Biotic Association Research Articles

THE ASSOCIATION OF BENTHIC MACROBIOTA OF THE LATE EDIACARAN OF PODILLIA IN THE DEPOSITS OF THE MOHYLIV-PODILSKYI GROUP IN THE QUARRY NEAR THE DNIESTER HPP

The maximum level of Ediacaran-type biota diversity in the Volyn-Podilskyi sedimentation basin existed in the time interval that corresponds to the Lomoziv and Yampil Members of the Mohyliv Formation. Studies of the isotopic age showed that this period ended 557 million years ago. Environmental conditions that prevented the existence of classical Ediacaran biota prevailed during the accumulation of the Lyadova Member. A less numerous biotic association of the transitional type with individual representatives of the Ediacara-type association is observed in the deposits of the Bernashivka Member. Paleoecological conditions in the sedimentation basin were reconstructed on the basis of the study of the section in the quarry near the Dniester HPP. More than a thousand specimens of fossils of soft-bodied organisms and tracefossils were collected there. More than three dozen species were discovered in Podilla for the first time. The study of a significant number of new species continues. It was established that the biotic association of the Mohyliv Formation was dominated by problematic frondomorphic and spherical organisms, which sometimes reached significant sizes.The existence of probable ancestors of several groups of biota of the Phanerozoic type:Cnidaria, Porifera, Lophotrochozoa, Mollusca and Metaphita were found in the Late Ediacaran shallow water ecosystem. Thefossil remains of the earliest probable members of the phylum Chordata of the subphylum Tunicata are collected here. These arethe most likely ancestors of vertebrates according to data from several research groups. It was established that some Ediacaran organisms used life strategies typical for representatives of later biota: combinations of different types of reproduction, activeresponse to external environmental factors, etc. New methods of fossil research were proposed and important results were obtained in the process of their use. It was established that quite sharp changes in the taxonomic composition of biotic associations in the section of sediments are caused by facies conditions and evolutionary processes. This makes it possible to use the fossilized remains of the Ediacaran biota for the needs of biostratigraphy and correlation with the same age deposits in other regions.

<strong><em>Calamagrostis nandadeviensis</em> (Poaceae, Agrostidinae), a new grass species from India</strong>

Calamagrostis nandadeviensis, a new species of Calamagrostis (Poaceae: Agrostidinae) from India (Valley of Flowers National Park of Uttarakhand and Rohtang Pass of Himachal Pradesh) is described and illustrated. C. nandadeviensis is morphologically allied to C. lahulensis and C. scabrescens but differs from them in having deeply bifid palea and fused lodicules. Data on distribution, habitat, biotic association are presented along with an illustration and comparative photo plate.

First record of Ubaghsicystis (Eocrinoidea - Echinodermata) from the Cambrian (Miaolingian, Wuliuan) of Sonora, Mexico: Biostratigraphical and paleoecological considerations

Introduction: The present work constitutes the first record of Ubaghsicystis Gil-Cid & Domínguez-Alonso (Echinodermata-Eocrinoidea) in the El Gavilán Formation, exposed in the El Sahuaral Hill, a new Cambrian locality of central Sonora, Mexico. The El Gavilán Formation is a sedimentary sequence mainly made up of shale interbedded with limestone, with abundant invertebrate fossils, deposited in an open shelf marine environment. Objective: The main objective of this research work is to describe the species Ubaghsicystis cf. U. segurae for the first time in Mexico, in addition to biostratigraphic and paleoecological considerations. Methods: A composite stratigraphic section of the El Gavilán Fm. was measured in central Sonora, where samples corresponding to eocrinods were collected, the material was examined in the Microscope Leica MZ10. Results: The biotic association is composed of reticulosan sponges, chancelloriids (Chancelloria eros, Allonnia tintinopsis, Archiasterella sp.), hyolithids, brachiopods, trilobites (Quadragnostus depressa, Peronopsis sp., Tonkinella valida, and Elrathina sp.), and echinoderms (Ubaghsicystis cf. U. segurae). Regarding the age, the trilobite association establishes a chronostratigraphic position from the middle Cambrian (Miaolingian, Wuliuan), Altiocculus Subzone, Ehmaniella Zone. The material studied is constituted by isolated echinoderm plates, which probably represent various cycles of theca plates assigned to Ubaghsicystis cf. U. segurae. The genus Ubaghsicystis has been scarcely recorded in a few Cambrian regions (e.g., Burgess Shale in Canada and Los Barrios de Luna in Spain), so that the information about this taxon is limited. Conclusions: The Cambrian succession of Sonora, where Ubaghsicystis occurred, was part of the border from the Laurentia craton during this period, located near the Paleoequator during this period, where ideal conditions for increasing diversity and abundance of species were developed, including echinoderms.

