Search

International audience

The palynogical data of two sites from northeastern Fram Strait (MSM5/5–712 and PS2863) encompassing the last 23,000 years are presented here. The data set first includes the palynomorph concentrations: dinocysts (cysts/g) and their fluxes (cysts/cm2/yr) as well as pollen grains, spores, organic linings, Halodinium, reworked palynomorphs and Pediastrum represented in #/g. It also includes the relative abundance (%) of dinocyst taxa at sites MSM5/5–712 and PS2863. Finally, this Data in Brief comprises reconstructions of sea-surface conditions at the two sites, which include sea-surface temperature (°C) in summer and winter, sea-surface salinity (psu) in summer and winter, sea-ice cover (month/yr) and productivity (gC/m2yr). The most probable values in addition to minimum and maximum possible are reported. The data is presented in function of the cores depth and age. For more details on this data and the chronology of the cores, see [1]. Keywords: Fram strait, Last glacial maximum, Late and postglacial, Holocene, Palynology, Temperature, Salinity, Sea-ice, Dinocysts

In marine sediments of late Cenozoic age, Spiniferites is a very common genus of dinoflagellate cysts (dinocysts). Despite some taxonomical ambiguities due to large range of morphological variations within given species and convergent morphologies between different species, the establishment of an operational taxonomy permitted to develop a standardized modern database of dinocysts for the mid-high latitudes of the Northern Hemisphere. In the database that includes 1490 surface sediment samples, Spiniferites mirabilis-hyperacanthus, Spiniferites ramosus and Spiniferites elongatus were counted in addition to Spiniferites belerius, Spiniferites bentorii, Spiniferites bulloideus, Spiniferites delicatus, Spiniferites lazus and Spiniferites membranaceus. Among these taxa, Spiniferites mirabilis-hyperacanthus, Spiniferites ramosus, and Spiniferites elongatus are easy to identify and are particularly common. Spiniferites bentorii and Spiniferites delicatus also are morphologically distinct and occur in relatively high percentages in many samples. Spiniferites lazus and Spiniferites membranaceus also bear distinctive features, but occur only in a few samples. The identification of other taxa (Spiniferites belerius, Spiniferites bulloideus, notably) may be equivocal and their reported distribution has to be used with caution. The spatial distribution of Spiniferites species, with emphasis on the five most common taxa, is documented here with reference to hydrography (salinity and temperature in winter and summer, sea ice cover), primary productivity and geographical setting (bathymetry, distance to the coastline). The results demonstrate distinct ecological affinities for Spiniferites elongatus, which has an Arctic-subarctic distribution and appears abundant in low productivity environments characterized by winter sea ice and large temperature contrast between winter and summer. Spiniferites mirabilis-hyperacanthus, which occurs in warm temperate water sites, is more abundant in high salinity environments. It shares its environmental domain with Spiniferites bentorii, which appears to have a narrower distribution towards the warm and high salinity end of the Spiniferites mirabilis-hyperacanthus distribution. In contrast, Spiniferites delicatus, which occurs in warm-temperate to tropical environments, shows preference for relatively low salinity and low seasonal contrasts of temperature. Spiniferites ramosus exhibits a particularly wide distribution that overlaps both cold and warm Spiniferites taxa. Its cosmopolitan occurrence and its long-ranging biostratigraphical distribution suggest a high plasticity of the species and/or co-occurrence of several cryptic species. Hence, whereas Spiniferites elongatus and Spiniferites mirabilis-hyperacanthus are useful palaeoecological indicators despite their large morphological variability, Spiniferites ramosus is a taxon with an unconstrained ecological significance.

