Spore Taxa Research Articles

Palynological assemblages from Hongguleleng Formation of Western Junggar, Northwest China and their correlation with conodont zonation

The Upper Devonian Hongguleleng Formation is a significant stratigraphic unit near the Frasnian/Famennian and Devonian/Carboniferous boundaries of the Kazakhstan Paleoplate. However, its age is still under debate. A new palynostratigraphic analysis was conducted at the Gennaren section to provide a more accurate biostratigraphic assignment. In this study, we identified 43 species belonging to 26 spore genera, including those in open nomenclature. Despite the poor preservation of the palynofloras, the spore taxa were categorized into two assemblages. Assemblage I is established at the lower part of the lower member of the Hongguleleng Formation, containing Cornispora varicornata, cf. Auroraspora pseudocrista, and Cyrtospora cristifera. Assemblage II is from the upper part of the lower member of the Hongguleleng Formation, including Grandispora cornuta, Grandispora famennensis var. famennensis, Grandispora cf. famennensis var. minutus, Grandispora microseta, and Rugospora radiata. These assemblages are compared with the Western European DV Oppel Zone (lower-middle Famennian), and the GF to VCo Oppel zones. The assemblages are equivalent to the conodont crepida–rhomboidea and marginifera to Lower trachytera zones (middle-upper Famennian).

Floral and faunal biostratigraphy of the Middle–Upper Triassic Karamay and Huangshanjie formations from the southern Junggar Basin, China

Abstract In the Junggar Basin, northwestern China, the biostratigraphy and vegetation patterns of the Middle–Late Triassic sediments are comparatively poorly resolved. Here we investigate Middle–Late Triassic successions of the Dalongkou Section in the southern Junggar Basin for palynostratigraphy and vegetation patterns. Three palynological abundance zones are proposed here: the Aratrisporites Abundance Zone (Middle Triassic), the Dictyophyllidites – Aratrisporites Abundance Zone (latest Middle to early Late Triassic) and the Lycopodiacidites – Stereisporites informal abundance zone (Late Triassic). A review of previous records of the Fukangichthys Fauna indicates that this vertebrate fossil assemblage is stratigraphically located within the uppermost part of the Karamay Formation and is Middle Triassic in age. The revised dating of this and other faunas are further used to constrain the palynological zones in the Junggar Basin. Although the palynoflora is consistently dominated by non-striate bisaccate pollen (produced by seed ferns and/or conifers) in the studied section, spores record a distinctive abundance increase during the late Middle Triassic. Spore taxon abundance changes indicate a vegetational shift from a Middle Triassic–early Late Triassic community characterized by abundant lycophytes (likely Annalepis and Pleuromeia ) to a Late Triassic ecosystem with abundant dipteridaceous ferns (e.g. Dictyophyllum ) in the Junggar Basin and across North China. This study updates the Triassic biostratigraphy in the Junggar Basin, and sheds light on temporal floral changes in this basin and elsewhere in North China during the Middle to Late Triassic.

Triassic palynology of the Swiss Belchentunnel: a restudy of the Scheuring samples

Well-preserved Carnian (Late Triassic) palynomorphs are rare in Switzerland, despite sediments include one of the important plant fossil localities, Neue Welt near Basel. Modern detailed palynological studies on Triassic palynomorphs in general and especially in the Carnian are scarce, most palynological studies were carried out more than 50 years ago. Nevertheless (Late) Triassic sediments still yield surprises for palynological research. Here, we present the results of the re-study of the famous Belchentunnel samples that were studied and published by Bernhard Scheuring in 1970. The less cheerful result concerns the preservation of slides: more than 60% of the slides are degraded. On the other hand, the restudy of the well-preserved slides showed an unexpected number of algae, acritarchs, and spore taxa not described so far. Especially the spores facilitate the correlation with the well-known biostratigraphic schemes established for the Germanic Basin. The distribution of Porcellispora longdonensis throughout the Belchentunnel succession is especially striking. The acme just below the Schilfsandstein might suggest the presence of ephemeral ponds.

