Traditional Morphometric Approaches Research Articles

Implementation of geometric morphometry in the study of shapes of Bronze Age sickles from the Volga-Ural region

This article aims at evaluating the potential of geometric morphometry by means of an example of analysis of shapes of the Bronze Age sickles from the Volga-Ural region, as compared with the traditional morphometric approach. For the study, cast bronze sickles with hooks, categorized by V.A. Dergachev and V.S. Bochkarev into the Ibrakaevo, Derbeden, Perelyub and Yavlenka types using the traditional morphometric approach, have been selected. The analysis was applied to only full drawings of the items, including reconstructed ones, while fragmented items were not considered. The sample constitutes 167 objects: 86 Ibrakaevo, 49 Derbeden, 24 Perelyub, and 8 of the Yavlenka type. Application of geometric morphometry tools shows that, within the sample, three main forms can be easily identified, with the exception of the sickles earlier attributed to the Yavlenka type, probably due to their small number. Prepara-tion of primary files for recording landmark coordinates and processing of files with recorded coordinates were carried out in the tpsUtil program. The analysis of characteristics of changes of the forms was carried out using the principal component method in the MorphoJ program. Summarizing the obtained results, we can say that the principal components method has been able to identify three main variations of the objects. Most clear are the differences between the Ibrakaevo and Derbeden types, which show virtually no overlap. An intermediate position between them is taken by the Perelyub type, which is also distinctively grouped in the graph being close to the Ibrakaev group. In terms of identifying individual types, the results of the study are rather consistent with the data obtained by the tradi-tional morphometry. At the same time, it is possible to trace the vectors of shape variability for all types of tools based on three main components. Overall, it can be concluded that the method of geometric morphometry demonstrates its efficiency for the analysis of shapes of metal sickles and in future it could be applied to wider sample groups.

Morphometric analysis of spiny lobster (Panulirus penicillatus) and bamboo lobster (Panulirus versicolor) in Sabang Waters

This research aims to analyze morphometrics of (P. penicillatus) and (P. versicolor) in waters of Sabang. A total of 50 samples from each species of P. penicillatus and P. versicolor were used for morphometric analysis using Traditional Morphometric and Truss Morphometric approaches. Morphological analysis indicated that both lobster species are categorized into two distinct groups. Traditional morphometric character testing using ANOVA showed that species differences significantly influence the variation in morphological characters (P<0.05) in both lobsters. Further Duncan post hoc tests revealed that four characters (HL), (CHW), and (CHL)) differed significantly between the species. P. penicillatus shared three characters similar to P. versicolor, namely (HL), (CHW), and (CHL). This similarity is based on the shape of HL, CHW, and CHL in both lobsters. In the Truss Morphometric character testing with ANOVA, it was found that species differences affect the characters significantly (P<0.05). The Duncan post hoc test revealed that five characters ([A1, A3], [B1, B3], [C5, C6], D4, [D5, D6]) differed significantly between species. DFA resulted in 1 function, with an eigenvalue of 27.595, indicating that it explains 100% of the total variance. The morphological characters that significantly contribute to the differentiation between species are A1, B1, C5, A5, and D5.

Geometric Morphometrics sheds light on the systematics affinities of two enigmatic dwarf Neotropical sedges (Carex, Cyperaceae).

Geometric morphometrics (GM) is a powerful analytical tool that enables complete quantification of shapes. Its use in Botany has a great potential for complementing plant evolutionary and ecological studies. Taxonomic delimitation in Carex has been complicated due to reduction of characters and frequent homoplasy. This problem is more marked in cases where the species exhibit dwarfism. South America is the continent with the least understood Carex flora. The systematic relationships of some bizarre-looking groups were not unraveled until molecular phylogenetic studies resolved their relationships. In particular, there are two species only known from their type material whose affinities remain uncertain: Carexherteri and C.hypsipedos. These two taxa are acaulescent plants that respectively grow in the Uruguayan pampa and Peruvian high-altitude meadows. Recently, both species were ascribed to the Carexphalaroides group (subgen. Psyllophorae, sect. Junciformes) due to superficial morphological similarities, such as the androgynous peduncled spikes. However, their character combination is also coincident for its circumscription to sect. Abditispicae species. Nevertheless, in the absence of confirmation from molecular analyses, their placement must be considered preliminary until additional data can be provided. In this work we employ for the first time geometric morphometrics (GM) tools to assess the systematic affinities of two taxonomically problematic sedge species based on fruit shape. We compared utricle morphology of C.herteri and C.hypsipedos with that of C.phalaroides group and species in sect. Abditispicae. To this end we used GM and traditional morphometric approaches. Utricle shape variation along with other morphological features support the exclusion of these two species from the C.phalaroides gr. and, at the same time, show clear affinities of C.herteri to sect. Abditispicae. Carexhypsipedos remains as an incertae sedis species. Our work shows the potential utility of GM for the exploration of systematic affinities in sedges and in other graminoids.