During the last glacial period, climate conditions in the North Atlantic region were determined by the alternation of relatively warm interstadials and relatively cool stadials, with superimposed rapid warming (Dansgaard‐Oeschger) and cooling (Heinrich) events. So far little is known about the impact of these rapid climate shifts on the seasonal variations in sea surface temperature (SST) within the North Atlantic region. Here, we present a high‐resolution seasonal SST record for the past 152 kyrs derived from Integrated Ocean Drilling Program “Shackleton” Site U1385, offshore Portugal. Assemblage counts of dinoflagellates cysts (dinocysts) in combination with a modern analog technique (MAT), and regression analyses were used for the reconstructions. We compare our records with previously published SST records from the same location obtained from the application of MAT on planktonic foraminifera. Our dinocyst‐based reconstructions confirm the impression of the Greenland stadials and interstadials offshore the Portuguese margin and indicate increased seasonal contrast of temperature during the cold periods of the glacial cycle (average 9.0 °C, maximum 12.2 °C) with respect to present day (5.1 °C), due to strong winter cooling by up to 8.3 °C. Our seasonal temperature reconstructions are in line with previously published data, which showed increased seasonality due to strong winter cooling during the Younger Dryas and the Last Glacial Maximum over the European continent and North Atlantic region. In addition, we show that over longer time scales, increased seasonal contrasts of temperature remained characteristic of the colder phases of the glacial cycle., Key Points New high‐resolution dinocyst‐based summer and winter SST record from IODP “Shackleton” Site U1385 for the last 150 kyrs is presentedDinocyst‐based SST confirms the D‐O cycles and HEs at Site U1385Increased seasonal contrast of SST (up to 12 degree C) during cold periods of the glacial cycle related to strong winter cooling is shown

The article: Atmospheric blocking events in the North Atlantic: trends and links to climate anomalies and teleconnections, written by Hussein Wazneh, Philippe Gachon, Rene Laprise, Anne de Vernal, Bruno Tremblay was originally published electronically on the publisher’s internet portal (currently SpringerLink) on 5 January 2021 without open access.

•A synthesis of existing literature on Holocene climate change in Arctic Canada and Greenland.•Warmest-to-coldest millennium temperature change in the Holocene in Arctic Canada and Greenland is 3.0 ± 1.0 °C.•Thermal maximum conditions occurred earlier in high latitudes and at sites less influenced by North Atlantic circulation.

As polynyas are often used around the globe as a window on tomorrow's marine polar ecosystems, this study presents reconstructions of primary production and sea-surface conditions near the North Water polynya, since ~ 1560 CE from palynological, isotopic and biomarker analyses of a sediment core. Quantitative reconstructions of sea-surface conditions (temperature, sea-ice cover and production) were derived from the Modern Analogue Technique (MAT) applied to dinoflagellate cyst assemblages. Production was also qualitatively estimated from the stable isotope composition of organic carbon and nitrogen and the concentration of organic biomarkers (IP 25, dinosterols). The results show relatively stable oceanographic conditions but suggest a slight warming accompanied by an increase in productivity after 1860 CE. The comparison of MAT reconstructions and the organic biomarker data suggests that IP 25 provides information about primary production associated with sea-ice but does not unequivocally reflect sea-ice concentration in this regional setting, which is marked by dense seasonal sea ice except during the short summer season.

Surface and subsurface conditions in the Labrador Sea during Marine Isotope Stage (MIS) 31 at the Integrated Ocean Drilling Program (IODP) Site U1305 off southwest Greenland are reconstructed based on dinocyst and foraminifer assemblages. Isotopic compositions of planktonic (Neogloboquadrina pachyderma -Np-) and benthic (Cibicides wuellerstorfi -Cw- and Oridorsalis umbonatus -Ou-) foraminifera provide further information about water properties in the mesopelagic layer as well as at seafloor. Dinocyst proxy-reconstructions indicate low salinities (32-34.5), cool winters (3-6 °C) and mild summers (10-15 °C) in the surface water layer during the MIS 31 "optimum". However, planktonic foraminifer assemblages largely dominated by Np suggest relatively cold subsurface conditions in winter (-2-0 °C) and summer (2-4 °C). Lower δ13C-values in Np vs. Cw further suggest either a lesser-ventilated mesopelagic layer than the bottom one, or high organic matter oxidation rates at Np habitat depth. The dinocyst and planktonic foraminifer records together suggest a strong stratification between the surface and subsurface water layers. Isotopic and micropaleontological data thus converge towards paleoceanographical conditions unsuitable for convection and intermediate or deep-water formation in the Labrador Sea during the "warm" MIS 31 interglacial, a situation similar to the one, which prevailed during the "warm" MIS 5e.

