese archipelago (eastern Eurasian Continent) and the Galapagos Islands (north-western South America) are separated by about 15,000 km from each other, and have never been adjoined throughout geological history. This fact, and also the morphological similarities between Cobanocythere species from Japan and the Galapagos Islands, suggests that this genus may have undergone global dispersal at several times in the past. Conversely, the genera Cobanocythere and Paracobanocythere are distributed not only around continents and continental islands but also around oceanic islands such as the Hawaiian and Galapagos Islands. We conclude, therefore, that the cobanocytherids seem to have been able to disperse long distances across oceans.

Two new ostracod species, Semicytherura maxima n. sp. and S. ikeyai n. sp., both belonging to the S. henryhowel group of the genus, are described. They were collected from Akkeshi Bay in northeastern Japan, and inhabit the marine sediment surface in places deeper than the intertidal zone. Their distributions in northern Japan seem to be influenced by the cold-water Chishima Current (Oyashio). The geological distribution and species diversity were surveyed for each of the subgroups recognized in the S. henryhowei group. The results suggest that these subgroups split from each other in the NW Pacific by the Early Miocene, and that one of them has spread around the Northern Hemisphere, while the other has remained in the NW Pacific since that time.

Ostracod faunas from Pacific hydrothermal vents include eucytherurine and pontocypridid Podocopa and are very similar to those previously recorded from experimental wood islands. Both vent and wood-island ostracods may belong to a single deep-sea faunal association that is adapted to a eutrophic regime. This regime, which is quite distinct from normal deep-sea conditions, is probably widespread in the world's ocean, although individual manifestations tent to be localized and ephemeral.

I describe the food and feeding habits of 61 adult palmate newts during their aquatic phase from three localities in NE Iberia. 1 used the stomach-flushing method to obtain the prey, of the newts with 100 % efficacy. Diptera were overall the most important prey of palmate newts. Diptera and Ostracoda were the main prey in two localities, but in the third locality only Ostracoda were the main prey. There was generally an interpopulation trophic segregation. Analyzing the data at different localities demonstrated trophic segregation at Serra de Daró and Canet d'Adri, while Podocopa dominated the diet at Fogars del Tordera.

CYCLOCYPRIDIDAE Cyclocypris Brady & Norman, 1889 ‡ Cyclocypris sp. —Bold (1975):577, Published as part of Perez-Gelabert, Daniel E., 2008, Arthropods of Hispaniola (Dominican Republic and Haiti): A checklist and bibliography, pp. 1-530 in Zootaxa 1831 (1) on page 21, DOI: 10.11646/zootaxa.1831.1.1

The attribute traditionally used to recognise the occurrence of ostracods in the Palaeozoic stratigraphic record has in essence been the presence of a bivalved arthropod carapace of small size. Discoveries offering unparalleled insight into the soft part palaeobiology of tiny bivalved Palaeozoic arthropods, when taken together with the notion that a bivalved carapace is a convergent phenomenon within the Arthropoda, have in the last decade revolutionised our understanding of the nature and stratigraphic record of the major groups of ostracod present in the Palaeozoic. Evidence from appendages and other soft parts is crucial in determining systematic affinity. Evidence from the soft part anatomy of bradoriids and phos-phatocopids has undermined the record of ostracods in the Cambrian, but molecular and fossil evidence implies that they may be present at that time. In the absence of soft parts the case that lepetditicopids (Ordovician-Devonian) are ostracods remains uncertain. Myodocopes certainly occur in the Palaeozoic, as determined on a wealth of new palaeobiological evidence. As yet, supposed Palaeozoic podocopes are represented in practical terms only by fossil shells. The systematic affinity of palaeocopes — a major group in the Palaeozoic and hitherto recognised as a coherent taxon — remains enigmatic, and they may turn out to represent an artificial grouping.

Leiocopes differ from all other major ostracode groups (e.g. Palaeocopa. Binodicopa, Podocopa, Myodocopa) mainly in having a simple rounded/convex shape and a strong (dorsal and/or ventral) asymmetry. These morphological features are highly conservative in leiocopes through the Palaeozoic (lower Ordovician-middle Devonian). Functional morphology and facies distribution suggest that typical ‘dome-like’ leiocopes (e.g. aparchitids) may have lived off the bottom in relatively deep water environments, contrasting with most (inferred) benthic Palaeozoic ostracodes (e.g. heavily calcified dimorphic palaeocopes). Reversely, smaller sized and both dorsally and ventrally asymmetrical leiocopes (e.g. Ordovician jaanussoniids) are considered as possible benthic dwellers with reduced mobility on or within the substratum. □Ostracodes, Leiocopa, Aparchitidae, Jaanussoniidae. Palaeozoic. Ordovician, Silurian, Devonian, asymmetry, functional morphology.

The hinge structure in the podocopan ostracode Loxconcha pulchra was examined throughout its molt cycle using ultrastructural and histological procedures. The structure consists of ligament and hingement, and develops along the attached margin of the right and left valves. In Stage C the hingement of both valves interdigitates beneath the ligament, and a series of outer epidermal cells (dorsal epidermal cells), exhibiting abundant granules, underlie the hinge structure. Apolysis occurs at Stage D1, and electron-dense granular materials of variable diameter are seen within the ecdysial space. Epicuticle formation begins at Stage D2 and is complete before Stage D4. In Stage D2 the new epicuticle appears as a dotted line consisting of numerous grain-like materials. The dorsal epidermal cells, which actively secrete the numerous granules during molting, increase their size and reveal the electron-dense substances in the cytoplasm from Stage D2. At early Stage D3 the procuticle deposition of ligament commences inside the epicuticle, and is completed in Stage D4. In Stage D4 the uncalcified procuticle is secreted under the whole area of carapace, and the new carapace is then ready for ecdysis. After ecdysis, calcification of the carapace commences from the dorsal and ventral marginal areas towards the central area. During Stage A there is no further cuticle deposition in the ligament, although the dorsal epidermal cells secrete as actively in the postmolt stage as in premolt. The dorsal epidermal cells begin to form the hingement just after ecdysis. Cuticle deposition of the hingement proceeds asynchronously in the two valves: the hingement of the right valve is formed prior to that of left one in L. pulchra. The right hingement functions as a mold for the left hingement to form the precise interdigitated structure in L. pulchra. These observations suggest that the ostracode ligament is a unique cuticle, which should not be confused with the cuticles of other arthropods. The work establishes, for the first time, a description of the formation of the hingement in podocopan ostracodes. J. Morphol. © 2007 Wiley-Liss, Inc.