Morphometric and genetic variations of four dominant species of snappers (Lutjanidae) harvested from the Northern Coast of Aceh waters, Indonesia

Lutjanus commonly known as snappers are economical fishes in the world, including in Indonesia. They have high morphological similarities and are difficult to distinguish. Therefore, this study aimed to validate the taxonomic status and kinship of four dominant snappers harvested from the northern coastal waters of Aceh, Indonesia, namely Lutjanus bengalensis, Lutjanus kasmira, Lutjanus gibbus, and Lutjanus fulviflamma. The samples were collected from Pulo Aceh and Lampulo fish landings. A total of 60 samples of each species were used for morphometric analysis using the traditional morphometric approach, while five from each of them served as samples for the genetic analysis with the COI gene. Morphological analysis showed that the four fish species were categorized into 3 different groups, where L. bengalensis and L. kasmira were in the same group. The genetic analysis revealed that they were grouped into four different clades, but L. bengalensis and L. kasmira were located in the same sister clade, indicating genetic closeness. L. bengalensis, L. kasmira, L. gibbus, and L. fulviflamma had two, three, three, and four haplotypes, respectively. Based on the results, the COI gene successfully distinguished the four species of snapper, where L. bengalensis and L. kasmira had morphological and genetic similarities. Furthermore, L. fulviflamma had higher genetic diversity than the others.

Morphometric classification of kangaroo bones reveals paleoecological change in northwest Australia during the terminal Pleistocene

Specimen identification is the backbone of archeozoological research. The challenge of differentiating postcranial skeletal elements of closely related wild animals in biodiverse regions can prove a barrier to understanding past human foraging behaviours. Morphometrics are increasingly being employed to classify paleozoological animal remains, however, the potential of these methods to discriminate between wild animal groups has yet to be fully realised. Here we demonstrate the applicability of a traditional morphometric approach to taxonomically classify foot and ankle bones of kangaroos, a large and highly diverse marsupial family. Using multiple discriminant analysis, we classify archaeological specimens from Boodie Cave, in northwest Australia and identify the presence of two locally extinct macropod species during the terminal Pleistocene. The appearance of the banded hare-wallaby and northern nail-tail wallaby in the Pilbara region at this time provides independent evidence of the ecological and human responses to a changing climate at the end of the last Ice Age. Traditional morphometrics provides an accessible, inexpensive, and non-destructive tool for paleozoological specimen classification and has substantial potential for applications to other diverse wild faunas.

Morphological discreteness of the estuarine croaker Pseudotolithus elongatus (Teleostei: Sciaenidae).

The estuarine croaker (Pseudotolithus elongatus, Sciaenidae) has long-term socio-economic and ecological significance in tropical and subtropical regions of the world, but little has been reported on the population demographics of this species. In this study, a traditional morphometric approach was used to test the hypothesis that island samples are morphologically distinctive from adjoining estuarine waters. The study involved a total number of 612 specimens from four islands (Alligator, Tobacco, Parrot and James) of the lower Cross River, Nigeria as well as from the mouth of the Cross River estuary, sampled from January to July 2020. Each specimen was subjected to morphometric measurements consisting of 14 allometrically modified characters. Results of principal component analysis explained 85.6% of the total variance. The pooled between-groups discriminant function analysis correctly classified 66.0% of individuals into two distinct stocks (Island and Estuary mouth). The present finding demonstrates that the Cross River Islands hold a unit stock of P. elongatus that is morphologically separable from the adjoining estuarine waters. We therefore recommend that the croaker population in Cross River should be managed as separate stocks.

