Western Limit Research Articles

Geophysical imaging of ophiolite structure in the United Arab Emirates

The Oman-United Arab Emirates ophiolite has been used extensively to document the geological processes that form oceanic crust. The geometry of the ophiolite, its extension into the Gulf of Oman, and the nature of the crust that underlies it are, however, unknown. Here, we show the ophiolite forms a high velocity, high density, >15 km thick east-dipping body that during emplacement flexed down a previously rifted continental margin thereby contributing to subsidence of flanking sedimentary basins. The western limit of the ophiolite is defined onshore by the Semail thrust while the eastern limit extends several km offshore, where it is defined seismically by a ~40–45°, east-dipping, normal fault. The fault is interpreted as the southwestern margin of an incipient suture zone that separates the Arabian plate from in situ Gulf of Oman oceanic crust and mantle presently subducting northwards beneath the Eurasian plate along the Makran trench.

Has the West been won? A field survey and a species distribution model of Iberolacerta horvathi in the Alps

The Horvath’s rock lizard (Iberolacerta horvathi) is a rupicolous mountain species endemic of the eastern Alps and northern Dinaric range. The species has its known western limit of the distribution in the Veneto region of Italy. It is not known whether the species is really rare in Veneto or whether the area has been insufficiently surveyed. In addition, it is not known whether the westward distribution of the species is limited by a physiographic or by a climatic barrier. During the period 2016-2018, 118 sites were surveyed in the Veneto and Trentino-Alto Adige regions. Four new occurrences of Iberolacerta horvathi were discovered in Veneto that: 1) largely fill the gap between the westernmost known site and the closest site to the east; 2) extend further west the known distribution by 9 km. In addition the species was confirmed in three already known sites. A species distribution model was developed with the software MaxEnt, using 100 occurrences from Italy, Austria and Slovenia. The best model shows that the distribution is explained by the asperity of their habitat, the sedimentary bedrock, the aspect, the average temperature of the coldest quarter, the rainfall seasonality and the average summer rainfall. The last variable appears as the most likely responsible for the rarefaction of the species at its western limit. In addition, the species distribution model suggest that the Horvath’s rock lizard might be present in some additional mountain groups where it has so far not been found yet.

Calcareous microorganisms as indicators of oceanographic conditions in South West Atlantic Ocean

Abstract The results of multivariate analysis applied to the associations of benthic foraminifers and ostracods from surface sediments of the north Argentine continental shelf are presented in this study. We evaluated the distribution patterns and ecological preferences of species found in modern sediments from the north Argentine continental shelf, at depths between 15 and 130 m. We identified 61 species of foraminifers corresponding to the orders Rotaliida, Miliolida, Lagenida, Buliminida, Lituolida and Trochamminida, in addition to 18 species of ostracods that belong to the suborder Podocopina. The distribution of the ostracods Bradleya kaeslery Ramos, Coimbra and Whatley was extended to higher latitudes. It was determined that water depth and temperature were the factors that most affected the distribution of both types of microorganisms. Based on these data, we established three physiographical zones, which could be linked to the different water masses. In addition, the western limit of the Malvinas current at 80 m of water depth was corroborated. Our study highlights the potential use of benthic foraminifers and ostracods individuals as bioindicators for identifying oceanographic conditions in the Argentine continental shelf.

First Report of <i>Pseudorhombus diplospilus</i> (Pleuronectiformes: Paralichthyidae) from East Coast of India

A large-tooth flounder, Pseudorhombus diplospilus Norman (1927) (Pleuronectiformes: Paralichthyide), is reported from east coast of India based on a single specimen collected from Royapuram fishing harbor, Chennai, Tamil Nadu with detailed meristic and morphometric study. This forms the ninth species in the genus Pseudorhombus and the second species in having palmate gill rakers from Indian waters. With this report of P. diplospilus, its western limit of distributional range is extended from Indonesia and west Australia to east coast of India.