The last meal of an Eocene pollen-feeding fly

One of the most important trophic interactions today is that between insects and their floral hosts. This biotic association is believed to have been critical to the radiation of flowering plants and many pollinating insect lineages over the last 120 million years (Ma). Trophic interactions among fossil organisms are challenging to study, and most inferences are based on indirect evidence. Fossil records providing direct evidence for pollen feeding, i.e., fossil stomach and gut contents, are exceptionally rare.1,2 Such records have the potential to provide information on aspects of animal behavior and ecology as well as plant-animal interactions that are sometimes not yet recognized for their extant relatives. The dietary preferences of short-proboscid nemestrinids are unknown, and pollinivory has not been recorded for extant Nemestrinidae.3 We analyzed the contents of the conspicuously swollen abdomen of an ca. 47.5 Ma old nemestrinid fly of the genus Hirmoneura from Messel, Germany, with photogrammetry and state-of-the-art palynological methods. The fly fed on pollen from at least four plant families-Lythraceae, Vitaceae, Sapotaceae, and Oleaceae-and presumably pollinated flowers of two extant genera, Decodon and Parthenocissus. We interpret the feeding and foraging behavior of the fly, reconstruct its preferred habitat, and conclude about its pollination role and importance in paratropical environments. This represents the first evidence that short-proboscid nemestrinid flies fed, and possibly feed to this day, on pollen, demonstrating how fossils can provide vital information on the behavior of insects and their ecological relationships with plants.

Lake Ecosystem Robustness and Resilience Inferred from a Climate-Stressed Protistan Plankton Network.

Network analyses of biological communities allow for identifying potential consequences of climate change on the resilience of ecosystems and their robustness to resist stressors. Using DNA metabarcoding datasets from a three-year-sampling (73 samples), we constructed the protistan plankton co-occurrence network of Lake Zurich, a model lake ecosystem subjected to climate change. Despite several documentations of dramatic lake warming in Lake Zurich, our study provides an unprecedented perspective by linking changes in biotic association patterns to climate stress. Water temperature belonged to the strongest environmental parameters splitting the data into two distinct seasonal networks (October–April; May–September). The expected ecological niche of phytoplankton, weakened through nutrient depletion because of permanent thermal stratification and through parasitic fungi, was occupied by the cyanobacterium Planktothrix rubescens and mixotrophic nanoflagellates. Instead of phytoplankton, bacteria and nanoflagellates were the main prey organisms associated with key predators (ciliates), which contrasts traditional views of biological associations in lake plankton. In a species extinction scenario, the warm season network emerged as more vulnerable than the cold season network, indicating a time-lagged effect of warmer winter temperatures on the communities. We conclude that climate stressors compromise lake ecosystem robustness and resilience through species replacement, richness differences, and succession as indicated by key network properties.