We attempt to assess the Holocene surface-subsurface seawater density gradient on millennial time scale based on the reconstruction of potential density (σθ) by combining data from dinoflagellate cyst assemblages and planktic foraminiferal (Neogloboquadrina pachyderma (s)) stable oxygen isotopes (δ18Oc). Following several calibration exercises, the likeliness of favorable seasonal preconditioning to open ocean convection is evaluated. The reconstructed σθ values reveal unfavorable conditions for vertical convection in the western Nordic Seas prior to ~7–6.5 ka B.P., with a westward increase and persistence of surface water buoyancy. Active overturning became more likely after 6.5 ka B.P. as suggested by a reduced and recurrently inverted vertical σθ gradient, while intermittent eastward spreading of lower density surface waters continued to modulate the area of potential overturning. Despite some reservation regarding the accuracy of the σθ values reconstructed, the documentation of relative changes of σθ gradients through time and space is suggested as a helpful tool for the appraisal of past overturning likeliness.

Dinoflagellate cyst (dinocyst) records from the southern Nordic Seas were compiled in order to evaluate the evolution of upper ocean conditions, on a millennial timescale and supported by a highly resolved record from the Vøring Plateau. After the transitional phase from the last deglaciation, three main phases define the Holocene. The early Holocene (>7.5 ka BP) features important numbers of cool-temperate species dominated by Nematosphaeropsis labyrinthus and Impagidinium pallidum in the west. The assemblage composition changes drastically at the transition from the early to the mid-Holocene, from when on Operculodinium centrocarpum dominates. The changeover is dated between ~6.1 and 7.5 ka BP, perhaps earlier closer to the Iceland–Scotland Ridge, and appears to be linked to the onset of a modern type of surface circulation. ‘Warmest’ assemblages occur at the Vøring Plateau shortly after the transition, when Atlantic waters also appear to have spread farthest westward. The recurrence of colder elements can be linked to cooling from ~2.4 ka BP at the Vøring Plateau and presumably earlier in the west but is difficult to date there because of the low sedimentation rates. This is a general issue in many areas of the Nordic Seas and appears to have an important effect on cyst concentrations and assemblage composition, with the possible loss of oxygenation-sensitive cysts in the older parts of the cores. Comparing dinocyst-based quantitative reconstructions with those retrieved from other plankton reveals a significantly different trend between proxies, linked to a differing autecological response to seasonal changes at their respective depth habitats.

To investigate the mechanisms behind Holocene regional climate trends from north of 58°N in the North Atlantic-Fennoscandian region Principal Component Analysis (PCA) was performed and a temperature anomaly stack produced from 81 proxy derived summer temperature time series from 74 sites. The PC results show distinctly different trends for near-surface versus surface temperatures, demonstrating the importance of handling these separately. The first PC of weighted sea surface summer temperature time series and continental time series explains 45 ± 8% of the variance, where the uncertainty is the standard deviation of the distribution of variance explained across the 1000 age-uncertain ensemble members. PC1 has a relatively uniform expression over the whole region, closely following the summer insolation at 65°N. The second PC explains 22 ± 4% of the variance and shows a non-uniform expression, with loadings in opposite directions in the northern and southeastern parts of the region. Comparing the PC time series with model runs and with the timing of the demise of the Laurentide Ice Sheet (LIS), suggest that this pattern reflects both topographic and albedo effects of the LIS as well as release of meltwater into the North Atlantic and Arctic Oceans. Comparing the stack of gridded records with published global stacks reveals an unusual Holocene temperature development in the North Atlantic-Fennoscandian region most likely resulting from the location relative to the decaying LIS.

Palynological and geochemical analyses were carried out on a sediment core collected in the shallow Alvarado lagoon (Veracruz, Southwestern Gulf of Mexico) in order to evaluate the impact of the significant decline in the surrounding native coastal vegetation on phytoplankton assemblages. The sedimentary sequence encompasses the last millennium and provides information on pre-industrial phytoplankton assemblages. Results highlight a recent increase of freshwater-sourced organic matter relative to marine organic matter in line with reduced total concentrations of cyst-producing dinoflagellates. These changes appear to be synchronous to the extensive conversion of wetlands into agricultural areas, with consequences on the stability and water retention capacity of the soils bordering the lagoon system. The data also show that Polysphaeridium zoharyi, a cyst produced by the potentially toxic dinoflagellate Pyrodinium bahamense, is present in high abundance in the dinoflagellate population of the lagoon. Consequently, the modern cyst bank of P. bahamense in sediment has the potential to initiate harmful blooms since surface sediments are prone to resuspension events related to strong seasonal winds and human activities.