Dating tectonic activity in the Lepontine Dome and Rhone-Simplon Fault regions through hydrothermal monazite-(Ce)

Abstract. Zoned hydrothermal monazite-(Ce) from Alpine-type fissures and clefts is used to gain new insights into the tectonic history of the Lepontine Dome in the Central Alps and the timing of deformation along the Rhone-Simplon Fault zone on the dome's western end. Hydrothermal monazites-(Ce) (re)crystallization ages directly date deformation that induces changes in physicochemical conditions of the fissure or cleft fluid. A total of 480 secondary ion mass spectrometry (SIMS) spot analyses from 20 individual crystals, including co-type material of the monazite-(Nd) type locality, record ages for the time of ∼19 to 2.7 Ma, with individual grains recording age ranges of 2 to 7.5 Myr. The combination of these age data with geometric considerations and spatial distribution across the Lepontine region gives a more precise young exhumation history for the area. At the northeastern and southwestern edges of the Lepontine Dome, units underwent hydrothermal monazite-(Ce) growth at 19–12.5 and 16.5–10.5 Ma, respectively, while crystallization of monazite-(Ce) in the eastern Lepontine Dome started later, at 15–10 Ma. Fissure monazite-(Ce) along the western limit of the dome reports younger ages of 13–7 Ma. A younger age group around 8–5 Ma is limited to fissures and clefts associated with the Simplon normal fault and related strike-slip faults such as the Rhone Fault. The data set shows that the monazite-(Ce) age record directly links the fluid-induced interaction between fissure mineral and host rock to the Lepontine Dome's evolution in space and time. A comparison between hydrothermal monazite-(Ce) and thermochronometric data suggest that hydrothermal monazite-(Ce) dating may allow us to identify areas of slow exhumation or cooling rates during ongoing tectonic activity.

Filling biogeographic gaps about the shrimp Farfantepenaeus isabelaeTavares amp; Gusmão, 2016 (Decapoda: Penaeidae) in South America.

Farfantepenaeus isabelae is a recently described pink shrimp species with occurrence restricted to the South Atlantic. The real geographic distribution of this species is still uncertain, probably due to difficulties on identification in relation to congeners. The present study aims to increase the knowledge about its occurrence by using an integrative approach with morphology, molecular and niche modeling analysis. Our results extend both western and eastern limits of occurrence of F. isabelae, elucidating gaps along the northern region of Brazil. The knowledge about its distribution will contribute to updating the politics of management and fishing in order to preserve its natural stocks.

Παρατηρήσεις στο θραύσμα ερυθρόμορφου σκύφου από την αρχαία Κυδωνία με αριθμό ευρετηρίου Αρχαιολογικού Μουσείου Χανίων Π 12489

The Attic red-figured fragment in the Archaeological Museum of Hania, inv. Π 12489, published here in detail, was found during a rescue excavation conducted by the κε´ Ephorate of Antiquities) in Hania (ancient Kydonia) at the former Agricultural Bank Property in Skalidi str. The findspot is within the western limits of the ancient settlement of Kydonia. οnly a small part of a skyphos is preserved. The incomplete scene depicts the upper part of two figures, a beardless Herakles, named by an inscription in white ηρακλησ, probably seated and a Nike offering a phiale. There is also a tripod with ribbons in white, part of a wreath and a stylized blossom, all suspended. Above the picture a band filled with an olive sprig. The depiction can symbolically imply a festive or competitive event in honor of Herakles echoing at the same time the cult background that is attested in Kydonia through a significant inscribed votive offering of a local named Aischylos. Based on the elements of style and iconography the fragment is attributed to Dinos painter, and can be dated around 420 BC

Sigmodontine community and species responses to El Niño and precipitation in different levels of forest degradation.

