The relationship between wall layers in dinoflagellate cysts was investigated with transmission electron microscopy. A simple method is described in which small cysts (<100 μm) were identified, isolated, and encapsulated in colored agarose. The individual cysts, now visible to the naked eye, were easy to track throughout the multi-step protocol. The routine TEM protocol for biological material was modified and simplified for dinoflagellate cysts, and is described in detail. This method ensures that all samples can be retained, an important consideration when working with rare or unique specimens. Specimens of Hystrichosphaeropsis Deflandre 1935 were orientated for sectioning relative to the natural plane of settlement of the cyst. Serial sections demonstrated that the relationship between the endophragm and periphragm is complex and irregular. Interpretation of micrographs and some common misinterpretations of artifacts are illustrated and discussed. The protocol is presented in detail and illustrated so that an inexperienced person, with the assistance of an electron microscopy unit, could successfully carry out the procedure. The technique has been used with minor adaptations to prepare a range of biological materials and palynomorph specimens for transmission electron microscopy.

Five new species of angiosperm pollen described from three localities in south-central Minnesota support a Cenomanian age for the Dakota Formation in this area. The new taxa, Cupliferoidaepollenites microscabratus, Dryadopollis minnesotensis, Nyssapollenites microfoveolata, Phimopollenites striolata, and Tricolpites labeonis, are described using both light and scanning electron microscopy, are easily recognizable, and are useful age indicator species. Because of the extent and transgressive nature of the Dakota Formation, age determination has been difficult. The new angiosperm pollen species described here may help to support age determination for the Dakota Formation over a broader geographic area.

Mississippian palynomorphs have been recovered from two successions of the Hannibal Shale in Missouri, U.S.A., which is the lowermost Carboniferous unit in the Mississippi Valley. The assemblages are dominated by acanthomorph acritarchs, with Micrhystridium stellatum being the principal species. The miospore assemblages are well-preserved and of low taxonomic diversity. They are dominated by long-ranging taxa that survived the latest Devonian mass extinction event. This assemblage closely resembles assemblages assigned to the Vallatisporites verrucosus-Retusotriletes incohatus (VI) Biozone of Western Europe. However the assemblage from the Mississippi Valley is relatively impoverished in comparison with European assemblages, and many key European zonal taxa are absent. Independent biostratigraphic correlation suggests that the Hannibal Shale is equivalent to the VI Biozone, the Cristatisporites hibernicus-Umbonatisporites distinctus (HD) Biozone, and possibly the lowermost part of the Spelaeotriletes balteatus-Rugospora polyptycha (BP) Biozone in Europe. This indicates the relatively condensed nature of the succession. Palynofacies analysis suggests a shelf to basin depositional environment for the Hannibal Shale; this is consistent with the paleogeographic location of this area during the Early Carboniferous.

During a detailed palynological study of the Milk River Formation in southern Alberta, Canada, a diverse and well-preserved assemblage of fungi including dispersed fungal spores and isolated fragments of microthyriaceous fruiting bodies were encountered and these are described. Based on ammonites, magnetostratigraphy, and palynomorphs, these strata are dated as latest Santonian to ?earliest Campanian (Late Cretaceous). This palynomorph assemblage represents one of the few documented occurrences of fungi of this age. Eighteen genera of fungal spores and three of microthyriaceous thyriothecia, comprising 45 species are recorded. The fungal assemblage is characterized by species of toruloid spores in chains, and cylindrical spores belonging to Dicellaesporites, Diporicellaesporites, Pluricellaesporites, Reduviasporonites, and Scolecosporites that mainly occur as saprophytes today. Helicoid spores belonging to Involutisporonites and Paragranatisporites are also represented and these generally occur in marshy and swamp-like conditions in an open environment mainly characterized by taxodiaceous forest. Microthyriaceous thyriothecia are represented by several specimens of Asterothyrites menonii, Phragmothyrites eocaenicus, and Trichothyrites sp. Although the assemblage consists of diverse fungal taxa, the dispersed spores and fruiting structures are not abundant, and only a few scattered specimens for many species were recorded. One reason for the low frequency may have been the unfavorable paleoenvironmental conditions which prevailed in these marine to nearshore terrestrial depositional settings. In spite of the low abundances, it is thought that documentation of the fungal occurrences in these strata will be of importance in future biostratigraphic and evolutionary studies of fungi. Many of the fungal species encountered are distinctive and probably restricted stratigraphically, being different from those recorded from the better documented Paleogene/Neogene assemblages, and may prove to be biostratigraphically useful.