Preliminary results on reproductive organs and in situ spores of an early land plant Tichavekia grandis Pšenička et al. from Přídolí (upper Silurian) of the Prague Basin, Czech Republic

Reproductive organs and in situ spores isolated from early land plant Tichavekia grandis from the Kosov, Přídolí, upper Silurian of the Prague Basin are described in detail. Subspherical to reniform sporangia are 2.2–3.0 mm wide and 1.6–2.0 mm long, and are formed by a thick layer of coaly matter showing a marginal rim. Trilete crassitate in situ spores 17–32 µm in diameter have microgranulate, microspinate to rugulate sculpture of proximal surface and are not comparable with any dispersed and in situ Silurian spore taxa and, therefore, it may represent a new spore taxon. Palynological comparison with other cooksonioid taxa is made.

Субфоссильные спорово-пыльцевые спектры как отражение высотной поясности Южного Сихотэ-Алиня

The correspondence of pollen spectra from surface soil samples from the Olkhovaya Mountain (height 1669 m) to vertical belt vegetation (coniferous-broadleaved forests, spruce-fir forests and golets belt) was analyzed. Attention is paid to the analysis of the pollen spectra formed under alpine vegetation, including spruce forests at an altitude of 1600 m and on a swampy area near the Alekseevskoye Lake, a unique alpine lake in the Southern Sikhote-Alin. Pollen of woody vegetation prevailed in subfossil spectra from all vegetation belts, the composition of pollen of herbaceous plants and spores was poor. 16 taxa of arboreal, 8 taxa of nonarboreal, 5 taxa of spores were identified. It was found that the ratio of the main taxa, in general, corresponds to the dominant plants of the vegetation cover. It is shown that the local vegetation is not fully reflected in the subfossil spectra in the alpine belt, especially there is little pollen from shrubs and grasses, and waterlogged habitats are poorly reflected. It was revealed which pollen from the leading plant families and genera of flora of the highlands is not reflected in the pollen spectra. It has been established how much allochthonous pollen and what taxa were carried by the wind from lower relief levels. Taxa with remote sources were found. In general, the pollen spectra from the Olkhovaya Mountain highlands reflect the widespread development of spruce forests near the peak. Presence of spruce forests and a small area of the alpine zone are the main reasons explaining why forest pollen spectra with a predominance of dark coniferous pollen were obtained above the forest boundary. The results obtained were compared with the data on subfossil spectra from soils and surface peat of the bogs of the Sergeevskoye and Shkotovskoye plateaus, as well as the Partizanskaya and the Kievka rivers basins. The data obtained are important for more correct paleogeographical reconstructions: biomization methods in the mountainous areas of the south Far East and the development of methodological techniques for assessing quantitative paleoclimatic parameters.

New Oligocene to Early Miocene Palynomorph Zonation of GZ-1 Well, Onshore Western Niger Delta, Nigeria

Palynological studies was carried out on GZ-1 well from the onshore western Niger Delta in order to recognized a new detected developments in the varieties of key pollen and spore taxa that have shorter and more distinguished interval zones to advance stratigraphical delineation. Palynological analysis was carried out using the conventional maceration technique for recovering acid insoluble organic-walled microfossils from sediments. The result yielded rich and diversified palynomorphs. The main assemblage were dominated by angiosperm pollen grain (dominant global flora from Late Cretaceous onwards) followed by pteridophytes/bryophyte spore. Dinoflagellate cysts, on the contrast, were less diverse while the Gymnosperm pollen were scarce. The identified palynomorph were used to establish seven main zones - AF1 Psilatricolporites crassus zone, AF2 Verrucatosporites usmensis zone, AF3 Triplochiton scleroxylon zone, AF4 Crassoretitriletes vanraadshooveni zone, AF5 Acrostichum aureum zone, AF6 Gemmatriporites ogwashiensis zone and AF7 Retitricolporites irregularis zone in this study. Established on quantitative events, the zones were also divided into seven subzones with some having finer subdivisions into (a) and (b) ranging in age from Early Oligocene to Early Miocene. Previous unfiled event trends of important indicator taxa of spores and pollen accredited to Pelliceria, Caesalapinoideae, Stenochlaena palustris, Polypodiaceae, Lygodium microphyllum, Polypodiaceae, Adiantaceae and Amanoa (Euphorbiaceae) have assisted improvement of formerly used palynological zonation schemes in the Niger Delta. It is anticipated that this quantitative zonation scheme erected, will help with imminent palynostratigraphical studies in the onshore Niger delta area.