Few studies have focused on rodent communities at the margins of an ecoregion or the limits of species’ distributions, where the community may be more sensitive to extrinsic variables, both biotic and abiotic. This study evaluates sigmodontine rodent species diversity and overall abundance, and variation associated with climatic variables, in three locations with differing levels of habitat degradation. The study was conducted in northeastern Paraguay, near the western limit of the Upper Parana Atlantic Forest and near the distributional limits of the three most abundant species in the study sites. Three mark-recapture grids were established and classified as least, moderately and most-degraded based on an analysis of several vegetation parameters. The grids were sampled for five consecutive nights, six times during two years. Shannon diversity and overall abundance were calculated for each sample. Monthly Multivariate ENSO Index and rainfall values were obtained from publicly available resources. Product-moment correlations were calculated between community and climatic parameters, including cumulative values for the climatic variables. The same correlations were calculated for the three common sigmodontine species. 1,632 captures were recorded, representing 13 sigmodontine species. Species richness in the samples (one session on one grid) varied from four to seven. Akodon montensis, Hylaeamys megacephalus and Oligoryzomys nigripes were the three most abundant species. In general, species diversity was negatively correlated with ENSO index, precipitation and precipitation anomaly, including cumulative one- to six-month cumulative values of each. Total sigmodontine abundance was positively correlated with the climatic variables. However, these correlations were not uniform among the three levels of habitat degradation, nor did the three abundant species show similar correlation patterns. The three most abundant species are each near their distributional limits, whereas several less abundant species have distributions that extend well beyond the study area. This somewhat counterintuitive result bears further investigation in other sites at ecoregional margins, to determine whether it is a commonly observed pattern, or an exception. Overall sigmodontine abundances were generally reflective of Akodon montensis abundance, which generally correlated with precipitation (including cumulative amounts). Our analyses of these longitudinal data showed two major effects on sigmodontine species diversity and population. First, they are impacted by habitat and secondly, they are affected by climate (ENSO, precipitation). However, individual species are not impacted similarly. Akodon montensis abundances primarily were correlated with abiotic (climatic) variables, and the correlations were consistent across habitats (biotic factors). In contrast, Hylaeamys megacephalus abundance was correlated with climatic variables in two habitats, but not the moderately-degraded habitat, and Oligoryzomys nigripes abundance was not correlated with climate in the most-degraded habitat.

Genetic status of the endangered plant species Gladiolus palustris in the western part of its distribution area

Many endangered plant species suffer from the effects of ongoing fragmentation of their populations leading to a loss of genetic diversity through genetic drift. In addition, populations of rare plants may also be affected by hybridization with other plant species. We studied the genetic population structure of populations of the endangered Gladiolus palustris in the western limit of its distribution area using AFLP markers. In addition, we clarified the taxonomic status of populations where hybridization with the closely related G. imbricatus was suspected based on morphology by sequencing the ITS region of the nuclear ribosomal DNA as well as two regions of the chloroplast DNA. Our analysis of the genetic population structure of G. palustris revealed a strong differentiation among geographical regions, which was much higher than the differentiation among populations within regions. Most populations retained a considerable amount of genetic variation. To counteract the future loss of genetic diversity through drift, we recommend using the largest populations per region as seed source to increase genetic diversity in genetic depauperate populations of the same region. Our genetic analyses indicated that some French populations of G. palustris are of hybrid origin. These hybridization events are likely to be ancient as these populations are very isolated and some parent taxa went regionally extinct. As these hybrid populations may elucidate post-glacial distribution patterns of related Gladiolus taxa, we advocate that they deserve the same conservation efforts as purebred ones.