Late Jurassic and Cretaceous palynomorph assemblages were recovered from the Macomia, Pemba, and Mifume formations from the onshore Rovuma Basin, northern Mozambique. These assemblages provide new evidence for an Aptian–Albian age for the Macomia Formation and the upper member of Pemba Formation, and confirm that these two stratigraphic units are coeval and laterally continuous. The lower member of the Pemba Formation contains Kimmeridgian–Tithonian palynomorphs, thus documenting for the first time the existence of Upper Jurassic strata north of Nacala in the onshore Rovuma Basin. The rich and diverse dinoflagellate cyst assemblage recovered from the Mifume Formation is of late Campanian age. This indicates an early Late Cretaceous hiatus between the sandstones of Pemba Formation, and the marls of the overlying Mifume Formation. The hiatus corresponds to a break in sedimentation prior to a rapid, global marine transgression, recognised in the Rovuma and Mozambique basins, during the middle Campanian, associated with the onset of Gondwana fragmentation. Earlier, Late Jurassic faulting produced local half-grabens filled with continental debris, for example the N'Gapa Formation of northern Mozambique.

Stable flies are an important pest of humans and livestock. Despite being blood feeders, they also visit flowers to eat nectar. Stable flies with pollen adhering to their exoskeletons were collected at the University of Florida Horse Teaching Unit and taken to the Paleobotany and Palynology Laboratory at the Florida Museum of Natural History for processing and identification. The pollen on all the specimens was identified as Carolina willow, Salix caroliniana Michaux 1803. This small shrub or tree is found throughout Florida in wetland areas. This study demonstrates the utility of pollen analysis in interdisciplinary studies.

The American Association of Stratigraphic Palynologists (AASP) is a relatively small international scientific organization dedicated to the furtherance of palynology. It is based in the U.S.A., but has a global membership. This contribution is a companion paper to a work on the early history (1967–1970) of the organization. The Association was born as a direct result of the rapid expansion of stratigraphic palynology in the oil industry, but then and now it has embraced all applications of organic microfossils and their modern counterparts. Following the inaugural meeting AASP had a membership of around 40; it now stands at just over 500. The maximum membership was approximately 1000 in 1987. AASP collaborates with other scientific bodies and has an extensive range of publications. The Association runs a comprehensive and widely-perused website, organises annual meetings, and gives several types of awards to deserving professional and student palynologists. The most ambitious project of the Association was the establishment of The AASP Center for Excellence in Palynology (CENEX) at Louisiana State University. For a small independent society, AASP has achieved much in its short history and has attained its stated intentions of promoting the science of palynology beyond its expectations.

The palynology of the Upper Cretaceous to Neogene non-marine succession in the Melut Basin, southeast Sudan was investigated. The palynomorphs are overwhelmingly of terrestrial origin, but rare brackish water dinoflagellate cysts and scolecodonts were encountered from the Lower Miocene and Oligocene-Miocene. Mangrove pollen, which is common in coeval West African coastal basins, is rare and inconsistent. Examples are Spinizonocolpites (Nypa) from the Campanian-Maastrichtian to Eocene and Rhizophoraceae (Zonocostites ramonae) from the Neogene. Based on the stratigraphic distribution of selected pollen and spores from four exploration wells, eight informal palynozones from the Campanian to the Neogene are proposed. The zones, in stratigraphically ascending order, are as follows: Assemblage Zone I, Campanian (lower Melut Formation); Assemblage Zone II, Campanian-Maastrichtian (middle Melut Formation); Assemblage Zone III, Maastrichtian (upper Melut Formation); Assemblage Zone IV, Paleocene (Yale Formation); Assemblage Zone V, Eocene (upper Yale and Adar formations); Assemblage Zone VI, Oligocene-Early Miocene (Jimidi and lower Miadol formations); Assemblage Zone VII, Early Miocene (uppermost Miadol and lowermost Daga formations); and Assemblage Zone VIII, Late Miocene-Pliocene (Daga Formation). The ages are based on stratigraphic positions and a series of first downhole appearances of key species such as Foveotricolpites cf. giganteus (Zone I), Auriculiidites reticulatus (Zone II), Ariadnaesporites spinosus (Zone III), Periretisyncolpites giganteus (Zone IV), Retistephanocolpites williamsii (Zone V), Cricotriporites camerounensis (Zone VI), Perfotricolpites digitatus (Zone VII), and Peregrinipollis nigericus (Zone VIII).

