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Author(s):  
Ésio de Castro Paes ◽  
Gustavo Vieira Veloso ◽  
Aymbiré Angeletti da Fonseca ◽  
Elpídio Inácio Fernandes Filho ◽  
Maurício Paulo Ferreira ◽  
...  

Author(s):  
D. G. Malikov ◽  
◽  
S. E. Golovanov ◽  
◽  

In this paper morphological structure of the first lower molar m1 tooth of the narrow-skulled vole from alluvial deposits of the Pre-Altai Plain Middle Neo-Pleistocene is described. Morphological study of the vole remains showed that they belong to the modern species Microtus gregalis. At the same time, the study sample showed significant differences, both in morphological structure and in the size of the first lower molar, in comparison with the recent representatives of the same territory. The set of morphological and morphometric data shows that the studied voles occupy an intermediate position between M. gregaloides of the Early and M. gregalis of the Late Neo-Pleistocene. The ratio of m1 morphotypes also showed the relative primitiveness of the M. gregalis sampling. Morphological study of remains of the narrow-skulled vole from the Solonovka, Petropavlovskoe and Malinovka-4 locations confirmed the previously determined age for sediments containing the remains of microtheriofauna.


Diversity ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 605
Author(s):  
Daniel Stec

To date, 34 tardigrade taxa have been recorded from Vietnam and this includes only two macrobiotid species belonging to the genus Mesobiotus. In this paper, two additional species of this genus, one of the M. harmsworthi group and one of the M. furciger group, are reported and described as new for science (Mesobiotus imperialis sp. nov., Mesobiotus marmoreus sp. nov.). Both descriptions have an integrative character providing detailed morphological and morphometric data collected by phase contrast and scanning electron microscopy that are linked to genetic data. The latter constitute DNA sequences of molecular markers that are commonly used in tardigrade taxonomy. The genus phylogeny is also provided, elucidating the phylogenetic position of the newly discovered taxa.


2021 ◽  
Author(s):  
Ellen J Coombs ◽  
Ryan N Felice

Three-dimensional measurements of morphology are key to gaining an understanding of a species' biology and to answering subsequent questions regarding the processes of ecology (or palaeoecology), function, and evolution. However, the collection of morphometric data is often focused on methods designed to produce data on bilaterally symmetric morphologies which may mischaracterise asymmetric structures. Using 3D landmark and curve data on 3D surface meshes of specimens, we present a method for first quantifying the level of asymmetry in a specimen and second, accurately capturing the morphology of asymmetric specimens for further geometric analyses. We provide an example of the process from initial landmark placement, including details on how to place landmarks to quantify the level of asymmetry, and then on how to use this information to accurately capture the morphology of asymmetric morphologies or structures. We use toothed whales (odontocetes) as a case study and include examples of the consequences of mirroring landmarks and curves, a method commonly used in bilaterally symmetrical specimens, on asymmetric specimens. We conclude by presenting a step-by-step method to collecting 3D landmark data on asymmetric specimens. Additionally, we provide code for placing landmarks and curves on asymmetric specimens in a manner designed to both save time and ultimately accurately quantify morphology. This method can be used as a first crucial step in morphometric analyses of any biological specimens by assessing levels of asymmetry and then if required, accurately quantifying this asymmetry. The latter not only saves the researcher time, but also accurately represents the morphology of asymmetric structures.