Morphometry of the shell in Scaphopoda (Mollusca): a tool for the discrimination of taxa

AbstractThe alpha taxonomy of scaphopods is based mainly on the shell morphology, as it is for most molluscs. In the last three decades, the employment of morphometric variables of the shell in combination with statistics has considerably increased to aid species discrimination, but this has not been used above species level. In this study, a traditional morphometric approach was used to distinguish congeners, genera and families within the orders Dentallida and Gadilida. We studied 28 species of scaphopods from Brazil, belonging to 12 genera and five families. Twelve morphometric variables were measured, and a correlation test was done to select a set of variables without correlation as input data to perform a discriminant analysis. In the analysis of congeners, the discrimination power was high in both orders. Among the genera studied, the robustness of the analysis was drastically reduced in Dentaliida, while Gadilida maintained a high percentage of correct classifications. At the family level, both orders presented high percentages of correct classification, but the imbalance of cases for each taxon masks an inconsistent result. Based on our results, the morphometric approach was a useful tool to discriminate congeneric species of both orders and to discriminate the genera of Gadilida.

DNA barcoding of the fire ant genus Solenopsis Westwood (Hymenoptera: Formicidae) from the Riyadh region, the Kingdom of Saudi Arabia.

The ant genus Solenopsis Westwood, 1840 is the largest in Myrmicinae subfamily having almost 200 described species worldwide. They are commonly distributed in the tropics and temperate areas of the world. Some invasive Solenopsis species are very dreadful. We have already reported a fire ant species, Solenopsis saudiensis Sharaf & Aldawood, 2011, identified using traditional morphometric approaches of species identification. Present study was carried out to develop DNA Barcoding to identify Solenopsis saudiensis and to elucidate genetic structure of the various S. saudiensis populations across their distribution range in Riyadh, Saudi Arabia. The comparison of DNA barcodes showed no genetic diversity among six populations and a queen from S. saudiensis analyzed from the Riyadh region. This genetic resemblance probably reflects their adaptation toward a specific habitat, thus constituting a single and strong gene pool. Our comprehensive field survey did not provide any evidence of Solenopsis species except S. saudiensis in the Riyadh region. Solenopsis saudiensis populations were only found around date palm trees indicating their strong association with date palm groves. Moreover, S. saudiensis has 83–86% sequence identity to other Solenopsis spp. from other parts of the world. Interestingly, the highest sequence identity of (86%) was with that of Solenopsis molesta Say, 1836, the thief ant, from the USA. This study provides a working laboratory procedure and a reference library for the identification of Solenopsis saudiensis.

Geometric morphometric analysis in female freshwater crabs of Sarawak (Borneo) permits addressing taxonomy-related problems

The taxonomy of freshwater crabs requires a paradigm change in methodological approaches, particularly in investigations that use morphological techniques. The traditional morphometric approach (two-dimensional measurements) tends to be inappropriate for the identification of freshwater crabs due to their variable external morphology and lack of gonopods (conventionally used for the identification of male crabs) in females. In this study, we explore the potential use of the geometric morphometric technique for identification of female freshwater crabs, and identify taxonomic key characteristics of species. The shape of the carapace could be a good characteristic for the identification of female crabs, especially when the geometric morphometric technique is used. It was observed that the shape of the carapace has an advantage over the shape of the pleon and chela because its relatively flat orientation allows more consistent and easier data preparation for geometric morphometric analysis. The geometric morphometric technique is inexpensive, relatively less time consuming to employ, and accurate. This technique is convenient when dissection to examine the gonopods is not possible, which can damage the specimen in the case of endangered or rare species. Since the technique was used herein for only two species, more compelling and extensive evidence is needed before the reliability of the method can be proven.

Sexual dimorphism in the carapace shape and length of the freshwater palaemonid shrimp Macrobrachium potiuna (Müller, 1880) (Decapoda: Caridea: Palaemonidae): geometric and traditional morphometric approaches

Sexual dimorphism is characterized by morphological, physiological, or behavioral differences between males and females. The genus Macrobrachium is a diverse group of freshwater shrimps distributed throughout tropical and subtropical regions. They have a great intra- and interspecific morphological variation, with some species showing sexual dimorphism. We investigated the sexual dimorphism of the size and shape of the carapace and body weight of Macrobrachium potiuna (Müller, 1880) in three populations of the State of Paraná through traditional and geometric morphometric techniques. The populations were sampled from three rivers: the Pombas River, Coastal Basin, the Piraquara River, First Plateau, and the Guabiroba River, Second Plateau. Morphometric analyses indicated that male shrimps showed differences in carapace length and body weight: the higher the distance from the sea, the smaller and lighter the shrimps. Carapace shape also differed significantly between the sexes in all three populations, with males having a less robust carapace, but a more elongated rostrum than females. The morphological differences between the genders seem to reflect the reproductive roles of males and females in this environment.