New Neogene index pollen and spore taxa from the Solimões Basin (Western Amazonia), Brazil

In western Amazonia, palynology has been the main source of chronological information for the Neogene Period. The Solimões Formation in northwestern Brazil has hundreds of meters of fine-grained rocks that have yielded rich pollen records informing on age and paleoenvironments. Here, we present new pollen data for two boreholes (1-AS-33-AM and 1-AS-37-AM) in the Solimões Basin and one outcrop (Patos) in the Acre Basin, and describe 36 new taxa (two pteridophyte spores and 34 angiosperm pollen) plus one emendation. Palynostratigraphic zonation schemes from Venezuela and Colombia were analyzed critically to provide relative ages for our sections. We found core 33AM to span pollen zones T14 (∼16–14.2 Ma), T15 (14.2–12.7 Ma) and T16 (12.7–7.1 Ma) sensu Jaramillo et al. (2011), while core 37AM spans zones T15? and T16. We also report the widespread occurrence of Cyatheacidites annulatus in outcrops of the Solimões Formation, implying the existence of latest Miocene (∼7 Ma) to Pliocene sedimentation and suggesting ages older than ∼7 Ma for the uppermost sediments of our boreholes. Biostratigraphic relationships also indicate that Echitricolporites mcneillyi and Ladakhipollenites? caribbiensis cannot be used as Pliocene markers as previously assigned. The implications of these results for the palynostratigraphy and paleoenvironmental reconstructions of western Amazonia are discussed.

Preliminary results of palynological investigation of lakes bottom sediments from Pechora Delta River

We studied spore-pollen spectrum of the arctic lake Arcto-Pimberto (Pechora river delta, Nenets Autonomous Okrug, Russian Arctic) from a short sediments core covering last ca. 6000 years. In total, 28 pollen and spore taxa have been identified. The spore-pollen spectrum from the sediments were dominated by arboreal taxa. Pollen of Betula sp., Cyperaceae and Sphagnum spore were present throughout the core in relatively constant percentages. Four palynological zones are definable under consideration on the basis of the spore-pollen data (PZ I PZ IV). The spore-pollen spectra from the PZ I are characterized by a prevailing share of arboreal taxa pollen mostly represented by Betula spp., Salix, Alnaster with the presence of heather (Ericaceae) communities. The PZ I was deposited in wetter conditions. The spore-pollen spectra from the middle layers of the core (PZ II PZ III) are characterized by an increased concentration of herbaceous taxa pollen. The climate was more arid. The pollen spectrum from the PZ IV reflects the development of moss and low-growing shrubs in wet climates.

Airborne Pollen Concentration in Nanjing, Eastern China, and its Relationship With Meteorological Factors

AbstractThis paper presents the results of airborne pollen and spore trapping in Nanjing city, eastern China, using a Burkard pollen trap during two consecutive years (2013–2014). A total of 103 pollen and spore taxa were identified. Two concentration peaks are observed in the annual cycle, a spring peak dominated by arboreal pollen types (Morus, Cupressaceae, Pinus, Pterocarya, and Quercus) and a fall peak dominated by upland herbs (Compositae, Poaceae, Humulus, and Cruciferae). Wetland herbs and ferns dominate summer assemblages and winter assemblages are characterized by sporadic records of Artemisia, Chenopodiaceae, and Pinus. Strong year‐to‐year differences in measured pollen concentration are seen, probably in response to interyear differences in weather. Compared to long‐term means, 2013 was comparatively hot and dry and 2014 had a higher than average number of rain days during the flowering periods. Rising temperatures in early spring are connected with the timing of flowering and therefore pollen release, while rainfall during the flowering period appeared to remove pollen from the air, leading to lower recorded pollen concentration values. Four taxa, Cupressaceae, Quercus, Pinus, and Humulus, were considered in more detail. Each has a different pattern of variation in pollen concentration between the studied years. Cross correlation between pollen concentration and daily temperature, relative humidity, and precipitation at lags from 0 to −30 days also showed different responses for each taxon, suggesting that pollen signal responses to weather conditions have to be considered at a taxon level rather than at the assemblage level.

