scholarly journals Anatomy and shell shape variability in a land snail Bostryx torallyi (Stylommatophora: Bulimulidae)

2020 ◽  
Vol 68 (1) ◽  
Author(s):  
María José Miranda
Keyword(s):  
Morphometric Analysis ◽  
Large Scale ◽  
Ventral View ◽  
Land Snail ◽  
The Other ◽  
Qualitative Description ◽  
Shell Shape ◽  
Shape Variation ◽  
Geometric Morphometric ◽  
Geometric Morphometric Analysis

Introduction: The gastropod Bostryx torallyi shows high variability in shell shape and coloration. Subspecies of this organism have been described based on shell characters but, since they were slightly different, they were synonymized afterwards. Until now, shell variability has been analyzed only descriptively and its anatomy is still unknown. Objective: In this study, I provide anatomical information of B. torallyi and apply a geometric morphometric analysis to evaluate the shell shape variation among specimens. Methods: To accomplish this, type material and numerous lots were examined and dissected out. Additionally, relative warp analysis, based on 9 landmarks in ventral view of the shell, was performed using 80 specimens of 9 localities from Bolivia and Argentina. Results: According to our results, geometric morphometrics is a suitable method to evaluate differences in shell shape among localities; for instance, distinctions in the shell were noticeable between gastropods of low and high altitudes. On the other hand, it was established that the coloration of this species is independent of large-scale factors since the examined specimens came from environments with similar conditions. Furthermore, the sculpture of the protoconch and anatomy of B. torallyi coincided with the other Argentinian species of the genus. Conclusions: Therefore, I concluded that a geometric morphometric analysis of shell shape is a good complement to traditional qualitative description of the characteristics of the shell in this species.

Shell shape as indicator of pollution in marine gastropods affected by imposex

2016 ◽  
Vol 67 (12) ◽  
pp. 1948 ◽  
Author(s):  
M. A. Primost ◽  
G. Bigatti ◽  
F. Márquez
Keyword(s):  
Morphometric Analysis ◽  
Human Activities ◽  
Relative Size ◽  
Shell Shape ◽  
Marine Snail ◽  
Geometric Morphometric ◽  
Marine Gastropods ◽  
Maritime Traffic ◽  
Geometric Morphometric Analysis ◽  
Tbt Pollution

Tributyltin (TBT) and other pollutants are present in Patagonia, and are associated with maritime traffic and human activities. Cause–effect relationship between TBT and imposex development in females of marine gastropods is well documented. We tested whether the imposex incidence associated with TBT pollution is related to detectable shell-shape variations in the edible marine snail (Buccinanops globulosus). We compared shell shape of B. globulosus in six contiguous sites on a gradient of imposex and maritime traffic, by using geometric morphometric analysis. Our results indicated that the registered differences in shell shape are associated to imposex incidence in the harbour zone where previous works have detected TBT pollution. Gastropods from areas of high maritime traffic presented a rounded shell with a shorter spire, and a smaller relative size of the shell aperture, whereas the opposite shape (fusiform shape, elongated-spired shell and bigger relative size of the shell aperture) occurred in gastropod shells from areas of low maritime traffic. Shell variation registered here could be useful to detect TBT pollution in populations of B. globulosus and another neogastropod species.

A geometric morphometric analysis of hominin upper premolars. Shape variation and morphological integration

2011 ◽  
Vol 61 (6) ◽  
pp. 688-702 ◽  
Author(s):  
Aida Gómez-Robles ◽  
María Martinón-Torres ◽  
José María Bermúdez de Castro ◽  
Leyre Prado-Simón ◽  
Juan Luis Arsuaga
Keyword(s):  
Morphometric Analysis ◽  
Morphological Integration ◽  
Shape Variation ◽  
Geometric Morphometric ◽  
Geometric Morphometric Analysis

scholarly journals A new species of Prosyntexis Sharkey, 1990 (Hymenoptera: Sepulcidae) from the Lower Cretaceous Crato Formation of Brazil confirmed by geometric morphometric analysis

