Ostracod Genus Research Articles

Six new species of Elpidium Müller, 1880 (Podocopida: Limnocytheridae) from Eastern Brazil

Elpidium is the most common ostracod genus occurring in phytotelmata in the Neotropical region, with distributions ranging from Florida, USA in the north to Rio Grande do Sul, Brazil in the south. However, the genus remains poorly known both in terms of diversity and of the distributional pattern of its species. Here, we describe six new species of Elpidium, E. oxumae n. sp., E. cordiforme n. sp., E. picinguabaense n. sp., E. eriocaularum n. sp., E. higutiae n. sp., E. purium n. sp., all from phytotelm environments in the Brazilian Atlantic rain forest. In addition, we discuss the distributional pattern and endemicity levels of Elpidium species in the light of these new taxonomic results and argue about possible misunderstandings on the distribution of the type species E. bromeliarum.

The Permian and Triassic history of the ostracod genus Liuzhinia

The ostracod genus Liuzhinia has been reported from Permian and Triassic marine deposits mainly from the Tethyan area but its classification and history remain obscure. Here we report on the discovery of a rare steinkern of Liuzhinia antalyaensis from the Early Triassic of South China bearing the first known adductor muscle scars, allowing for first insights into its supra-generic classification. We demonstrate that Liuzhinia does not belong to Bairdiidae and propose that the observed muscle scars could illustrate ancestral characters of Paracyprididae or Bythocyprididae. We summarize the diversity of Liuzhinia through time, including the newly described Liuzhinia phetchabunensis Forel & Chitnarin sp. nov. from the Middle Permian of central Thailand, and discuss its geographical distribution and environmental preferences over its stratigraphical range.

A new genus, Tuberocandona gen. nov. (Crustacea, Ostracoda, Candonidae) and past to present ostracod species diversity in Texas (USA)

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.).

The genus Bradleya Hornibrook, 1952 (Crustacea: Ostracoda) in South America and adjacent oceanic areas, with description of a new bradleyine genus.

The ostracod genus Bradleya Hornibrook is an important taxon of Cenozoic assemblages, occurring practically in all oceanic regions. The wide distribution both in shallow and deep waters turns Bradleya interesting for studies involving phylogeny and paleoceanography. The present work aims at the study of fossil and recent species in South America and adjacent regions, based on bibliographic review and the restudy of samples from the Brazilian continental margin, the Navidad Formation (lower Miocene) and El Peral Beds (meso-upper Miocene), both cropping out in the Central Chile. The chronostratigraphic, (paleo)bathymetric and (paleo)zoogeographic distribution of the species is reviewed and updated. The bridge composition was studied in all species recorded and revealed to be important taxonomic character. The taxa identified were gathered into three morphological groups: two proposed previously (i.e., the dictyon-group and the arata-group) and a new one in the present work (i.e., the normani-group). The dictyon-group and the arata-group gather deep-sea species, while the normani-group is predominantly neritic, including most of the species of Brazilian margin. Bradleya victorjarai sp. nov. is proposed for the Miocene of Chile, and Bradleya ybate (Bergue et al.) is reassigned to Rigracythere gen. nov. Questionable or misidentified species ascribed to Bradleya are briefly discussed.

Four new Parasterope (Ostracoda, Myodocopina) from the Northwest Pacific and their phylogeny based on 16S rRNA

Parasterope Kornicker, 1975 is a marine ostracod genus with 49 species described so far, which makes it the most diverse representative of the subfamily Cylindroleberidinae, as well as the entire family Cylindroleberididae. Despite its global distribution no species are reported from South Korea. Three new species collected from the Korean coast of the Sea of Japan (Parasteropebusanensissp. nov., P.singulasp. nov., and P.sohisp. nov.), and one from the Japanese coast of the Pacific Ocean (P.sagamisp. nov.) are described. A taxonomic key to all named species from East Asia is provided. A phylogenetic tree is reconstructed based on partial 16S rRNA sequences of the four new species and other Cylindroleberidinae available from GenBank. Monophyly of Parasterope is supported by high posterior probabilities, but the phylogenetic analyses also indicate that some of the GenBank data attributed to this genus are probably misidentifications. A map of distribution and a checklist of all described Parasterope species are also provided.