2021 ◽  
Author(s):  
◽  
Katie Susanna Collins

<p>A novel, highly-integrated approach combining morphometric, stratocladistic and sclerochronological methods has been applied to two genera of New Zealand Cenozoic crassatellid bivalve (Family Crassatellidae): Spissatella Finlay, 1926 and Eucrassatella Iredale, 1924. This study builds on previous work on Spissatella that demonstrated their amenability to shape analysis and provided a foundation for evolutionary studies of the group. The taxonomy of these crassatellids has been in need of revision; a number of changes to generic placement having been proposed in recent publications without redescription. These bivalves are character-depauperate and known only from fossil material within New Zealand, making them challenging subjects for the phylogenetic analysis that would, ideally, inform taxonomic revision. Geometric morphometric methods have been used to characterise the morphological variation of the study group in terms of shape. Landmarks/semilandmarks that capture internal hard-part morphology and external shell shape, have been compared with internal landmarks only, outline shape semilandmarks only, and outline shape Fourier transform methods, and are shown to best combine comprehensive coverage of total shell form with high correct reassignment of individuals to taxa in multidimensional morphospace. Procrustes-superimposed landmark/semilandmark configurations have been ordinated using Principal Components Analysis (PCA), and PCA plots have been used to compare the shape variation of each species. The independance in morphospace of Spissatella n. sp. C from S. trailli and S. clifdenensis has been established. Covariation of internal morphology and shell-shape has been interpreted as supporting the interdependance of shell and body/mantle proposed by Stasek (1963). PCA scores have been combined with traditional morphological characters and stratigraphic data to produce a phylogenetic tree using stratocladistics, a form of parsimony-based analysis which seeks to minimise combined morphological and stratigraphic debt. This technique also assesses the placement of taxa in ancestral positions on internal nodes of the tree. Combining discretised morphometric data with stratigraphic and morphological data in a single analysis has been shown to produce a more resolved tree than analyses based only on continuous morphometric data. The new analyses demonstrate paraphyly of both Eucrassatella and Spissatella as previously recognised. A taxonomic revision of the studied taxa has been undertaken, incorporating information from both morphometric and phylogenetic studies. Spissatella subobesa and S. maudensis are referred to Eucrassatella. Spissatella discrepans is synonymised with S. acculta. Triplicitella n. gen. and S.maxwelli n. sp. are described. Oxygen isotope analysis has been employed to show that shell-banding in these species is, on average, likely to have been laid down annually. Using this information, the longitudinal dataset of outlines from Crampton & Maxwell (2000) has been recalibrated to use chronological age rather than size to compare shape across taxa, and investigate heterochrony in twelve pairs of species representing either ancestor-descendant, sister-group or lineage-segment relationships. All of the heterochronic processes sensu Gould (1977), namely progenesis, neoteny, acceleration and hypermorphosis, as well as proportioned dwarfism and proportioned gigantism, are identified as having affected evolution within this clade.</p>


2021 ◽  
Author(s):  
◽  
Katie Susanna Collins

<p>A novel, highly-integrated approach combining morphometric, stratocladistic and sclerochronological methods has been applied to two genera of New Zealand Cenozoic crassatellid bivalve (Family Crassatellidae): Spissatella Finlay, 1926 and Eucrassatella Iredale, 1924. This study builds on previous work on Spissatella that demonstrated their amenability to shape analysis and provided a foundation for evolutionary studies of the group. The taxonomy of these crassatellids has been in need of revision; a number of changes to generic placement having been proposed in recent publications without redescription. These bivalves are character-depauperate and known only from fossil material within New Zealand, making them challenging subjects for the phylogenetic analysis that would, ideally, inform taxonomic revision. Geometric morphometric methods have been used to characterise the morphological variation of the study group in terms of shape. Landmarks/semilandmarks that capture internal hard-part morphology and external shell shape, have been compared with internal landmarks only, outline shape semilandmarks only, and outline shape Fourier transform methods, and are shown to best combine comprehensive coverage of total shell form with high correct reassignment of individuals to taxa in multidimensional morphospace. Procrustes-superimposed landmark/semilandmark configurations have been ordinated using Principal Components Analysis (PCA), and PCA plots have been used to compare the shape variation of each species. The independance in morphospace of Spissatella n. sp. C from S. trailli and S. clifdenensis has been established. Covariation of internal morphology and shell-shape has been interpreted as supporting the interdependance of shell and body/mantle proposed by Stasek (1963). PCA scores have been combined with traditional morphological characters and stratigraphic data to produce a phylogenetic tree using stratocladistics, a form of parsimony-based analysis which seeks to minimise combined morphological and stratigraphic debt. This technique also assesses the placement of taxa in ancestral positions on internal nodes of the tree. Combining discretised morphometric data with stratigraphic and morphological data in a single analysis has been shown to produce a more resolved tree than analyses based only on continuous morphometric data. The new analyses demonstrate paraphyly of both Eucrassatella and Spissatella as previously recognised. A taxonomic revision of the studied taxa has been undertaken, incorporating information from both morphometric and phylogenetic studies. Spissatella subobesa and S. maudensis are referred to Eucrassatella. Spissatella discrepans is synonymised with S. acculta. Triplicitella n. gen. and S.maxwelli n. sp. are described. Oxygen isotope analysis has been employed to show that shell-banding in these species is, on average, likely to have been laid down annually. Using this information, the longitudinal dataset of outlines from Crampton & Maxwell (2000) has been recalibrated to use chronological age rather than size to compare shape across taxa, and investigate heterochrony in twelve pairs of species representing either ancestor-descendant, sister-group or lineage-segment relationships. All of the heterochronic processes sensu Gould (1977), namely progenesis, neoteny, acceleration and hypermorphosis, as well as proportioned dwarfism and proportioned gigantism, are identified as having affected evolution within this clade.</p>


