Maria Cristina Cabral

Ostracodes from the Upper Cretaceous deposits of the Potiguar Basin, northeastern Brazil: taxonomy, paleoecology and paleobiogeography. Part 2: Santonian-Campanian

Sixty-four Ostracoda taxa were recorded from the Santonian–Campanian of Potiguar Basin, northeastern Brazil. The following new species were described: Triebelina anterotuberculata, Triebelina obliquocostata, Cophinia ovalis, Fossocytheridea potiguarensis, Ovocytheridea anterocompressa, Ovocytheridea triangularis, Perissocytheridea jandairensis, Semicytherura musacchioi and Protocosta babinoti. The faunal association indicates predominantly shallow marine environments, intercalated with typically mixohaline levels. These species are mostly endemic, although the presence of six species common to West and North Africa shows that migration was still possible by the end of the Cretaceous.

Sinuocythere n. gen. (Ostracoda, Limnocytheridae, Timiriaseviinae); a new genus of limnic ostracode from southern Tethyan Middle and Upper Jurassic

A new genus of limnic ostracode, Sinuocythere n. gen., belonging to the family Limnocytheridae, subfamily Timiriaseviinae, and three new species, Sinuocythere subsinuosa n. sp., Sinuocythere pedrogaensis n. sp. and Sinuocythere candeeirosensis n. sp. are described. This genus belongs to the Timiriasevia-Metacypris group, which first appeared at the end of the Triassic and began to diversify during the Middle Jurassic. It differs from other members of the group by its elongate subovate carapace, slightly compressed posterior margin, and its sinuous and posteriorly upturned dorsal margin. All the known species of this genus have a stratigraphical distribution limited to the Middle and early Upper Jurassic (Bathonian-Oxfordian) of the southern Tethyan realm (Tunisia, Morocco and Portugal). Sinuocythere has a typical euryhaline behavior, contrasting with the salinity tolerance of living and fossil species of the genera Metacypris and Vecticypris, which are essentially limnic-oligohaline.

BIO-SEDIMENTARY SIGNATURES OF HIGH-FREQUENCY SALINITY/SUBAERIAL EXPOSURE CHANGES: EXAMPLES FROM THE OXFORDIAN OF PORTUGAL (CABAÇOS FORMATION)

The detailed sedimentary and micropalaeontological analysis of a complex association of continental to marginal-marine deposits from the Oxfordian of Portugal (Cabacos Formation) has allowed the recognition of high-frequency, subtle changes in the environmental conditions. The main factors controlling the palaeobiological responses to such minor-scale fluctuations were also identified. Two factors have shown to be especially significant: subaerial exposure duration and frequency (estimated by assigning type of features to the exposure index) and salinity trends, as suggested by the sedimentary and fossil records. In the west of the basin, salinity fluctuations were much stronger and more frequent (fresh- brackish-restricted marine-hypersaline), and subaerial exposure more marked for longer periods, than in the east of the basin. The microfossil assemblages, as a whole, but in particular the ostracod faunas, show differences in abundance, diversity, dominant species, degree of intrageneric and intraspecific variations, both along the successions and between west and east. The western populations seem to have been much less stable, which suggests that high-frequency changes in salinity (more than its absolute values) and degree of exposure were the most important controls on the palaeobiota. PDF

First occurrence of the genus Zonocypris (Ostracoda) in the Pleistocene of Western Europe (Portugal)

The Recent distribution of the freshwater ostracod genus Zonocypris G. W. Müller, 1898 (type-species Zonocypris madagascariensis Müller, 1898) is restricted to Africa, Madagascar and, occasionally, the eastern Mediterranean (Turkey: Zonocypris inconspicua Schafer, 1952; Zonocypris costata (Vávra, 1897); and pers. comm. K. Martens and O. Külköylüoǧlu).

Tanycythere new genus and its significance for Jurassic ostracod diversity

Abstract The new genus Tanycythere (Crustacea, Ostracoda) is described from the Jurassic (Hettangian–Bathonian) of western and central Europe based on T. caudata new species, T. praecaudata praecaudata new subspecies, T. praecaudata parallela new subspecies, T. duartei new species, T. posteroelongata new species, and T. wattonensis new species. Another new species, T. procera, is described from the Lower Cretaceous (?Barremian). Recognition of a new genus comprising six new species and subspecies indicates that overall Jurassic and Early Cretaceous ostracod biodiversity is underestimated.

First occurrence of the genus Sclerocypris Sars, 1924 (Ostracoda) in the ?Pleistocene of Western Europe (Portugal)

