Six New Species of Fresh and Brackish Water Ostracods (Crustacea) from Yakushima, Southern Japan

Twelve species of brackish and freshwater ostracods were collected from the island of Yakushima in southern Japan. Six species, belonging to the genera Cypria, Dolerocypris, Stenocypris, Schellencandona and Paracypria, are new and are described herein. The genus Schellencandona is reported for the first time outside Europe. Although a wide range of apparently suitable habitats was sampled for ostracods across the island, all specimens were recovered from or near the coast; further inland yielded no ostracods. The freshwater habitats around the coast of the island consist of springs and rockpools at the top of the shore above most high tide levels.     

Species richness and the proportion of predatory animal species in temporary freshwater pools: relationships with habitat size and permanence

The proportion of predatory animal species is often believed not to vary systematically across communities. However, we predict that larger temporary freshwater pools, and pools that are more permanent, will contain a higher proportion of predatory animal species. In 24 temporary rockpools in Northern Israel (supporting communities dominated by ostracods, copepods, cladocerans, flatworms, dipterans and amphibians), the mean proportion of macroscopic predatory species (averaged over a series of samples) increased with increasing pool area. For the highest possible proportion of predatory species (including microscopic species with uncertain diets), the relationship with pool area was not statistically significant. We did not find significant relationships between permanence and the proportion of either macroscopic or all possible predatory species. Larger pools and pools that were more permanent had more species. Species richness and the proportion of macroscopic predators were positively correlated. These patterns imply that species-poor ecosystems are likely to be functionally different from species-rich systems.     

Distribution of Recent ostracod species in the Lake Qinghai area in northwestern China and its ecological significance

In order to interpret the climate-change data using the ecological characteristics of the ostracods from the drill cores in Lake Qinghai, the distribution of Recent ostracods was studied in Lake Qinghai area. A total of 34 species belonging to the Ostracoda class of Crustacea were collected from different bodies of water in the Lake Qinghai area, and the ecological information for Recent ostracod species was studied. Among these 34 species, Cypris pubera, Eucypris dulcifons, Ilyocypris sp. 1, Ilyocypris sp. 2, Fabaeformiscandona caudata, Fabaeformiscandona hyalina, Herpetocypris reptans, Prionocypris gansenensis, Potamocypris villosa, Potamocypris smaragdina, Paralimnocythere compressa and Subulacypris sp. were first reported by us in the Lake Qinghai area. Some of the species identified exhibited cosmopolitan distributions, at least in the Holarctic region, but P. gansenensis and Ilyocypris echinata appeared to be restricted to the cold regions in northwestern China.The ecological significance of the primary ostracod species in the Lake Qinghai area was described according to the observations made during our time in the field and according to data from a number of reports. Our results indicate that the species diversity and abundance of ostracods may be related to water salinity in the Lake Qinghai area. The ecological information for ostracods can be used to distinguish different water environments and types based on the characteristics of one species or of an assemblage of several species.     

Physiological tolerance to hyperthermia and hypoxia and effects on species richness and distribution of rockpool fishes of Loggerhead Key, Dry Tortugas National Park

Rockpools on Loggerhead Key in the Dry Tortugas National Park experience cyclic tidal changes in water quality and physical dimension resulting in ichthyofaunal assemblages that differ markedly from the adjacent coral reef. Within the beach rock formations and areas transitioning to the nearby reef, we observed 45 fish species; however, only four species - schoolmaster, Lutjanus apodus, French grunt, Haemulon flavolineatum, cocoa damsel, Pomacentrus variabilis, and frillfin goby, Bathygobius soporator - were found in all rockpools. All fishes were transient juveniles except for frillfin goby, which was a pool resident. High temperature tolerance, (Critical Thermal Maxima), and low oxygen tolerance, (Critical Oxygen Minima) for schoolmaster, French grunt, cocoa damsel, and frillfin goby were 40.9, 36.2, 37.6, 40.9 °C and 0.56, 0.77, 0.50, and 0.27 mg/L, respectively. All four species demonstrated thermal and hypoxia tolerance values similar to those published for species traditionally noted as abiotic specialists. Although fish distribution patterns in rockpools were likely influenced by structural complexity and spatial limitations, the relationship between pool morphology and species richness was weak, suggesting that physiological tolerance to high temperature and low oxygen among reef fishes may be more influential in determining which species inhabit the rockpools. Harsh thermal and oxic conditions that cannot be exploited by less tolerant species may be beneficial for some Loggerhead Key reef fishes in providing refuge from predators, foraging grounds, or potential nursery areas.     