DNA ploidy in Salix retusa agg. only partly in line with its morphology and taxonomy

Salix retusa agg. encompasses small, prostrate willows occurring in the subalpine and alpine zones of European mountains. Karyological relationships among taxa in this group remain unclear. In this study, DNA ploidy was estimated using flow cytometry of silica‐dried specimens, covering the entire distribution area of the species. As a result, the presence of two main lineages was revealed: the exclusively diploid S. serpillifolia and the predominantly octoploid S. retusa s.l. Only at the western and eastern limits of the distributional range of the latter species different levels of DNA ploidy occurred: hexaploidy in the western Pyrenees, and up to decaploidy in the southern Carpathians. These results were compared with leaf morphology analyses presented in the work of Kosiński et al. (2017). In the western Pyrenean populations, the lower ploidy corresponded to smaller leaf sizes as compared to other populations of S. retusa s.l. The elevated ploidy in the southern Carpathian populations did not translate into bigger dimensions of plants in this area. However, the populations from the northern part of the Carpathian arc, distinguished by larger leaves and sometimes considered as a distinct taxon (S. kitaibeliana), consisted mainly of octoploid individuals. Thus, DNA ploidy estimations did not confirm the separate taxonomic status of S. kitaibeliana.

Ufadendron Elongatum sp. nov., an Angaran Lycopsid from the Upper Permian of Inner Mongolia, China

A new species Ufadendron elongatum sp. nov., attributed to the family Tomiodendraceae Naugolnykh, is represented by two well-preserved stems in the collection under study. This new species was recently discovered from the Upper Permian Linxi Formation in the Jalaid locality, the Inner Mongolia Autonomous region, China. The genus Ufadendron is characterized as having the long fusiform leaf cushions, with small and rounded leaf scar containing a central point-like scar which is situated at the upper part of leaf cushion; the infrafoliar bladder of fusiform shape positioned in the middle part of leaf cushion; the wings and heel well-developed in the lateral parts and the lower part of leaf cushion, respectively. The new species is different from the type species U. ufaense (Naugolnykh 2014) collected from the Lower Permian of the Cis- Urals, western limits of Angaraland, in the elongated leaf cushion and in the well-pronounced heel. It should be noted, that a vascular bundle (conductive strand) occupied the middle part of the central point-like scar. So far, only 5 genera of Angaran elements among lycopsids have been discovered in the region geographically belonging to Angaran Realm (Phytogeoprovince) in China. The new species U. elongatum not only enlarges our knowledge on the taxonomy of Tomiodendraceae lycopsids, and also provides an opportunity to understand the difference between Angaran and Cathaysian floras in paleoclimatic context.

Las Palmas de Gran Canaria. La ciudad, su litoral y su puerto

La ciudad de Las Palmas de Gran Canaria es una urbe atlántica que derivó en área metropolitana ya avanzada su historia. El hecho de ser encrucijada de rutas e influencias humanas, comerciales y culturales, la convierte en un espacio de profunda vocación marítima. La ciudad quedó inicialmente confinada a un espacio reducido, entre el mar, por naciente, y un relieve de disposición norte-sur que representó durante siglos el límite occidental de expansión urbana. El objeto del presente trabajo es estudiar la transformación del litoral capitalino en relación al proceso de origen y desarrollo del puerto y la consecuente expansión urbana. Las fuentes básicas son el archivo de la Autoridad Portuaria de Las Palmas, la Oficina de Planeamiento del Ayuntamiento de Las Palmas de Gran Canaria, Museo Canario, fondo cartográfico y fotografías aéreas del Departamento de Geografía de la Universidad de Las Palmas de Gran Canaria, fondo fotográfico de la Fundación para el Estudio y Desarrollo de la Artesanía Canaria (Fedac). Se realiza un estudio diacrónico y se establecen etapas del proceso.

