Dinoflagellate Cyst Species Research Articles

Late Eocene (Priabonian) dinoflagellate cysts from Primorsky Quarry, southeast Baltic coast, Kaliningrad Oblast, Russia

Forty-seven rock samples from the stratotypes of upper Paleogene formations - Prussian, Palvé and Kurshskaya formations – are collected from the biggest amber deposit worldwide (Primorsky quarry, Kaliningrad oblast, SE Baltic coast), and have been palynologically analyzed. The presence of age-diagnostic dinoflagellate species has allowed us to refine and update the previously questionable age of regional lithostratigraphic units. Based on the presence of Rhombodinium perforatum, the “Upper Wild Earth” and “Upper Blue Earth” members of the Prussian Formation correspond to the early Priabonian (Late Eocene) Rhombodinium perforatum Zone. The overlying “Upper Quicksand” and “White Wall” members of the Prussian Formation contain the key-species Thalassiphora reticulata, and are correlated with the late Priabonian T. reticulata Zone. The overlying Palvé Fm (“Green Wall”), comprises a dinoflagellate cyst assemblage very close to that recorded from the Prussian Formation, and also corresponds to the T. reticulata Zone, late Priabonian. The lower part of the Kurshskaya Formation – “Chocolate clays” and lower “Brown sands” members, contain an impoverished dinoflagellate cyst assemblages as a result of significant environmental changes. However, the common presence of Areosphaeridium diktyoplokum and Glaphyrocysta semitecta, along with an absence of early Oligocene key-species Wetzeliella gochtii or Chiropteridium galea, and pollen key-species Boehlensipollis hohli or Aglaoreidia cyclops, suggest the lower Kurshskaya Formation can be correlated with the latest Eocene, and very close to the Eocene/Oligocene boundary. Based on the revised stratigraphic ages presented here, we suggest an important regional marine transgression occurred during the Priabonian, which allowed the direct marine connection between the NW European Basin and Peri-Tethys via the Polish-Luthuanian Seaway. This was then followed by a regression at the end of Priabonian that culminated in a transition to continental sedimentation in the early Rupelian. A new dinoflagellate cyst species Oligokolpoma balticus sp. nov. is formally described.

Calcareous dinoflagellate cyst distribution across the K/Pg boundary at DSDP site 577, Shatsky Rise, western North Pacific Ocean

An analysis of calcareous dinoflagellate cysts has been carried out on sixteen samples from across the K/Pg boundary interval from Deep Sea Drilling Project Site 577 situated on Shatsky Rise in the western North Pacific. This is the first time that a detailed study of this microfossil group has been undertaken from deep sea sediments of Late Cretaceous–early Paleocene age in the North Pacific realm. Eight species of calcareous dinoflagellate cysts were found to comprise low diversity assemblages of which half are representative of extant taxa. The most pronounced bioevent is that of Cervisiella operculata reaching its highest proportions at the K/Pg boundary transition underscoring the utility and cosmopolitan distribution of the species with its acme as a marker for the earliest Danian. We also identify an indirect sea surface paleotemperature signal as represented by variance in wall thickness in two distinct morphotypes of Thoracosphaera heimii (morphotypes A and B). The cyst concentrations and relative abundances of these taxa are interpreted to reflect the late Maastrichtian warming event and subsequent late Maastrichtian cooling phase prior to the interval of gradual warming in the early Danian marked by the opportunistic capitalization of Cervisiella operculata during a time of ocean recovery following the terminal Cretaceous.

Middle Miocene dinoflagellate cyst assemblages and changes in marine productivity in western Colombia

Changes in dinoflagellate assemblages indicate regional paleoceanographic events affecting western Colombia. Integration of palynomorph, planktonic foraminifera, and calcareous nannoplankton data from a 616 m thick outcrop section in the Ladrilleros-Juan Chaco region allows the construction of a detailed and reliable chronological framework and identification of marine high-productivity intervals. Results indicate marine deposition from middle (~15 Ma) to late (~10 Ma) Miocene. Dinoflagellate cyst assemblages are consistent with known regional assemblages and include more warm water taxa than cold ones. Correlation of the palynomorphs with the other microfossils studied allows calibration of the biostratigraphic ranges of seven species of dinoflagellate cysts commonly reported from tropical zones. The ratio between autotrophic and heterotrophic dinoflagellate cysts indicates an overall increase of paleoproductivity at ~13.8 Ma. Gonyaulacoid taxa dominate the lower interval (15–13.8 Ma), while peridinioid taxa dominate the upper segment (~13.8–10.5 Ma). This change coincides with the global cooling related to the growth of the Antarctic ice sheet (~14 Ma) and presumably increased the recurrence of events like La Niña in the equatorial Pacific. These conditions increased the primary productivity in the Pacific coastal region of northwestern Colombia, and four high-productivity intervals are tentatively correlated to the Mi3a, Mi-3b, Mi-4, and Mi-5 isotope events.