Scanning electron microscope and light microscope investigations of pollen from an atypical mid-Eocene coal facies in Stolzenbach mine (PreußenElektra) near Borken (Kassel, Lower Hesse, Germany)

Light microscope (LM) and scanning electron microscope (SEM) investigations of palynomorphs from a mid-Eocene coal lens at the Stolzenbach brown-coal mine (“Borken brown coal field”) yielded a remarkable microflora assemblage, with 76 pollen and spore taxa, dominated by monolete fern spores. Numerous pollen and pollen clumps of Myrtaceae and Salicaceae might represent in-situ growth of these families, which were associated with pollen of Aralia-type, Eotrigonobalanus spp., Flueggea-type, Nyssa-type, three Pentapollenites taxa, and Spinaepollis spinosus, plus many others. Ericaceae such as Erica-type, Kalmia-type, and Rhododendron-type pollen are described from here for the first time; the last represents the earliest known occurrence of the genus. Additionally, five tropical south Asian Sapotaceae taxa (Mimusopeae- and Isonandreae tribes), and one tropical South American bombacoid Eriotheca-type occur. Several previously undescribed pollen taxa for the Eocene have been found; some are amongst the oldest examples of these pollen taxa: the Nuphar-type pollen represents the earliest occurrence in Europe and, whilst the Acalypha-type and Trochodendron-type are the oldest pollen occurrences in general, the Viburnum-type, affiliable to Viburnumclemesiae probably represents a tropical south Asian lineage.

The late Pliocene palaeoenvironments and palaeoclimates of the western Iberian Atlantic margin from the Rio Maior flora

Using a revised chronology, a new palynological study on the late Pliocene (Piacenzian and earliest Gelasian) Rio Maior site of the Tagus Basin in western Portugal has been undertaken from the F98 core. Combining light microscopy and scanning electron microscopy, a total of 127 different pollen and spore taxa have been identified from the Piacenzian Lake and indicate the presence of a subtropical to warm-temperate mixed forest during the majority of the Piacenzian (3.6–2.8 Ma). It is only in the latest Piacenzian (after 2.8 Ma) that progressive extinctions of climate sensitive taxa and a drop in diversity indicate a cooling and drying climate trend that has also been recorded from high-latitude localities. By the earliest Gelasian (2.58 Ma), a low diversity Ericaceae and Pinus dominated vegetation remained. The Piacenzian flora of Rio Maior also shows fluctuations in the presence of climate sensitive taxa and pollen-spore diversity that may be related to Piacenzian glaciations.

Comparative palynology of Macrotermes sp. mounds and Vespula vulgaris nests on the University of Lagos campus, Akoka: preliminary study

AbstractIn order to assess the environmental indicator potential of wasp nests and termite mounds, the palynomorph content of three randomly selectedMacrotermessp. mounds (termitaria) and twoVespula vulgarisnests collected on the University of Lagos campus were examined. Palynological analysis showed the presence of 298 well-preserved palynomorphs showing characteristic morphological features. The recovered palynomorphs included pollen, pteridophyte spores and fungal spores, along with insect parts (106), diatoms (7) and a protist (1). The pollen assemblage of termite mounds comprised 78 pollen and pteridophyte spores, with Poaceae and Arecaceae pollen as dominants. In the wasp nest the pollen assemblage comprised 28 pollen and spore taxa, with Poaceae and Arecaceae pollen also dominant. Both mounds and nests had, besides diatoms, six pollen and spore taxa: Poaceae, Amaranthaceae, Pteridophyte spores, Arecaceae,Raffiasp. andRhizophorasp. Vegetational grouping of the recovered pollen and spores indicated five phytoecological groups: secondary forest, mangrove swamp forest, freshwater, open vegetation and Poaceae. In statistical analyses, termite mounds had a higher species richness value (2.08 as compared to 1.99 from the wasp nests), while the wasp nests had a higher species diversity value (0.997 as compared to 0.845 from the termite mounds). Pollen analyses of the termite mounds and wasp nests suggest that both could be useful tools in environmental studies. This is the first attempt to evaluate the potential of termite mounds and wasps nest as natural pollen accumulators in Nigeria. The results suggest new possibilities for the use of the pollen records preserved in termite mounds and wasp nests for environmental studies.

