Mariner Elements Research Articles

A preliminary study on the intensity of cold wave storm surges of Laizhou Bay

Dike failure and marine losses are quite prominent in Laizhou Bay during the period of cold wave storm surges because of its open coastline to the north and flat topography. In order to evaluate the intensity of cold wave storm surge, the hindcast of marine elements induced by cold waves in Laizhou Bay from 1985 to 2004 is conducted using a cold wave storm surge–wave coupled model and the joint return period of extreme water level, concomitant wave height, and concomitant wind speed are calculated. A new criterion of cold wave storm surge intensity based on such studies is developed. Considering the frequency of cold wave, this paper introduces a Poisson trivariate compound reconstruction model to calculate the joint return period, which is closer to the reality. By using the newly defined cold wave storm surge intensity, the ‘cold wave grade’ in meteorology can better describe the severity of cold wave storm surges and the warning level is well corresponding to different intensities of cold wave storm surges. Therefore, it provides a proper guidance to marine hydrological analysis, disaster prevention and marine structure design in Laizhou Bay.

Inventory of an essential marine element

Ocean Chemistry Sulfur is necessary for marine primary production and has a large impact on climate processes. Because it is difficult to detect accurately, the amount of dissolved organic sulfur in the ocean is poorly defined. Ksionzek et al. measured dissolved organic sulfur in the Atlantic to

Molecular Signatures of Biogeochemical Transformations in Dissolved Organic Matter from Ten World Rivers

Rivers carry large amounts of dissolved organic matter (DOM) to the oceans thereby connecting terrestrial and marine element cycles. Photo-degradation in conjunction with microbial turnover is considered a major pathway by which terrigenous DOM is decomposed. To reveal globally relevant patterns behind this process, we performed photo-degradation experiments and year-long bio-assays on DOM from ten of the largest world rivers that collectively account for more than one-third of the fresh water discharge to the global ocean. We furthermore tested the hypothesis that the terrigenous component in deep ocean DOM may be far higher than biomarker studies suggest, because of the selective photochemical destruction of characteristic biomolecules from vascular plants. DOM was molecularly characterized by a combination of non-targeted ultrahigh-resolution mass spectrometry and quantitative molecular tracer analyses. We show that the reactivity of DOM is globally related to broad catchment properties. Basins that are dominated by forest and grassland export more photo-degradable DOM than other rivers. Chromophoric compounds are mainly vascular plant-derived polyphenols, and partially carry a pyrogenic signature from vegetation fires. These forest and grassland dominated rivers lost up to 50% of dissolved organic carbon (DOC) during irradiation, and up to 85% of DOC was lost in total if subsequently bio-incubated for one year. Basins covered by cropland, on the other hand, export DOM with a higher proportion of photo-resistant and bio-available DOM which is enriched in nitrogen. In these rivers, 30% or less of DOC was photodegraded. Consistent with previous studies, we found that riverine DOM resembled marine DOM in its broad molecular composition after extensive degradation, mainly due to almost complete removal of aromatics. More detailed molecular fingerprinting analysis (based on the relative abundance of >4000 DOM molecular formulae), however, revealed clear differences between degraded riverine and deep-sea DOM (molecular Bray-Curtis dissimilarity of ~50%). None of our experimental treatments enhanced the molecular similarity between the rivers and the deep ocean. We conclude that terrigenous DOM retains a specific molecular signature during photo-degradation on much longer time scales than previously assumed and that substantial, thus far unknown, molecular transformations occur prior to downward convection into the deep oceanic basins.

