Geometric Morphometric Analysis Research Articles

Unveiling otolith shape variation: geometric morphometric analysis of three croaker species (Acanthuriformes: Sciaenidae)

Unveiling otolith shape variation: geometric morphometric analysis of three croaker species (Acanthuriformes: Sciaenidae)

Mid-Pliocene hominin diversity revisited

Geometric morphometric analyses are used to examine the maxillary shape of the Kenyanthropus platyops Leakey, Spoor, Brown, Gathogo, Kiarie, Leakey & McDougall, 2001 holotype KNM-WT 40000 and the Australopithecus deyiremeda Haile-Selassie, Gilbert, Melillo, Ryan, Alene, Deino, Levin, Scott & Saylor, 2015 holotype BRT-VP-3/1, expanding on the work of Spoor et al. (2010, 2016) by using more accurate data and a larger comparative sample. The main objective is to assess whether these two specimens differ from the contemporary taxon Australopithecus afarensis Johanson, White & Coppens, 1978 and more broadly from species of Australopithecus Dart, 1925 and ­Paranthropus Broom, 1938, as well as from each other. Five two-dimensional landmarks recorded on virtual models obtained from computed tomography scans quantify key features of the maxilla used in the differential diagnoses of K. platyops and A. deyiremeda. Principal component analyses were performed to describe shape differences, and the magnitudes of these differences and their statistical significance were assessed using Procrustes and Mahalanobis distances, respectively. The maxillary shapes of both KNM-WT 40000 and BRT-VP-3/1 are significantly different from A. afarensis, the former more so than the latter, and they differ from A. afarensis in dissimilar ways. Where KNM-WT 40000 has a more anterosuperiorly positioned zygomatic process with a longer, more orthognathic, and transversely flat subnasal clivus than A. afarensis, the shape difference of BRT-VP-3/1 is best described as a posterior shift (retraction) of the entire dental arcade. The findings of this study quantitatively support the species status of K. platyops and A. deyiremeda, and corroborate the notion that hominin diversity extended well into the mid-Pliocene of eastern Africa.

The mandible of Salbatore II: A new Ursus deningeri site in the northern Iberian Peninsula

Ursus deningeri, together with Ursus spelaeus sensu lato, are chronospecies that belong to the Quaternary iconic cave bear lineage. They inhabited Iberia from the late Early to the late Middle Pleistocene. Here we describe a complete bear mandible recovered from Salbatore II cave (Basque Country). To assess its taxonomy, we compared it with other European Pleistocene cave and brown bears. Comparisons were made concerning its morphology and using both traditional and 3D geometric morphometrics analyses. The mandible has several morphological similarities with the cave bears such as a high corpus and deep masseter fossa. However, it exhibits a coronoid process that leans backwards, a pointed pterygoid process, and the p1 and p3 are present. These are characteristics customarily associated with U. deningeri and U. arctos. Metric analyses show that Salbatore II fits within the cave bears variation, with a minimum overlap with brown bears once size is accounted for. However, geometric morphometric analyses show that Salbatore II is similar to U. arctos, but within U. deningeri variation. Based on the overall size and the morphological characteristics, Salbatore II displays U. deningeri affinities with many ancestral characteristics, suggesting a minimum mid-Middle Pleistocene age rarely recorded in the Cantabrian region.

Phylogenetic conflict between species tree and mitochondrial gene trees in Murininae (Mammalia, Chiroptera) and validation of the genus Harpiola

AbstractThe subfamily Murininae is renowned for its inherent taxonomic challenges associated with sampling difficulties and morphological similarities. At present, three genera are acknowledged within the subfamily; however, their phylogenetic interrelations and systematic classification remain debated. In this study, the separation of Harpiola at the genus level was robustly supported by our phylogenomic analyses based on the mitochondrial genome, coding sequences (CDSs) and ultraconserved elements (UCEs) from 12 individuals covering all three genera of Murininae. Notably, a distinctive mito‐nuclear discordance emerged, with the nuclear genealogy ((Harpiocephalus, Harpiola), Murina) contrasting with the mitochondrial genealogy (Harpiocephalus, (Harpiola, Murina)). The integration of these findings with inferences of demographic history reveals that dramatic environmental changes during the Pleistocene glacial and inter‐glacial cycles have shaped the current distribution of Murininae. Moreover, the detection of extensive gene flow between ancient lineages of Harpiola and Murina suggests that an ancestral ‘ghost’ Murina lineage may have contributed its mitochondrial DNA, along with a limited portion of nuclear DNA, to Harpiola in a bygone hybridization zone. In addition to molecular analyses, we employed traditional and geometric morphometric analyses of skulls to differentiate the three genera. Harpiocephalus is readily distinguishable, but Harpiola and certain species of Murina exhibit overlapping characteristics both morphometrically and geometrically which may be the outcome of ancient introgression events. This finding highlights the importance of fine‐scale morphological distinctions within the latter genera, which may be the outcome of ancient introgression events.