Craniofacial shape in children with and without a positive otitis media history

ObjectivesPast studies using traditional morphometric approaches have reported a handful of differences in craniofacial dimensions between individuals with and without otitis media (OM). In this study, a geometric morphometry (GM) approach was used to determine if craniofacial shape is different among children with no history of OM and a history of recurrent acute OM (RAOM) at two different ages. MethodsNineteen standard landmarks were identified on lateral cephalometric radiographs from 79 children (41 Control, 38 RAOM) at 4 years and 52 children (27 Control, 25 RAOM) at 6 years of age. Following Procrustes superimposition of the landmark coordinate data, comparisons of group differences in overall size and shape were performed. Discriminant function analysis and principal component analysis were used to determine which, if any, aspects of shape variation distinguished RAOM from Control groups. ResultsAt 4 years of age, craniofacial size and shape were significantly different between RAOM and Control groups (p<0.05). Shape differences were evident in the relative positions of the mandible, cranial base, external acoustic meatus, sphenoid and palate. Those shape differences were not found in the 6-year old group. ConclusionsAt 4 years of age, the RAOM and Control groups have distinct craniofacial morphologies, but by 6 years of age these differences have largely disappeared. This is consistent with the clinical observation that excess RAOM risk resolves around 6 years of age and the hypothesis that this resolution is partially a result of age-related craniofacial changes.

Geometric and traditional morphometrics for the assessment of character state identity: multivariate statistical analyses of character variation in the genusArrenurus(Acari, Hydrachnidia, Arrenuridae)

Geometric and traditional morphometric approaches are tested to describe and reveal taxonomic characters and character states in variation of shape and size of idiosoma morphology in the Arrenuridae. Patterns of variation of idiosoma and glandularia features of males from 11 Mexican species of Arrenurus (Megaluracarus) and two species of subgenus Dadayella were explored with five landmark configurations and three sets of interlandmark distances. Separate principal component analyses (PCA) and canonical variate analyses (CVA) were performed for each data set. The eight multivariate analyses of variance among 13 a priori groups (species) detected significantly different morphometric variants, which were interpreted as different taxonomic character states. Patterns of character state similarity among species were examined with unweighted-pair grouping method using averages (UPGMA) cluster analyses on Mahalanobis distances. Analyses of five landmark configurations revealed important taxonomical variation in the anterior idiosoma outline (10 character states), the outline of the posterior region or cauda (13 states), the distribution of postocularia, and the second and third pairs of dorsoglandularia (nine states), the fourth pair of dorsoglandularia (three states), and ventroglandularia on the posterior side of idiosoma (nine character states). Multivariate analyses of three sets of distance measurements also resulted in the detection of potential taxonomic characters related to idiosoma size (12 character states), postocularia and dorsoglandularia (13 states), and ventroglandularia (nine character states). Morphometric analyses of distances and shapes provide a formal basis for the interpretation of taxonomic characters, and for the discovery of character states. These characters should be investigated further in a wider sample of species for the phylogenetic systematics of these water mites. In the meantime, idiosoma regions and structures were tested for congruence in a phylogenetic analysis, and were proposed as homologous among the species sampled.

Where to Live? How Morphology and Evolutionary History Predict Microhabitat Choice by Tropical Tadpoles

AbstractTadpoles have diverse morphologies and occupy diverse habitats. The morphological differences between tadpoles can be represented by linear and geometric measurements and used to explain the organization of tadpole assemblages. However, the effects of evolutionary history must be isolated from the morphological differences before we can determine which patterns result from the use and sharing of common ecological resources. Here, we aimed to determine how morphological similarities and phylogenetic distances affect microhabitat choice by tadpoles. We analyzed the tadpoles of 101 anuran species and classified them according to ecomorphological guild, habitat use, position in the water column, and floor substrate. We used geometric and traditional morphometric approaches to describe the morphological variation among tadpoles and calculated the patristic distance for each species. Afterwards, we used morphometric and phylogenetic matrices as predictors of the variance in the ecological matrix, using a partial redundancy analysis. When we used traditional morphometric data, phylogeny explained a large amount of the ecological variation. By contrast, when we used geometric morphometric data, morphology and phylogeny explained similar amounts of the ecological variation, showing that the technique used to extract morphological variation affects the results. We provide evidence that both morphology, as a surrogate for contemporary factors, and evolutionary inertia are important in determining the behavior of tadpoles. Thus, niche conservatism can be important in modeling the behavior of tadpoles, but does not explain all the preferences of tadpoles.