Grazing dynamics in intertidal rockpools: Connectivity of microhabitats

Differences between rockpool and emergent rock communities are often attributed to their contrasting physical conditions. However, differences in grazing pressure between rockpools and open rock could also exert an important structuring role. Greater densities and/or the lack of tidal constraints on foraging may allow grazing intensity to be greater in rockpools. Here, wax discs were deployed to compare grazing intensity between rockpool and emergent rock habitats at each of three tidal heights on a moderately exposed shore in SW England. Grazing intensity was then examined in relation to herbivore density. Grazing intensity in pools was twice that on emergent rock, despite a lower density of herbivores in the rockpools. Of these herbivores, patellid limpets are the dominant grazers on rocky shores throughout the NE Atlantic and are recognised to have a major role in structuring intertidal communities. Thus, subsequent experiments focussed on the influence of limpets in determining the differences in consumer pressure between rockpools and emergent rock. Three alternative explanations were considered: (1) the effect of continuous immersion on grazing intensity in rockpools; (2) differences in limpet species abundance between the two habitats; (3) movement of limpets from emergent rock into pools to feed. The level of grazing pressure exerted by Patella ulyssiponensis (Gmelin), the predominant species living constantly immersed in rockpools, was similar to that of P. vulgata (Linnaeus) which is predominantly found on emergent rock. P. vulgata were observed moving from emergent rock into rockpools during high tide. Manipulative experiments confirmed that these foraging excursions resulted in a 2-fold increase in grazing intensity in the pools. Grazing activity of P. vulgata in rockpools was not consistent between sites and may be influenced by differences in wave exposure and/or the abundance of microbial resources. Elevated consumer pressure in rockpools may be an important factor influencing algal assemblages and probably explains the predominance of grazer resistant-species in these pools.     

The Neogene Ostracod Genus <Emphasis Type="Italic">Advenocypris</Emphasis> from the Intermontane Depressions of the Southeastern Altai

This paper presents new data on ostracods of the genus Advenocypris. The distribution of these ostracods in the Neogene deposits of the intermontane depressions of Central Asia is analyzed. Species of this genus were selective regarding their habitats. This habitat specificity can be used to reconstruct the paleogeography of the depositional environments, origin and connections of water bodies in Central Asia. A new species of the genus Advenocypris is described. The previously known species of this genus are illustrated.     

Ostracods of the genus Palaeocytheridea Mandelstam in the Middle and Upper Jurassic of Europe: 1. Development of ideas on the content of the genus and the results of its revision

The analysis of ostracods (Crustacea) of the genus Palaeocytheridea, widespread in the Boreal and Tethyan regions of Europe, allows establishing several correlated sequences in the Middle Jurassic of these regions, thus showing the stratigraphical significance of this genus. However M.I. Mandelstam misdescribed the hinge in carapace valves of the ostracod genus Palaeocytheridea in his characterization of the type species of P. bakirovi Mandelstam, 1947, and subsequently P.S. Lyubimova (1955) replaced the original type species by Eucythere denticulata Sharapova, 1937, thus confusing the understanding of the content of the genus Palaeocytheridea and triggering the assignment to it of more than 90 forms, belonging not only to different genera but also to different families. The revision reveals 11 valid Palaeocytheridea species, belonging to the two subgenera: Palaeocytheridea s. str. and Malzevia subgen. nov. One species, Palaeocytheridea kalandadzei sp. nov., is described as new. This paper, the first of the series of three papers dealing with ostracods of the genus Palaeocytheridea, considers the history of the development of ideas on the content of the genus, presents the results of its revision, and describes new taxa.     

Middle Permian Ostracods from Tak Fa Limestone, Phetchabun Province, Central Thailand

This paper presents the first Permian ostracod fauna discovered in Thailand. The ostracods are recovered from the Tak Fa Limestone (Middle Permian) in Phetchabun province, central Thailand. The ostracods belong to eight genera and 15 species. Four species are newly described: Sargentina phetchabunensis nov. sp., Geffenina bungsamphanensis nov. sp., Reviya subsompongensis nov. sp. and Bairdia takfaensis nov. sp. The ostracod assemblages characterize a shallow marine, near shore environment at the time of deposition. Except for one species, which shows palaeobiogeographical links between Central Thailand and South China, all the other species are endemic.     