Making Parasite-Host Associations Visible using Global Biotic Interactions

A wealth of information about how parasites interact with their hosts already exists in collections, scientific publications, specialized databases, and grey literature. The US National Science Foundation-funded Terrestrial Parasite Tracker Thematic Collection Network (TPT) project began in 2019 to help build a comprehensive picture of arthropod ectoparasites including the evolution of these parasite-host biotic associations, distributions, and the ecological interactions of disease vectors. TPT is a network of biodiversity collections whose data can assist scientists, educators, land managers, and policymakers to better understand the complex relationship between hosts and parasites including emergent properties that may explain the causes and frequency of human and wildlife pathogens. TPT member collections make their association information easier to access via Global Biotic Interactions (GloBI, Poelen et al. 2014), which is periodically archived through Zenodo to track progress in the TPT project. TPT leverages GloBI's ability to index biotic associations from specimen occurrence records that come from existing management systems (e.g., Arctos, Symbiota, EMu, Excel, MS Access) to avoid having to completely rework existing, or build new, cyber-infrastructures before collections can share data. TPT-affiliated collection managers use collection-specific translation tables to connect their verbatim (or original) terms used to describe associations (e.g., "ex", "found on", "host") to their interpreted, machine-readable terms in the OBO Relations Ontology (RO). These interpreted terms enable searches across previously siloed association record sets, while the original verbatim values remain accessible to help retain provenance and allow for interpretation improvements. TPT is an ambitious project, with the goal to database label data from over 1.2 million specimens of arthropod parasites of vertebrates coming from 22 collections across North America. In the first year of the project, the TPT collections created over 73,700 new records and 41,984 images. In addition, 17 TPT data providers and three other collaborators shared datasets that are now indexed by GloBI, visible on the TPT GloBI project page. These datasets came from collection specimen occurrence records and literature sources. Two TPT data archives that capture and preserve the changes in the data coming from TPT to GloBI were published through Zenodo (Poelen et al. 2020a, Poelen et al. 2020b). The archives document the changes in how data are shared by collections including the biotic association data format and quantity of data captured. The Poelen et al. 2020b report included all TPT collections and biotic interactions from Arctos collections in VertNet and the Symbiota Collection of Arthropods Network (SCAN). The total number of interactions included in this report was 376,671 records (500,000 interactions is the overall goal for TPT). In addition, close coordination with TPT collection data managers including many one-on-one conversations, a workshop, and a webinar (Sullivan et al. 2020) was conducted to help guide the data capture of biotic associations. GloBI is an effective tool to help integrate biotic association data coming from occurrence records into an openly accessible, global, linked view of existing species interaction records. The results gleaned from the TPT workshop and Zenodo data archives demonstrate that minimizing changes to existing workflows allow for custom interpretation of collection-specific interaction terms. In addition, including collection data managers in the development of the interaction term vocabularies is an important part of the process that may improve data sharing and the overall downstream data quality.

Fossil amber reveals springtails\u2019 longstanding dispersal by social insects

BackgroundDispersal is essential for terrestrial organisms living in disjunct habitats and constitutes a significant challenge for the evolution of wingless taxa. Springtails (Collembola), the sister-group of all insects (with Diplura), are reported since the Lower Devonian and are thought to have originally been subterranean. The order Symphypleona is reported since the early Cretaceous with genera distributed on every continent. This distribution implies an ability to disperse over oceans, however symphypleonan Collembola have never been reported in marine water contrary to other springtail orders. Despite being highly widespread, modern springtails are rarely reported in any kind of biotic association. Interestingly, the fossil record has provided occasional occurrences of Symphypleona attached by the antennae onto the bodies of larger arthropods.ResultsHere, we document the case of a ~ 16 Ma old fossil association: a winged termite and ant displaying not some, but 25 springtails attached or in close proximity to the body. The collembola exhibit rare features for fossils, reflecting their courtship and phoretic behaviours. By observing the modes of attachment of springtails on different arthropods, the sex representation and ratios in springtail antennal anatomies in new and previously reported cases, we infer a likely mechanism for dispersal in Symphypleona. By revealing hidden evidence of modern springtail associations with other invertebrates such as ants and termites, new compelling assemblages of fossil springtails, and the drastic increase of eusocial insects’ abundance during the Cenozoic (ants/termites comprising more than a third of insects in Miocene amber), we stress that attachment on winged castes of ants and termites may have been a mechanism for the worldwide dispersal of this significant springtail lineage. Moreover, by comparing the general constraints applying to the other wingless soil-dwelling arthropods known to disperse through phoresy, we suggest biases in the collection and observation of phoretic Symphypleona related to their reflexive detachment and infer that this behaviour continues today.ConclusionsThe specific case of tree resin entrapment represents the (so far) only condition uncovering the phoretic dispersal mechanism of springtails - one of the oldest terrestrial arthropod lineages living today.