Geometric morphometric analysis of cranium shape differences in sheep from colonial Sydney, Australia

Geometric morphometrics (GMMs) is a valuable tool that can be used to identify variability within species, thereby distinguishing between breeds and closely related animals (e.g. sheep and goats). Identifying fine morphological differences is key to better understanding early herd management practices. Interestingly, GMMs has yet to be used in a colonial Australian context, particularly in the foundational period of colonial Sydney from 1790 to 1850. Given the overall importance of sheep to the development of colonial Australia, this analytical gap provides an opportunity to identify potential morphological variability, and so better understand colonial herd management strategies. Here we use GMMs to analyse an archaeological assemblage of sheep crania (n = 27) from the colonial Clarence Street site, in Sydney, Australia. These crania are compared to modern sheep specimens to test GMMs’ effectiveness at distinguishing between, as well as potentially allocating individuals to, specific breeds. We found certain morphological variations between the study assemblages, and so discuss our results in the context of a variety of explanatory frameworks such as differences in husbandry practices in colonial Sydney.

Blank predetermination in the Iberian Acheulean. Insight from the cleaver on flake assemblage of Casal do Azemel site (Leiria, Portugal) by a Geometric Morphometric approach

Over the last decades, the increase of data available for the study of the archaeological topic in the Iberian Peninsula during the Middle Pleistocene has favoured the understanding of the technological trends of the Iberian Acheulean assemblages. These have features of a Large Flake Acheulean (LFA), displaying, among other traits, a significant presence of cleavers on flake, a specific tool type that is of great cultural and technological value. Particularly, these artefacts are privileged to discuss the importance of blank predetermination in the Acheulean techno-complex. Following this reason, in the present work we aimed to explore this topic through the 2D Geometric Morphometric Analysis of the cleaver on flake assemblage from Casal do Azemel (Leiria, Portugal), an example of a paradigmatic Iberian Acheulean site that has one of the largest collections of this type of tools in Western Europe.
 The results obtained revealed that no significant morphological differences were found according to the technological solutions applied to the acquisition of the blank and its secondary transformation. Considering that in most of the cases these tools display a low degree of secondary transformation, these data suggest that underlying the production of Casal do Azemel’s cleaver on flake assemblage was not only a technological and cognitive flexibility (given its typological composition), but also a conceptual, structural, and morphological standardisation. These observations allowed us to discuss the significance of blank predetermination in the Acheulean, implying the existence of greatly structured technical and cognitive prerequisites.

Ecomorphology of Longnose Gar (Lepisosteus osseus): on the influence of size, sex, and river location

AbstractEcomorphology is essential to understanding the evolution and biogeography of species. However, morphological studies that focus on nongame or ‘rough’ fish groups such as Gar (Lepisosteidae), outside of a phylogenetic context, are comparatively rare. Herein, we investigate the effects of sex, size, and location in a river to assess the potential for sexual dimorphism, allometry, habitat, or some combination to drive observed morphologic variation. Our dataset includes 230 Longnose Gars (Lepisosteus osseus) made up of both males and females of a wide range of sizes collected from three different sites corresponding to the upper, middle, and lower Great Pee Dee River in South Carolina. Dorsal and lateral photographs were taken from each specimen and landmarked for 2D geometric morphometric analyses. Discriminant function analyses (DFA) were also conducted on a few linear trusses to compare the accuracy of sex-related shape aspects that emerged from morphometrics as a possible field-based tool to help fisheries managers understand their stock populations. Overall, location was a statistically significant predictor of shape, yet the differences were not biologically meaningful. Additionally, sex and size were strong predictors of shape, with the greatest differences seen in the largest individuals. DFA of field measurements found that the Snout Length-to-Total Length ratio accurately predicted sex 71% of the time, with females having longer snouts than males. Differences in ratio between sexes can allow tentative sex assignments without lethal gonadal inspection. This study presents the first standardized whole-body 2D geometric morphometrics protocol for Longnose Gar.