Distribution and taxonomy of shallow marine Ostracods from Northern Socotra Island (Indian Ocean) - Yemen

Forty-seven species belonging to 30 genera of ostracods have been identified from Recent shallow marine sediments collected along the northern coastline of the island of Socotra (Indian Ocean). The systematics and distribution of these ostracods are discussed. Three genera, Loxoconcha, Bosasella, and Xestoleberis are found to have high species diversity. The species Loxoconcha ghardaqensis, Moosella striata are best documented in the Red Sea and Gulf of Aden while Kotoracythere inconspicua and Triebelina sertata were found to be the most widespread species. The fauna shows a close affinity to other ostracod assemblages of the Indo-Pacific region, East African coast and Red Sea.     

Interspecific competition in metapopulations

The assumptions and predictions of metapopulation models for competing species are discussed in relation to empirical studies of colonization and extinction in metapopulations. In three species of Daphnia in rockpools, interspecific competition increased local extinction rates, while no effects on colonization rates were detected. Distributional patterns were consistent with several predictions of the competition model; for example, the number of species on an island increased with the number of pools and the proportion of pools occupied by each species decreased with increasing species number. It is concluded that interspecific competition is important for the distributional dynamics of Daphnia species in rockpools, but the question whether the coexistence of these species depends on metapopulation dynamics is still unresolved. Other studies on the effects of interspecific competition on colonization and extinction rates are discussed.     

Molecular ecology and phylogenetics of the water beetle genus Ochthebius revealed multiple independent shifts to marine rockpools lifestyle

Marine rockpools represent a dynamic ecosystem where inhabiting species usually suffer changeable conditions, with consequent phenomena of local populations’ size expansions and reductions. Nevertheless, a few specialized insect groups are known to live in marine rockpools, and among them, several species belong to the water beetle family Hydraenidae. Three groups of Ochthebius sensu lato (s.l.) live in fact in marine rockpools: the putative subgenus Calobius, the former subgenus Cobalius (both mostly Mediterranean–Macaronesian) and two species of the O. capicola group from South Africa. In this work, we performed a molecular phylogeny of Ochthebius s.l., running molecular clocks, aiming to address the following questions: Are these three groups related? Which is their position within Ochthebius s.l.? How many different times and in how many lineages of Ochthebius s.l. a shift from inland waters to marine rockpools environments happened? Is the current taxonomic status of these three groups supported by genetics? We found that Calobius, Cobalius and the O. capicola group represent three distinct groups, with no sister relationships, suggesting that a shift from fresh/brackish waters to marine rockpools happened independently at least three different times along the diversification of the genus. Cobalius represents an effective separate subgenus, whereas such a rank is not supported by molecular data for Calobius, which represents a monophyletic clade within the nominal subgenus Ochthebius sensu stricto (s.str.). However, as Calobius is monophyletic and characterized by strongly peculiar and distinguishing morphology, we suggest referring to this group as the ‘Calobius’ lineage. Three Mediterranean taxa within this lineage represent likely valid new species, to be described soon. In the same way, the taxonomy of Cobalius should be revised, with two previously formally recognized species found to be paraphyletic, and the possible presence of two additional cryptic species.     

On the Cyprideis species flock (Crustacea, Ostracoda) in Lake Tanganyika, with the description of four new species

Four new species, belonging to three genera, of ostracods from Lake Tanganyika are described: Mesocyprideis nitida sp.nov., Romecytheridea belone sp.nov., R. plegma sp. nov. and Cyprideis loricata sp. nov. The Cyprideis species flock of Lake Tanganyika now consists of 17 formally described species (16 endemic) in 6 genera (4 endemic). The geographical and ecological distribution of the four species is briefly discussed and some supplementary remarks on the radiation of the Cyprideis species flock in Lake Tanganyika are offered.     