A new report confirming the presence of Bennett’s stingray, Hemitrygon bennettii (Elasmobranchii: Myliobatiformes: Dasyatidae), from the western Bay of Bengal

The occurrence of Bennett’s stingray, Hemitrygon bennettii (Muller et Henle, 1841), is confirmed from Indian waters, based on a single male specimen (370 mm DW) collected from Visakhapatnam, western Bay of Bengal on 28 January 2017. Existing, updated reports on the distribution of the species, places it in the Indo-Pacific region with the western limit being the Strait of Malacca. With the presently confirmed occurrence from the western Bay of Bengal, the known distribution of the species extends further westwards to the Indian east coast, although it is likely to be a rare species in Indian waters

The evolution of the Levantine Iron Age geomagnetic Anomaly captured in Mediterranean sediments

The geomagnetic field can vary dramatically over only decades and thousands of kilometers; the Levantine Iron Age geomagnetic Anomaly (LIAA) is probably the best-known example of such short-lived feature of the Earth's magnetic field. Yet, the size, shape and temporal variations of this phenomenon are currently still enigmatic. Here we provide continuous full-vector records of the variations in the geomagnetic field from three marine sediment cores from the Mediterranean, to better constrain the LIAA in time and space. The cores are located (1) between Spain and Morocco (Alboran), (2) East of Calabria, Italy (Taranto Gulf), and (3) North of the Nile Delta (Levant). Geomagnetic field variations between 6000 BC and 1000 AD are captured for a total of 681 samples. Rock magnetic analyses indicate the sediment cores as reliable recorders for geomagnetic field variations. Between 750 and 250 BC, high intensities are observed for the Levant and Taranto Gulf core, with their peak – 150 ZAm2 at 500 BC – shortly after the occurrence of the LIAA. Low paleointensities are obtained from the Alboran core providing a western limit of the extent of the LIAA until at least 250 BC. From 500 BC onwards the location of the highest paleointensities moves slightly westwards while diminishing in intensity. The LIAA moves from 40 to 55° East at 1000 BC to ∼25° East at 0 AD, while decaying from ∼150 ZAm2 to ∼110 ZAm2 in the same time span. This results in a westward movement of 15–30° in 1000 yr.

Assessing the environmental and dispersal controls onFagus grandifoliadistributions in the Great Lakes region

AbstractAimThis paper assesses the relative importance of environmental filtering and dispersal limitations as controls on the western range limit ofFagus grandifolia, a common mesic late‐successional tree species in the easternUnited States. We also test for differences in species–environment relationships between range‐edge populations ofF. grandifoliain eastern Wisconsin and core populations in Michigan. Because environmental conditions between the states differ moderately, while in Michigan dispersal presumably no longer limitsF. grandifoliadistributions,F. grandifoliaoffers a classic case study for biogeographers, foresters, and palaeoecologists interested in understanding processes governing species range limits.LocationWisconsin and Michigan,USA.TaxonFagus grandifolia.MethodsThis study combines historical datasets ofF. grandifoliafrom the Public Land Survey, environmental covariates from soil maps and historical climate data, three spatial scenarios of dispersal limitation, and five species distribution models (SDMs). We test dispersal limitation and environmental filtering hypotheses by assessingSDMtransferability between core and edge populations, measuring the importance of dispersal and environmental predictors, and using a residual autocovariate model to test for spatial processes not represented by these predictors.ResultsFagus grandifoliapresence was best predicted by total snowfall in Michigan and by dispersal, summer precipitation, and potential evapotranspiration (PET) in Wisconsin. Following the addition of dispersal as a predictor, most Wisconsin models improved and spatial autocorrelation effects largely disappeared. Transferability between core and edge populations was moderate to low.Main conclusionsBoth environmental and dispersal limitations appear to govern the western range limit ofF. grandifolia. Species–environment relationships differ between range‐edge and core populations, suggesting either stronger environmental filtering at the range edge or fine‐scale, spatially varying interactions between environmental factors governing moisture availability in core populations. Although lakes, like Lake Michigan, both moderate regional climates and act as dispersal barriers, these effects can be disentangled through the joint analysis ofSDMs and historic observational datasets.