Early Eocene palynofloras and geochemistry from the Garo Hills in Meghalaya (India)

We analyzed a rich palynological assemblage from the Tura Formation consisting of 55 genera and 89 species of dinoflagellate cysts, fungal remains; spores and pollen grains, along with a numerous marine microforaminiferal linings. The composition of palynotaxa, clay minerals and stable isotope ratios indicate a warm, humid climate with tropical–subtropical climate conditions during sediment deposition. Based on similar palynotaxa compositions and carbon isotope signatures, we conclude that the Tura Formation was deposited during early Eocene. The presence of terrestrial, coastal and marine elements in the assemblages is indicative of a shallow marine environment in proximity to the shore line. The rock eval pyrolysis results suggest that the organic matter composition is primarily type III kerogen, which is a primary source of thermally immature hydrocarbons.

Phelodinium fensomei sp. nov.: a protoperidineacean dinoflagellate cyst from the lower Paleocene (Danian) of the Oyster Bay Formation, Vancouver Island, Canada

Phelodinium fensomei is a new species of organic-walled dinoflagellate cyst described from the Appian Way section of the Oyster Bay Formation, Vancouver Island, British Columbia, Canada. Phelodinium fensomei sp. nov. differs from other species of Phelodinium in its unique combination of characters including an elongate epicyst, bilobate endocyst antapex, and microgranulate to verrucate surface ornamentation. The species occurs exclusively within Dinoflagellate Cyst Zone D4 of the Oyster Bay Formation along with the Danian indicator taxon Danea californica. This is also the first study to perform scanning electron microscopy and epifluorescence analysis on a specimen belonging to the protoperidinioid genus Phelodinium, revealing minute features and a negative response to ultraviolet light exposure, indicating a heterotrophic feeding strategy for the motile cell. Although P. fensomei sp. nov. occurs at markedly low relative and absolute abundances in the examined interval, it is restricted to strata of Danian age suggesting potential biostratigraphic utility.

New acritarch and peridinioid dinoflagellate cyst species from the Oligocene–Miocene of Colombia

New marine palynomorph taxa recovered from an upper Oligocene–lower Miocene (upper Chattian–upper Burdigalian; ~24–17 Ma) shallow-marine succession drilled in northern Colombia, northwestern South America, are herein formally described. These new taxa comprise two peridinioid dinoflagellate cyst species, Cristadinium lucyae sp. nov., and Trinovantedinium uitpensis sp. nov., and the acritarch Quadrina? triangulata sp. nov. During the Aquitanian, C. lucyae sp. nov. occurs consistently, whereas T. uitpensis sp. nov. occurs sporadically. Q.? triangulata sp. nov., a potential key biostratigraphic marker in the tropical Americas, occurs during the middle and upper Burdigalian. Cristadinium lucyae sp. nov. is characterized by having solid, distally tapered to truncated, sutural spinules forming linear low crests. Quadrina? triangulata sp. nov. is characterized by having conical to subconical processes. Trinovantedinium uitpensis sp. nov. is characterized by having verrucate to slightly baculate penitabular processes and denticulate cingulum. In addition, Cristadinium lucyae sp. nov. and Trinovantedinium uitpensis sp. nov. improve our understanding of protoperidiniacean taxonomic diversity.

