Morphological characterization, cytogenetic analysis, and geographical distribution of the Pygmy Marbled Newt Triturus marmoratus pygmaeus (Wolterstorff, 1905) (Caudata: Salamandridae)

Triturus marmoratus pygmaeus, a problematicsubspecies of the Marbled Newt from the southern part of the Iberian Peninsula, is redescribed using specimens collected in the “typical” area. Diagnostic external morphological features are provided to permit the accurate determination of the specimens belonging either to T. m. marmoratus or to T. m. pygmaeus. These diagnostic features were applied to individuals both from the field and from museum collections. The results indicate a larger distributional area for to T. m. pygmaeusto than was previously recognized. The distribution of to T. m. marmoratusto ranges over the northern half of the Iberian Peninsula and most of France; to T. m. pygmaeusto occupies the southwestern part of the Iberian Peninsula. The contact area between the two subspecies seemsto be located alongthe Central Range Mountains (Sistema Central) in Portugal and Spain. to T. m. marmoratusto extends southwards beyond this borderline in three areas: Serra da Estrela (Portugal), Sierra de Gata (Spain) and Sierra de Guadarrama (Spain). The only point at which to T. m. pygmaeusto reaches northwards beyond the Central System is near Puerto de Malagón (Madrid Province, Spain). No cases of strict sympatry, nor individuals with intermediate morphologicalfeatures have been observed. The results of an extensive cytogenetical analysis do not show any differences between to T. m. pygmaeusto and to T. m. marmoratusto . Interestingly, however, the to T. m. pygmaeusto populations from Doñana (Huelva Province, Spain) showed an exclusive, though little differentiated, C-banding pattern.

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Penultimate Glacial Cycle marks the maximum glacier extent in the Iberian Peninsula: New evidence from the Serra da Estrela (Central System, Portugal)

Geomorphology ◽

10.1016/j.geomorph.2021.107781 ◽

2021 ◽

pp. 107781

Author(s):

Gonçalo Vieira ◽

David Palacios ◽

Nuria Andrés ◽

Carla Mora ◽

Lorenzo Vázquez Selem ◽

...

Keyword(s):

Iberian Peninsula ◽

Glacial Cycle ◽

Central System ◽

Serra Da Estrela ◽

New Evidence

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Habitat differentiation and geographic separation of Isoetes velata populations in central Iberian Peninsula

Botanica Complutensis ◽

10.5209/bocm.75525 ◽

2021 ◽

Vol 45 ◽

pp. e75525

Author(s):

José Antonio Molina

Keyword(s):

Iberian Peninsula ◽

Late Glacial ◽

Diagnostic Features ◽

Central System ◽

System A ◽

Habitat Differentiation ◽

Northwestern Spain ◽

Geographic Separation ◽

Spanish Central System

Populations of Isoetes velata were studied in order to provide more information on their habitat and distribution in the Western and Northwestern Iberian Peninsula. Habitat together with morphology of megaspores were used as diagnostic features. The form I. velata subsp. velata f. lereschii is considered here as a synonym of I. velata subsp. asturicense and therefore only two taxa remain within the species: I. velata subsp. velata and I. velata subsp. asturicense. Intermediate individuals have been found in the Western Central System. The differentiation within the I. velata group appears to be the result of gradual genetic divergence after isolation. Palaeobotanical data confirm the presence of I. velata subsp. asturicense in Late Glacial lake sediments in northwestern Spain. Cluster classification of the soft-water vegetation with Isoetes velata subsp. asturicense revealed two main groups in the Spanish Central System. A single association, the Sparganio angustifolii-Callitrichetum fontqueri which includes Iberian Atlantic stands of Sparganium angustifolium and Isoetes velata subsp. asturicense, is here recognized. Besides, a variant of the association with Eleocharis acicularis is identified in shallow temporary waters in the Western Sierra de Gredos.