Morphology predicting ecology: incorporating new methodological and analytical approaches

Associations between the morphology of animals and their ecology have contributed to our understanding of phenotypic diversity by helping to relate form and function. Most early studies on fishes used traditional measurements of linear distances on the body or fins to quantify morphological variation among taxa. More recently, geometric morphometric analyses have gained popularity for assessing phenotypic shape variation. Along with new methodologies for quantifying morphological variation, researchers have become increasingly aware of the influence of phylogeny on morphological and ecological traits. Our study, which spanned seven cyprinid genera, assessed the abilities of traditional and geometric morphometric approaches to characterize ecologically relevant morphological variation. Furthermore, we compared morphometric approaches employing two analyses (partial Mantel test and Phylogenetic Canonical Correlation Analysis (PCCA)) that test for correlations among data sets while explicitly accounting for phylogenetic relationships. Traditional morphology and body shape showed similar correlations with habitat use in all analyses. In contrast, only traditional morphology was correlated with diet; however, this was only revealed by the PCCA. Our findings indicated the taxonomic span of species under study and the statistical treatment of data are important factors to consider when choosing between traditional or geometric morphometric approaches. In addition, a better understanding of phylogenetic relationships will improve our ability to establish associations between morphology and ecology.

Morphological variability and taxonomy of Coraebus hastanus Gory & Laporte de Castelnau, 1839 (Coleoptera: Buprestidae: Agrilinae: Coraebini: Coraebina).

Coraebus hastanus Gory & Laporte de Castelnau, 1839 is easily distinguished from the other species of the genus Coraebus Gory & Laporte de Castelnau, 1839. It was divided into three subspecies, but the main diagnostic characters were variable. In order to understand the morphological variability and taxonomy of subspecies of C. hastanus, shape of elytral apex, lateral margin of elytra and the aedeagi were analyzed using geometric morphometric and traditional morphometric approaches. Based on the results and distribution patterns of the three subspecies, C. hastanus oberthueri Lewis, 1896 is treated as synonym of C. hastanus Gory & Laporte de Castelnau, 1839, and C. hastanus ephippiatus Théry, 1938 is elevated to species rank, and these two species are also redescribed and illustrated.

Comparison of dental measurement systems for taxonomic assignment of Neanderthal and modern human lower second deciduous molars

Traditional morphometric approaches for taxonomic assignment of Neanderthal and modern human dental remains are mainly characterized by caliper measurements of tooth crowns. Several studies have recently described differences in dental tissue proportions and enamel thickness between Neanderthal and modern human teeth. At least for the lower second deciduous molar (dm 2), a three-dimensional lateral relative enamel thickness index has been proposed for separating the two taxa. This index has the advantage over other measurements of being applicable to worn teeth because it ignores the occlusal aspect of the crown. Nevertheless, a comparative evaluation of traditional crown dimensions and lateral dental tissue proportion measurements for taxonomic assignment of Neanderthal and modern human dm 2s has not yet been performed. In this study, we compare various parameters gathered from the lateral aspects of the crown. These parameters include crown diameters, height of the lateral wall of the crown (lateral crown height = LCH), lateral enamel thickness, and dentine volume of the lateral wall, including the volume of the coronal pulp chamber (lateral dentine plus pulp volume = LDPV), in a 3D digital sample of Neanderthal and modern human dm 2s to evaluate their utility in separating the two taxa. The LDPV and the LCH allow us to discriminate between Neanderthals and modern humans with 88.5% and 92.3% accuracy, respectively. Though our results confirm that Neanderthal dm 2s have lower relative enamel thickness (RET) index compared with modern humans ( p = 0.005), only 70% of the specimens were correctly classified on the basis of the RET index. We also emphasize that results of the lateral enamel thickness method depend on the magnitude of the interproximal wear. Accordingly, we suggest using the LCH or the LDPV to discriminate between Neanderthal and modern human dm 2s. These parameters are more independent of interproximal wear and loss of lateral enamel.

