Charophyte Flora Research Articles

Ostracoda (marine/nonmarine) and palaeoclimate history in the Upper Jurassic of Central Europe and North America

The role of Ostracoda in determining climate developments in the Upper Jurassic of Central Europe and North America is reviewed, based upon two different studies. The Late Jurassic is a period of time for which a change from a humid to a more arid climate has been suggested for several parts of the world. However, a correlation, though almost logical, between the arid phase in the middle and late Tithonian and a generally cooler climate, combined with a sea-level lowstand and lower water temperatures, has only been demonstrated in very few papers. This study intends to seeks palaeoclimatic evidence for the Late Jurassic by the use of Ostracoda. Development of marine ostracod palaeobiogeography in Central and Western Europe parallels a suggested cooling trend. During the Oxfordian, Kimmeridgian, Tithonian, and Berriasian, a growing diversification of marine ostracod biogeography and an increase in the degree of endemism can be observed. In addition, there is a gradual southward migration of many species from the subboreally influenced areas in the northwest towards the margin of the Tethys in the southeast, mainly from the Kimmeridgian into the Tithonian. Moreover, the genus Cytherelloidea, which has a long tradition (despite some recent contradictions) as an indicator for relatively warm water temperatures, shifts its northern boundary of occurrence towards the south during the Kimmeridgian, Tithonian, and Berriasian. This occurs independently from the general change of facies, because conditions principally suitable for Cytherelloidea (salinity, water depth) have at times also existed in some northern basins during the Tithonian/Berriasian. These data are in correspondence with a suggested increase in the influx of cold boreal waters into central Europe with the beginning of the Tithonian, leading to slightly colder water temperatures in the shallow seas, reduced atmospheric moisture, cool-arid conditions on the neighbouring continents, and also to the diversification of biogeographic regions as a reaction to the conflicting boreal (increased) and Tethyan (still steady) influences. For the Kimmeridgian/Tithonian nonmarine Morrison Formation in the Western Interior Basin, USA, both temporal and latitudinal trends from warm climates in the south and near the base of the formation to slightly cooler climates in the north and in the upper parts of the sections have been detected on the basis of the charophyte floras. Monospecific δ 18O isotope data from charophytes and ostracods have revealed a trend towards lighter compositions towards the top of the formation. This might be interpreted as a general cooling, but other interpretations must also be discussed. From preserved vital effects and δ 18O/δ 13C plots of charophyte/ostracod associations showing coherent groupings similar to those from modern lakes, it is likely that the calcite shells have preserved a high degree of isotopic fidelity. Different scenarios to explain the observed patterns are discussed. A global change towards colder temperatures and arid conditions near the end of the Jurassic period is in good correspondence with all the results. More local factors, however, would also be able to explain the data.

Towards a Biogeography of North American Charophytes

The great bulk of the world’s charophyte literature of the past 100 years or more suffers from several major limitations. Much is entirely descriptive with but few attempts to ascribe any functionality to the features under consideration, or how they adapt such species to their respective ecological niches. Charophyte distributions have been attributed almost entirely to physical parameters with virtually no consideration given to the role of aquatic herbivores or other biotic environmental factors. Furthermore, most workers have focused on relatively restricted areas with little or no reference to others either near or far removed. That there is much to be gained from a wider focus (both spatially and conceptually) that incorporates greater conjecture as well as enhanced collaboration is here suggested. How are the charophyte floras of one region similar to, or different from, those of another, and, of particular significance, ‘Why?’ The authors, being North American, focus on that continent but with the firm conviction that most generalities applicable there hold equally true for other landmasses, and have done so for the previous 10, if not 100, million years. This account focuses first, if somewhat superficially, on 14 widely distinct North American charophyte communities (plus South American Lake Titicaca) and then in greater detail on four of those. Among other issues considered are how species richness relates to latitude; why some geographical entities support more charophyte species than do others; the extent to which charophyte floras reflect the availability of different habitats; the contributions of herbivory to the preceding; the stability of the North American charophyte flora; the ecological considerations most often reflected by charophyte zonation and how–or to what extent–range extensions reflect niche preferences or requirements. While the authors well appreciate just how minimal their efforts may appear a century hence, at least they hope to have placed on the table some considerations with which colleagues from other landmasses may agree, disagree or suggest modifications.