Convergent evolution in shape in European lineages of gobies.

During their radiation, certain groups of animals evolved significant phenotypic disparity (morphological diversity), enabling them to thrive in diverse environments. Adaptations to the same type of environment can lead to convergent evolution in function and morphology. However, well-documented examples in repeated adaptations of teleost fishes to different habitats, which are not primarily related to trophic specialization, are still scarce. Gobies are a remarkable fish group, exhibiting a great species diversity, morphological variability, and extraordinary ability to colonize very different environments. A variety of lifestyles and body forms evolved also in European lineages of gobies. We conducted two-dimensional geometric morphometric and phylomorphospace analyses in European lineages of gobies and evaluated the extent of convergent evolution in shape associated with adaptation to various habitats. Our analyses revealed the change in shape along the nektonic-cryptobenthic axis, from very slender head and body to stout body and wide head. We showed convergent evolution related to mode of locomotion in the given habitat in four ecological groups: nektonic, hyperbenthic, cryptobenthic and freshwater gobies. Gobies, therefore, emerge as a highly diversified lineage with unique lifestyle variations, offering invaluable insights into filling of ecomorphological space and mechanisms of adaptation to various aquatic environments with distinct locomotion requirements.

Comparying two methods of disparity analysis of the anterior portion of m1 in the gray voles (Rodentia, Arvicolini) in a model sample: frequency analysis of morphotypes and geometric morphometrics

An analysis of disparity of the anterior portion of m1 shape in the gray voles in an artificial sample consisting of 5 groups with different frequency distributions of 5 morphotypes was carried out. Two main approaches were applied: (a) traditional analysis of frequency distribution of discrete morphotypes and (b) geometric morphometrics (GM) based on a strictly quantitative description of the shape of anterior portion of m1. The groups were compared quantitatively: Cavalli-Sforz–Edwards’ coefficient was applied in the first case, while the thin plate spline and Procrustes analyses in the second; their results were analyzed using a number of standard statistical methods (dispersion analysis, discriminant analysis, multidimensional scaling). Disparity within the groups was assessed using Shannon entropy index and averaged Procrustes distance. Traditional and GM approaches were shown to provide very similar results, with GM having a number of important advantages by being strictly quantitative. The second approach is recommended as the basic to replace the traditional one for explorations in disparity of tooth crown shape in the voles.

Exploring Shape Variance in Waterbirds' Pad Feet: A Geometric Morphometric Analysis

Waterbirds usually have webbed feet, which help them move easily through water. These pad feet fall into four main categories: palmate, semipalmate, totipalmate, and lobate. In this study, morphological diversity among the pad feet of different waterbirds breeds such as the West Indian whistling duck (Anas bahamensis), mandarin duck (Aix galericulata), red-breasted goose (Branta ruficollis), wood duck (Aix sponsa), mute swan (Cygnus olor), greylag goose (Anser anser), mallard (Anas platyrhynchos), Pekin duck (Anas platyrhynchos domesticus), redhead duck (Aythya americana), Egyptian goose (Alopochen aegyptiaca), and pelican (Pelecanus onocrotalus) was examined by the geometric morphometric method. 2D images of 12 waterbirds pad feet from different parts of Türkiye were analyzed from dorsal view. In total thirteen landmarks were used. The analysis focused on principal component 1 and principal component 2 values. Principal component 1 shows slightly greater changes occurring on the lateral toes II and IV, as well as in the interdigital webbing below the average. Principal component 2 reveals greater shape changes also on the toes II and IV, which are more lateral. Geometric morphometric analysis proves valuable in identifying variations in the shape of the pad feet among various breeds of waterbirds, making it an effective tool for taxonomic purposes.