Three new organic-walled dinoflagellate cysts from the Upper Cretaceous deposits in the western External Rif, northwestern Morocco: Taxonomy and stratigraphic distribution

Three new species of organic-walled dinoflagellate cysts (dinocysts) have been spotted during our palynological investigations in the Upper Cretaceous deposits from the western External Rif Chain, northwestern Morocco. They have been previously mentioned and figured under different names, but have not been formally described. In this paper, the formal descriptions of these new species are presented, based on several specimens observed within rich, diverse and well-preserved upper Campanian dinocyst assemblages from the Sekada, Tattofte and Bou Lila sections. Canningia wilsonii sp. nov. is a holocavate cyst, characterized by having densely packed pillars, supporting a finely reticulate ectophragm on the mid-dorsal surface to coarsely reticulate elsewhere, mainly in the periphery. Impagidinium sekadensis sp. nov. is distinguished by the combination of a smooth central body wall, rigid and well-developed sutural septa, narrow longitudinal apical plates (1′, 4′) which are rarely separated (partially) by a discontinuous sutural septum, a strongly leavorotatore cingulum and a narrow sulcus with a differentiated posterior sulcal (ps) plate. Nematosphaeropsis lilaensis sp. nov. differs from the published species of Nematosphaeropsis by having a smooth central body wall and numerous sutural (gonal and intergonal) processes that are flexible, hollow and joined proximally by low and discontinuous sutural ridges and distally by pairs of thin penitabular trabeculae. The taxonomic synonyms and stratigraphic ranges of the new species, as well as their comparison with published dinoflagellate taxa, which morphologically resemble them, are given and discussed.

Species Assemblages and Distribution of Dinoflagellate Cysts from three Estuaries Sediment’s of Makassar Strait, Eastern Indonesia

Makassar Strait encompasses high fisheries resources and high biodiversity and primary productivity. Algae blooms often occur in these areas, but there is a lack of studies that have been carried out on HABs in these locations specifically determining the collection and abundance of dinocyst. The study aimed to determine species assemblages of dinoflagellate cysts from three estuaries of Makassar Strait. Sampling was conducted at three locations, i.e., Jeneberang, Maros and Pangkep Estuaries during July 2020. Each location of sampling consisted of 4 stations and 3 substations as a sampling replication. Variables that were measured in this study were dinoflagellate cysts abundance species assemblages and distribution. Results showed that there was no clear group of dinoflagellate cysts assemblages between locations, however dinoflagellate cyst assemblages from Jeneberang Estuary was significantly grouped. We recorded 48 dinoflagellate cysts species that belonged to 5 families, namely Goniodomaceae, Gonyaulacaceae, Gymnodiniacea, Peridiniaceae and Protoperidiniaceae. The dominant species of dinoflagellate cysts from Jeneberang Estuary was Scrippsiella crystallina, meanwhile the dominant dinoflagellate cyst from Maros and Pangkep Estuary was Gonyaulax verior and Pentapharsodinium tyrrhenicum, respectively. Scrippsiella trifida was a dinoflagellate cysts species was contributed to the dissimilarity of cyst assemblages between locations. We also found potential five toxic dinoflagellate cyst species. In conclusion, the dinoflagellate cysts species composition, diversity, species richness and cyst abundance was not significant difference between stations of all locations. The abundance of dinoflagellate cysts was significantly correlated by sediment grain size. All sampling sites has a potentially occurred of HABs due to the five potential cysts toxic and harmful species discovered.

Biostratigraphy and paleoenvironments of the Pelotas Basin, southernmost Brazil, using Miocene dinoflagellate cysts

Dinoflagellate cysts assigned to the subfamily Protoperidinioideae are frequently recorded in Miocene coastal deposits, and their relative abundance is directly related to primary productivity and favorable post depositional conditions. However, these microfossils are poorly studied in Brazilian Miocene sequences. This paper presents the results of a palynological study on 18 samples obtained from the core CBM001-ST-RS drilled in the coastal plain of southernmost Brazil, related to the Cidreira Formation, Pelotas Basin. Forty-nine taxa are identified, 46 dinoflagellate cysts, two genera of chlorophyte algae, and one acritarch species. Overall, the samples are characterized by large numbers of Spiniferites spp. and Brigantedinium spp., as well as a significant richness of the subfamily Protoperidinioideae. Several species of dinoflagellate cysts indicate a Miocene age, but the record of Sumatradinium hamulatum and Quadrina? condita restricts the age of the interval analyzed to the middle Miocene. Both the PMI and the P/G palynological indices indicate a neritic marine environment and moderate primary productivity, respectively.