Charophyte Flora of South-eastern South Australia and South-western Victoria, Australia: Systematics, Distribution and Ecology

The charophytes (Charales, Charophyta) from south-eastern South Australia and south-western Victoria were studied on the basis of collections from 56 waterbodies, 39 of which included charophytes. Chara globularis var. globularis (Thuillier) Wood, C. globularis var. virgata (KÜtzing) Wood, C. fibrosa var. fibrosa (Agardh ex Bruzelius) Wood, C. fibrosa var. acanthopitys (Braun) Wood, C. hookeri Braun, C. preissii (Braun) Wood, Lamprothamnium macropogon (Braun) Ophel, Nitella ignescens García, N. ungula García, N. lhotzkyi (Braun) Braun, N. aff. lhotzkyi, and N. congesta (Brown) Braun were recognised. An identification key for these species makes determination possible. A brief characterisation of the environment where the charophytes were found is provided, as a first approximation of the ecological requirements of Australian charophytes. At this stage their distribution can be mainly related to salinity, with charophytes living in fresh to hypersaline conditions (0.0–58.0 g L–1). Special attention is put on L. macropogon, a euryhaline calcifying species, which has the broadest distribution in the area. The floristic analysis shows endemism, dioecism and a high diversification of non-calcifying taxa as the main characteristics of the charophyte flora analysed.

Revision of the Charophyte Flora of the Siwalik Group (Neogene-Quaternary) of the Lesser Himalaya, India

On the basis of a re-examination of the topotype material of the Siwalikcharophytes described by Bhatia and Mathur (1978) and on additional materialcollected from six new localities, the taxonomy of the charophyte flora isbrought up to date. In all, 17 taxa are recorded and illustrated. At thespecific level, generic shifts have been made in the case ofChara rantzieni sivalensis,Chara contraria (non Braun et Kuetzing),Tectochara sahnii andSphaerochara pecki. The following taxa were hitherto notknown from the Siwalik Group:Chara globularis globularis Thuillier,C. globularis aspera (Deth. ex Wild.),C. sp. cf. hispida Linné,Lychnothamnus breviovatus Lu & Luo,Lamprothamnium papulosum (Wallr.) Groves,L. succinctum (A.Braun),Nitellopsis (Tectochara)bicarinata (MÄdler), N.(T.) helvetica (MÄdler) andSphaerochara prolifera (Zizermann ex A.Braun).

Charophytivory, Playas y Papalotes, a Local Paradigm of Global Relevance

The Llano Estacado region of western Texas and adjacent New Mexico has one of the most species-rich charophyte floras known for North America, but upon closer inspection this flora is seen to consist of two, strictly non-overlapping segments, one of 12 taxa, the other of nine. The larger group of species is confined to a vast series of shallow, ephemerally inundated depressions known as playas. These normally fill with run-off rainwater in late May or early June, remain flooded through early to mid-September before eventually drying to the curling polygon stage near the end of September. Approximately 8 months later the cycle is repeated. The remaining nine charophytes are confined to permanently inundated sites, the most common of which are livestock-watering windmill complexes, known as papalotes. Rarely, if ever, are members of the playa-12 encountered in papalotes or members of the papalote-9 in playas. The underlying bases for this ‘two flora’ dichotomy stem from the contrasting amphipod populations engendered by the two habitat types. Most freshwater amphipods (scuds), including the common North American herbivore Hyalella azteca (Saussure), cannot withstand complete desiccation which, accordingly, prevents its colonisation of playas. By contrast, scuds often reach exceptionally high densities in the associated concrete or metal tanques of papalotes, since such specialised habitats are usually free of vertebrate predators, e.g. birds, fish, turtles, salamanders. Scud- resistant charophytes are larger and slower to develop gametangia, features inimical to success in short- lived playas. By contrast, precocious charophyte opportunists–typical of playa floras–cannot withstand the grazing pressures of papalote (or papalote-like) environments. While charophytivory is assumed to be of worldwide occurrence and significance, it has been clearly demonstrated only in the unique juxtaposition of ‘playas y papalotes’.