Qualitative and quantitative analyses of the Carboniferous ostracod genus Carbonita from Rod El-Hamal area, Wadi Araba, north Eastern Desert, Egypt

ABSTRACT The present work provides a qualitative analysis of the studied ostracod carapaces of the genus Carbonita. Thirty-seven ostracod specimens were collected from the Late Carboniferous Rod El-Hamal Formation at Rod El-Hamal area, Wadi Araba, north Eastern Desert, Egypt. The collected ostracods were assigned to four species in genus Carbonita; C. fabulina (Jones and Kirkby), C. inflata (Jones and Kirkby), C. humilis (Jones and Kirkby), and C. bairdoides (Jones and Kirkby) according to the qualitative traits. In order to assess the discrimination among the different Carbonita species, a new technique, geometric morphometric analyses, was carried out using ImageJ and MorphoJ software packages. Geometric morphometric analyses included landmark configurations, procrustes superimposition, principle component analysis, and thin plate spline deformation plots. Using nine landmarks, average shapes of the different Carbonita species have been provided. The principle component analysis separated Carbonita fabulina and C. bairdoides from the morphologically overlapped C. inflata and C. humilis. Shape variations in the carapace length, height, anteroventral arc, posterodorsal arc, posteroventral arc, and the anterior margin were demonstrated through the deformation plots. These quantitative analyses, along with the qualitative examination, provided considerable variations among the different Carbonita species, and hence the best way for species discrimination.

Microorganismos calcáreos y silíceos de la Laguna “Don Tomás”, Provincia de La Pampa, Argentina

Calcareous and siliceous microorganisms of the “Don Tomás” Lagoon, La Pampa Province, Argentina. Studies on diatoms, cysts and ostracods in shallow lakes are very scarce in the Province of La Pampa. The aim of this study is to collect new information on the diversity and abundance of microorganisms present in a hypertrophic body of water and their seasonal changes. The samplings were carried out seasonally in the period from January to October 2014. From the sediment analysis of the "Don Tomás" lagoon, 21 diatom taxa were identified, of which three correspond to the order Centrales and 18 to the order Pennales; four genera of ostracods and two morphotypes of chrysophyte cysts (ornamented and smooth) were also recorded. The data obtained from the study of current samples will allow us to interpret with a greater degree of certainty the Holocene deposits from lake environments of temperate climates. Keywords: diatoms, chrysophyte cysts, ostracods, shallow lake.

Review of the history of the deep-sea ostracod genera Abyssocythere Benson and Dutoitella Dingle, and their responses to Cretaceous - Cenozoic oceanic water-mass changes

Abyssocythere and Dutoitella are extant benthic bathyal ostracod genera that evolved during Coniacian to Santonian/Campanian time from shallow-water progenitors around southeastern Africa. Their Late Cretaceous development was primarily in the South Atlantic, but during the Palaeogene they spread to the Indian and Pacific oceans. The establishment of the psychrosphere (late Eocene-mid-Oligocene) flushed populations of each genus from their central Atlantic cradles into the Pacific, presumably through the Panama Seaway, so that contemporaneous centres of evolution developed disjunct clades: A. trinidadensis and D. praesuhmi. The psychrospheric oceanic event defined temporal thermophyllic and cryophyllic populations of the two genera. Three Neogene ocean events appear to have affected several regionally-confined species, inter alia one of which entailed a counterflow migration of A. atlantica from the eastern Pacific back into the central Atlantic during the mid-Miocene. Modern distributions of Abyssocythere and Dutoitella are disjunct: in the Atlantic both genera occur south of approximately 40 degrees N (Dutoitella), and equatorial areas (Abyssocythere); in the Indian Ocean both are confined to the southern part; and in the Pacific, Abyssocythere is restricted to central and north-eastern areas, and Dutoitella to the west and northwest. Neither genus evolved species that were more than para-cosmopolitan: A. diagrenona (South Atlantic-Indian; Eocene-Oligocene), A. trinidadensis complex (central Atlantic-NW Pacific; Oligocene-Miocene), D. crassinodosa complex (South Atlantic-Indian; Eocene), and D. praesuhmi (north and central Atlantic-central Pacific; Oligocene-Miocene).

Quaternary Ostracoda and Foraminifera from the Pelotas Basin, southernmost Brazil: Assemblage variation in gas-hydrate bearing sediments

Late Quaternary ostracod and foraminifera assemblages from five piston cores in Pelotas Basin, southern Brazilian margin, were analyzed in this paper. The study revealed a diverse bathyal fauna of ostracods, with abundance of the genera Apatihowella, Cytheropteron and Cytherella, interspersed with peaks of allochthonous neritic faunas. Benthic foraminifera are represented mainly by the genera Bolivina, Bulimina, Cassidulina, Epistominella, Globobulimina, Globocassidulina, Nonion, Oridorsalis and Uvigerina. Biostratigraphic analysis of planktic foraminifera positioned the samples in Pleistocene-Holocene interval. The ostracod genera Paracytherois, Cytheropteron, Cytherella, Macropyxis and the species Krithe hunti, Krithe reversa, Henryhowella asperrima, Eucytherura fossapunctata, Rimacytheropteron longipunctatum, Apatihowella besnardi and Apatihowella convexa, and also the benthic foraminifera Bolivina, Bulimina, Nonion, Nonionellina, Oridorsalis, Uvigerina, Epistominella and Cassidulina are related to environments of gas hydrates and associated with a chemosynthetic community in eutrophic-mesotrophic environments.