Prior to performing stable isotope analysis in tree rings, investigators usually extract cellulose from wood samples, which represents a tedious and time-consuming task. In this experiment, two different protocols for holocellulose extraction were compared, namely the Jayme-Wise technique and the Accelerated Solvent Extractor (ASE), a relatively new device operating under high temperature and pressure. We found that both techniques are equivalent regarding resin removal, produce comparable δ 13 C results, do not damage the samples, and leave no resin in the xylem rays after treatment. However, the ASE is a lot less time-consuming, being ten times faster than the soxhlet based method, in addition to being safer and more convenient.

We present a new version of the standardized Northern Hemisphere “modern” dinoflagellate cyst (“dinocyst”) database, which includes abundances of 71 taxa at 1968 sites across the Northern Hemisphere, cross-referenced with 17 environmental parameters extracted mostly from the 2013 World Ocean Atlas. Several taxa with tropical to warm temperate affinities were added to the previous database version. Dinocyst concentrations in the surface sediments reach 106 cysts g−1, with maximum values along the continental margins and minimum values offshore in distal open ocean settings. Assemblages are characterized by the co-occurrence of phototrophic (n = 41) and heterotrophic taxa (n = 30), with maximum proportions of heterotrophic taxa in high productivity regions, notably at the sea-ice edge and in upwelling regions. The main pattern of assemblage distributions includes north–south and nearshore–offshore gradients, with maximum diversity of species along the continental margins and towards the south, in warm temperate and tropical areas. Canonical correspondence analyses performed on heterotrophic and phototrophic taxa independently yield consistent results, hence suggesting similar, but not identical, ecological affinities for both taxonomic groups. For both groups, sea-surface temperature and sea-ice are the most determining parameters, but the phototrophic taxa seem more sensitive to onshore–offshore gradients marked by salinity changes. Productivity-related parameters also determine dinocyst distribution, especially primary productivity in the fall and winter, with a stronger relationship for the combined dataset of phototrophic and heterotrophic taxa.

Dinoflagellate cyst (=dinocyst) assemblages are widely used for the reconstruction of multiple oceanographic variables through the application of transfer functions. There is evidence that the number and kind of variables driving compositional changes in dinocyst assemblages vary regionally and that the selection of driving factors and the evaluation of transfer function performances are method-specific and complicated by spatial autocorrelation. Here, we used two new modern datasets from the Northern Hemisphere Atlantic-Arctic and the Northern Hemisphere Pacific oceans to re-evaluate the impact of sea-surface properties in dinocyst assemblages. We determined the dimensionality of the dinocyst ecological response and identified the main drivers for both regions. We calibrated and evaluated transfer function methods for the prediction of these variables and estimated their performances considering spatial autocorrelation. In both datasets, multiple environmental variables mutually and independently affect assemblage compositions, but the number and kind of these variables differ between datasets. We detected spatial autocorrelation, which was often due to environmental similarity, but some variables appeared to reflect geographical closeness, implying that spatial independence between sample sites depends upon the variables. We identified different primary drivers in both areas, highlighting the merit of regional calibrations and the necessity to carry out variable selection for each region separately. The multiple gradients identified imply that potentially multiple parameters could be reconstructed from the same fossil dinocyst assemblages. However, as the multiple gradients reflect geographical structuring, we propose that regional calibrations, even at the expense of generalisation, could improve the reliability and interpretation of transfer function reconstructions.