Charophytes and otoliths from theCyrena Beds of the northern Alpine foreland

Charophytes and otoliths from theCyrena Beds of the northern Alpine foreland (Hausham and Miesbach synclines, Upper Bavaria) have been studied. A very abundant charophyte flora comprising 12 species, includingStephanochara martinii n. sp., is described and figured. The moderately diverse otolith fauna is documented by tables and SEM-pictures. The studiedCyrena Beds can be dated biostratigraphically as early Chattian and correlated with theChara microcera Zone.

Karyology and cytotaxonomy ofChara wallichiiandChara brauniifrom West Bengal, India

Summary Cytotaxonomic study of Charophyte flora from lateritic belt of West Bengal, India, is being carried out. In the present communication, we present karyological observations of two ecorticated species of Chara, viz. C. wallichii A. Br. (dioecious) and C. braunii Gm. f. braunii R.D.W. (monoecious) collected from this region. Following refined pretreatment schedule, we have achieved marked improvement in chromosome preparation which helps to determine chromosome number accurately and reveal minute details of chromosome morphology. Chromosome numbers determined for both the taxa are n = 14, which confirms the earlier reports. Karyotypic details reveal distinct differences between these two species. This supports their distinct taxonomic position on the basis of differences in the disposition of sex organs, though there are some morphological similarities between these two species. Total form percent values (TF %) for C. wallichii and C. braunii f. braunii are 34.64 and 37.85 respectively, indicating sy...

A charophyte flora from the Lower Pechelbronn Formation (?Upper Eocene/?Lower Oligocene) of Malsch south of Heidelberg (SW Germany)

Abstract. The Lower Pechelbronn Formation (?Upper Eocene/?Lower Oligocene) of Malsch (clay-pit ‘Am Viehweg’) yielded a moderately abundant charophyte assemblage. One new species, Chara rhenana sp. nov., is erected, two more species, Harrisichara lineata and Nitellopsis (Tectochara) cf. wonnacotti, are recorded in the Rhine Graben area for the first time. The Lower Pechelbronn Formation may be correlated to the Stephanochara vectensis zone (Riveline, 1986) and the mammalian level MP 20 (reference locality: St. Capraise; Schmidt-Kittler, 1987). The associated ostracod fauna clearly indicates a limnic depositional environment.

The paleoecological implications of the charophyte flora of the Trinity Division, Junction, Texas

The Trinity Division exposures at Junction, Kimble County, Texas, yield a rich charophyte flora dominated by clavatoraceans. The presence of Atopochara trivolvis ssp. trivolvis (Peck, 1938) Grambast, 1968, and Clypeator corrugatus (Peck, 1941) Grambast, 1962, indicates an Aptian age for these strata and makes them the continental equivalent of the Lower Glen Rose. Atopochara trivolvis, whose type-material was recovered from the Trinity in a deep well in southern Texas, is known from numerous freshwater to oligohaline lakes from the Mesogean area in Europe and North Africa as well as from Cretaceous oil-bearing basins in China. Charophytes are clear indicators of supratidal environments and the abundant remains at Junction suggest a positive structural feature in this part of central Texas that might have been either an island or directly connected to the Llano Uplift.

Charophyte remains from Wadi Howar as evidence for deep mid-Holocene freshwater lakes in the eastern Sahara of Northwest Sudan

Field research in the eastern Sahara (Northwest Sudan) revealed extensive early- to mid-Holocene lake marl deposits bearing gyrogonites of Charophytes (green algae, stoneworts) along the lower course of the Wadi Howar, an extinct tributary to the Nile. The Charophyte flora of a paleolake southwest of Jebel Rahib ( 17°31′N 26°52′E ) dated prior to 4720 ± 110 yr B.P. is mainly composed of the ecologically sensitive species Nitellopsis obtusa which indicates permanent, relatively deep (4–12 m) and cool oligotrophic freshwater. The study of Nitellopsis sites provides a new and promising approach to the reconstruction of Quaternary paleoenvironments of deserts.