New genera and species of ostracods from the El Ma El Abiod Miocene Basin (Tébessa, NE Algeria)

Two new ostracod genera of the family Trachyleberididae Sylvester-Bradley, 1948, each based on a new species, are described and commented here. The specimens were collected in Tortonian sediments cropping out at El Hadjra Safra in the El Ma El Abiod basin (region of Tébessa, north-eastern Algeria).

Intra‐Valve Elemental Distributions in Arctic Marine Ostracodes: Implications for Mg/Ca and Sr/Ca Paleothermometry

AbstractReconstructing intermediate and bottom‐water temperature in the Arctic Ocean is key for understanding paleoclimatic phenomena, such as the region's interactions with warm Atlantic waters, stratification, and sea‐ice dynamics. However, benthic proxy archives are sparse throughout the Arctic circle compared to lower latitudes. Trace‐element ratios (E/Ca) derived from ostracodes, a group of bivalved microscopic crustaceans, have shown promise in this regard. Samples for E/Ca measurements typically require rigorous cleaning prior to analysis, and signs of contamination are routinely monitored through the presence of other trace elements such as Al, Fe, and Mn, which are associated with suspected sources of overprinting. However, there has not yet been an intra‐valve investigation of all of these trace elements, which may hinder our ability to effectively identify geochemical overprinting. Here, we present several elemental concentration and E/Ca ratio measurements in two ostracode genera, Krithe and Polycope, extracted from Chukchi Sea sediment samples. We further investigate the intra‐valve distribution of elements within single shells of adult and juvenile specimens using electron probe microanalysis (EPMA). Our findings suggest that brushing and bleach treatments may not be effective for completely eliminating clays from the edges of valves, which can bias paleoclimatologically relevant trace‐element proxies such as Mg/Ca ratios, particularly in the case of incomplete or small samples with low amounts of calcite material. In addition, we report the first trace‐element data from the genus Polycope, which shows potential as a new Arctic paleotemperature archive.

New Ostracoda Species in the Upper Part of the Tanjero Formation (Late Maastrichtian), Sulaimaniyha City, Kurdistan Regin-NE- Iraq

The present work is focused on the ostracoda study from the upper part of the Tanjero Formation (Late Maastrichtian), Qlyassan area, Sulaimaniya city, Northeasten Iraq. The Tanjero Formation in Qlyassan section (5 m thick) consists of brownish grey to dark gray marl to silty marl with thin graded sandstone, more than one hundred specimens picked up, fourteen species from nine genera of ostracods were identified and illustrated in the upper unit of the Tanjero Formation. Three new species from the fourteen identified species are recognized which are Cytherella sulaimaniensis sp. nov., Cardobairdia tanjeroiensis sp. nov. and Pontocyprella qlyasaniensis sp .nov. These three new species support the age of the Tanjero Formation as the Late Masstrichtian (Upper Cretaceous).

Evolution of the genus Cribroconcha (Ostracoda, Crustacea) in relationship to palaeoecological changes during the late Palaeozoic

To date, 37 species and 2 subspecies (36 species plus 1 species that with 2 subspecies) of the ostracode genus CribroconchaCooper, 1941 have been reported worldwide, ranging in age from the Middle Devonian to the Early Permian with an acme during the Carboniferous. Based on the geographical distribution and morphological characteristics of Cribroconcha, two evolutionary lineages (i.e., Lineage 1 and Lineage 2) are identified, which originated in the European and the Kazakhstan plates, respectively. Lineage 1 can be subdivided into three types: 1-A (stable type), 1-B (reshaped type) and 1-C (spiny type). Lineage 2 has a simpler pattern of evolution compared to Lineage 1. Although there were certain accompanying changes in the morphology of carapaces, the general pattern and most successful evolutionary novelty of Cribroconcha appears to be the appearance of spiny forms in the Early Carboniferous, which continued to be preserved until the Early Permian. The habitats of Cribroconcha may have changed from shallow, warm waters to deep, calm and colder waters in the basinal environments. Four Cribroconcha biozones, extending from the Givetian Stage to Serpukhovian Stage are established in the Euramerica plate, namely C. beckmanni Zone, C. triquetra triquetra Zone, C. cooperi Zone and C. caneyensis Zone.