Successive first downhole sporomorph-events: Applied biostratigraphic tool for fault delineation within Baharyia Formation, Abu Sennan area, Abu Gharadig Basin, Egypt

Two hundred and seventy four samples, covered the Bahariya sections encountered in 13 boreholes, drilled in three main fields of the General Petroleum Company concession, Abu Gharadig Basin, north Western Desert, were critically investigated for their palynomorphs content. A standard acid-based palynological processing technique is employed to extract the palynomorphs. Fair to moderate diversity and moderate to good preserved palynomorph assemblage has been recovered. This study yielded 107 species of spores, pollen grains and dinoflagellate cysts. Six remarkable successive first downhole appearance (FDA) sporomorph-events are defined and biostratigraphically utilized for dividing the Bahariya Formation and delineating the Bahariya/Kharita contact. The upper Bahriya unit includes the first Afropollis jardinus event dated latest early Cenomanian, while the middle Bahriya unit comprises the second Elatersporites klaszii event dated early Cenomanian. The lower Bahriya unit, dated early Cenomanian-late Albian, contains the third, fourth, and fifth Cretaceieporites densimurus, Trilobosporites laevigatus and Stellatopollis sp. events, respectively. The contact between Bahriya Formation and the upper part of the underlying Kharita Formation, dated early-middle Albian, is placed on Concavisimisporites punctatus event. The authors found the possibility of these six zones to be widely traced and provide potential bio-correlation tool for the Bahariya sections in Abu Gharadig Basin. According to the presence or absence of such six successive events and their average zonal thicknesses, the intra-formational disconformities and positions of the faults could be allocated with confidence. The remarkable thinning in the thickness of such zones could localize the position of disconformities caused by non deposition or erosion/faulting within the Bahariya sections. The aforementioned six events could be correlated and nicely matched with their equivalent six log-based cycles on the log responses. The authors encourage the Egyptian industrial geologists to follow the presented successive six sporomorph-events in the future palynological-steering exploration and production activities in the Bahariya rock unit and effectively utilize such events as intra- and inter-basinal dating tool and possible correlation control for the Bahariya sections across the northern basins of Egypt.

Two new dinoflagellate cyst species and their biostratigraphical application in the Eocene and Oligocene of the North Sea

The Cenozoic of the North Sea is among the best-documented stratigraphical successions in the world, and multiple palynological events have been recognised for chronostratigraphical control across the region. The ever-increasing number of wells studied for hydrocarbon exploration and production results in the generation of new biostratigraphical data that constantly increase our palynological knowledge of the area. Here we describe two new dinoflagellate cyst species from an Lower Eocene (Ypresian) to Lower Oligocene (Rupelian) succession in Gannet Field (UK Central North Sea). These are Reticulatosphaera valdereticulata sp. nov., a short-lived Rupelian index taxon, and Alisocysta heilmannii sp. nov., previously informally known as Alisocysta sp. 2, which is an Ypresian marker widely used by biostratigraphers working the North Sea region. The development of a dense network of trabeculae connecting the processes distally allows Reticulatosphaera valdereticulata sp. nov. to be clearly distinguished from the closely similar Reticulatosphaera actinocoronata. The main diagnostic feature in Alisocysta heilmannii sp. nov. is the development of delicate penitabular septa. Both species show widespread palaeogeographical distribution across the North Sea region. We also document the diverse palynofloras in which the two new species are encountered and discuss biostratigraphical application and palaeoenvironmental settings.

<i>Desmocysta hadra</i>, a new Late Cretaceous dinoflagellate cyst species: stratigraphic range, palaeogeographic distribution and palaeoecology

Abstract. A new species of dinoflagellate cyst, Desmocysta hadra sp. nov., is described from the early Campanian (Late Cretaceous) in the Norwegian Sea. This new taxon differs from the other three known species by its particularly robust but highly folded wall and the short, fine filaments arising from the antapex. The short stratigraphic range of early Campanian for this new species was calibrated with other regional well-dated dinoflagellate cysts, making it a good biostratigraphic marker. A review of the taxonomic description of the genus has also been undertaken using the available published data. The available data shows a consistent presence of Desmocysta in the fossil record from the Early Cretaceous to the late Paleocene, although some Late Jurassic occurrences have been reported in the North Sea Basin. The current records also indicate that this genus is restricted to higher latitudes in the Northern Hemisphere. Based on Paleocene and Late Cretaceous occurrences of the genus, and its association with dinoflagellate cysts, prasinophytes and acritarchs, a proximal, highly stressed marine environment for Desmocysta is suggested.