The Recent distribution of the freshwater ostracod genus Sclerocypris Sars, 1924 (type species Sclerocypris clavularis Sars, 1924; synonyms Bharatcypris Battish, 1978 and Candonopsis Sars, 1894 pro parte), subfamily Megalocypridinae Rome, 1965, is restricted to Africa and India (Martens, 1986; Martens & Coomans, 1990). Recovery of fossils of Sclerocypris are not frequent and are restricted to Plio-Quaternary deposits of Kenya, with Sclerocypris clavularis Sars, 1924 from Lakes Turkana and Bogoria (Carbonel & Peypouquet, 1979; Carbonel et al., 1983, 1987; Cohen et al., 1983) and Sclerocypris jenkinae Klie, 1933 from Lakes Elmenteita and Naivasha (Lindroth, 1953; Cohen & Nielsen, 1986) and the Pliocene basal member of the Omo Series, Lake Turkana (Peypouquet et al., 1979). Sclerocypris bicornis (G. W. Müller, 1900) has been recorded (identified as Chlamydotheca sp.) in the Pleistocene of Egypt (Boukhari & Guernet, 1985). Recent field work in Algarve, southern Portugal (Cabral et al., 2003, 2004, 2005), recorded the presence of Sclerocypris. It was represented by numerous juvenile specimens of a species related closely to the Recent species Sclerocypris bicornis in a probable Pleistocene lacustrine ostracod assemblage at Bolqueime associated with other Cypididae, Candonidae, Darwinulidae, Limnocytheridae and Cypridopsidae. The instars are characterized by the presence of long spines on the margins, as is common in many species of this genus (Martens, 1986, 1991), such as Sclerocypris tuberculata (Methuen, 1910), Sclerocypris venusta (Vavra, 1897) [illustrated in Martens, 1986] and Sclerocypris clavularis Sars, 1924 (Pl. 1, fig. 2). They also possess three large conical tubercles not present on adults, an important …

Cyprideis torosa (Jones, 1850) in mainland Portugal: what do we know?

The distribution of Recent and Holocene Cyprideis torosa (Jones, 1850) from brackish estuaries and lagoons of mainland Portugal is presented; older Cenozoic C. torosa are also briefly mentioned. Around 550 specimens were found alive, in Melides lagoon (456) and salt marshes from large estuaries (90). Thousands of empty valves and carapaces, with different ornamentation, were found in the lagoon, the estuaries and in Holocene samples from boreholes, in the latter with higher concentration in sediments deposited in lagoons. The modern C. torosa was found living mainly in Melides lagoon, associated with brackish and freshwater ostracod species, in soft mud or muddy sand sediments from quiet zones, with salinities from 4.1 to 15.1; it is also found in soft mud to muddy sand sediments whose interstitial waters have salinities from 19.0 to 34.1, on salt marshes (tidal flat and low marsh) of large estuaries, similar to lagoons, in low hydrodynamic areas, together with other brackish ostracods. The main parameters controlling the distribution of C. torosa appear to be the substrate, water dynamics and emersion time, whereas water chemistry is more related to the morphology of valves. In general, C. torosa presents the same ecological characteristics in the Holocene and in modern times.

Advances in the Stratigraphy and Geochemistry of the Organic-Rich Lower Jurassic Series of the Lusitanian Basin (Portugal)

Here we present the main results of a study of the high-resolution stratigraphy of the Lower Jurassic organic-rich marine series in the Lusitanian Basin, Portugal. In this basin, the Lower Jurassic consists mainly of an alternating marl–limestone succession (upper Sinemurian–Toarcian), with some intervals enriched in organic matter (upper Sinemurian and Pliensbachian). These Lower Jurassic carbonate units correspond to the Coimbra, Agua de Madeiros, Vale das Fontes, Lemede, and S. Giao/Cabo Carvoeiro formations. In the last few years, these units have been the subject of a multidisciplinary and integrated stratigraphic analysis, based on the study of a range of biotic and abiotic parameters. In our study, high-resolution analysis of these units in the main reference sections of the basin have allowed seven main themes to be developed, involving sedimentological and sequential analysis, ammonite biostratigraphy, macroinvertebrate palaeontology and palaeoecology, ostracod analysis, chemostratigraphy, organic and petrographic geochemistry, and gamma-ray analysis. Besides the novel results obtained in each scientific domain, the integration of all the collected data has improved our knowledge of not only the stratigraphy and sedimentary knowledge of the Lower Jurassic carbonates but also the hydrocarbon generation potential of the different Sinemurian and Pliensbachian units.

Middle Jurassic Tethyan–Boreal ostracod faunal links: a case study from the Callovian of Portugal

Late Callovian (athleta Chronozone) age sediments of Pedrógão, west coast Portugal, yielded a low diversity ostracod assemblage with relatively little in common with coeval NW European assemblages except at the weak level of comparative (cf.) species identification. Five new marine species are described (Neurocythere multiforma sp. nov., Palaeocytheridea (Malzevia)? dorsocostata sp. nov., Praebythoceratina parascrobiculata sp. nov., Praeschuleridea lisensis sp. nov., Virgulacytheridea posteroacuminata sp. nov.) and three previously described non-marine species recorded that so far are indigenous to Portugal (Septacandona azeredae, Sinuocythere pedrogaensis, Theriosynoecum helmdachi). Ostracod taxonomic links to western Tethys are evident but weak. Calcareous nannofossil assemblages were analysed for biostratigraphical control. Supplementary material: Sample data and raw ostracod counts are available at https://doi.org/10.6084/m9.figshare.c.3271394.v1

Gomphocythere besni n. sp. (Crustacea, Ostracoda) from a man-made pool (Adıyaman, Turkey)

We describe a new species (Gomphocythere besni n. sp.) from the Tavaş man-made pool in Besni town (Adıyaman, Turkey). The species has several differences from its congeners in furcal structures (forked organ, seta of caudal ramus), numbers of setae on maxillula and maxillular palp, particular ornamentation with up to eight fossae in each mesh of the reticulation and in the presence of two types of lateral pore-canals (single pore opening with a sensillum and sieve plates) on the carapace. The finding of the new species extends the known geographical distribution of the living forms of the genus further to the North. The new species was found from relatively cool (16.6 ºC) and medium oxygenated waters (7.36 mg/L) in a mixture of sand and gravel substrate. Details about its ecology and taxonomic status are also compared and discussed with other species of the same genus.