Description and ontogeny of Pattersoncypris minima sp. nov. (Crustacea: Ostracoda), Araripe Basin, Northeast Brazil.

Representatives of the Class Ostracoda are widely used as tools in applied paleoecological and biostratigraphical studies in all continents. In the Araripe Basin, located in the northeastern of Brazil, the Romualdo Formation is one of the most studied, not only for the preservation but also for the abundance of its fossils. The ostracod genus Pattersoncypris Bate, 1972 is well-represented in this formation and it is the most abundant, which reinforces the importance of its taxonomic study. In this work, Pattersoncypris minima sp. nov. is described for the Romualdo Formation as a contribution to the knowledge on Brazilian Cretaceous non-marine ostracods. Taphonomic aspects are also presented, considering the complete ontogenetic stages of the material.

Molecular and Morphological Diversity of Heterodesmus Brady and Its Phylogenetic Position within Cypridinidae (Ostracoda)

Ostracod genus Heterodesmus Brady, 1866 is known thus far to contain only three species: H. adamsii Brady, 1866; H. apriculus Hiruta, 1992; and H. naviformis (Poulsen, 1962). This genus has been recorded from the Sea of Japan, and the coastal areas of Thailand and Vietnam. The main generic character is the presence of antero-dorsal and postero-dorsal tube-like processes on the rostrum on both valves. The three species mostly differ in the shell lateral projections. Their relationship and the position of Heterodesmus within family Cypridinidae are poorly understood, partly due to the lack of publication of DNA data so far. We study Heterodesmus collected from several localities in the Northwest Pacific, namely Tsushima and Iki Islands in Japan and Maemul Island in Korea. Besides morphological characters, we also use two mitochondrial markers (16S rRNA and mtCOI) and three nuclear regions (18S rRNA, 28S rRNA, and internal transcribed spacer - ITS) in the samples to detect the biodiversity of this genus. Our phylogenetic tree based on molecular data coupled with morphology reveals the presence of two species, H. adamsii and H. apriculus. We report on their morphological variability, molecular diversity, and phylogenetic position within Cypridinidae based on 16S, 28S and 18S rRNAs, and provide a taxonomic key for all living genera of this family. For the first time, we give an overview of the intrageneric and intrafamily DNA distances of the above markers for the entire subclass Myodocopa.

Lowermost occurrence of ostracod Cypridea species in East Asia and implications for the non-marine Jurassic/Cretaceous boundary

Cypridea Bosquet, 1852 is a non-marine ostracod genus of the Superfamily Cypridoidea, and the extinct Family Cyprideidae, which achieved high diversity in the Early Cretaceous. This genus plays an important role in the subdivision and correlation of strata, as well as in paleogeographic and paleoclimatic studies. Cypridea species are remarkably abundant and diverse, and are extensively distributed across East Asia. However, the lowermost occurrence of Cypridea species (LOOC) in East Asia is still being debated, varying from the Upper Jurassic to Lower Cretaceous. Here, we aim to conduct a preliminary investigation of the Cypridea-bearing strata of East Asia (China, Mongolia, Korea and Japan), and attempt to update the strata correlation, based on new progress of the ostracod correlations, as well as the progress of other research methods on the relative Jurassic/Cretaceous (J/K) strata of these areas. Results show that the LOOCs in most basins of East Asia are documented in Lower Cretaceous (∼Berriasian) strata. However, Cypridea species are extremely rare near the J/K boundary interval but flourish until Valanginian–Hauterivian in most basins of East Asia. Therefore, we propose that the LOOC in each corresponding basin of East Asia can be used as an auxiliary marker of the non-marine J/K boundary. Cypridea species may have travelled first from Africa (Kimmeridgian) to Europe (J/K period), and then East Asia (Early Cretaceous), which resulted in the LOOC in East Asia later than in the other continents.