Evolutionary trends of caviomorph rodents as elucidated using their oldest foot anatomy

AbstractExtant caviomorph rodents exhibit a wide array of locomotor types and substrate preferences, which are reflected in their foot morphology. It is not known when these patterns were established or how they evolved in this taxonomically and ecologically diverse clade. We studied the anatomy of the earliest preserved feet of caviomorphs represented by the late Oligocene stem octodontoid Platypittamys and the Early Miocene cavioid Neoreomys, stem octodontoid Sciamys and erethizontoid Steiromys. Integrating information provided by extant species, we performed qualitative and geometric morphometric analyses, reconstructing ancestral morphologies to interpret the evolution of the foot of caviomorphs through a time‐scaled phylogeny, and infer locomotor behaviours. We identified an important morphological disparity in these early genera that is explained by the presence of different locomotor adaptations and phylogenetic signal at different taxonomic levels. Neoreomys was probably generalized ambulatory, Steiromys possibly scansorial, Platypittamys possibly ambulatory with digging abilities, and Sciamys was probably agile ambulatory–scansorial. Our study indicated that several foot features can distinguish higher taxonomic groups of caviomorphs, at least since the Early Miocene. Early in their history, morphological constraints would have limited the capacity of evolutionary change more markedly in Cavioidea and Chinchillidae. In Cavioidea, at least two evolutionary trends were detected. Among octodontoids, extant octodontids and Platypittamys showed convergent anatomical patterns. Erethizontoidea retained a foot essentially unchanged since the Early Miocene after acquiring a noteworthy evolutionary innovation. In sum, the earliest foot morphologies of caviomorphs are very important in identifying evolutionary tendencies and the origin of their postcranial disparity.

Genetic and Phenotypic Divergence in a Dung Beetle 50 Years After Its Introduction to Australia.

Species translocations are increasingly being used in conservation and for biological control. The success of a translocation can be strongly influenced by the evolutionary processes occurring during the early phase of the introduction and the subsequent spread to new regions. In this study, morphological variation and population genetic structure were assessed in the African dung beetle Digitonthophagus gazella, a species that was intentionally introduced to Australia for biological control in 1968 and subsequently spread widely across the northern part of the continent. A dataset based on 1594 neutral single nucleotide polymorphism (SNP) loci that were genotyped in 187 individuals from 12 sites revealed significant genetic divergences between sites (global F ST = 0.118) and provides evidence of restricted gene flow among established populations at small to moderate spatial scales (74-500 km). Geometric morphometric analyses revealed significant divergence among populations in the shape of the foretibia, a trait ecologically important for tunnelling in soil and dung. Moreover, phenotypic divergence in this trait for both sexes was significantly higher than genetic differentiation at selectively neutral loci (P ST > F ST), suggesting that directional selection is contributing to the phenotypic divergences among populations. Our study shows how population structure can establish quickly in an introduced species and highlights the importance of considering local adaptation when performing translocations on established populations.

Analyzing 3D facial morphology: Insights from a comparative European and South African study on population affinity, sex, age, and allometry

Variable growth patterns and multifactorial mechanisms cause variation in facial shape. These differences in facial morphology pose challenges for craniofacial reconstruction. Three-dimensional (3D) imaging modalities are a valuable resource for examining these variations. In this study, we used geometric morphometric methods to evaluate the effects of population affinity, sex, age, and allometry on the variation and covariation of hard and soft tissue facial morphology matrices in a sample of French and white South African individuals. Seventy-six and 108 cone-beam computed tomography scans of white South African and French nationals, respectively, were retrospectively acquired. Three-dimensional anatomical structures (hard and soft tissue matrices) were extracted using MeVisLab© v. 2.7.1 software for dense landmarking of 43 craniometric, 50 capulometric, and 559 sliding landmarks. Geometric morphometric analyses were used to quantify shape differences attributed to population affinity, sex, age, and allometry and assess the covariation between hard tissue structures and soft facial tissues. Hard and soft tissue facial matrices were influenced by population differences, sexual dimorphism, and aging. Compared to sex and age, population affinity had the strongest influence on variation. In French individuals, all hard and soft tissue matrices were sexually dimorphic, except for the eyes and left external auditory meatus (EAM). In white South Africans, sexual dimorphism was observed for the mouth, midface, and left EAM. Significant shape differences were also observed for specific age groups. The underlying skull and overlying soft tissues were strongly associated with the nose and anterior nasal aperture (correlation, r2-PLS = 0.976), followed by the right ear and right EAM (r2-PLS = 0.875) and the left ear and left EAM (r2-PLS = 0.871) in white South Africans. For French individuals, relatively weak to moderate correlations were observed, and the covariation between matrices was nonsignificant, except for the association between the right ear and right EAM (r2-PLS = 0.499). The smallest covariation was observed between the mouth and midfacial matrix in both populations (South African: r2-PLS = 0.464; French: r2-PLS = 0.367), which was also nonsignificant. This study revealed that 3D imaging technology and geometric morphometric methods can accurately quantify and visualize facial morphology differences. These methods can also evaluate the association between skull structure and soft facial features.