Replacement names for botanical taxa involving algal genera

A cross-check of botanical names databases revealed the presence of 19 cases of homonymy which are hereby resolved by proposing replacement names. Most cases concern diatom genera (Bacillariophyta) names which are preoccupied by spermatophytes. While Loranthella nom. nov. (Spermatophyta, Loranthaceae) and Ochradiscus nom. nov. (Spermatophyta, Resedaceae) are proposed as new names for spermatophytes, new diatom names are proposed for genera that are currently placed in the families Amphipleuraceae, Coscinodiscaceae, Hemiaulaceae, Hemidiscaceae, Melosiraceae, Metascolioneidaceae nom. nov., Naviculaceae, Pyxillaceae, Stictodiscaceae and Surirellaceae. With one exception (i.e. Eileencoxia nom. nov.) all remaining diatom genera that are discussed in the present paper are marine and/or fossil elements. The particularities of each case are briefly discussed. A total of one hundred and three new combinations are proposed.

Mariner Transposons Contain a Silencer: Possible Role of the Polycomb Repressive Complex 2.

Transposable elements are driving forces for establishing genetic innovations such as transcriptional regulatory networks in eukaryotic genomes. Here, we describe a silencer situated in the last 300 bp of the Mos1 transposase open reading frame (ORF) which functions in vertebrate and arthropod cells. Functional silencers are also found at similar locations within three other animal mariner elements, i.e. IS630-Tc1-mariner (ITm) DD34D elements, Himar1, Hsmar1 and Mcmar1. These silencers are able to impact eukaryotic promoters monitoring strong, moderate or low expression as well as those of mariner elements located upstream of the transposase ORF. We report that the silencing involves at least two transcription factors (TFs) that are conserved within animal species, NFAT-5 and Alx1. These cooperatively act with YY1 to trigger the silencing activity. Four other housekeeping transcription factors (TFs), neuron restrictive silencer factor (NRSF), GAGA factor (GAF) and GTGT factor (GTF), were also found to have binding sites within mariner silencers but their impact in modulating the silencer activity remains to be further specified. Interestingly, an NRSF binding site was found to overlap a 30 bp motif coding a highly conserved PHxxYSPDLAPxD peptide in mariner transposases. We also present experimental evidence that silencing is mainly achieved by co-opting the host Polycomb Repressive Complex 2 pathway. However, we observe that when PRC2 is impaired another host silencing pathway potentially takes over to maintain weak silencer activity. Mariner silencers harbour features of Polycomb Response Elements, which are probably a way for mariner elements to self-repress their transcription and mobility in somatic and germinal cells when the required TFs are expressed. At the evolutionary scale, mariner elements, through their exaptation, might have been a source of silencers playing a role in the chromatin configuration in eukaryotic genomes.

Prediction Research of Red Tide Based on Improved FCM

Red tides are caused by the combination effects of many marine elements. The complexity of the marine ecosystem makes it hard to find the relationship between marine elements and red tides. The algorithm of fuzzyc-means (FCM) can get clear classification of things and expresses the fuzzy state among different things. Therefore, a prediction algorithm of red tide based on improved FCM is proposed. In order to overcome the defect of FCM which is overdependent on the initial cluster centers and the objective function, this paper gains the initial cluster centers through the principle of regional minimum data density and the minimum mean distance. The feature weighted cluster center is added to the objective function. Finally, the improved FCM algorithm is applied in the prediction research of red tide, and the results show that the improved FCM algorithm has good denoising ability and high accuracy in the prediction of red tides.

浅析卢梭对19世纪浪漫主义代表作家夏多布里昂和雨果的影响—以“海”的意象为例

作为法国启蒙运动领军人物的卢梭，其作品的文学价值长期被世人低估。卢梭不仅为18世纪启蒙运动作出巨大贡献，也给法国浪漫主义文学带来深刻影响。本文将以“海洋”元素为例，从卢梭作品中的“海”的意象出发，分析其浪漫主义色彩，并以浪漫主义文学先驱夏多布里昂，以及浪漫主义代表人物雨果为例，指出卢梭的“大海情结”对他们写作的影响和启发，以及他们在卢梭的影响下对法国“海洋话题”文学的继承与发展。 As an icon of the Enlightenment, Jean-Jacques Rousseau’s literary value is often understated. However, Rousseau not only contributed greatly to the 18th century Enlightenment, but influ-enced the Romanticism in France as well. This study will use the ocean featured in his works as an example, and analyse its effects on Romanticism. In addition, this study will present how the marine element in Rousseau’s works inspired well-known writers, such as Victor Hugo, and Francois-Rene de Chateaubriand, and how they thereafter inherited and developed French literature related to marine element.