Site fidelity of intertidal fish to rockpools

Gobius paganellus, Lipophrys pholis and Coryphoblennius galerita are wide‐spread intertidal fish that spend their earlier life stages in rock pools, and yet very little is known about their site fidelity behaviour. For these species, fidelity to rockpools may result in increased fitness costs in a predicted scenario of warmer sea water, due to the low thermal inertia of these water bodies. In this context, it is relevant to investigate these species' site fidelity. We made a mark‐recapture study to assess the mentioned species' movements within and between rockpools. We tagged a total of 530 individuals of the aforementioned species with the Visible Implant Elastomer and tracked their movement for a 7‐month period. We found that site fidelity and specific rockpools conditions are important factors in distribution of intertidal blennies and gobies. We also examined the relations between rockpool volume, depth and site fidelity. We found that G. paganellus tends to remain in its original marking pool, with an average recapture rate of 20.5%, but showed no evidence of inter‐pool movement. Rockpool depth, however, proved to be important in the blennies' movements. Our findings are among the first to prove that a mark‐recapture method can be successfully used to track intertidal fish movements. In particular, we showed that G. paganellus presents site fidelity in intertidal rockpools during its early ontogeny for a period of two to three months.     

Ostracodes turoniens de la region de Cassis,La,Bedoule (Bouches-du-Rhone,France): Associations et affinites paleogeographiques

The study of 15 species of ostracods from the Turonian of Provence is especially concernedin this paper; two new species are proposed: Mauritsina provencialis nov. sp. and Spinoleberis ectypus nov. sp.Two associations can have been recognized: one in the marly lower Turonian, theother in the zone of transition from the lower to the upper Turonian.These ostracods are replaced in the general stratigraphic context of the country and some comparisons can have been made with others countries.Some ecologic and paleogeographic remarks are proposed to contribute for a betterknowledge of the paleoenvironments.     

Ostracoda and Mollusca biodiversity and hydrochemical features in Late Miocene brackish basins of Italy

Late Miocene brackish ostracods and molluscs collected in three Italian basins show noticeable differences in their taxonomic composition, despite their capability of dispersing across wide geographic areas. In the Venetian-Friulian Basin (northern Italy), the upper Tortonian sediments contain oligotypic ostracod assemblages including Hemicyprideis dacica dacica, Hemicytheria pejinovicensis, and Loxoconcha cf. L. josephi and few gastropods referable to Planorbidae and Stenothyroides, which are typical of the central Paratethys. In central Italy, the brackish ostracods and molluscs recovered from upper Tortonian-lower Messinian deposits from four Tuscan basins (Volterra-Radicondoli, Velona, Baccinello-Cinigiano, and Valdelsa) display high affinity at a generic level but strong endemicity at a specific level. At Cessaniti (southern Italy), the upper Tortonian unit contains oligotypic brackish ostracods and molluscs: Mediocytherideis (Sylvestra) posterobursa, Cyprideis ruggierii, Loxoconcha cf. L. biformata, and Zonocypris membranae quadricella characterise the ostracod fauna, while Granulolabium bicinctum and Hydrobia frauenfeldi are the dominant molluscs. The recovered ostracods have a strong affinity with brackish species from central and eastern Palaeo-Mediterranean areas, whereas the molluscs present a Paratethyan origin. Despite the fact that the basins are all brackish and partly coeval, the systematics of these assemblages highlights the absence of common species among the three studied areas. Geochemical analyses (stable isotopes and trace elements) are performed on ostracods, and ⁸⁷Sr/⁸⁶Sr ratios are established in molluscs and echinoids. The results suggest brackish environments with different compositions and origins of solutes in the three different areas. The Tuscan basins are characterised by brackish waters, with NaCl-enriched waters coming from aquifers of Triassic evaporite bedrock. The brackish deposits of the Venetian-Friulian Basin and Cessaniti are true marginal marine environments, although the northern basin may have been influenced by both the Paratethyan Sava Basin and the northern portion of the Palaeo-Mediterranean water bodies.     

Crayfish co-introduced symbiotic ostracod found on native crab in Japan: The first record of epibiont ostracod found a new host

Ankylocythere sinuosa (Rioja, 1942), a symbiotic ostracod native to North America, was found from the Japanese mitten crab Eriocheir japonica (De Haan, 1835), a species native to Japan, collected from a pond in Shizuoka City, Shizuoka Prefecture, central Japan. Introduced North American crayfish Procambarus clarkii (Girard, 1852), which is a host of A. sinuosa in their native range, inhabits ponds sympatrically with Japanese mitten crabs, and it is thought that the ostracods transferred from the exotic crayfish to the native crabs. In recent years, along with the artificial transportation of crayfish around the world, their symbiotic ostracods also have been found on the body surfaces of exotic crayfish in Europe and Japan. However, no studies have confirmed the infestation of exotic ostracods on native crustaceans in the field. A wide range of developmental stages of A. sinuosa from juveniles to adults were found in Japanese mitten crabs, and mating individuals were also found. This strongly suggests that they can reproduce on the body surface of Japanese mitten crabs. In the future, it will be necessary to strengthen measures against alien species to prevent these exotic symbionts from infestating native ecosystems, and we also need to investigate the exact impact of this symbiont on Japanese mitten crabs.     