Multiple Paths to a Larger Mouth: Morphological Divergence in Two Island Populations of Australian Tiger Snakes (Notechis scutatus)

We studied ontogenetic variation in skull morphology in tiger snakes sampled from mainland South Australia (Coffin Bay), mainland Western Australia (Herdsman Lake), Franklin Island, and Hopkins Island. The snakes from the two islands were selected because of their unusually large absolute body and head size, likely attained as a result of dietary constraints and strong selective pressure during thousands of years of isolation on islands. We performed geometric morphometric analysis of the skulls from these snakes to identify and precisely quantify morphological differences. Island snakes are born larger (trunk length) than mainland snakes, and consequently also tend to have larger absolute head size at birth. The heads of island snakes also show a faster relative growth rate (positive allometry) compared to those of mainland snakes, likely to cope with the large prey items found on these islands. However, the snakes from the two islands differ from each other in terms of morphological change associated with ontogeny, especially with regard to a palatal bone (ectopterygoid), which, compared to mainland snakes, is relatively longer in the snakes from Hopkins Island but shorter in the snakes from Franklin Island. Some morphological traits potentially associated with promoting a larger gape were also observed in one of the mainland populations (Herdsman Lake), consistent with standing variability for selection. Our results reveal that discernible changes in morphology and allometry in skull bones have evolved in island populations of tiger snakes in less than 10 000 years, and suggest that the large heads of island tiger snakes might develop via slightly different paths through morphospace on different islands.

The Oriental hornet, Vespa orientalis Linnaeus, 1771 (Hymenoptera, Vespidae): diagnosis, potential distribution, and geometric morphometrics across its natural distribution range.

We present a short review of the biology, diagnostic characteristics, and invasiveness of the Oriental hornet, Vespa orientalis. We also performed an analysis of the shape of the forewings (geometric morphometrics) of different geographic groups along their native distribution and their potential geographical distribution using the MaxEnt entropy modeling. Our results show a wide potential expansion range of the species, including an increase in environmentally suitable areas in Europe, Asia, and Africa but more especially the Western Hemisphere, where the species was recently introduced. The geometric morphometric analysis of the forewings shows that there are three different morphogroups: one distributed along the Mediterranean coast of Europe and the Middle East (MEDI), another along the Arabian Peninsula and Western Asia but excluding the Mediterranean coast (MEAS), and one more in northern Africa north of the Sahara and south of the Mediterranean coast (AFRI), all of which show differences in their potential distribution as a result of the pressure from the different environments and which will also determine the capacity of the different morphogroups to successfully invade new habitats.

Insights into archaeological and modern neotropical biomes: Examining diet and shape variation through white-tailed deer lower third molar

The white-tailed deer (Odocoileus virginianus Zimmermann 1780) holds significant ecological importance across the Americas, both historically and in modern times. This species ranges from southern Canada to Brazil and exhibits polytypic characteristics, adapting well to diverse habitats including temperate, subtropical, semi-arid, rainforest, and savanna environments. In paleontology and archaeology, the comparison of dental characteristics between extant mammal species with known diets is commonly employed to infer the feeding behaviors of their ancient counterparts. This method assumes that extant and fossil species share similar dietary preferences, aiding in the identification of past environmental contexts. Consequently, we employed a multiproxy approach, combining the study of dental wear and 2D geometric morphometrics, to investigate potential relationships between molar shape, diet, and biomes among extant white-tailed deer populations across the Americas. Our analysis included a comparison with archaeological data from Panama. We sampled 274 extant lower second molar specimens for micro- and mesowear analysis, along with 105 lower third molar specimens from natural science museums for 2D geometric morphometric analysis. These were compared with a sample of 65 archaeological specimens from Panama. Our findings revealed distinct variations in the shape of lower m3 molars among extant white-tailed deer populations across different biomes, with notable differences observed in the archaeological samples as well. Micro- and mesowear analyses also indicated biome-related differences, suggesting a general browsing diet for white-tailed deer with nuanced variations across biomes. Mesowear analysis further suggested a dietary spectrum ranging from pure browsers to browser-mixed feeders. These findings offer valuable insights for the interpretation of fossil deer specimens recovered from archaeological sites.