2021 ◽  
Vol 4 (2) ◽  
pp. 171-177
Author(s):  
CORENTIN JOUAULT ◽  
ANDRÉ NEL
Keyword(s):  
New Species ◽  
Morphometric Analysis ◽  
Lower Cretaceous ◽  
The Other ◽  
New Taxon ◽  
Additional Specimen ◽  
Geometric Morphometric ◽  
Geometric Morphometric Analysis ◽  
A New Species

Examination of new fossil specimens of Prosyntexis from the Lower Cretaceous Crato Formation of Brazil reveled a new species namely Prosyntexis sennlaubi sp. nov. To ensure the validity of the new taxon we examined previously described and figured specimens but we also figured an additional specimen of Prosyntexis gouleti Sharkey, 1990. The new species can be differentiated from the other Prosyntexis species of the Crato formation by its larger size but also in having the cell 2R1 small, the cell 2M small and short, the cell 3R1 narrow and the vein a directed toward wing apex. We performed a Geometric Morphometric Analysis (GMA) to estimate the variation in the forewing venation of the two species from the Crato Formation and ensure our placement.

scholarly journals Geometric morphometric analysis of the skull of Podocnemis spp. (Pleurodira, Podocnemididae) and its implications on the taxonomic status of Podocnemis bassleri Williams, 1956

2015 ◽  
Author(s):  
Pedro S. R. Romano ◽  
Sergio A. K. Azevedo ◽  
Alexander W. A. Kellner ◽  
Gustavo R. Oliveira
Keyword(s):  
Multivariate Regression ◽  
Phylogenetic Signal ◽  
Ventral View ◽  
Taxonomic Status ◽  
Shape Variation ◽  
Diagnostic Features ◽  
Geometric Morphometric ◽  
Geometric Morphometric Analysis ◽  
Independent Variable ◽  
The Individual

Background. Podocnemis bassleri Williams, 1956 is the oldest definite record for Podocnemis, dating back to the Miocene of South America. However, the diagnosis of P. ba. is fragile, as assumed by Williams himself. Here we evaluated the hypothesis of P. ba. as a synonym of P. expansa by exploring the shape variation of the skull among Podocnemis spp. Methods. We collected 19 landmarks on the left side of the skull in ventral view from 33 Podocnemis spp. skulls. We included in the sample a new specimen of P. ba. from the Miocene of Acre, Brazil (MCT/RJ unnumbered) and the holotype (AMNH 1662) from the Miocene of Peru, along with: P. erythrocephala (n=3), P. ex. (n=9), P. lewyana (n=1), P. sextuberculata (n=9), P. unifilis (n=6), and P. vogli (n=3). The data was then Procrustes superimposed and a Relative Warps Analysis (RW) was performed to evaluate shape variation. Also, a multivariate regression of the Partial Warps (i.e.: the eigenvectors of the “bending energy” matrix) versus the log-transformed centroid size (the independent variable) was computed in order to evaluate the allometry in the data. All analyses were fulfilled using Rohlf’s TPS softwares. Results. The two first RWs accumulated ~52% of shape variation. The individual projection of the specimens in RW1 and RW2 showed a structure partially explained by a phylogenetic signal. P. ex. and P. se., previously considered as sister-groups, were projected in the negative scores of RW1. Also, these two species were projected, respectively, in the positive and negative scores of the RW2. The two specimens of P. ba. were nested among P. ex. specimens. Furthermore, the multivariate regression revealed an effect of the size in the shape variation: larger skulls have wider maxillae and posterior region laterally extended. Discussion. According to the literature, P. ex. and P. ba. are nearly indistinguishable (besides the larger size of the second), and Williams seems to have used the Miocene age of the second as a criterion for differentiating the two taxa. Indeed, one of the diagnostic features pointed out by Williams – slightly shorter relative distance from snout tip to posterior borders of the orbits – seems to be a taphonomic outcome. Moreover, the second diagnostic character – internal palatal processes of the maxillae abruptly dorsally projected – is extended anteroposteriorly in the MCT/RJ P. ba. specimen, as in all recent taxa. So, this character is polymorphic or also results of a taphonomic outcome. As consequence, P. ba. lacks a suitable diagnosis. Our preliminary results revealed little differences in shape of P. ex. and P. ba. and a clear allometric effect in the shape variation. In conclusion, it seems reasonable to suggest that P. ba. is a junior synonym of P. ex., although we will wait to claim it after additional analyses.

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