VHICA, a New Method to Discriminate between Vertical and Horizontal Transposon Transfer: Application to the Mariner Family within Drosophila.

Transposable elements (TEs) are genomic repeated sequences that display complex evolutionary patterns. They are usually inherited vertically, but can occasionally be transmitted between sexually independent species, through so-called horizontal transposon transfers (HTTs). Recurrent HTTs are supposed to be essential in life cycle of TEs, which are otherwise destined for eventual decay. HTTs also impact the host genome evolution. However, the extent of HTTs in eukaryotes is largely unknown, due to the lack of efficient, statistically supported methods that can be applied to multiple species sequence data sets. Here, we developed a new automated method available as a R package “vhica” that discriminates whether a given TE family was vertically or horizontally transferred, and potentially infers donor and receptor species. The method is well suited for TE sequences extracted from complete genomes, and applicable to multiple TEs and species at the same time. We first validated our method using Drosophila TE families with well-known evolutionary histories, displaying both HTTs and vertical transmission. We then tested 26 different lineages of mariner elements recently characterized in 20 Drosophila genomes, and found HTTs in 24 of them. Furthermore, several independent HTT events could often be detected within the same mariner lineage. The VHICA (Vertical and Horizontal Inheritance Consistence Analysis) method thus appears as a valuable tool to analyze the evolutionary history of TEs across a large range of species.

Mariner transposons are sailing in the genome of the blood-sucking bug Rhodnius prolixus.

BackgroundThe Triatomine bug Rhodnius prolixus is a vector of Trypanosoma cruzi, which causes the Chagas disease in Latin America. R. prolixus can also transfer transposable elements horizontally across a wide range of species. We have taken advantage of the availability of the 700 Mbp complete genome sequence of R. prolixus to study the dynamics of invasion and persistence of transposable elements in this species.ResultsUsing both library-based and de novo methods of transposon detection, we found less than 6 % of transposable elements in the R. prolixus genome, a relatively low percentage compared to other insect genomes with a similar genome size. DNA transposons are surprisingly abundant and elements belonging to the mariner family are by far the most preponderant components of the mobile part of this genome with 11,015 mariner transposons that could be clustered in 89 groups (75 % of the mobilome). Our analysis allowed the detection of a new mariner clade in the R. prolixus genome, that we called nosferatis. We demonstrated that a large diversity of mariner elements invaded the genome and expanded successfully over time via three main processes. (i) several families experienced recent and massive expansion, for example an explosive burst of a single mariner family led to the generation of more than 8000 copies. These recent expansion events explain the unusual prevalence of mariner transposons in the R. prolixus genome. Other families expanded via older bursts of transposition demonstrating the long lasting permissibility of mariner transposons in the R. prolixus genome. (ii) Many non-autonomous families generated by internal deletions were also identified. Interestingly, two non autonomous families were generated by atypical recombinations (5' part replacement with 3' part). (iii) at least 10 cases of horizontal transfers were found, supporting the idea that host/vector relationships played a pivotal role in the transmission and subsequent persistence of transposable elements in this genome.ConclusionThese data provide a new insight into the evolution of transposons in the genomes of hematophagous insects and bring additional evidences that lateral exchanges of mobile genetics elements occur frequently in the R. prolixus genome.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-2060-9) contains supplementary material, which is available to authorized users.