Palynostratigraphy and palaeoclimate of the Valanginian–Cenomanian subsurface succession in Hamza-1X well, Matruh Basin, Egypt

Diverse palynomorph assemblages of spores, pollen grains and dinoflagellate cysts have been yielded from the palynological analyses of 115 ditch cutting samples covering the Valanginian– Cenomanian succession encountered in Hamza-1X well, Matruh Basin, north Egypt. The complex sit- uations in the north Western Desert requires more revisited palynozones for better understanding of the subsurface successions therein. Consequently, the first downhole palyno-events will be very helpful in solving some issues concerning the age determination and correlation. Seventy palynomorph species (47 spores and pollen grains; 23 dinoflagellate cyst species) were identified from all the productive samples which used to divide the studied succession into numerous sporomorph and dinoflagellate biozones based on the last occurrence datum for the recovered marker taxa. Four sporomorph inter- val biozones and six dinoflagellate cyst interval biozones were differentiated from the same studied stratigraphic succession. The four sporomorph biozones are presented, in ascending order as follows: Aequitriradites spinulosus and Impardecispora apiverrucata Interval Zone (late Valanginian– early Barremian), Pilosisporites trichopapillosus I. Z. (late Barremian), Murospora florida I. Z. (early Aptian–late Aptian), and Elaterosporites klaszii I. Z. (early Albian– early Cenomanian). The seven dinoflagellate cysts biozones are Muderongia simplex I. Z. (late Valanginian–early Barremian), Pseudoceratium anaphrissum I. Z. (late Barremian– early Aptian), Cribroperidinium edwardsii I. Z. (early Aptian), Subtilisphaera perlucida I. Z. (late Aptian), Oligosphaerdium complex I. Z. (early– late Albian), Dinopterygium cladoides and Coronifera oceanica Assemblage Zone (early Cenomanian). From the palaeoclimatic point of view, the studied interval could be differentiated into two climatic intervals; the lower arid interval that comprises the Alam El Bueib Formation and dominated by the arid xerophyte elements like Sphaeripollenites and Classopollis. The upper humid interval represents the Alamein, Dahab, Kharita and Bahariya formations that is dominated by the humid hygrophyte elements, such as Murospora, Crybeolsporites, Elaterosporites, Afropollis and Deltoidospora.

Cretaceous Oceanic Anoxic Event 2 in eastern England: further palynological and geochemical data from Melton Ross

The lowermost 1.45 m of the Welton Chalk Formation, including the regional sedimentary record of Oceanic Anoxic Event 2 (OAE-2), has been sampled at Melton Ross Quarry in eastern England, UK. The section is investigated for organic geochemistry and stable isotopes for the first time, while a detailed palynological study follows previously published preliminary results. It comprises a condensed interval that spans the Cenomanian–Turonian Stage boundary. A locally preserved, lower ‘anomalous’ succession (Beds I–VII) and a ‘Central Limestone’ (Bed A) are shown to correlate respectively with the pre-Plenus sequence and Plenus Bed at Misburg and Wunstorf in the Lower Saxony Basin (LSB), NW Germany. They are overlain by a succession of variegated marls (Bed B to Bed H), including the Black Band (Beds C–E), that can be correlated across eastern England. Based on a carbon isotope (δ 13 C) profile and dinoflagellate cyst and acritarch bio-event correlation, Beds B–H appear to be a highly attenuated post-Plenus equivalent of the LSB succession, including part of the ‘Fish Shale’. The δ 13 C profile shows possible ‘precursor’/‘build-up’ events in the lower succession at Melton Ross, with the main OAE-2 δ 13 C excursion occurring in the Central Limestone and overlying Beds B–H. The darker coloured marls from the Black Band and Bed G contain 1.43–3.47% total organic carbon (TOC), hydrogen index values of 78–203 mg HC/g TOC and oxygen index values of 15–26 mg CO 2 /g TOC, indicating type III and type II–III organic matter, of mixed terrigenous and marine algal sources. The corresponding palynological assemblages are dominated by marine dinoflagellate cysts, comprising mainly gonyaulacoid taxa, with subordinate terrigenous miospores, mainly gymnosperm bisaccate pollen, consistent with a distal marine setting. The interbedded lighter-coloured marls contain less than 0.4% TOC and lower proportions of miospores and peridinioid dinoflagellate cysts compared with the darker layers. This is suggestive of moderately raised levels of productivity during deposition of the darker layers, possibly related to greater nutrient availability from land-derived sources. The occurrence of the peridinioid taxa Eurydinium saxoniense and Bosedinia spp., together with higher proportions of prasinophyte phycomata in the darker layers, may also point to stimulation of organic-walled phytoplankton productivity by reduced nitrogen chemo-species encroaching the photic zone, possibly by expansion of an oxygen-minimum zone. Exceptionally high concentrations of palynomorphs (in the tens of thousands to lower hundreds of thousands per gramme range) in the darker layers at Melton Ross and eight other eastern England localities is consistent with increased quality of seafloor preservation in a low oxygen environment, coupled with a high degree of stratigraphic condensation. Two new dinoflagellate cyst species are described from Melton Ross, Canninginopsis ? lindseyensis sp. nov. and Trithyrodinium maculatum sp. nov., along with two taxa described in open nomenclature. Supplementary material : One pdf file, with detailed sample positions and descriptions, tables of supporting information (also available in Excel format), quarry photographs and a palynological distribution chart, is available at https://doi.org/10.6084/m9.figshare.c.4987205