Trilobite-based biostratigraphy (arthropoda-trilobita) and related faunas of the Cambrian from Sonora, Mexico

A biostratigraphic analysis based on trilobites of the main Cambrian outcrops from Sonora, Mexico is performed. The data are based on a combination of field work and published sources, including four previously studied locations from northern and eastern Sonora (Caborca, Cananea, Mazatán, and Arivechi) as well as a new location in the central part of the state of Sonora (San José de Gracia). Chronostratigraphic positions are assigned to the Cambrian outcrops according to Peng et al., 2012 and Cohen et al., 2017. In the Caborca area, the Puerto Blanco, Proveedora, Buelna, Cerro Prieto, Arrojos and El Tren formations comprise a wide range of biozones, which starts from the Fritzaspis Zone until the Glossopleura walcotti Zone (Begadean-Lincolnian Series, global Stage 3-Stage 5, Series 2-Series 3). The Bolsa Quartzite and the Abrigo Limestone exposed in Cananea area are assigned to the Cedaria/Cedarina dakotaensis Zone until the Crepicephalus Zone (Lincolnian Series-Marjuman Stage, global Series 3-Guzhangian). In the San José de Gracia area, The Proveedora, Buelna, Cerro Prieto and El Gavilán formations range from the ?Bristolia mohavensis or ?Bristolia insolens zones until the upper part of Mexicella mexicana Zone, Albertella highlandensis Subzone (Series 2-Series 3, Stage 4-Stage 5). In the Arivechi area, the La Sata, El Mogallón, La Huerta and the Milpillas formations range from Poliella denticulata Zone to the Elvinia Zone (Lincolnian-Millardan, Delamaran-Steptoean, global Series 3-Furongian, Stage 5-Paibian). Paleozoic marine fauna distribution in northwest Mexico and the southwest United States of America, suggest that during this time an extensive faunal province existed, containing a great variety of marine invertebrates with notorious intraspecific affinity. The biotic association includes poriferans, archaeocyathids, brachiopods, mollusks, arthropods and echinoderms as predominant elements.

El equinodermo Gogia granulosa (Echinodermata: Blastozoa) del Cámbrico temprano-medio en Sonora, México: paleoecología y paleogeografía

The echinoderm Gogia granulosa (Echinodermata: Blastozoa) of early-mid Cambrian in Sonora, Mexico: paleoecology and paleogeography.Blastoids of Gogia granulosa Robison, 1965 and Gogia sp. have previously been reported from San Jose de Gracia, Sonora, Mexico. Here we report on the implications of their presence in limestone, shale, and sandstone from the lower-middle Cambrian of that site. The biotic association consists of blastoids, as well as trilobites (Onchocephalus, Bonnia, Bristolia, Olenellus), hyolithids (Hyolithes, Haplophrentis), sponges, algae and ichnofossils of echinoderms (Asteriacites, Asterosoma). The community suggests that the depositional environment was a carbonated platform of tropical, shallow sea, with well oxygenated water. The biota belonged to a large faunistic province that comprised parts of Canada, USA and Mexico (Panthalassic Ocean). Rev. Biol. Trop. 65(Suppl. 1): S160-S167. Epub 2017 November 01.

Cryptic serpulid-microbialite bioconstructions in the Kakoskali submarine cave (Cyprus, Eastern Mediterranean)

The biostalactites from the Kakoskali cave in Cyprus represent a new example of the complex biotic relationships between skeletal organisms and microbial communities in building bioconstructions of cryptic marine environments. Biostalactites are mainly constituted of polychaetes of the family Serpulidae and, to a lesser degree, foraminifers and bryozoans. Within the skeletal framework of these organisms, two types of microcrystalline calcite (micrite) have been recognized: autochthonous and detrital micrite. The autochthonous fraction is syndepositionally lithified and occurs as clotted peloidal and, subordinately, aphanitic (structureless) textures, suggesting the presence of heterotrophic microbial activities thriving on decaying metazoan organic matter. This fraction is limited to the protected portions of the bioconstructions, especially in the inner and lower parts. The presence of iron and manganesiferous oxidizing bacteria is suggested by the deposition of ferromanganesiferous crusts and Frutexites-like structures. These microbial-induced biomineralizations are the main evidence of carbonatogenetic and Fe–Mn, autotrophic and chemoheterotrophic, bacterial activities. The Kakoskali cave is frequently visited by divers who, during their immersions, resuspend the fine bottom sediment, which later covers the surface of the bioconstructions, disturbing the delicate equilibrium of the biotic association. This perturbation, which is also caused by strong waves and currents, during winter months, reflects on the bioconstruction morphologies, community composition, and colonization pattern. Bioconstructions exhibit an upper smooth surface, produced by few taxa (e.g., polychaetes, foraminifers), hosting a low number of living individuals, and a lower comparably rough surface, colonized by a more abundant community showing a higher species richness. The ratio surface roughness/smoothness is related to micrite sediment type: the upper part is mainly characterized by loose detrital micrite while the internal and lower parts by syndepositional cemented autochthonous micrite.