Sounding the aquapelago

This article reviews the cultural-environmental context of the Leweton community’s liquid percussion practice and the production of the Vanuatu Women’s Water Music (henceforth VWWM) DVD with regard to the conceptual framework of the aquapelago. The latter has contended that human societies closely interacting with marine environments can be characterized as inhabiting an aquapelago by virtue of their activities creating an aquapelagic assemblage of terrestrial and marine elements. Following a summary discussion of aspects of the aquapelago, the article first considers the nature of the Leweton community’s liquid percussion practice in its traditional context and then addresses the contemporary developments that led to the production of the DVD, with particular regard to aspects of community livelihood and cultural transition. Drawing on these, the article posits the practices as quintessentially aquapelagic.

Precise repair of mPing excision sites is facilitated by target site duplication derived microhomology.

BackgroundA key difference between the Tourist and Stowaway families of miniature inverted repeat transposable elements (MITEs) is the manner in which their excision alters the genome. Upon excision, Stowaway-like MITEs and the associated Mariner elements usually leave behind a small duplication and short sequences from the end of the element. These small insertions or deletions known as “footprints” can potentially disrupt coding or regulatory sequences. In contrast, Tourist-like MITEs and the associated PIF/Pong/Harbinger elements generally excise precisely, returning the genome to its original state. The purpose of this study was to determine the mechanisms underlying these excision differences, including the role of the host DNA repair mechanisms.ResultsThe transposition of the Tourist-like element, mPing, and the Stowaway-like element, 14T32, were evaluated using yeast transposition assays. Assays performed in yeast strains lacking non-homologous end joining (NHEJ) enzymes indicated that the excision sites of both elements were primarily repaired by NHEJ. Altering the target site duplication (TSD) sequences that flank these elements reduced the transposition frequency. Using yeast strains with the ability to repair the excision site by homologous repair showed that some TSD changes disrupt excision of the element. Changing the ends of mPing to produce non-matching TSDs drastically reduced repair of the excision site and resulted in increased generation of footprints.ConclusionsTogether these results indicate that the difference in Tourist and Stowaway excision sites results from transposition mechanism characteristics. The TSDs of both elements play a role in element excision, but only the mPing TSDs actively participate in excision site repair. Our data suggests that Tourist-like elements excise with staggered cleavage of the TSDs, which provides microhomology that facilitates precise repair. This slight modification in the transposition mechanism results in more efficient repair of the double stranded break, and thus, may be less harmful to host genomes by disrupting fewer genes.Electronic supplementary materialThe online version of this article (doi:10.1186/s13100-015-0046-4) contains supplementary material, which is available to authorized users.

Evolutionary history of the Azteca-like mariner transposons and their host ants.

Three different complete mariner elements were found in the genome of the ant Tapinoma nigerrimum. One (Tnigmar-Mr) was interrupted by a 900-bp insertion that corresponded to an incomplete member of a fourth mariner element, called Azteca. In this work, we isolate and characterize full-length Tnigmar-Az elements in T. nigerrimum. The purpose of this study is to clarify the evolutionary history of Azteca elements and their hosts as well as the possible existence of horizontal transfer processes. For this, Azteca-like elements were also retrieved from the available sequences of various ant genomes, representing four different ant subfamilies: Dolichoderinae, Formicinae, Myrmicinae, and Ponerinae. The tree topology resulting for the Azteca-like elements bore very little resemblance to that of their respective hosts. The pervasive presence of Azteca-like elements in all ant genomes, together with the observation that extant copies are usually younger than the genomes that host them, could be explained either by lineage sorting or by recent horizontal transfer of active elements. However, the finding of closer genetic relationships between elements than between the ants that host them is consistent with the latter scenario. This is clearly observed in Sinvmar-Az, Tnigmar-Az, Acepmar-Az, and Cflomar-Az elements, suggesting the existence of horizontal transfer processes. On the contrary, some elements displayed more divergence than did the hosts harboring them. This may reflect either further horizontal transfer events or random lineage sorting.