Variation of fluorescence intensity in Pleistocene pollen and the correlation of fluvial deposits in the Khorat Plateau, Thailand

ABSTRACTFluorescence analysis of modern pollen grains is a well-established technique, but its use on fossil material is significantly less prevalent. A study focused on pollen and spore fluorescence and its indication was carried out using samples collected from a 14-m-deep exposed section at an abandoned fluvial terrace in the Khorat Plateau, the center of the Indochina peninsula. Fluorescent signals were well preserved in the deposits at various depths. Thirty-seven fluorescent pollen and spore taxa were discovered in six layers dated from Middle to Late Pleistocene. An alternative algorithm method was used to calculate the fluorescence intensity (FI) in the layers. The FI of each fossil pollen taxon, represented by an assigned value, is different among the layers throughout the section. Differences in the FI indicate varied preservation conditions. General linear analysis indicates that the total FI value is related to the pollen taxa but not to the deposit depth.

A new quantitative approach to identify reworking in Eocene to Miocene pollen records from offshore Antarctica using red fluorescence and digital imaging

Abstract. Antarctic palaeoclimate evolution and vegetation history after the formation of a continent-scale cryosphere at the Eocene–Oligocene boundary, 33.9 million years ago, has remained a matter of controversy. In particular, the reconstruction of terrestrial climate and vegetation has been strongly hampered by uncertainties in unambiguously identifying non-reworked as opposed to reworked sporomorphs that have been transported into Antarctic marine sedimentary records by waxing and waning ice sheets. Whereas reworked sporomorph grains over longer non-successive geological timescales are easily identifiable within younger sporomorph assemblages (e.g. Permian sporomorphs in Pliocene sediments), distinguishing non-reworked from reworked material in palynological assemblages over successive geological time periods (e.g. Eocene sporomorphs in Oligocene sediments) has remained problematic. This study presents a new quantitative approach to identifying non-reworked pollen assemblages in marine sediment cores from circum-Antarctic waters. We measured the fluorescence colour signature, including red, green, and blue fluorescence; brightness; intensity; and saturation values of selected pollen and spore taxa from Eocene, Oligocene, and Miocene sediments from the Wilkes Land margin Site U1356 (East Antarctica) recovered during Integrated Ocean Drilling Program (IODP) Expedition 318. Our study identified statistically significant differences in red-fluorescence values of non-reworked sporomorph taxa against age. We conclude that red fluorescence is a reliable parameter for identifying the presence of non-reworked pollen and spores in Antarctic marine sediment records from the circum-Antarctic realm that are influenced by glaciation and extensive reworking. Our study provides a new tool to accurately reconstruct Cenozoic terrestrial climate change on Antarctica using fossil pollen and spores.

The middle Miocene palynoflora and palaeoenvironments of Eskihisar (Yatağan basin, south-western Anatolia): a combined LM and SEM investigation

Anatolia was a crossroads for mammal migration during the Miocene due to intermittent land connections between Africa and Anatolia and persisting warm conditions. Here, we investigated a palynological section from middle Miocene sediments of Eskihisar (southwestern Anatolia) in order to establish biogeographic links of the palynoflora and to infer the palaeoenvironment. Four algal palynomorphs, nine spore taxa, eight gymnosperms, three monocots, and 67 dicot pollen types were encountered and investigated using the “single grain method” that combines light microscopy and scanning electron microscopy. Two pollen zones reflect different phases of basin development. Zonal vegetation remained fairly stable across the section and reflects heterogeneous environments including broad-leaved deciduous forest, subtropical forest, and sclerophyllous and semi-evergreen oak forest. Conifers were accessory elements in the broad-leaved deciduous forest communities and replaced these at higher elevations. Some herbaceous taxa (Plumbaginaceae) indicate scattered occurrences of sandy and/or rocky soils. Biogeographic affinities are general Northern Hemispheric, North American, and East Asian as also suggested by the macro fossil record. Only two taxa provide potential biogeographic links with the African flora. This suggests that biome shifts of plant taxa between African subtropical /tropical biomes and Anatolian (western Eurasian) temperate forests and shrublands may have been rare in the middle Miocene.