Palynofacies investigations indicated differences between the Late Cretaceous and Paleogene-Neogene paleoenvironments of the sections studied. The coexistence of structured organic palynodebris with pteridophyte spores, including those of water ferns (Ariadnaesporites), in the Upper Cretaceous strata suggests swampy conditions within a predominantly fluvial setting. The frequent occurrence of Palmae pollen indicates warm, humid conditions during the Late Cretaceous, although seasonal or hinterland aridity is suggested because of the occurrence of ephedroid pollen. Late Paleogene and Neogene assemblages are characterized by amorphous organic matter, fern spores, freshwater algae, and Gramineae pollen. Deposition in lacustrine habitats under warm, humid conditions is inferred. The occurrence of Gramineae pollen, mainly in the Neogene, indicates the development of grassy areas in a seasonally dry climate. A short marine incursion may have taken place during the Oligocene-Miocene, due to the rare occurrence of brackish water dinoflagellate cysts and scolecodonts.

Four new dinoflagellate cyst species from the Lower and Middle Miocene strata of the Porcupine Basin, offshore southwest Ireland, are formally described. Batiacasphaera edwardsiae sp. nov. was previously described under open nomenclature from the Miocene of the adjacent Rockall Plateau. Lejeunecysta challengerensis sp. nov. is recorded sporadically from the Burdigalian and Serravallian. Selenopemphix porcupensis sp. nov. and Trinovantedinium henrietii sp. nov. are large-sized dinoflagellate cysts with maximum dimensions of approximately 100 μm. Selenopemphix porcupensis sp. nov. is recorded in the uppermost Burdigalian and Langhian, and Trinovantedinium henrietii sp. nov. is present in the Langhian and lowermost Serravallian. Batiacasphaera edwardsiae sp. nov. is possibly biostratigraphically significant for the Middle Miocene.

The morphology and ultrastructure of megaspores, microspores, and massulae of Salvinia Séguier 1785 species from Argentina, Bolivia, southern Brazil, Chile, Paraguay, and Uruguay have been analyzed. The analyses were performed using light microscopy, stereo microscopy, scanning electron microscopy, and transmission electron microscopy. The taxa studied were Salvinia auriculata Aublet 1775, Salvinia biloba Raddi 1825, and Salvinia minima Baker 1886. The spores of Salvinia biloba are described and illustrated here for the first time. The spores of Salvinia adnata Desvaux 1827 were not described here because all the specimens analyzed had megasporangia and microsporangia which had not developed, or were aborted. The megaspores in all the species analyzed are trilete, 224–402 μm in polar diameter and 179–378 μm in equatorial diameter, with a circular outline, an irregular margin in polar view, and are ovoid in equatorial view. The surface is ridged and perforated and the sporoderm in cross section comprises a compact, two-layered exospore and a thick lacunose epispore which is projected proximally. The apertural area has unique characteristics in each species. The microspores are enclosed in spheroidal to elliptical massulae 145–240 μm in diameter. The individual microspores are trilete, regulate, 15–36 μm in diameter, and spheroidal. In cross section, the exospore is two-layered. Both types of spores produced by the species analyzed exhibit little interspecific and intraspecific variability. Differences in general shape and proximal characteristics were found in megaspores at the species level. According to these, and previous, results Salvinia is a genus with stable palynological characteristics, all of them related to its adaptation to the aquatic environment.

The late Early to Mid Permian palynomorph biozones OSPZ5 and OSPZ6 for the Arabian Peninsula sporadically contain diverse and well-preserved pollen and spore assemblages. These are described here for the first time, concentrating on taxa used in the recognition of biozones. Some of these forms were previously assigned to informal morphotypes. The new spore species Indotriradites ater, Indotriradites mundus, Kendosporites robustus, and the new pollen species Kingiacolpites subsaccatus and Tiwariasporis? granulatus are described and illustrated. These distinctive palynomorphs may be useful in future biostratigraphic studies. For example, the first uphole occurrences of Indotriradites mundus and Tiwariasporis? granulatus are close to the base of OSPZ6. Indotriradites ater and Kingiacolpites subsaccatus have relatively narrow ranges within OSPZ5. Hamiapollenites dettmannae and Hamiapollenites karrooensis are common in the lower part of OSPZ5.