Palynofacies patterns of the Devonian of the Parnaíba Basin, Brazil: Paleoenvironmental implications

To help describe the paleoenvironmental interpretation of one the most extensive marine Devonian successions in Brazil, palynofacies analyses were conducted on 46 samples from the Itaim (Pragian–Givetian), Pimenteira (Givetian–Frasnian) and Cabeças (Famennian) formations of the Parnaíba Basin in north–central Brazil. For the palynofacies analyses, kerogen categories were counted and subjected to cluster analyses. Five palynofacies associations were identified for three studied sections: PseudoAOM palynofacies, which consists of amorphous organic matter (AOM), pseudoamorphous and coenobial algae Quadrisporites; Transl/Nbiostr. palynofacies, which consists of translucent non-biostructured phytoclasts (well-preserved and degraded), cuticles (well-preserved and degraded), Spongiophyton and Botryococcus; Marine microplankton palynofacies, which consists of acritarchs, prasinophytes and translucent biostructured phytoclasts; Opaque palynofacies, which consists of opaque phytoclasts (equidimensional and lath shaped); and Sporomorphs palynofacies, which consists of zoomorphs (e.g., Chitinozoa) and sporomorphs (e.g., spores). The stratigraphic distribution of the five palynofacies associations reflects a continuous terrestrial influx throughout marine succession. At the Pragian–Emsian age, the woody material of Transl/Nbioestr. palynofacies prevails, suggesting a marine depositional paleoenvironment (presence of marine palynomorphs), but under deltaic influence due to the input of terrigenous material. An increasing trend of marine elements of Marine microplankton palynofacies is recorded for the Givetian, which suggests a progressive marine influence. However, during the Frasnian, the highest abundance of marine elements was recorded (Marine microplankton palynofacies). Moreover, a bloom of Maranhites spp. and prasinophytes (e.g., Tasmanites and Cymatiosphaera) was also recorded. The abrupt increase of marine palynomorphs in the Frasnian – here termed the “Maranhites Event” – has been recorded by other authors. Finally, in the Famennian, woody material was most abundant in Transl/Nbiostr. palynofacies and Sporomorphs palynofacies, which reflects a depositional trend that is strongly controlled by fluvial input into a shallow marine environment.

Mariner and the ITm Superfamily of Transposons.

The IS630-Tc1-mariner (ITm) family of transposons is one of the most widespread in nature. The phylogenetic distribution of its members shows that they do not persist for long in a given lineage, but rely on frequent horizontal transfer to new hosts. Although they are primarily selfish genomic-parasites, ITm transposons contribute to the evolution of their hosts because they generate variation and contribute protein domains and regulatory regions. Here we review the molecular mechanism of ITm transposition and its regulation. We focus mostly on the mariner elements, which are understood in the greatest detail owing to in vitro reconstitution and structural analysis. Nevertheless, the most important characteristics are probably shared across the grouping. Members of the ITm family are mobilized by a cut-and-paste mechanism and integrate at 5'-TA dinucleotide target sites. The elements encode a single transposase protein with an N-terminal DNA-binding domain and a C-terminal catalytic domain. The phosphoryl-transferase reactions during the DNA-strand breaking and joining reactions are performed by the two metal-ion mechanism. The metal ions are coordinated by three or four acidic amino acid residues located within an RNase H-like structural fold. Although all of the strand breaking and joining events at a given transposon end are performed by a single molecule of transposase, the reaction is coordinated by close communication between transpososome components. During transpososome assembly, transposase dimers compete for free transposon ends. This helps to protect the host by dampening an otherwise exponential increase in the rate of transposition as the copy number increases.

Phylogenetic diversity of sulphate-reducing Desulfovibrio associated with three South China Sea sponges.