Status, habitat and diet of breeding Barbary falcons from a rugged oceanic island in the western limit of its distribution

Status, habitat and diet of breeding Barbary falcons from a rugged oceanic island in the western limit of its distribution

Western Limits of Russia until the Beginning of the 20th Century

Western Limits of Russia until the Beginning of the 20th Century

The genus Gymnospermium (Berberidaceae) in Italy: identity and relationships of the populations at the western limit of the genus range

Gymnospermium is a small genus of 7–12 taxa subject to diverging taxonomic treatments and distributed from east China to the Balkans. The recent discovery of Gymnospermium in the S-Apennines posed questions about origin and identity. Accordingly, we performed a systematic investigation by means of morphological, karyological and molecular tools. All populations were diploid with 2n = 14 as for the Balkan G. scipetarum (incl. G. maloi), and also morphology suggested a close affinity to the latter. However, the Italian populations differed from typical G. scipetarum by the lower stamen:petal length and style:carpel length. By including all European and most Asian taxa in a phylogenetic analysis, we shed new light into the species-level relationships in this genus. In the combined ITS-trnL-F phylogeny, two major clades were retrieved. One included the central Asian and eastern European taxa plus the Greek endemic G. peloponnesiacum sister to G. odessanum, and one the Balkan and Apennine populations. Such findings further corroborated that the Apennine plant belong to G. scipetarum. The native status of the Italian population is supported by exclusive SNPs in both ITS1 and trnL-F sequences. Along with morphological evidence, this allows to refer it to the new subspecies G. scipetarum subsp. eddae.

The snakehead fish Channa aurolineata is a valid species (Teleostei: Channidae) distinct from Channa marulius.

Channa aurolineata is a valid species of the Marulius group. Previously treated as a synonym of C. marulius, C. aurolineata is readily distinguished from C. marulius by a different colour pattern, in which a conspicuous white posterior margin is present on the black scales that form the dark lateral blotches in larger juveniles and adults (vs. scales without white margin but with white spots in C. marulius). Channa aurolineata also differs from C. marulius by having more lateral line scales (65-71 vs 62-65), more dorsal-fin rays (55-58 vs 52-56) and more vertebrae (63-66 vs 59-63). In addition to these morphological differences, C. aurolineata is genetically more than 8% different (uncorrected p-distance) from C. marulius at the COI barcoding gene, a difference consistent with levels of genetic divergence observed among different species. The same characters that distinguish C. aurolineata from C. marulius also distinguish it from C. pseudomarulius, the other Indian member of the Marulius group. Channa aurolineata has a widespread distribution in larger rivers in Myanmar, including the Chindwin, Ayeyarwaddy, Sittaung and Thanlwin river basins. The Indo-Burman ranges appear to delineate the western geographical limit of this species, with C. marulius restricted to the western side of this mountain chain.

Migration and recent range expansion of Seminole bats (Lasiurus seminolus) in the United States

Bat species are facing increasing threats due to climate change, large-scale changes in vegetation, windpower development, and white-nose syndrome, which make research on changes in bat communities essential for conservation planning in North America. The Seminole bat (Lasiurus seminolus) occurs throughout the southeastern United States, and recent evidence suggests they may be expanding their range in North America. I used museum records, publications, and data derived from mist-net surveys conducted by various individuals and organizations to determine changes in the seasonal and historical range of Seminole bats over the past 48 years across eastern North America. Based on records obtained, Seminole bats spend winter along the Gulf Coast, Carolinas, and southern Arkansas, but migrate as far north as Missouri and Kentucky during the summer maternity season. During the autumn juvenile-dispersal period, Seminole bats undergo widespread, long-distance movements and have been recorded in unexpected locations, including the Caribbean, Wisconsin, and New York. Over the past 48 years, the northern edge of their range has advanced 521 km and the western limit of their range has advanced 185 km, at a rate of approximately 11 km/year northward. These data suggest a recent and rapid shift northward, likely in response to climate change, and an expansion westward possibly due to changes in vegetation communities across historic grassland regions.