2021 ◽  
Author(s):  
Norman MacLeod ◽  
Benjamin Price ◽  
Zachary Stevens

Abstract The phylogenetic ecology and wing ecomorphology of the Afro-Asian dragonfly genus Trithemis have been investigated previously. Curiously, results reported for the forewing and hindwing shape variation in the latter were, in some ways, at odds with expectations given the mapping of landscape and water-body preferences over the Trithemis cladogram. To confirm these results we conducted a wing-shape investigation of 27 Trithemis species that employed a robust statistical test for phylogenetic covariation, more comprehensive representation of Trithemis wing morphology and a wider range of morphometric data-analysis procedures. Contrary to results published previously, statistical comparisons of forewing and hindwing mean shapes with the Trithemis cladogram revealed no statistically significant pattern of phylogenetic covariation. Moreover, landmark-based and image-based geometric morphometric analysis results, as well as embedded image-contrast deep learning analysis results, all demonstrated that both wings exhibit substantial convergent wing-shape similarities among, and differences between, species that inhabit open and forested landscapes and species that hunt over temporary/standing or running water bodies. Geometric morphometric data and data-analysis methods yielded the worst performance in identifying wing shape distinctions between Trithemis habitat guilds and the direct analysis of wing images using an embedded, image-contrast, convolution (deep learning) neural network delivered the best performance. Bootstrap and jackknife tests confirmed that our results are not artifacts of overtrained discriminant systems or the “curse of dimensionality”. In addition to our conclusions pertaining to Trithemis ecomorphology, the discrepancy between the previous investigation’s results and ours appears to reflect decisions made with regard to the manner in which complex morphological structures are sampled and analyzed. Naturally, results and interpretations of patterns in morphometric data pertain only to the data collected, not necessarily to other aspects of the structures from which those data were collected. For samples of morphologically similar taxa, landmark-based sampling strategies may be effective provided a sufficient number of landmark points distributed across all structures of potential interest exist. However, in a large number of instances analysis of full digital images of the structures under consideration may prove to be a more robust and effective sampling strategy, especially when coupled with analysis via machine learning procedures.


Zootaxa ◽  
2021 ◽  
Vol 5067 (3) ◽  
pp. 429-438
Author(s):  
SEVİLAY OKKAY ◽  
C. TOLGA GÜRKANLI ◽  
YILMAZ ÇİFTÇİ ◽  
VİOLETTA YURAKHNO ◽  
AHMET ÖZER

Members of the class Myxosporea Bütschli, 1881 have a cosmopolitan distribution in a wide variety of fish species worldwide. In the present study, the black scorpionfish Scorpaena porcus collected from the Sinop coasts of the Black Sea was investigated for myxosporean parasites using both conventional and molecular methods in the period between September 2015 and August 2019. Using morphological and morphometric data, the myxosporean parasite Ceratomyxa scorpaeni Garbouj, Rangel, Castro, Hmissi, Santos, Bahri, 2016 was identified in the gall bladder of host fish. Molecular analysis of the 18S rDNA gene confirmed the identity of this parasite as C. scorpaeni. This is the first report of its occurrence in the Black Sea.  


2021 ◽  
Author(s):  
◽  
Michael J Dann

<p>This work provides new information about the native Southern Ant complex Monomorium antarcticum. In the first experimental chapter (chapter two) the diversity of species within the complex, the utility of DNA barcode molecular data in such taxonomic work and how DNA barcode data combines with traditional morphological and morphometric data is investigated. The second experimental chapter (chapter three) explores the genetic structuring of the complex and how that relates to the complexs recent biogeographic history and the dispersal potential, both natural and human mediated. The two experimental chapters (chapters two and three) in this thesis have overlap of portions of the methods and results as they have been written as a pair of papers so as they can be read independently from each other.</p>


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