Marine sponges harbour dense and diverse micro-organisms which includes sulphate-reducing bacteria (SRB). SRB are known to play a key role in the cycling of marine elements. However, in contrast to carbon and nitrogen cycling bacteria, SRB associated with marine sponges are largely unexplored. In this study, we explored the phylogenetic diversity of the SRB associated with three shallow-water sponges Arenosclera heroni, Dysidea arenaria and Astrosclera willeyana from the South China Sea by cloning-and-sequencing approach of SRB 16S rRNA gene with specific primers. The results showed that SRB associated with sponges mainly belonged to the genus Desulfovibrio in the class Deltaproteobacteria, i.e. a total of 14 Desulfovibrio-related OTUs were obtained from three sponges. The exception is identical OTUs from different sponges. Each sponge species harboured a unique set of Desulfovibrio OTUs, with only a few shared OTUs observed between species, suggesting different species of Desulfovibrio in different species of sponges. Meanwhile, some Desulfovibrio OTUs had a low similarity (<97%) with related sequences in GenBank and phylogenetic analysis indicating novel Desulfovibrio symbionts in sponges. The results contribute to the overall understanding of the phylogenetic diversity of SRB associated with sponges. To date, in contrast to carbon and nitrogen cycling bacteria, sulphate-reducing bacteria (SRB) associated with marine sponges are largely unexplored; little is known about the phylogenetic diversity of SRB in different species of sponges. In the present study, phylogenetically diverse sulphate-reducing Desulfovibrio communities, including potential sponge species-specific and novel SRB, were revealed to be associated with South China Sea demosponges by cloning-and-sequencing approach of SRB 16S rRNA gene.

Seasonal variations of coastal sedimentary trace metals cycling: Insight on the effect of manganese and iron (oxy)hydroxides, sulphide and organic matter

The combination of analysis, multivariate treatment (PCA) and chemical speciation calculation confirmed the control of Fe, Mn, sulphide and organic matter on metals dynamics in coastal sediments (0–5cm surface sediments and sediments cores) of Toulon Bay (NW Mediterranean). The temporal monitoring of the physic-chemical parameters as well as the dissolved/particulate minor (Fe/Mn) and trace elements (i.e. Ag, Cd, Co, Cu, Ni, Pb, Zn, …) concentrations in porewaters and sediments were assessed. Multivariate treatment revealed different behaviours for marine elements, terrestrial ones and contaminants. Seasonal variations of metals mobilization in porewater were observed, related to diagenesis activity. Element mobility was studied by selective extractions (ascorbate, acid and alkaline) on sediments. Thermodynamic simulation (PHREEQC) was performed to calculate the elemental dissolved speciation, the mineral saturation index and then to simulate the solid/liquid interaction through precipitation processes, studying the contrasted influence of dissolved organic matter and sulphide.

Characterization of mariner-like transposons of the mauritiana Subfamily in seven tree aphid species.

Mariner-like elements (MLEs) are Class II transposons present in all eukaryotic genomes in which MLEs have been searched for. This article reports the detection of MLEs in seven of the main fruit tree aphid species out of eight species studied. Deleted MLE sequences of 916-919bp were characterized, using the terminal-inverted repeats (TIRs) of mariner elements belonging to the mauritiana Subfamily as primers. All the sequences detected were deleted copies of full-length elements that included the 3'- and 5'-TIRs but displayed internal deletions affecting Mos1 activity. Networks based on the mtDNA cytochrome oxidase subunit-I (CO-I) and MLE sequences were incongruent, suggesting that mutations in transposon sequences had accumulated before speciation of tree aphid species occurred, and that they have been maintained in this species via vertical transmissions. This is the first evidence of the widespread occurrence of MLEs in aphids.