Temporal trends of the airborne fungal spores in Catalonia (NE Spain), 1995–2013

To establish the trends in the period 1995–2013 of the annual fungal spore index of 20 taxa in 8 aerobiological sites of Catalonia, located in 4 phytoclimates, we use the nonparametric Spearman’s Rho and Mann–Kendall tests; when significant, we calculate the magnitude of the change applying the Theil–Sen estimator. We analyze whether the proportional annual change is significantly different from zero, according to phytoclimate, station, and spore taxon, with the Wilcoxon–Mann–Whitney test. Cladosporium, Coprinaceae and Agrocybe are the most prevalent taxa. The proportional annual change analysis shows that 12 taxa present significant increasing trends and 2 decreasing, that the Fresh-Continental Oriental-Humid phytoclimate and Agrocybe show the highest significant increase, while Roquetes-Tortosa (Fresh-Tethyc-Semiarid phytoclimate) and Torula the lowest. The greater significant decreasing proportional annual change corresponds to Drechslera–Helminthosporium and the lesser to Curvularia, and there are no results per phytoclimate and locality. The diversity of characteristics of the sites studied brings the opportunity to evaluate the variability of the fungal values and the magnitude of their change across the study period as depending on the intensity of the land use (urbanization versus agriculture) and the distance to the sea (inland versus littoral), but the effect of the change of the meteorological patterns in the recent years is not negligible. The increasing temperatures and precipitation instability established as effects of the climate change in Catalonia in the last 50 years could be stimulating the sporulation in mountain areas and affecting it in the southern Catalan littoral, thus affecting spore counts.

Apparent changes in the Ordovician–Mississippian plant diversity

This study aims to approximate an illustrative vision of the apparent temporal dynamics of land plant diversity during the terrestrialization process (i.e., the invasion of the land by plants). This problem has often been addressed through studying the Silurian–Devonian megafossil-based diversity patterns of land plants (embryophytes). However, the inclusion of the dispersed spore fossil record is essential for characterizing the first steps of this process (i.e., Eoembryophytic flora). Consequently, this new study includes both spore taxa and plant megafossils in order to discern the diversity trajectories from the first phases of early land plant diversification until the stabilization of early Carboniferous forests (i.e., Palaeophytic flora). The diversity patterns of the primary recognized plant lineages (i.e., Lycophyta and Euphyllophyta) have been also traced in order to discern the origin of the major fluctuations of plant megafossil-based diversity. Results reveal that while the dispersed spore diversity curve shows a sustained increase towards the end of the Devonian Period – with a first maximum towards the late Silurian – the megafossil embryophyte diversity curve is characterized by a set of sequential ascending peaks at the Pragian (Early Devonian), Givetian (Mid-Devonian), and Visean (Mississippian), with a single significant depletion in the Eifelian (Mid-Devonian). The comparative analysis of the lycophyte and euphyllophyte diversity patterns suggests that the substantial embryophytic diversity changes are driven by diversification within lineages rather than by the rhythm of the appearance of key morphological traits. This evidence (1) advocates for an intrinsic ecological control on the apparent changes in taxic richness and (2) implies that the observed plant diversity dynamics respond to the overlapping of the various expansion phases of the plant lineages involved.