Tectonic and environmental factors controlling on the evolution of Oligo-Miocene shallow marine carbonate factories along a tropical SE Circum-Caribbean

The evolution of the Cenozoic Circum-Caribbean shallow marine carbonate factories and ecosystems has been for long attributed to major global climatic and environmental changes. Although temporal variations in the Cenozoic shallow marine carbonate factories in this region seem to follow global trends, the potential effects of regional processes, such tectonic activity and local environmental change, on the evolution of the shallow marine carbonate factories are not well established. Here we present detailed sedimentologic and stratigraphic information from Middle Oligocene - Middle Miocene (Chattian-Burdigalian) shallow marine carbonate successions of the Siamana Formation in the Cocinetas sub-basin, Alta Guajira Basin, Guajira Peninsula, northern Colombia. We document the potential effects of regional tectonics and local environmental deterioration on the evolution of the Oligocene-Miocene tropical shallow marine carbonate factories along the SE Circum-Caribbean. Our results show that mixed heterozoan-photozoan biotic associations dominated the shallow marine carbonate factories during the Chattian, while purely photozoan biotic associations constituted the primary carbonate factory during the Aquitanian-Burdigalian transition. The Chattian mixed heterozoan/photozoan biotic association is associated with the development of mixed carbonate/siliciclastic shelves along which detached patchy reef areas occur. The onset of the Aquitanian-Burdigalian purely photozoan biotic associations parallels the increase in coral diversity as well as the occurence of rimmed/detached carbonate platforms in the northern part of the basin. The development of the rimmed/detached platforms coincides with a time of increased basin subsidence and increased silicilcastic input along the southernmost part of the basin. A significant change in the carbonate factory occurs in the Late Burdigalian, when purely heterozoan (rodalgal) biotic associations constituted the main shallow marine carbonate factory. This shift in the carbonate factory was favored by a major extensional component that resulted in subsidence and relative sea level rise along the Caribbean - South American margin. This extensional component is evidenced by the occurrence of normal faults that controlled the thickness and lateral extension of shallow marine rodalgal biostromes. The onset of the rodalgal biostromes, which elsewhere is associated with excellent carbonate reservoirs, also parallels the initiation of the Urumaco Trough and a further increase in silicilastic input toward the Cocinetas sub-basin. It also parallels a major tectonic reactivation along the Caribbean - South American plate boundary which resulted from the initial closure of the Panama Seaway.