This paper examines the distribution of 91 modern dinoflagellate cyst taxa from 3636 locations across the world's oceans. Patterns of distributions among the taxa included bi-polarity, cosmopolitan, northern versus southern hemispheres, and geographically restricted. Of the 91 taxa, three dominate these 3636 assemblages at the global scale, Brigantedinium species, Operculodinium centrocarpum sensu Wall and Dale 1966 and some species of Spiniferites. Whereas Brigantedinium is a true cosmopolitan taxon, with high abundances in each ocean, Operculodinium centrocarpum sensu Wall and Dale 1966 shows high abundances in polar to temperate regions in the Northern Hemisphere, and in tropical to sub-tropical waters in the Southern Hemisphere. Spiniferites species show highest occurrences in the Southern Hemisphere. This study also highlights three true bi-polar species, Impagidinium pallidum, Islandinium minutum and cyst of Polarella glacialis. Only a few taxa are strictly endemic, either being relics of ancient seas such as the Paratethys (Spiniferites cruciformis) or linked to specific environmental conditions. However, recent studies have shown recent worldwide dispersal of these endemic species possibly due to human activities. Overall, this compilation has highlighted the progress made since the early 1970s on our understanding of these important tracers of environmental conditions but also gaps in our knowledge of their distribution in pelagic regions of the Pacific and Indian Oceans as well as under Arctic sea ice.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Analyses of marine palynomorphs, including dinocysts and acritarchs, from Pliocene-Pleistocene sediments of the Ocean Drilling Program (ODP) Site 887 in the Gulf of Alaska allowed the development of a biostratigraphic scheme, which we compared with bio-events in regional diatom and radiolarian zonations. The dinocyst biostratigraphic scheme includes five biozones and four major boundaries. A first stratigraphic boundary, at 4.4 Ma, is associated with a change in productivity. The other boundaries, at 2.7 Ma, 1.7 Ma, and 0.7 Ma, correspond to the onset of the modern halocline, an intensified cooling period, and the end of the Mid-Pleistocene Transition respectively. Moreover, the analyses of dinocyst assemblages illustrate long-term changes in the surface ocean after 5.3 Ma. The occurrence of Ataxiodinium zevenboomii, Impagidinium velorum, and Impagidinium patulum suggests warm-temperate conditions until approximately 4.2 Ma. Between 4.2 and 2.7 Ma, colder and less saline events marked by an increase in cold-tolerant species, such as Habibacysta tectata, suggest regional cooling and/or lower salinity of surface water, which might be related to Alaskan glacier meltwater discharges. From 2.7 to 1.2 Ma, the presence of Impagidinium pallidum and cysts of Pentapharsodinium dalei suggests low-salinity, cold, and stratified surface waters, whereas major drops in dinocyst fluxes are linked to a decrease in productivity and harsh conditions. Progressive change from cold, stratified waters to warmer and saltier conditions occurred between 1.2 and 0.7 Ma during the Mid-Pleistocene Transition. After 0.7 Ma, dinocyst assemblages are characterized by the alternating dominance of Brigantedinium spp. and Operculodinium centrocarpum, suggesting fluctuations between nutrient-rich, low-salinity, cold waters and cool-temperate environments.

Lake pollen records from southwest Greenland and eastern Baffin Island show strong regionalism in climate trends of the last 7000 cal years. July surface air temperature reconstructions from pollen indicate larger amplitude cooling in southwest Greenland (>3.0°C) than in eastern Baffin Island (

Sea-surface conditions in northeastern Fram Strait since the last glacial maximum (LGM) were reconstructed from cores MSM5/5-712-2 and PS2863/1–2 based on palynological assemblages, ecological preferences of dinocysts and application of the modern analog technique. Dinocyst in LGM sediments are sparse, but their assemblages reflect mild summer conditions. Given the regional context and evidence from other tracers, the dinocyst assemblages of the LGM could relate to regional fluxes of dinocysts during exceptional mild summers. From 19 to 14.7 ka, dinocyst data suggest very cold conditions with extensive sea-ice cover, while abundant reworked palynomorphs indicate intense glacial erosion. An abrupt transition at 14.7–14.5 ka was marked by a peak in summer temperatures coinciding with a rapidly deposited sediment layer related to a regional meltwater plume event in western Svalbard. From 14.7 to 12.6 ka, large seasonal temperature contrasts with mild summers and cold winters together with low salinity indicate continuous melting of the Svalbard Barents Sea ice sheet fostered by warm climate. At 12.6 ka, the regional onset of the Younger Dryas was marked by cooling and increased salinity. On a regional scale, the 12.6–12 ka interval corresponds to an important transition involving enhanced circulation of Arctic waters around Svalbard and establishment of coastal fronts along its northern and western margins. Modern-like oceanic conditions with relatively high salinity and low seasonal temperature contrast developed at about 7.6 ka. Since then, a slight cooling is observed, especially in winter. This study offers a comprehensive picture of the deglacial phases in eastern Fram Strait with unique data on the sea-surface salinity, which controls surface water stratification and plays an important role in ocean circulation.

Presentation atCANQUA/AMQUA 2018, Ottawa, August 11, 2018.

In the version of this Review Article originally published, ref. 10 was mistakenly cited instead of ref. 107 at the end of the sentence: “This complexity of residual ice cover makes it likely that HTM warming was regional, rather than global, and its peak warmth thus had different timing in different locations.” In addition, for ref. 108, Scientific Reports was incorrectly given as the publication name; it should have been Scientific Data. These errors have now been corrected in the online versions.

