Saccate Pollen Grains Research Articles

COMPOSITION AND OCCURRENCE OF THE GRANDISPORA MACULOSA ZONAL ASSEMBLAGE (MISSISSIPPIAN) IN THE SUBSURFACE OF THE CARNARVON BASIN AND THE COOLCALALAYA SUB-BASIN OF WESTERN AUSTRALIA, AND ITS GONDWANAN DISTRIBUTION

The Grandispora maculosa miospore assemblage – initially described in 1968 from Middle-Late Mississippian strata of New South Wales (eastern Australia) – is well represented in samples examined herein from 10 Western Australian subsurface sections located in the northern Perth Basin (Coolcalalaya Sub-basin) and, to its immediate north, in several sub-basins of the southern and northern sectors of the Carnarvon Basin. Of particular stratigraphic-correlative importance is the presence of the eponymous G. maculosa together with, inter alia, Reticulatisporites magnidictyus, Verrucosisporites quasigobbettii, V. gregatus, Apiculiretusispora tersa, Raistrickia accinta, R. radiosa, Foveosporites pellucidus , and Cordylosporites asperidictyus . Four species are newly described herein: Apiculatasporites spiculatus, Dibolisporites sejunctus, Raistrickia corymbiata, and Vallatisporites valentulus . Published accounts from elsewhere in Gondwana collectively signify the widespread dissemination of the G. maculosa palynoflora, particularly through northern and western regions of the supercontinent, thus affording an effective means of intra-Gondwanan stratal correlation. Limited absolute dating and stratigraphic-successional considerations across Gondwana indicate that the age of the G. maculosa Assemblage can be bracketed within the middle Visean-early Serpukhovian of the Middle-Late Mississippian. This age is supported by the complete absence of bilaterally symmetrical, non-striate, saccate pollen grains, produced by walchian conifers, which were introduced globally (including in Australia) and near-synchronously late in the Serpukhovian. Cryptogamic land plants (ferns, articulates, lycophytes) are the inferred source of the palynoflora.

Aerodynamic Characteristics of Saccate Pollen Grains

The pollen grains of several gymnosperm groups consist of a main body and one to three air-filled bladders, or sacci. Although sacci may serve a buoyancy function to orient the grain on the ovular pollination droplet in some taxa, sacci have also been shown to increase pollen volume while adding minimal mass, thus decreasing density and thereby increasing the aerodynamic efficiency of wind pollination. However, no published studies have quantitatively addressed the effects of grain geometry or surface ornamentation at the low Reynolds numbers that pollen grains demonstrate. The objectives of this study were to empirically investigate the effects of varying geometries and surface ornamentation on the aerodynamic properties of saccate pollen grains through the experimental determination of drag coefficients and shape factors. Structurally different grains of two extant conifers (Pinus and Falcatifolium) were studied, and using electron microscopy, mathematical modeling, and solid modeling, we created scaled-up physical models of the pollen types. Models were produced with and without sacci, as well as with and without surface texture on the main body. Sacci increased the shape factor, or resistance coefficient, in all pollen types studied, compared to the same types that had been modeled without sacci. The presence of surface ornamentation also decreased the drag coefficients for saccate pollen grains of Pinus. This study is the first to experimentally demonstrate the effect of surface texture on drag for any biological or nonbiological particle at low Reynolds numbers. This study also provides additional empirical evidence for the aerodynamic role of sacci, supporting their adaptive significance for anemophily.

Fossilized pollination droplet in a new seed genus from the Middle Triassic of Nidpur, India

The present article reports a fossilized pollination droplet at the micropylar orifice in a compressed seed Gopadispermum papillatus gen. et sp. nov. from the Middle Triassic beds of Nidpur, Madhya Pradesh, India. The shapeless droplet forming a convexity above the micropylar orifice is comprised of a resinous crystalline substance. Entrapped within the droplet are a few saccate pollen grains. The seeds are small, oblong to widely elliptical in shape, about 3 mm long and generally 2 mm broad. The micropylar end shows a short straight beak-like micropyle often extended beyond a persistently adhering wrinkled tissue lying outside the seed coat. The seed is composed of four membranes excluding the adherent tissue. They are the outer and inner cuticles of integument, the nucellar cuticle distally modified to form a dark collar-like pollen chamber and the innermost megaspore membrane. Cuticles of the tissue adhering to seed coat are different from seed coat cuticles. The pollen grains inside the pollen chamber...