Charophytes in time and space: zonal distribution pattern

SummaryThe communication deals with the composition of charophyte flora of the world distributed into eight zones, viz., North American, South American, African, European, Asian, Indian Subcontinent, Pacific Island region, and Australian. The extent of similarities in the flora between each zone and the rest has been indicated. Depending on the extent of world distribution, charophyte taxa have been categorized into four groups namely, cosmopolitan, sub-cosmopolitan, restricted and endemic.Among all the zones, the Indian Sub-continent is found to have comparatively maximum number of taxa. It is interesting to note that the flora of the majority of zones contains almost invariably the next maximum number of the constituent taxa which are also found in the Indian Sub-continent, inspite of their distant geographical position from the latter zone. The importance of recording specific geographical position of the localities with exact altitude, latitude, longitude together with some ecological parameters like ...

Characeae of Llano Estacado (Texas and Adjacent New Mexico) Playas

From sixty-four playas (temporary lakes) on the of which ever colonizes playas. Bulbil-forming Characeae Llano Estacado of the Texas Panhandle, eleven are absent from playas, and dioecious species of little sig- charophytes are reported, plus an additional nine from nificance in terms of total biomass, as both generally are on permanent bodies of water in the same area. Virtually no oceanic islands as well. The total of twenty for the Llano overlap of species exists between the two habitats. Domi- Estacado, considerably higher than previously reported for nating the playas, but never present in permanent bodies of most areas of North America, is thought to reflect the dual water, was eurythermic and opportunistic Chara braunii nature of the habitats, i.e. temporary and permanent. The Gm. Also present in approximately 25% or more of the maximum number of charophytes per playa was seven; the playas, but no permanent bodies, were C. haitensis Turpin, mode 2. Undisturbed playas, though transient in nature, C. foliolosa Miihl. ex Willd. and C. hydropitys Reich., all of apparently support charophyte floras that are fairly stable tropical affinity. Playas are normally inundated only during from year to year. the summer months. Permanent bodies of water in the area are dominated by cool-temperate charophytes, e.g. C. con- Key words. Charophytes, temporary lakes (playas), Texas traria Br. ex Kutz and 'C. globularis' (Proctor, 1971), none Panhandle, biogeography, ecology.

Earliest known proboscidean from early Eocene of north-west Africa.

The earliest known proboscidean remains have now been found at a new early Eocene locality at Brezina in southern Algeria (El Kohol). These new finds, represented by complete skulls and postcranial material, show several unexpected derived characters shared with the modern representatives of the Elephantoidea and the Deinotheriidae, suggesting close phylogenetic affinities and demonstrating also the great antiquity of the differentiation of modern proboscideans in Africa. These remains have been dated by associated charophyte flora and vertebrate remains which constitute the oldest known vertebrate community from the African Eocene.

Charophytes du Crétacé moyen et données nouvelles sur l'Evolution des Clavatoracées

The discovery of new localities in the South of France shows that Embergerella cruciata, Atopochara restricta and A. brevicellis (Clavatoraceae) continued into the Cenomanian. A relationship between the genera Embergerella (Barremian-Cenomanian) and Septorella (Maastrichtian) is suggested on the basis of a new interpretation of the structure of the utricle. Representatives of the family Characeae are described for the first time, Peckisphaera revesti n. sp. in the Cenomanian and Mesochara fusiformis n. sp. in the Turonian. Biostratigraphic information: in the present state of knowledge of Middle Cretaceous Charophyte floras, only the Cenomanian is well characterized, by A. multivolvis to which is now added a new association of four species. Although new information is presented on the Albian and Turonian, they are still inadequately understood.

Observations sur les niveaux a charophytes de l'Aptien des monts des Oulad-Nail (Atlas saharien, Algerie)

Abstract With slow retreat of the Aptian sea from the Oulad Naiel mountain region, Algeria, lagoonal- marine beds graded into continental Albian (Cretaceous) deposits. The transitional zone contains remains of charophytes; these plants, considered lacustrine, are here associated with foraminifers, showing that they had become adapted to a brackish-water environment like the modern characeans. The marshy emergent coast of that time was comparable to the Cape Hatteras region of today. The charophyte flora is described.