Quantitative analysis of facial shape in children to support respirator design

The COVID-19 pandemic demonstrated the need for respiratory protection against airborne pathogens. Respirator options for children are limited, and existing designs do not consider differences in facial shape or size. We created a dataset of children's facial images from three cohorts, then used geometric morphometric analyses of dense and sparse facial landmark representations to quantify age, sex and ancestry-related variation in shape. We found facial shape and size in children vary significantly with age from ages 2 to 18, particularly in dimensions relevant to respirator design. Sex differences are small throughout most of the age range of our sample. Ancestry is associated with significant facial shape variation in dimensions that may affect respirator fit. We offer guidance on how to our results can be used for the appropriate design of devices such as respirators for pediatric populations. We also highlight the need to consider ancestry-related variation in facial morphology to promote equitable, inclusive products.

Sphaeroptica: A tool for pseudo-3D visualization and 3D measurements on arthropods.

Natural history collections are invaluable reference collections. Digitizing these collections is a transformative process that improves the accessibility, preservation, and exploitation of specimens and associated data in the long term. Arthropods make up the majority of zoological collections. However, arthropods are small, have detailed color textures and share small, complex and shiny structures, which poses a challenge to conventional digitization methods. Sphaeroptica is a multi-images viewer that uses a sphere of oriented images. It allows the visualization of insects including their tiniest features, the positioning of landmarks, and the extraction of 3D coordinates for measuring linear distances or for use in geometric morphometrics analysis. The quantitative comparisons show that the measures obtained with Sphaeroptica are similar to the measurements derived from 3D μCT models with an average difference inferior to 1%, while featuring the high resolution of color stacked pictures with all details like setae, chaetae, scales, and other small and/or complex structures. Shaeroptica was developed for the digitization of small arthropods but it can be used with any sphere of aligned images resulting from the digitization of objects or specimens with complex surface and shining, black, or translucent texture which cannot easily be digitized using structured light scanner or Structure-from-Motion (SfM) photogrammetry.

Gradual exacerbation of obstetric constraints during hominoid evolution implied by re-evaluation of cephalopelvic fit in chimpanzees.

Under the obstetrical dilemma hypothesis, sexual dimorphism in pelvic shape is a solution to accommodate high fetopelvic constraints. It is therefore unclear why chimpanzees display a human-like pattern of pelvic sexual dimorphism despite having easier births enabled by small neonates and capacious pelvic canals. Here we reassessed chimpanzee fetopelvic fit using three-dimensional simulations, revealing a similarly constricted midpelvis as in humans, with even narrower outlet dimensions. Geometric morphometric analyses confirm that female chimpanzees have larger pelvic canals than males despite a smaller body size and a morphology that maximizes pelvic dimensions favourable for parturition, particularly in smaller-bodied individuals. Together with evidence for increased neurological immaturity at birth relative to monkeys, our findings imply substantial obstetric constraints in chimpanzees and possibly other apes. We therefore propose that difficult birth did not arise abruptly in Homo with increasing encephalization but evolved gradually through a series of obstetric compromises from an already constricted birth canal shared across anthropoid primates. Specifically, we propose that obstetric selection pressures exacerbated incrementally with the stiffening of the symphysis that accompanied body size increase in hominoids, while subsequent adaptations to bipedalism shortened the ilium. The resulting contorted birth canal required obligatory fetal rotation, thus greatly increasing birth difficulty.

Analysis of the pharyngeal structure of the genus Oreochromis for species identification through geometric morphometrics in the Aguamilpa reservoir, Nayarit, Mexico

Tilapia is an important fishing resource in economic terms for continental ecosystems such as dam reservoirs and lagoons. In Nayarit, the Aguamilpa Dam reservoir contributes around 50 % of the tilapia production in the state. However, despite the social and economic importance of the resource, there are few studies on it in this reservoir, and it is still unknown with certainty which species are found in the reservoir. This work is the first report for the Aguamilpa reservoir, where geometric morphometrics was used as a tool for the identification of tilapia species. The pharyngeal plate of 230 organisms was used for the geometric morphometrics analysis. According to this study, the existence of three species of the genus Oreochromis (O. aureus, O. niloticus and Oreochromis mossambicus) is confirmed; according to the analysis of canonical variables, the three species were correctly discriminated. This allows us to conclude that the use of geometric morphometrics in the pharyngeal plate is a useful structure for the identification of species in the reservoir.