Flotation preferentially selects saccate pollen during conifer pollination

• Among many species of living conifers the presence of pollen with air bladders (saccate pollen) is strongly associated with downward-facing ovules and the production of pollination drops. This combination of features enables saccate pollen grains captured in the pollination drop to float upwards into the ovule. Despite the importance of this mechanism in understanding reproduction in living conifers and in extinct seed plants with similar morphologies, experiments designed to test its effectiveness have yielded equivocal results. • In vitro and in vivo pollination experiments using saccate and nonsaccate pollen were performed using modeled ovules and two Pinus species during their natural pollination period. • Buoyant saccate pollen readily floated through aqueous droplets, separating these grains from nonbuoyant pollen and spores. Ovules that received saccate pollen, nonsaccate pollen or a mixture of both all showed larger amounts and higher proportions of saccate pollen inside ovules after drop secretion. • These results demonstrate that flotation is an effective mechanism of pollen capture and transport in gymnosperms, and suggest that the prevalence of saccate grains and downward-facing ovules in the evolutionary history of seed plants is a result of the widespread use of this mechanism.

Palinologia da Formação Piauí, Pensilvaniano da bacia do Parnaíba: biocronoestratigrafia de intervalo selecionado do poço 1-UN-09-Pi (Caxias, MA, Brasil)

PALYNOLOGY OF THE PIAUI FORMATION, PENNSYLVANIAN OF THE PARNAIBA BASIN: BIOCHRONOSTRATIGRAPHY OF A SELECTED INTERVAL WITHIN THE BOREHOLE 1-UN-09-PI (CAXIAS, MA, BRAZIL). The Pennsylvanian Piaui Formation, basal unit of the Balsas Group, is constituted by sandstones, shales and limestones, with scarce palynological records. This unit is interpreted mainly as continental to shorefacies in origin. This paper presents the palynostratigraphical results obtained for the interval between 110.60 m and 178.12 m of the borehole 1-UN-09-PI, located in Caxias, Maranhao State, which corresponds to the upper microclastic portion of this unit in the borehole. Most part of the twelve core samples studied furnished palynological associations. Among the continental palynomorphs, saccate pollen grains are dominant, mainly taeniate bisaccate and non tateniate monosaccate species. Taking into account that there is no available palynological zonation of the Pennsylvanian-Permian interval of this basin, the scheme erected for the neighboring Amazonas Basin was used for comparisons. The records of certain species from spores and pollen, such as Raistrickia cephalata Playford & Dino, Protohaploxypinus amplus (Balme & Hennelly) Hart, Lunatisporites onerosus Playford & Dino, Verticipollenites sp., Striatopodocarpites sp. and Meristocorpus explicatus Playford & Dino, allow the correlation of most of the studied interval with the Raistrickia cephalata Zone, which was recognized for the middle portion of the Nova Olinda Formation (Amazonas Basin), regarded as Pennsylvanian (Moscovian) in age.

Earliest Zanclean age for the Colombacci and uppermost Di Tetto formations of the “latest Messinian” northern Apennines: New palaeoenvironmental data from the Maccarone section (Marche Province, Italy)

The occurrence of planktonic foraminifers in the latest Messinian deposits (uppermost Di Tetto Formation and Colombacci Formation) of the Marche Province (Apennine foredeep, Italy) has stimulated a debate since the 1970s. An earlier palynological study of the entire Maccarone section revealed a pronounced, and a sudden increasing frequency of saccate pollen grains which indicates more distal conditions, and thus a transgression. At first attributed to tectonic activity, this transgression is now interpreted as representing the Zanclean marine transgression after the discovery of Ceratolithus acutus, the calcareous nannofossil marker of the earliest Zanclean in the Mediterranean Sea. Evidence from marine dinoflagellate cysts and planktonic foraminifers supports this result. The Colombacci Formation and uppermost part of the Di Tetto Formation (i.e. the entire p–ev2 stratigraphic unit) belong to the earliest Zanclean. The so-called Lago Mare no longer has a regional chronostratigraphic sense, and should be understood as the invasion of Paratethyan organisms via surface waters owing to a connection at high sea-level between the Aegean Sea and the Eastern Paratethys (Dacic Basin). A new robust environmental reconstruction of the northern Apennine foredeep is proposed, which respectively considers the effects of tectonics and Mediterranean eustasy.

Intraspecific Variation of Taeniate Bisaccate Pollen Within Permian Glossopterid Sporangia, from the Prince Charles Mountains, Antarctica

Permineralized sporangia from Late Permian sediments of the Amery Group in the Prince Charles Mountains, East Antarctica, are assigned to Arberiella sp. cf. A. africana Pant and Nautiyal. These sporangia contain between 2000 and 3000 taeniate, saccate pollen grains that are predominantly haploxylonoid bisaccate and referable to the palynotaxon Protohaploxypinus limpidus (Balme and Hennelly) Balme and Playford. However, the sporangia also contain greater than 4% of diploxylonoid bisaccate forms comparable to Striatopodocarpidites cancellatus (Balme and Hennelly) Hart 1963, together with sporadic monosaccate and trisaccate grains that, if found dispersed, would be assigned to several different pollen form genera. Morphometric analysis of in situ bisaccate pollen grains and taeniate bisaccate pollen in the dispersed palynoflora indicates that in situ grains occupy only the smaller end of the total size range. The tendency for in situ grains to cluster into two different size groups may reflect differential predispersal expansion of the corpus. The in situ pollen grains are variable in most qualitative and quantitative features used for taxonomic discrimination of dispersed taeniate bisaccate pollen, and this may lead to unreliable estimates of Late Permian floristic diversity if an overly restrictive species delimitation scheme is used.