Cretaceous dinoflagellate cyst biostratigraphy in the Facai-1 well of the Tenere Graben in eastern Niger, Africa

Sixty-five genera and 115 species of dinoflagellate cysts were discovered in the samples from the depth of 600–2652 m in the Facai-1 Well in the Tenere Graben of Niger, Africa. The low diversity and abundance in each single sample make it difficult to divide the dinoflagellate cyst assemblage into biozones. The dinoflagellate cyst assemblage is indicative of a Late Cretaceous age and suggests an abnormal neritic palaeoenvironment.

Late Triassic dinoflagellate cysts from the Northern Carnarvon Basin, Western Australia

The Late Triassic radiation of cyst-forming dinoflagellates in the Southern Hemisphere is investigated in the Northern Carnarvon Basin, Western Australia. This major depocentre, situated on the southern margin of the Tethys Ocean, accumulated extensive deltaic and shallow marine successions at this time, that frequently host early dinoflagellate cyst assemblages. Numerous petroleum exploration wells in the basin have penetrated the fluvially dominated Mungaroo Formation and shallow marine Brigadier Formation, of Anisian–Norian and Rhaetian ages, respectively. Consequently, huge numbers of cuttings and sidewall core samples from these northwest prograding deltaic systems are available for study. Many of the dinoflagellate cysts from the Mungaroo and Brigadier formations have not been taxonomically formalised, including many forms that are used in open nomenclature within the oil and gas industry. This study formally documents these occasionally abundant and diverse dinoflagellate cyst assemblages with the aim of providing a consistent taxonomic framework for future work on the Upper Triassic successions of the Northern Carnarvon Basin. This will aid the recognition of individual flooding events via their characteristic palynomorph signatures and help to build on significant recent advances in regional sequence stratigraphy. One new genus, 14 new dinoflagellate cyst species and one new subspecies are described from the most diverse Late Triassic dinoflagellate assemblage yet published. A further nine genera and 15 dinoflagellate species are also recorded from the Carnian–Rhaetian R. wigginsii, W. listeri, H. balmei, R. rhaetica and D. priscum dinoflagellate zones. The documented assemblages are not only significant biostratigraphically, but it is also postulated that high diversity Triassic dinoflagellate cyst associations were paleoclimatically controlled, and were likely confined to the temperate and cool temperate paleolatitudes.

Distribution of dinoflagellate cysts along the salinity gradient in two tropical estuaries along the West coast of India

Abstract Dinoflagellate cysts are known to be potential seed banks which have an essential role in providing bloom history and also serve as useful indicators of eutrophication in marine environments. The present study is focused on the surface distribution of dinoflagellate cysts along the salinity gradient in two tropical estuaries, namely Chapora and Sal in Goa along the West coast of India. Surface sediments and water samples were collected monthly from February 2016–March 2017 which included all three seasons (pre-monsoon, monsoon, post-monsoon). A total of sixteen species of dinoflagellate cysts belonging to the order, Gymnodiniales, Gonyaulacales, and Peridiniales were recorded in the surface sediments. Cysts of heterotrophic dinoflagellates dominated the assemblage in both estuaries. Based on Redundancy Analysis (RDA), it was observed that the distribution of the dinoflagellate cysts were influenced by various physico-chemical parameters in both estuaries with salinity and grain size being the main explanatory variable. Nitrate limitation is noted to be a triggering factor for dinoflagellate cyst formation. Also, yessotoxin producer species, such as Gonyaulax spinifera, encountered in both estuaries showed an inverse relationship with nitrate concentration. This suggests that, high nitrate input in these estuaries might lead to excystment of Gonyaulax spinifera eventually leading to harmful blooms under eutrophic conditions.