The marine ostracod genus Tasmanocypris from the Neogene of southeastern Australia: Systematic and palaeoceanographical relationships, palaeoecology and palaeobiogeography

Abstract A new fossil paracypridine ostracod, Tasmanocypris lochardi sp.nov. is described from late Miocene shallow marine strata of southeastern Australia. It has morphological features similar to a number of modern southern Australian and southwest African Tasmanocypris species, here termed the dartnalli-group. This species group was likely present in early Cenozoic temperate, shallow seas around Antarctica. The first appearance of Tasmanocypris lochardi in late Miocene marine strata of the Bass Strait hinterland of SE Australia, equates to a late Miocene (9–7 Ma) intensification and northward latitudinal shift of the Antarctic Circumpolar Current (ACC). Late Miocene occurrences of Tasmanocypris lochardi in southeast Australia were likely associated with temperate eastward flows of the ACC north of the Subantarctic Front. During the early Pliocene, the warm Zeehan Current (aka Leeuwin Current) replaced the ACC as the dominant easterly flowing current across Bass Strait, and this 4.4 Ma palaeoceanographical event correlates with the temporary, but widespread disappearance of T. lochardi from southeast Australian marine waters. However, the presence of refugia populations of T. lochardi along the east Australian continental shelf between 4.4 and 3.4 Ma, likely enabled the brief re-establishment of T. lochardi in the east of Bass Strait during the late Pliocene (3.2–3.0 Ma). Tasmanocypris lochardi became permanently extinct in this region during the latest Pliocene to early Pleistocene (

Chelonocytherois omutai gen. et sp. nov. (Crustacea: Ostracoda) from the back of loggerhead sea turtles.

Chelonocytherois omutai gen. et sp. nov., is found on the back of female loggerhead sea turtles on the nesting beach of the Yakushima Island, Kagoshima Prefecture, Japan. The present study provides the first species-level identification and description of Ostracoda as sea turtle epibionts. The new genus and species, which belongs to the family Paradoxostomatidae Brady and Norman, 1889, can clearly be distinguished from other genera by the morphology of the carapace and the appendages. Especially, the quite large sieve structure on the pore system of the carapace is characteristic to this genus. Although a similar structure is also found in the commensal ostracod genus Redekea de Vos, 1953, the new genus has distinctive mandibular and maxillular morphologies. From examination of the appendages, C. omutai gen. et sp. nov. seems to be an epibiotic species associated with sea turtles, but not a strictly commensal species. Additionally, the nearly complete 18S rRNA gene sequence is determined for C. omutai gen. et sp. nov. for future molecular phylogenetic studies. Since the sea turtles migrate across the oceans in their ontogenetic stages, they may play a role as a long-distance dispersal vector for C. omutai gen. et sp. nov.

Ostracod Genus Rostrocytheridea from the Bagh Formation (Upper Cretaceous) of narmada Basin, Madhya Pradesh and Gujarat, India

Ostracod Genus Rostrocytheridea from the Bagh Formation (Upper Cretaceous) of narmada Basin, Madhya Pradesh and Gujarat, India

Revision of the ostracod genus Velibeyrichia Henningsmoen, 1954 from the Silurian and Lower Devonian of North America

Camilleri, T.A., Warne, M.T., Holloway, D.J. & Weldon, E.A., 10 May 2019. Revision of the ostracod genus Velibeyrichia Henningsmoen, 1954 from the Silurian and Lower Devonian of North America. Alcheringa XXX, X–X. ISSN 0311-5518.Known occurrences of the ostracod genus Velibeyrichia are restricted to a number of Silurian to Lower Devonian geological strata in North America: the McKenzie Member of the Mifflintown Formation of Maryland and West Virginia; the Tonoloway Limestone of Maryland, West Virginia, Virginia and Pennsylvania; the Bloomsburg Formation of Maryland, Virginia and Pennsylvania; the Manlius Limestone of New York; and the Decker Limestone of New Jersey and New York. The genus includes six species: V. moodeyi (type species), V. mesleri, V. paucigranulosa, V. reticulosaccula, V. tonolowayensis and V. tricornia. The diagnostic combination of characters for this genus are: distinct deflection of the velum where it crosses the crumina in heteromorphs (adult female specimens), dorsal nodes on lobes L1 and L3, sexual dimorphism of the velum, and in tecnomorph specimens, either a shallow sulcus on lobe L3 or a zygal ridge (in adult tecnomorph specimens) extending from lobe L2 to lobe L3. The presence of one or the other of the latter two characters defines two distinct species groups.Tamara T.A. Camilleri* [tamara.camilleri@deakin.edu.au], Mark T. Warne* [mark.warne@deakin.edu.au] and Elizabeth A. Weldon [l.weldon@deakin.edu.au], Deakin University, Geelong, School of Life and Environmental Sciences & Centre for Integrative Ecology (Melbourne Campus), 221 Burwood Highway, Burwood, Victoria 3125, Australia; David J. Holloway [dhollow@museum.vic.gov.au], Museums Victoria, GPO Box 666, Melbourne, Victoria 3001, Australia. *Also affiliated with: Museums Victoria, GPO Box 666, Melbourne, Victoria 3001, Australia.