Lignites from the Red Hills Mine in Mississippi, U.S.A. contain pollen and spores derived from paratropical swamp vegetation on the U.S. Gulf Coast during the Late Paleocene. Most previous studies of the Gulf Coast sporomorph record have been limited to a restricted taxonomic group, or merely those taxa that are relevant to biostratigraphy, meaning that the true sporomorph diversity may be higher than previously appreciated. Eight samples were collected for palynological analysis from the Red Hills Lignite Mine in Ackerman, Mississippi. All the taxa observed during counting (a minimum of 300 grains per sample) were included in the sample count. Rarefaction, relative abundance distributions, and non-metric multidimensional scaling were used to analyze floral composition, richness, and evenness. The lignite samples are heterogeneous in terms of composition and relative abundances, indicating patchiness in the swamp communities. Clay horizons representing temporary marine incursions contain significantly higher proportions of bisaccate pollen, which may have originated a considerable distance inland from the swamps. These samples therefore represent a much larger source area (regional to sub-continental), compared to the local signal contained in the lignite samples. Richness in the Red Hills Mine assemblage is higher than has previously been recorded for the Late Paleocene of the eastern Gulf Coast. This, combined with the recognition of 23 previously undescribed taxa, suggests that a detailed reappraisal of the Gulf Coast Paleocene sporomorph record is needed to improve understanding of the evolution of the North American vegetation type.

A new acanthomorph acritarch genus, Auritusphaera, is erected to accommodate a distinctive form whose processes form a pseudo-reticulum on the surface of a spherical vesicle. The genus is present in, and restricted to, the Upper Shale Member of the Nolichucky Shale in eastern Tennessee, U.S.A., where it is found in two cores drilled in the grounds of the Oak Ridge National Laboratory. The Upper Shale Member corresponds to the upper part of the Cedaria–Crepicephalus biozone and the lower part of the Aphelaspis biozone, and is Late Cambrian in age. The distinctive morphology of this acritarch may render it a potential marker for the Upper Cambrian Marjuman/Steptoean Stage boundary.

Palynology is the main method of correlating the subsurface glaciogenic Al Khlata Formation (Pennsylvanian to Lower Permian) of Oman due to the extreme lateral variability of facies and poor seismic resolution. The chief operating company in Oman, Petroleum Development Oman (PDO), has developed a robust in-house palynozonation during almost 40 years of exploration and production based on thousands of samples and hundreds of well sections. In this paper, the formal definitions of the biozones are published and the biozones are correlated in detail with faunally-calibrated palynomorph biozones in Western Australia. This allows correlation to the standard Russian stages. Seven biozones are distinguished. The oldest two subdivisions, biozones 2159A and 2159B, of probable Late Pennsylvanian age, are characterized by low diversity assemblages of Punctatisporites and monosaccate pollen. Biozone 2159A has a lower proportion of monosaccate pollen than Biozone 2159B. Biozone 2165A, of probable Asselian age, is characterized by common cingulicamerate spores and the Microbaculispora Group. Biozone 2165B contains common Horriditriletes Group, and is likely to be Asselian–Sakmarian in age. The Biozone 2141A is characterized by common taeniate and non-taeniate bisaccate pollen and Cycadopites cymbatus, particularly toward the top. The succeeding Biozone 2141B is recognized by common Microbaculispora Group and Cycadopites cymbatus. Biozones 2141A to 2141C are believed to be Sakmarian in age. The youngest unit, Biozone 2141C, is characterized by the Microbaculispora and Horriditriletes groups, with the former being more abundant. This seven-fold subdivision is a significant improvement on previous palynozonations of the Al Khlata Formation, which only allowed three- or four-fold subdivisions. However, there still remain considerable uncertainties in dating the lowermost biozones, 2159A and 2159B. Improvements in the dating of the Al Khlata Formation are most likely to come from palynological correlations with radiometrically- or faunally-dated successions in South America, eastern Australia, and southern Africa.

Based on the lithology of the Izucar de Matamoros (IzM) sections, and the occurrence of index taxa such as Armeria, Cicatricosisporites dorogensis, Corsinipollenites, Eucommia, Momipites coryloides, Momipites tenuipolus, Mutisiapollis, and Ranuculacidites operculatus, a correlation between the IzM sections and the Cuayuca Formation stratotypes is proposed. The IzM sections are Late Eocene–Early Oligocene, and they are part of the evaporitic member (Mcy) of the Cuayuca Formation. These new data are consistent with the paleoenvironmental interpretations proposed for the formation. It was probably deposited under local xeric conditions in a semiarid climate that allowed the development of grassland (Gramineae with Amaranthaceae–Chenopodiaceae and Ephedra) and a thorn shrub community with Acacia, other Leguminosae, Linum, and Plumbaginaceae. The neighboring communities were probably tropical deciduous forests, low tropical deciduous forest, thorn forest, and chaparral. There were also regional temperate vegetations such as a Picea–Pinus forest, and a cloud forest community. Using parsimony analysis of endemicity, a biogeographic method, a palynofloristic relationship between the Cuayuca Formation and the Pie de Vaca Formation (Late Eocene–Early Oligocene) is proposed. Both formations are within the Balsas Group, and are correlated with San Gregorio Formation (Oligocene) of southern Baja California.