Microfacies of a Permian calcisponge reef in Lichuan, western Hubei, South China

The Lichuan Jiantianba reef is located at the platform margin between the carbonate platform and the marine trough in western Hubei, China. The water depth of this area became shallow in the late Permian Changhsingian Age, and a huge aggradation-progradation platform marginal reef developed. Based on precise field measurements and microscopic observation, this paper describes the petrological characteristics and biological assemblages of the reef in detail and distinguishes 10 microfacies: small echinoderm wackestone, sponge floatstone, bound sponge bioliestone, bound sponge framestone, large echinoderm wackestone, red algal limestone, bioclastic grainstone, dasycladales wackestone, shelly wackestone, and microbialites. Sponge floatstone and bound sponge bioliestone are defined as toppled sponge limestone. Comparisons of the petrological characteristics and biotic association of toppled sponge limestone, bound sponge framestone and bioclastic wackestone and grainstone revealed that the toppled sponge limestone and the bound sponge framestone are similar in sponge content in terms of the types and contents of reef-dwellers, except that the sponge content is slightly lower, and the preservation state is mainly toppled for the former and upright or inclined for the latter. The toppled sponge limestone is dominated by tabular calcite, and the bound sponge framestone is dominated by fibrous calcite. The bioclastic wackestone and grainstone do not contain reef-building sponge organisms, and the bioclast content is very high and often dominated by a certain class, such as echinoderms, foraminifers, green algae or shells. The toppled sponge limestone below the framework, which was classified as fore-reef breccia or bioherm bafflestone-bindstone in previous studies, should be defined as reef-core sponge limestone deposited in situ that experienced serious post-karstification. The vertical evolution of the sedimentary facies of the reef is analyzed based on the microfacies and sedimentary environment. The toppled sponge limestone and the bound sponge framestone should be classified as reef core, which is the only subfacies of the reef facies. The underlying small echinoderm wackestone should be classified as the shelf facies, whereas the overlying bioclastic wackestone and grainstone should be classified as the open platform facies. These classifications represent a modification of the sedimentary facies subdivision of the Jiantianba reef in Lichuan, Hubei Province, South China, and provide a new reference model for the subdivision of the Permian calcisponge reefs on platform margin.

A lithostratigraphic and palaeoenvironmental framework for the late Miocene El Caracolar section (Granada Basin, Betic Cordillera, Spain) and description of decapod crustaceans

The locality of El Caracolar in the Granada Basin (Central Betic Cordillera, southern Spain) has yielded a rich late Miocene assemblages composed of marine invertebrates and vertebrates, accompanied by microfossils, macroflora and trace fossils. Exposed strata consisting of sands, sandy siltstones, silty sandstones, siltstones and calcirudites are divided into four local units. Lithostratigraphically, the studied section is placed between the top of the La Peza Formation and the Quéntar Formation. Based on foraminifers, the age of units 2 and 3 is estimated to be early Tortonian (11.0–9.9 Ma), whereas units 1 and 4 do not yield any reliable biostratigraphic markers. The diverse biotic association suggests that deposition took place in a near-shore outer neritic zone of a narrow to open seaway in a mesotrophic regime, responsible for the establishment of a chemosynthetic community under (sub)tropical conditions. The palaeo-depth of the depositional setting is estimated between 70 and 130 m. We further focused on decapod crustaceans that represent the first formally reported fossil decapod assemblage from the Granada province. The faunule consists of eight genera from two assemblages representing different palaeoenvironments. The assemblage of units 1 and 4 is dominated by the ghost shrimp “Callianassa” cf. almerai and accompanied by the hermit crab Petrochirus, whereas the assemblage from unit 3 includes the ghost shrimp Ctenocheles and the brachyuran crabs Raninoides, Calappa, Goneplax, Styrioplax, and Typilobus. Unit 2 does not yield any identifiable decapod remains. Styrioplax sp. represents the first occurrence of the genus outside the Central Paratethys, substantially expanding its palaeogeographical distribution. The decapod faunule from El Caracolar shows affinities with assemblages from the Proto-Mediterranean and Paratethys. This study provides a lithostratigraphic and palaeoenvironmental framework for further palaeontological studies in this unique Western Mediterranean outcrop.

Global variation in woodpecker species richness shaped by tree availability

AbstractAimSpecies richness patterns are generally thought to be determined by abiotic variables at broad spatial scales, with biotic factors being only important at fine spatial scales. However, many organism groups depend intimately on other organisms, raising questions about this generalization. As an example, woodpeckers (Picidae) are closely associated with trees and woody habitats because of multiple morphological and ecological specializations. In this study, we test whether this strong biotic association causes woodpecker diversity to be closely linked to tree availability at a global scale.LocationGlobal.MethodsWe used spatial and non‐spatial regressions to test for relationships between broad‐scale woodpecker species richness and predictor variables describing current and deep‐time availability of trees, current climate, Quaternary climate change, human impact, topographical heterogeneity and biogeographical region. We further used structural equation models to test for direct and indirect effects of predictor variables.ResultsThere was a strong positive relationship between woodpecker species richness and current tree cover and annual precipitation, respectively. Precipitation also showed a strong indirect effect on woodpecker richness via the effects on tree availability. Deep‐time tree availability, Quaternary climate change, human influence and other abiotic factors showed weaker direct effects. Human influence had a negative effect on tree availability, and hence a negative indirect effect on woodpecker species richness.Main conclusionsGlobal species richness of woodpeckers is primarily shaped by current tree cover and precipitation, reflecting a strong biotic association between woodpeckers and trees. Human influence can have a negative effect on woodpecker diversity when humans reduce tree availability. Hence, woodpeckers exemplify how broad‐scale diversity patterns are predominantly shaped by a biotic factor, and how climate and human influence can have indirect effects on animal biodiversity via the effects on tree availability and forest cover.