Spatial organization of process domains in headwater drainage basins of a glaciated foothills region with complex longitudinal profiles

Lithologic transitions and glaciations create complex longitudinal profiles that control contemporary erosion and deposition processes. In areas with these characteristics, traditional morphometric approaches for predicting process domains, such as area‐slope plots, can be augmented by considering other predictors measured from high resolution lidar‐derived digital elevation models (DEMs). Ordinal logistic regression was used to model the distribution of hillslope, swale, colluvial channel, and fluvial channel domains, as identified during field surveys. The study area was a glaciated region of the Rocky Mountain foothills with a complex lithostructural setting. Relationships between domains and a suite of geographic information system–derived descriptors were explored. Predictors included profile anomalies measured at the reach and basin scale using a normalized stream length–gradient (SL/k) index. Drainage area was the dominant factor controlling domains. A model with area as the only predictor was 82% accurate. Reach slope relations were not consistent. A model that also included lithology and basin‐scale SL/k index variation was 87% accurate. Domain transitions had larger area thresholds in basins with resistant conglomerate versus sandstone or shale formations and where SL/k index was more variable along a profile. In a restricted model of hillslope, swale, and colluvial channel domains, profile curvature measured over 100 m was also related to domain occurrence. A model for regional‐scale mapping applications with six additional predictors was 95% accurate. The results showed that ordinal logistic regression can be used to predict and map process domains in regions with complex physiography using descriptors measured from high ‐resolution DEMs.

Morphological diversification in introduced pumpkinseed (Lepomis gibbosus): assessing trussbased and geometric morphometric approaches

We examined morphological diversification in introduced pumpkinseed, Lepomis gibbosus from Iberian reservoirs using traditional morphometric (TM) and geometric morphometric (GM) approaches to assess the degree of external differentiation among pumpkinseeds occupying four habitats separated along simultaneous dimensions of flow and trophic structure. Results from both approaches showed significant differentiation among pumpkinseeds occupying these habitats. Among functional characters deemed significant in differentiating among morphs, body depth and caudal dimensions were the most consistently significant under the TM approach, whereas differences in the caudal peduncle region were more evident under the GM approach. Recent comparative studies advocate the use of GM over TM; however, our results demonstrate that TM is beneficial for quantifying differences in specific morphological characters, which is the crux of studies in functional morphology.

A new species of Buchia (Bivalvia: Buchiidae) from British Columbia, Canada, with an analysis of buchiid bipolarity

Critical reinvestigation of the bivalve Buchia cf. blanfordiana Jeletzky, 1965 from the Upper Jurassic of western British Columbia indicates that it is morphologically distinct from B. blanfordiana Stoliczka, 1866 of the Indo-Pacific region. We analyzed collections from relatively coeval sections containing multiple buchiid species from the Northern and Southern Hemispheres and used ten morphological characters to describe Buchia shell shape and size. We tested for taxonomic differences on left and right valves using a traditional morphometric approach with both linear and angular measurements and Fourier (outline) analyses. Phenetic discrimination revealed considerable overlap in the morphospace, but high classification rates between the two groups when compared with a step-wise discriminant analysis. This study supports the retention of the Indo-Pacific genera Australobuchia Zakharov, 1981 and Malayomaorica Jeletzky, 1963 and confirms that Buchia (=Australobuchia) blanfordiana is restricted to the Southern Hemisphere. Consequently, we propose the new name Buchia columbiana n. sp. for material assigned to Buchia cf. blanfordiana Jeletzky, 1965. Our results have implications for bipolarity and migration of the genus Buchia, supporting previous suggestions that buchiids formerly identified as Buchia from the Southern Hemisphere should be grouped as a separate genus.

Insular morphological divergence in the lizard Liolaemus pictus (Liolaemidae)

AbstractLiolaemus pictus is a widely distributed arboreal lizard species in southern Chile. Within this species, mainland and island subspecies have been described mainly based on external morphological characters, however, their diagnostic characters have not been accurately demarcated. We used both traditional and geometric morphometrics to study the morphological divergence in L. pictus subspecies. Since geographic isolation can be related to environmental variation (e.g., variation in abundance and richness of insects or fruits), we predict that the L. pictus morphology could vary in head shape between mainland and island localities.Our results show morphological divergence in all variables analyzed among the island and mainland localities. The traditional morphometric approach reveals differences between populations from the mainland and island localities, where the mainland populations show a larger head size. Geometric morphometric data indicate that the eye orbits of the island specimens are more extended than in the mainland specimens in the dorsal view; this is probably related to a different capacity of substrate used. Also, in the lateral view, the eye orbits are extended and the head shape is less dorso-ventrally compressed in the island locality than in mainland populations and the terminal mouth position is more posterior in island specimens. We suggest that the morphological variation between mainland and island localities could be related to the fact that these populations were isolated during the last maximum glacial period in southern Chile, a period in which geomorphologic and bioclimatic features of this area were modified forming the present archipelago.