Ostracods from the Upper Cretaceous–Paleocene Jiaozhou Formation of Jiaozhou,Shandong, China and their biostratigraphic significance

Late Mesozoic–Cenozoic non-marine deposits are well developed in the Jiaolai Basin, eastern Shandong Province, China, yielding abundant fossils including ostracods. In order to further understand the geological settings of the basin during the Late Cretaceous–Paleogene, three boreholes (JK-1, JZK-01 and JZK-02) were drilled in the city of Jiaozhou. Nine genera and sixteen species (including six indeterminate species) of ostracods are described from the Jiaozhou Formation in the three boreholes, including Cypridea, Mongolocypris, Talicypridea, Candona, Eucypris, Cyprois, Porpocypris, Sinocypris and Timiriasevia. Of these, Porpocypris sphaeroidalis Guan, 1978 is reported from northern China for the first time, indicating that this species has great potential to be an indicator of the K/Pg boundary. Correlation of these species with the known Cretaceous–Paleogene ostracod assemblages suggests that the age of the Jiaozhou Formation could be latest Cretaceous–Paleocene in borehole JK-1, Campanian–Maastrichtian in borehole JZK-01, and Maastrichtian–Danian in borehole JZK-02. The exact position of K/Pg boundary, however, is unavailable for the present in the Jiaozhou Formation from boreholes JK-1 and JZK-01.     

Palaeozoic roots of the sigilliid ostracods

Podocopine ostracods rapidly increased in species diversity after the Palaeozoic, and 32 out of the 36 podocopine families are extant (Whatley et al., 1993), but the phyletic origins are known for only a few. The Sigilliacea are unique in having a long and detailed fossil record. The Sigilliidae known from the recent and Mesozoic faunas differ from others ostracods in having large adductor muscle scars with many spots, a character typical rather to Palaeozoic forms. Paleozoic Microcheilinellidae were morphologically close to the sigilliids, but details of their hingement and carapace margin structures were unknown until now.Silicified specimens of Microcheilinella mendelgrammi, new species, from the Early Carboniferous of southern China and Microcheilinella mandelstami, from the Middle Devonian of north-western Poland show merodont hingement and narrow calcified inner lamella. This makes their relationship to the Mesozoic, Tertiary, and recent sigilliids Saipanetta, Cardobairdia, Sigillium, and Kasella likely. The sigilliid lineage was thus established already in the Devonian.Tubulibairdia, with adont hingement and tubulous shell wall, and Microcheilinella s. s., with merodont hingement and no tubules, are distinct genera in different families.     

Ostracods of the genus Palaeocytheridea Mandelstam in the Middle and Upper Jurassic of Europe: 3. Stratigraphy and paleobiogeography

The analysis of distribution of endemic and cosmopolitan ostracods of the genus Palaeocytheridea shows that, in the Bajocian and Bathonian, the Tethyan and Boreal-Atlantic regions of Western and Eastern Europe developed in partial isolation, while beginning from the middle of the Lower Callovian, these parts of the European paleobasin were connected. For the Middle Jurassic of Western and Eastern Europe and, in particular, for Ukraine, the ostracod zones are recognized based on stratigraphic distribution of species of the genus Palaeocytheridea.     

The osmoregulatory capacity of the Ostracoda

All ostracods that inhabit inland waters are osmoregulators. Freshwater ostracods must be hyperosmotic regulators while ostracods that live in hyperhaline water are hypoosmotic regulators. Some euryhaline species are hypoosmotic regulators in salinities above 8 g·l^-1 and hyperosmotic below. Hyperosmotic regulation in ostracods is partly dependent on salt consumed in the food but hypoosmotic regulation is dependent on the excretion of salt brought about by special cells located on the inside of the carapace.