Three new taxa of Impatiens (Balsaminaceae) from southern Western Ghats, India

Three new taxa of Impatiens L., viz. I. kawttyana sp. nov., I. taihmushkulni sp. nov. and I. nilgirica Fisch. var. nawttyana var. nov. are described from southern Western Ghats of Tamil Nadu, India. Detailed descriptions, colour photographs, illustrations, distribution and biotic association are provided for the identification of these taxa.

An attempt to reconstruct 2700 years of seismicity using deep-sea turbidites offshore eastern Taiwan

The Taiwan area, where the Philippine Sea Plate collides with Eurasia, is one of the most seismically active areas in the world and has been consequently struck repeatedly by destructive earthquakes. To better constrain the occurrence of large earthquakes, we have conducted two cruises in 2012 and 2013 from which five piston, gravity and box-cores were retrieved from selected sites in targeted areas that contain continuous and accurate turbidite deposition offshore eastern Taiwan. Forty-seven turbidite layers deposited between 675BC and 2012AD have been described in the cores with facies varying from silty clay to coarse sand. We modeled each turbidite layer using the sedimentation rate deduced from radiocarbon age measurements performed on planktonic foraminifers. Precise dating based on 210Pb–137Cs chronology provided ages for the XXth century turbidites. Coring sites' locations, biotic association within turbidites beds and seismic calibration over the instrumental period, suggest that earthquakes are the most likely triggering mechanisms of turbidity currents over the last 2700years. Calibration of correlations between turbidites and instrumental earthquakes allowed us to determine the minimum magnitude of recorded events (Mw=6.8) and the maximum distance between the epicenter and the slope failure. Turbidites' synchroneity between cores has been tested but results showed that this criterion cannot be used in our study area because of the high level of seismicity, i.e., a M>6.8 earthquake recurrence interval much smaller than the uncertainty on radiocarbon ages. The excellent accuracy of dating allows correlating all the turbidites deposited since 1920 with instrumental earthquakes. For each core, we established a return time ranging between 112 and 147years for the period pre-1900 and ~27 and 34years for the period post-1900. The discrepancy between pre-1900 and post-1900 recurrence either suggests, that slope stability varies, with higher slope instability after 1900 possibly due to increased sediment delivery by rivers.

Impatiens sahyadrica sp. nov (Balsaminaceae)—a new species from southern Western Ghats, India

Impatiens sahyadrica (Balsaminaceae), a new scapigerous balsam from Silent Valley National Park, southern Western Ghats is described and illustrated. The new species is phenotypically similar to I. lawsonii. However, it differs from the latter in its smaller flowers; oblong, free upwardly curved basal lobes of the lateral united petals; smaller dorsal auricle and curved spur. A detailed description, notes on distribution, biotic association and relevant taxonomic notes are provided along with colour photographs and illustrations.

Early Ordovician reefs from the Taebaek Group, Korea: constituents, types, and geological implications