North Andean environmental and climatic change at orbital to submillennial time-scales: Vegetation, water-levels and sedimentary regimes from Lake Fúquene between 284 and 130 ka

We present a record of environmental and climatic changes in the northern Andes during the penultimate interglacial–glacial cycle based on integrated information from pollen and grain size distributions (GSDs). The record reflects the 58.33–26.21m interval of a new sediment core from Lake Fúquene (2540m elevation; 5°N) in the Colombian Andes. The age model is mainly based on cyclostyratigraphy and shows that this core interval reflects the period from 284 to 130ka. The 1cm sample increments yield a resolution of ~60yr. In 2553 samples we analyzed 66 selected pollen and spore taxa with the best known ecological ranges. We reconstructed upper forest line (UFL) positions between ~2000 and ~3400m elevation and the most abrupt temperature shifts ranged up to 10°C/100yr at Terminations II and III. Regional vegetation change is mainly driven by eccentricity (100kyr) and obliquity (41kyr) cycles, while changes in local aquatic vegetation show variability in the obliquity and precession (21kyr) bands. Millennial-scale climate variability reflecting Dansgaard–Oeschger (DO) climate cycles in the upper part of the record, continues in this penultimate intergalcial–glacial cycle strongly suggesting that this variability has a persistent character in Pleistocene vegetation and climate dynamics. Short-lived upslope excursions of the UFL reflect 20 DO-style cycles during marine isotope stages (MIS) 7 and 6. Changes in species composition of montane forest are evident, and trees with most pioneer qualities (Alnus, Morella, Quercus and Weinmannia) migrated at the forefront. Other arboreal taxa like Podocarpus, Miconia, and Hedyosmum mostly followed later. Changes in regional vegetation distribution and forest composition, as well as in local aquatic vegetation and GSD of sediments supplied to the lake, allowed the development of an integrated reconstruction of the biotic and abiotic environments in the drainage basin.

Effects of meteorological factors on the composition of selected fungal spores in the air.

The aim of the study was to determine functional relationships between composition of air spora and meteorological factors, using multivariate statistical technique: canonical correspondence analysis (CCA). Analyses were conducted for the data collected during the 4 year (2007–2010) and, in order to show the dynamics of such relationships, for each year separately. The CCA results indicated that all statistically significant variables accounted for 15.3 % of the total variance in the spore data in the 4 years. The largest amount of the total variance was explained in this period by the mean air temperature (9.2 %). The meteorological factors impacted spore composition differently in different years, when analysis was done for each year separately. The highest values of the total variance in the spore data, explained by the statistically significant variables, were found in 2010 (32.3 %), with the highest contribution of mean air temperature (23.8 %). In that year, the above-mentioned parameter had the lowest value in comparison to other years. Canonical correspondence analysis provides not only a comprehensive assessment of the impact of meteorological factors on specific spore combinations in the air, but also informative graphical presentations of the results, illustrating the correlation between the occurrence of particular spore taxa and meteorological variables.

New marsileaceous fossils from the Late Cretaceous of South America and a reevaluation of Marsileaceaephyllum

Herein we report new macrofossils and associated microfossils representing the aquatic fern family Marsileaceae from the Campanian to Maastrichtian Canadon del Irupe locality, La Colonia Formation, Chubut Province, Argentina. The macrofossils include compound leaves, detached leaflets, and sporocarps. The venation of the leaflets is consistent with the diagnosis of Marsileaceaephyllum, which we argue is poorly defined. Consequently, the circumscription and diagnosis of Marsileaceaephyllum are emended in order to limit the taxon to include only leaves or rhizomes bearing leaves with four leaflets that most resemble those of Marsilea among extant genera of Marsileaceae. The Canadon del Irupe leaves and leaflets are assigned to the new genus Mirasolita, erected to encompass compound leaves bearing two petiolulate leaflets, each leaflet having a reniform lamina and reticulate venation. The architecture of Mirasolita leaves and leaflets is distinct from that of leaves of any of the living marsileaceous genera. The stalked sporocarps are assigned to the new genus Lugiomarsiglia. They are attributed to Marsileaceae because each has a sclerenchymatous wall surrounding circular bodies interpreted as sporangia. Associated megaspores are assigned to Molaspora lobata, a geographically widespread, primarily Late Cretaceous dispersed spore taxon. The co-occurrence of Molaspora lobata with an extinct marsileaceous leaf form fits a pattern wherein Cretaceous Regnellidium-like megaspores are associated with or found in situ within marsileaceous macrofossils that display a variety of morphologies.