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A quantitative approach to inner shell losses

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010977x ◽

1978 ◽

Vol 36 (1) ◽

pp. 526-527 ◽

Cited By ~ 2

Author(s):

R.D. Leapman ◽

P. Rez ◽

D.F. Mayers

Keyword(s):

Energy Transfer ◽

Cross Section ◽

Cross Sections ◽

Accurate Determination ◽

Background Intensity ◽

Core Excitation ◽

Quantitative Basis ◽

Cross Section Differential ◽

Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

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Fast calibration of CBED patterns for quantitative analysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100149209 ◽

1993 ◽

Vol 51 ◽

pp. 674-675

Author(s):

M.A. Gribelyuk ◽

M. Rühle

Keyword(s):

Reciprocal Lattice ◽

Accurate Determination ◽

Incident Beam ◽

Crystal Thickness ◽

Structure Model ◽

Beam Direction ◽

Transmitted Beam ◽

Reciprocal Vector ◽

On Line

A new method is suggested for the accurate determination of the incident beam direction K, crystal thickness t and the coordinates of the basic reciprocal lattice vectors V1 and V2 (Fig. 1) of the ZOLZ plans in pixels of the digitized 2-D CBED pattern. For a given structure model and some estimated values Vest and Kest of some point O in the CBED pattern a set of line scans AkBk is chosen so that all the scans are located within CBED disks.The points on line scans AkBk are conjugate to those on A0B0 since they are shifted by the reciprocal vector gk with respect to each other. As many conjugate scans are considered as CBED disks fall into the energy filtered region of the experimental pattern. Electron intensities of the transmitted beam I0 and diffracted beams Igk for all points on conjugate scans are found as a function of crystal thickness t on the basis of the full dynamical calculation.

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Computer-Assisted High-Re Solution TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100179567 ◽

1990 ◽

Vol 48 (1) ◽

pp. 162-163

Author(s):

F.A. Ponce ◽

H. Hikashi

Keyword(s):

Signal To Noise Ratio ◽

Accurate Determination ◽

Computer Software ◽

Video Camera ◽

Image Contrast ◽

Objective Lens ◽

Computer Assisted ◽

Optical Parameters ◽

Astigmatism Correction

The determination of the atomic positions from HRTEM micrographs is only possible if the optical parameters are known to a certain accuracy, and reliable through-focus series are available to match the experimental images with calculated images of possible atomic models. The main limitation in interpreting images at the atomic level is the knowledge of the optical parameters such as beam alignment, astigmatism correction and defocus value. Under ordinary conditions, the uncertainty in these values is sufficiently large to prevent the accurate determination of the atomic positions. Therefore, in order to achieve the resolution power of the microscope (under 0.2nm) it is necessary to take extraordinary measures. The use of on line computers has been proposed [e.g.: 2-5] and used with certain amount of success.We have built a system that can perform operations in the range of one frame stored and analyzed per second. A schematic diagram of the system is shown in figure 1. A JEOL 4000EX microscope equipped with an external computer interface is directly linked to a SUN-3 computer. All electrical parameters in the microscope can be changed via this interface by the use of a set of commands. The image is received from a video camera. A commercial image processor improves the signal-to-noise ratio by recursively averaging with a time constant, usually set at 0.25 sec. The computer software is based on a multi-window system and is entirely mouse-driven. All operations can be performed by clicking the mouse on the appropiate windows and buttons. This capability leads to extreme friendliness, ease of operation, and high operator speeds. Image analysis can be done in various ways. Here, we have measured the image contrast and used it to optimize certain parameters. The system is designed to have instant access to: (a) x- and y- alignment coils, (b) x- and y- astigmatism correction coils, and (c) objective lens current. The algorithm is shown in figure 2. Figure 3 shows an example taken from a thin CdTe crystal. The image contrast is displayed for changing objective lens current (defocus value). The display is calibrated in angstroms. Images are stored on the disk and are accessible by clicking the data points in the graph. Some of the frame-store images are displayed in Fig. 4.

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