Earliest pollen-dominated microfloras from the early late carboniferous of the Tian Shan Mountains, NW China: their significance for the origin of conifers and palaeophytogeography

The earliest known pollen-dominated palynomorph assemblages, which occur in the early Bashkirian and Moscovian (the early Late Carboniferous) strata of the Tian Shan Mountains in northwestern China, are described and illustrated. The ages of these assemblages are well-documented from co-occurring marine fossils, such as the fusulinid Millerella and the ammonoid Reticuloceras. More than half of the palynomorphs found are saccate pollen grains, monosaccate, or bisaccate with non-striate predominating over less frequent striate forms. The early Late Carboniferous pollen-dominated assemblages from the Tian Shan area, along with similar previously reported assemblages from the Urals, Yukon Territory and Ellesmere Island, Canada, suggest that a distint early occurrence of conifers and suggest that they might have evolved in xeric, seasonal environments before the Bashkirian.

Chytrid-Like Fossils of Pennsylvanian Age

Chytrid-like fungal sporangia are described occurring in saccate pollen grains of Pennsylvanian age. Both endo- and epibiotic sporangia are present, and may exhibit discharge papillae and a coarse rhizomycelium. Sporangial features, choice of substrate, and the presence of a light refractile body in presumed zoospores suggest relationships with the Chytridiales.

In situ pollen from gymnospermous cones from the Upper Permian of the Italian Alps — A preliminary account

Saccate pollen grains have been found in situ in gymnospermous male cones from Late Permian deposits of the Dolomites and the Vicentinian alps (northern Italy). Bisaccates assignable to the dispersed form-taxa Lunatisporites spp., Jugasporites delasaucei and Lueckisporites virkkiae originate from structurally similar conferalean cones. The monosaccate pollen described as Nuskoisporites dulhuntyi has also been isolated from coniferalean cones but the affinity of a cone yielding bisaccates assignable to Gigantosporites hallstattensis is not yet clear. The material studied confirms the view of a frequent intraspecific variability among the Late Permian coniferalean pollen grains found in dispersed assemblages in western Europe.

IDANOTHEKION GEN. N., A SYNANGIATE POLLEN ORGAN WITH SACCATE POLLEN FROM THE MIDDLE PENNSYLVANIAN OF ILLINOIS

Idanothekion glandulosum gen. et sp. n. is a synangiate pollen organ represented by approximately 30 specimens contained in coal balls from the middle Pennsylvanian of Illinois. Each synangium is composed of seven to nine elongate sporangia that are fused laterally for approximately four‐fifths of their length, and are radially arranged about, and fused to, a short central column; the central column is restricted to the proximal one‐third of the synangium. Distal to the column the sporangia surround a hollow central area. Dehiscence occurred by means of a longitudinal slit along the mid‐line of the inner face of each sporangium. The outer walls of the sporangia have a complex histology involving an external epidermis, a middle presumably glandular layer containing scattered enlarged cells, and an inner layer made up of thin‐walled parenchyma. Vascular tissue is present in the central column and outer walls of the sporangia. Each sporangium has a prominent, attenuate, multicellular tip. Large numbers of saccate pollen grains similar to those found in numerous fossil and extant coniferophytes as well as some Mesozoic pter‐idosperms were produced in each sporangium. Idanolhekion resembles some synangia assignable to Paleozoic members of the Marattiales; however, the new genus compares most closely with pollen organs believed to have been produced by members of the Pteridospermales. It seems most likely that Idanothekion represents the pollen organ of some member of the Lyginopteridaceae that produced pollen of a type which up to now has not been known from Paleozoic seed ferns.

A Miospore assemblage from the Liassic coal of Cresten, Austria

A dispersed miospore assemblage comprising 10 miospore genera and 14 species, of which 4 species are new, has been described from the Liassic coal of Cresten, Austria. The mioflora is qualitatively impoverished and peculiar by lacking the nonstriated saccate pollen grains which are so well associated with other miofloras of the comparable age. A brief comparison of this assemblage has been given with comparable miofloras. From this, it appears that the present assemblage may be an incomplete representation of the whole mioflora of its time.

The Saccate Pollen Grains of Pinaceae Mainly of California

The Saccate Pollen Grains of Pinaceae Mainly of California

Saccate pollen grains from the Lower Triassic of Hallstatt, Austria

A dispersed miospore assemblage consisting of 8 miospore genera and 19 species is described from a shale of Werfen, Hallstatt, Austria. 6 species are new. Saccate pollen grains, the only constituents of this miofiora are abundantly represented. The predominant occurrence of Luekisporites (Pot. & Kl.) Potonie and Gigantosporites Klaus appears to be very characteristic for this assemblage. A brief comparison of the present miofiora with comparable ones has been given.