Age of the earliest transgressive event in the Krishna-Godavari Basin, India: evidence from dinoflagellate cysts and planktonic foraminifera biostratigraphy

A combined biostratigraphic study of dinoflagellate cysts and foraminifera was carried out on Early Cretaceous subsurface well cutting sediments from well A (DNG) (2800–2746 m depth) from the Krishna-Godavari Basin, India. The last appearance datum of marker species of dinoflagellate cysts and planktonic foraminifera was considered for the construction of the biostratigraphic framework. The study shows dominance of Early Cretaceous marker dinoflagellate cysts Cassiculosphaeridia magna, Cribroperidinium perforans, Hystrichodinium voigtii, Kleithriasphaeridium eoinodes, and planktonic foraminifera Hedbergella aptiana, Hedbergella mitra, Hedbergella praelippa, Hedbergella tardita, Microhedbergella miniglobularis and Hedbergella mitra species. In addition to this, the dinoflagellate cyst data were compared with the dinoflagellate biozones of Austral and Tethyan provinces. Based on earlier micropalaeontological records from the Krishna-Godavari Basin and the present study, a latest Barremian-early Aptian age has been determined for the earliest marine transgression in the Krishna-Godavari Basin. The early marine incursion during late Barremian-earliest Aptian in the Krishna-Godavari Basin compared to Albian age in Cauvery Basin suggests the opening of east coast from north to south.

New Selandian species of Glaphyrocysta and Spinidinium from offshore Northwest Europe

This article presents the formal description of three dinoflagellate cyst species recovered from Selandian sediments in the Faroe-Shetland Basin and offshore Norway. These species have been recognized informally by the regional biostratigraphy community to support the sequence stratigraphic subdivision of Paleocene sediments and used as intra-Selandian markers but have never been formally described. This paper outlines the characteristic features and paleogeographical distribution of Glaphyrocysta granulosa sp. nov. and Glaphyrocysta shetlandensis sp. nov., and compares these taxa with known published species of Glaphyrocysta. Both new species of Glaphyrocysta have a sub-spherical/sub-circular outline with processes connected distally by irregular broad trabeculae terminations, however, G. granulosa has a tendency to have a wider body width and a relatively dense granulate central body ornamentation compared with G. shetlandensis which has significantly reduced surface ornament, and punctate wall structure. Spinidinium selandicum sp. nov. is stratigraphically older than the two new Glaphyrocysta species described and is characterized by having an unusually delicate ornamentation and very low sutural ridge which allows for comparison with other species of Spinidinium. The paleogeographical distribution of these new species covers an area ranging from the Faroe-Shetland Basin to the Vøring Basin (offshore Norway).

CISTOS DE DINOFLAGELADOS DO HOLOCENO DA PLANÍCIE COSTEIRA DE SANTA CATARINA (POÇO PSC-03): DESCRIÇÕES TAXONÔMICAS E IMPLICAÇÕES PALEOAMBIENTAIS

Estudos palinológicos de detalhe abordando cistos de dinoflagelados quaternários de depósitos sedimentares brasileiros são relativamente escassos. A análise palinológica de sedimentos do Holoceno do poço PSC-03 (27º53'22"S; 48º39'04'' W) perfurado na Planície Costeira de Santa Catarina, sul do Brasil, revelou associações palinológicas abundantes e diversificadas que incluem palinomorfos terrestres (esporos, grãos de pólen, fungos, algas de água doce) e marinhos (cistos de dinoflagelados, palinoforaminíferos). A não exposição das amostras a métodos agressivos, tais como oxidação e acetólise, durante o processamento laboratorial permitiu a recuperação de cistos da Família Protoperidiniaceae. Três gêneros (Brigantedinium spp., Lejeunecysta spp., Spiniferites spp.) e quatro espécies (Brigantedinium simplex, Selenopemphix nephroides, S. quanta, Operculodinium centrocarpum) de cistos de dinoflagelados são descritos e ilustrados aqui, constituindo uma das associações fósseis mais diversificadas do grupo para o Holoceno brasileiro. A associação de cistos de dinoflagelados sugere ambiente marinho marginal, com águas superficiais susceptíveis a variação de salinidade e alta concentração de nutrientes.