International audience; Over the past 3.5 million years, there have been several intervals when climate conditions were warmer than during the pre-industrial Holocene. Although past intervals of warming were forced differently than future anthropogenic change, such periods can provide insights into potential future climate impacts and ecosystem feedbacks, especially over centennial-to-millennial timescales that are often not covered by climate model simulations. Our observation-based synthesis of the understanding of past intervals with temperatures within the range of projected future warming suggests that there is a low risk of runaway greenhouse gas feedbacks for global warming of no more than 2 °C. However, substantial regional environmental impacts can occur. A global average warming of 1–2 °C with strong polar amplification has, in the past, been accompanied by significant shifts in climate zones and the spatial distribution of land and ocean ecosystems. Sustained warming at this level has also led to substantial reductions of the Greenland and Antarctic ice sheets, with sea-level increases of at least several metres on millennial timescales. Comparison of palaeo observations with climate model results suggests that, due to the lack of certain feedback processes, model-based climate projections may underestimate long-term warming in response to future radiative forcing by as much as a factor of two, and thus may also underestimate centennial-to-millennial-scale sea-level rise.

Treatment of the Climatic Signal in Time and Space: From Instrumental and Proxy Data to Modelling; Rouen, France, 18–20 April 2017

We present a summary of two round-table discussions held during two subsequent workshops in Montreal (Canada) on 16 April 2014 and Ostend (Belgium) on 8 July 2015. Five species of the genus Achomosphaera Evitt 1963 Evitt WR. 1963. A discussion and proposals concerning fossil dinoflagellates, hystrichospheres, and acritarchs, I. National Academy of Sciences, Washington, Proceedings. 49(2):158–164.[Crossref], [PubMed], [Web of Science ®], , [Google Scholar] and 33 of the genus Spiniferites Mantell 1850 emend. Sarjeant 1970 Sarjeant WAS. 1970. The genus Spiniferites Mantell, 1850 (Dinophyceae). Grana. 10(1):74–78.[Taylor & Francis Online], , [Google Scholar] occuring in Pliocene to modern sediments are listed and briefly described along with remarks made by workshop participants. In addition, several holotypes and topotypes are reillustrated. Three species previously assigned to Spiniferites are here considered/accepted as belonging to other genera: Impagidinium inaequalis (Wall and Dale in Wall et al. 1973 Wall D, Dale B, Harada K. 1973. Descriptions of new fossil dinoflagellates from the Late Quaternary of the Black Sea. Micropaleontology. 19(1):18–31.[Crossref], , [Google Scholar]) Londeix et al. 2009 Londeix L, Herreyre Y, Turon J-L, Fletcher W. 2009. Last Glacial to Holocene hydrology of the Marmara Sea inferred from a dinoflagellate cyst record. Rev Palaeobot Palynol. 158(1-2):52–71.[Crossref], [Web of Science ®], , [Google Scholar], Spiniferites? rubinus (Rossignol 1962 Rossignol M. 1962. Analyse pollinique de sédiments marins quaternaires en Israël II. - Sédiments pleistocènes. Pollen et Spores. 4:121–148. [Google Scholar] ex Rossignol 1964 Rossignol M. 1964. Hystrichosphères du Quaternaire en Méditerranée orientale, dans les sédiments Pléistocènes et les boues marines actuelles. Revue de Micropaléontologie. 7:83–99. [Google Scholar]) Sarjeant 1970 Sarjeant WAS. 1970. The genus Spiniferites Mantell, 1850 (Dinophyceae). Grana. 10(1):74–78.[Taylor & Francis Online], , [Google Scholar], and Thalassiphora balcanica Balteş 1971. This summary forms the basis for a set of papers that follows, where points raised during the workshops are explored in greater detail.

The use of dinoflagellate cyst assemblages as a tool for palaeo-environmental reconstructions strongly relies on the robustness of cyst identification and existing information on the distribution of the different species. To this purpose, we propose a functional key for the identification of Pliocene and Quaternary Spiniferites bearing intergonal processes and depict the range of morphological variation of the different species on the basis of new observations from estuarine and coastal regions. Accordingly, the description of Spiniferites mirabilis is emended to include the new subspecies Spiniferites mirabilis subsp. serratus. We also report the occasional presence of intergonal processes in Spiniferites bentorii and Spiniferites belerius. This key aims to facilitate identification of this group of Spiniferites bearing intergonal processes and standardize cyst identification among researchers.