渤海湾春季水体光谱特征分析

基于2011年5月渤海湾典型站点的CTD观测数据和实测光谱数据分析了渤海湾的水体光谱特性。通过对比实测站位水体光谱和温度、盐度、密度、光合有效辐射和叶绿素浓度在水体中的分布状况，分析了海洋环境要素对水体光谱特性的影响。结果表明在510~620 nm光谱范围内，水体光谱辐射峰的高度由叶绿素浓度和光合有效辐射共同作用决定；在380~440 nm和705~800 nm波长范围水体光谱辐射峰的高度不仅受叶绿素浓度和光合有效辐射影响，还受其他环境要素影响。 Based on the CTD data and the measured spectral data of Bohai Bay in May, 2011, the water spec-tral characteristics of typical survey stations are analyzed. In this paper, the effects of marine en-vironmental elements on the spectral properties of the water body are analyzed by comparing water spectra and the distribution of temperature, salinity, density, photosynthetic active radiation and chlorophyll concentration of Bohai Bay. The results showed that the water body spectral radiation peak height is determined by the chlorophyll concentration and photosynthetic active radiation interaction in the 510 - 620 nm spectral range, but it is determined not only by the chlo-rophyll concentration and photosynthetic active radiation interaction, but also by other environ-mental factors in the 380 - 440 nm and 705 - 800 nm spectral range.

Heterochromatin and molecular characterization of DsmarMITE transposable element in the beetle Dichotomius schiffleri (Coleoptera: Scarabaeidae).

Cytogenetic studies of the Neotropical beetle genus Dichotomius (Scarabaeinae, Coleoptera) have shown dynamism for centromeric constitutive heterochromatin sequences. In the present work we studied the chromosomes and isolated repetitive sequences of Dichotomius schiffleri aiming to contribute to the understanding of coleopteran genome/chromosomal organization. Dichotomius schiffleri presented a conserved karyotype and heterochromatin distribution in comparison to other species of the genus with 2n=18, biarmed chromosomes, and pericentromeric C-positive blocks. Similarly to heterochromatin distributional patterns, the highly and moderately repetitive DNA fraction (C 0 t-1 DNA) was detected in pericentromeric areas, contrasting with the euchromatic mapping of an isolated TE (named DsmarMITE). After structural analyses, the DsmarMITE was classified as a non-autonomous element of the type miniature inverted-repeat transposable element (MITE) with terminal inverted repeats similar to Mariner elements of insects from different orders. The euchromatic distribution for DsmarMITE indicates that it does not play a part in the dynamics of constitutive heterochromatin sequences.

Spore assemblages from Upper Ordovician and lowermost Silurian sediments recovered from the Qusaiba-1 shallow core hole, Qasim region, central Saudi Arabia

Palynological analysis of a sequence of Upper Ordovician to lowermost Silurian sediments from the Qusaiba-1 core hole drilled in the Qasim region of central Saudi Arabia has yielded rich palynomorph assemblages. The palynomorphs are abundant, exceptionally well preserved and of low thermal maturity. The sequence represents marine sediments that encompass glacial deposits representing the end Ordovician (Hirnantian) glaciation. All of the palynomorph assemblages are dominated by marine elements (acritarchs, chitinozoans, scolecodonts), although land-derived spores are present in most assemblages and are often moderately abundant. There is clear evidence for reworking into some of the glacial deposits. The strata are tightly age constrained based on chitinozoan and acritarch biostratigraphy, in addition to graptolite biostratigraphy in the lowermost Silurian deposits. In this paper we systematically describe the spores and erect two new taxa: a cryptospore permanent tetrad Tetraplanarisporites laevigatus gen. et sp. nov. and a trilete spore Chelinospora prisca sp. nov. We discuss the biostratigraphical implications of these tightly age constrained spore assemblages and recognise the need to establish regional rather than global spore biostratigraphic schemes in the Ordovician–early Silurian. We also discuss the palaeobotanical implications of the spore assemblages. The presence of true trilete and hilate spores, some of which are ornamented, suggests that a clade of plants characterised by trilete/hilate spore production may have evolved earlier in Gondwana than elsewhere. We develop evolutionary and palaeophytogeographical hypotheses to explain this early occurrence of trilete and hilate spores.