The Early Ordovician (early to middle Floian) bioherms of the Dumugol Formation, Korea, are compiled and their paleoenvironmental and paleogeographic implications are discussed. These reefs are mostly made up of microbialite (stromatolite and thrombolite) and lithistid sponge Archaeoscyphia, with subordinate “receptaculitid” calathids. Three types of reefs are identified based on biotic association and texture: 1) lithistid sponge-microbialite, 2) microbialite (thrombolite) with minor lithistid sponge, and 3) lithistid sponge-microbialite-calathid. The first and third type reefs are surrounded by intraclastic-skeletal packstone to grainstone and overlain by lime mudstone, whereas the second type reefs are surrounded and overlain by bioturbated wackestone and nodulebearing shale. These relationships appear to reflect varying depositional conditions during development of the reefs. The constituents of the Dumugol reefs are roughly comparable to coeval structures of Laurentia and South China with the exception of the absence of incorporated sessile organisms (i.e., Lichenaria, Pulchrilamina, and bryozoan) and delayed arrival (more than 10 myr) of calathids in the Sino-Korean Craton. This temporal disparity of biotic appearance is probably related to differential dispersal rates and patterns of sessile organisms which are largely controlled by the relative position of landmasses, epicontinental seas and major oceans. Further discovery and study of the Early Ordovician reefs from the Sino-Korean Craton will provide crucial information for understanding migration pathways of sessile organisms and paleogeographic reconstruction of the western margin of Gondwana in the Early Paleozoic.

The Evolutionary Ecology of Biotic Association in a Megadiverse Bivalve Superfamily: Sponsorship Required for Permanent Residency in Sediment

BackgroundMarine lineage diversification is shaped by the interaction of biotic and abiotic factors but our understanding of their relative roles is underdeveloped. The megadiverse bivalve superfamily Galeommatoidea represents a promising study system to address this issue. It is composed of small-bodied clams that are either free-living or have commensal associations with invertebrate hosts. To test if the evolution of this lifestyle dichotomy is correlated with specific ecologies, we have performed a statistical analysis on the lifestyle and habitat preference of 121 species based on 90 source documents.Methodology/Principal FindingsGaleommatoidea has significant diversity in the two primary benthic habitats: hard- and soft-bottoms. Hard-bottom dwellers are overwhelmingly free-living, typically hidden within crevices of rocks/coral heads/encrusting epifauna. In contrast, species in soft-bottom habitats are almost exclusively infaunal commensals. These infaunal biotic associations may involve direct attachment to a host, or clustering around its tube/burrow, but all commensals locate within the oxygenated sediment envelope produced by the host’s bioturbation.Conclusions/SignificanceThe formation of commensal associations by galeommatoidean clams is robustly correlated with an abiotic environmental setting: living in sediments (). Sediment-dwelling bivalves are exposed to intense predation pressure that drops markedly with depth of burial. Commensal galeommatoideans routinely attain depth refuges many times their body lengths, independent of siphonal investment, by virtue of their host’s burrowing and bioturbation. In effect, they use their much larger hosts as giant auto-irrigating siphon substitutes. The evolution of biotic associations with infaunal bioturbating hosts may have been a prerequisite for the diversification of Galeommatoidea in sediments and has likely been a key factor in the success of this exceptionally diverse bivalve superfamily.

Marine Red Staining of a Pennsylvanian Carbonate Slope: Environmental and Oceanographic Significance

Abstract Red-stained platform facies are a common feature of many carbonate settings throughout the geological record. Although the mechanisms involved in red staining of subaerially exposed or argillaceous, peri-platform limestones are reasonably well understood, the environmental and oceanographic significance of red carbonates often remains uncertain. Here, sedimentological, sequence stratigraphic, geochemical, paleontological, and quantitative bathymetric data from Pennsylvanian red intervals across a well exposed carbonate platform top and slope are documented and interpreted in a process-oriented context. On the upper slope (80–350 meters below the shelf break), red intervals alternate with gray, mainly microbial algal boundstones. On the lower slope (350–600 meters below the shelf break), redeposited red-stained mud builds matrix-supported breccia tongues interbedded with predominantly redeposited, clast-supported carbonate debris. The presence of large volumes of fibrous calcite biocementstones as well as firmgrounds point to low sedimentation rates or omission. In terms of sequence stratigraphy, red intervals occur within maximum flooding intervals and reflect near platform drowning. Elevated δ18O values (2–3‰) and an essentially cool-water, heterotrophic biotic association in red intervals on platform top and slope suggest deposition during sea-level highs, associated with colder water masses and high nutrient levels. The most likely drivers are an elevated thermocline and upwelling. The red staining is the result of iron oxidation which occurred during early diagenesis, likely by iron bacteria. These red intervals provide an important bathymetric benchmark against which other (mainly Paleozoic) red facies can be tested and calibrated.