Geometric Morphometric Approach Research Articles

Geometry of posterior larval spiracles to identify medically and forensically important calliphorids in Thailand

Fly identification is the primary step of analysis in forensic entomology. Although morphology and molecular techniques are considered satisfactory methods, some constraints may arise from a financial or even human point of view. Over the past decade, the geometric morphometric approach has been increasingly advocated for the classification and identification of arthropods. This study explored the method for species identification of 800 third-instar larvae of eight blow fly species of medical and forensic importance: Chrysomya chani Kurahashi, Chrysomya megacephala (Fabricius), Chrysomya (Ceylonomyia) nigripes Aubertin, Chrysomya pinguis (Walker), Chrysomya (Achoetandrus) rufifacies (Macquart), Hemipyrellia ligurriens (Wiedemann), Lucilia cuprina (Wiedemann), and Lucilia porphyrina (Walker). Based on the posterior spiracles geometry, the cross-validation revealed a relatively high percentage of correct classification in most species, ranking from 86% to 100%. The results of this study confirmed that the geometric morphometric (GM) analysis of posterior spiracles might be utilized as a larva identification tool. Therefore, this GM method represents one way of overcoming difficulties with the identification of blow fly larvae and can support further studies of these flies.

Ctenocephalides orientis and Ctenocephalides felis in Thailand: Head geometry by species, sex and geography.

Fleas in the genus Ctenocephalides serve as biological vectors or intermediate hosts of microorganisms such as bacteria, rickettsia, protozoa and helminths. Ctenocephalides felis has a worldwide distribution, while C. orientis has long been considered as a subspecies of C. felis in Asia. To help the morphological recognition of these two species and further explore their differences, we used the geometric morphometric approach applied to the head. Both sexes were examined. Five anatomical landmarks of the head were used, and to capture the curvature of the front head, 10 semilandmarks were added. There was a consistent difference in species classification accuracy when considering landmarks only versus their combination with semilandmarks, suggesting the importance of the curve of the head as a taxonomic signal. Using or not the labels in the reclassification analyses, the head shape allowed by itself almost perfect recognition of the two species, in both sexes, even after adjustment for prior probabilities. The same approach disclosed a high level of sexual size and shape dimorphism in both species. The contribution of size variation to the discrimination by shape was much more important between sexes (from 27% to 45%) than between species (from 0.7% to 7.1%). Nevertheless, in our data, size never could represent a way to reliably recognise the sex of an individual, even less its species. Geographical variation in head shape could only be explored for the C. orientis sample. No significant correlation of morphometric variation with geography could be detected, which would be consistent with gene flow between Thai provinces. The geometric morphometric approach of the flea head, when it incorporates head curves, is a promising tool for rapid, economical, and accurate species and sex identification. It is, therefore, a useful tool for future epidemiological and demographic studies.

A geometric morphometric approach to identify uncomplete snake vertebrae from raptor bird feeding remains

The Hungarian meadow viper (Vipera ursinii rakosiensis) is an endangered subspecies of Vipera ursinii, which faces high predation pressure, partially due to avian species. To create a systematic method for estimating the measure of predation pressure, we developed a geometric morphometric approach to identify both undamaged and damaged vertebrae of snake species found in Hungarian meadow viper habitats from raptor feeding remains. We used linear discriminant analysis with a reference material of vertebrae from identified snake species as training data. We also tested its efficiency by predicting the identification results of different simulation levels based on vertebra completeness. We practiced this method on vertebrae of unknown species of snakes obtained from nests and pellets of short-toed snake eagles (Circaetus gallicus, n = 9), common buzzards (Buteo buteo, n = 14) and Montagu's harriers (Circus pygargus, n = 3). The identification approach showed high accuracy, even in the case of missing landmarks to some extent. We identified vertebrae remnants of Natrix natrix (n = 172, 83.9%), Coronella austriaca (n = 10, 4.9%) and V. u. rakosiensis (n = 23, 11.2%). Both, the reptile specialist C. gallicus and the generalist B. buteo proved to be preying on V. u. rakosiensis, while samples of C. pygargus did not contain any snake remains despite of previous observations of V. ursinii predations. Our approach is applicable for other studies and taxa as well, therefore can be a practical tool for classification of incomplete vertebrae, which is otherwise hardly identifiable. Furthermore, it could be applied to help estimate predation pressure on endangered snake species.

Investigating temporal bone variation of colonial populations from St-Lawrence Valley, Quebec: A 3D geometric morphometric approach.

In Quebec, genetic and genealogical research are used to document migratory events and family structures since colonial times, because bioarchaeological analysis is limited by poor skeletal preservation. This article aims to fill this gap by exploring past population structure in the St-Lawrence Valley from the French (1683-1760) and British (1760-1867) regimes using morphological variation of well-preserved temporal bones. 3D geometric morphometrics shape data from seven populations (five Catholics of French descent and two Protestants of British descent; n = 214) were collected from temporal bones. Using Procrustes distances and both MANOVA and Discriminant Function Analysis, morphological differences were measured to calculate affinities patterns among populations. Shape variations were explored with between-group analysis, Mahalanobis distances and quantified by means of Fst estimates using Relethford-Blangero analysis. Despite strong affinities between all Catholic cemeteries, all show divergent morphological regional diversity -especially Montreal and the fortified villages dedicated to its defense. Montreal exhibits low increase in morphological variance over three centuries. As our results show no morphological differences between the Catholic and the Protestant cemeteries in Montreal, this fact may highlight the potential presence of Irish or admixed individuals in Montreal cemeteries after the British takeover. Patterns of morphological diversity highlighted that French colonists did not equally contribute to the descendant populations as reflected by significant interregional variation. Although historical records show that French and English-speaking populations did not tend to admix, morphological affinities between Protestants and Catholics in the beginning of the industrial era in Montreal could reflect the genetic contribution of Catholic Irish migrants. All Catholic cemeteries display distinct morphologies, highlighting differential contributions from French colonists and founder effects, which have increased regional differences. Montreal Catholic (French descent) and Protestant (English colonists) cemeteries show significant morphological affinities at the beginning of the industrial era. The Irish migration following the British conquest may explain morphological similarities observed between Catholic and Protestant cemeteries.

Pervasive cranial allometry at different anatomical scales and variational levels in extant armadillosAlometría craneal generalizada a diferentes escalas anatómicas y niveles de variación en armadillos actuales.

Allometry, i.e., morphological variation correlated with size, is a major pattern in organismal evolution. Since size varies both within and among species, allometry occurs at different variational levels. However, the variability of allometric patterns across levels is poorly known since its evaluation requires extensive comparative studies. Here, we implemented a 3D geometric morphometric approach to investigate cranial allometry at three main variational levels-static, ontogenetic, and evolutionary-and two anatomical scales-entire cranium and cranial subunits-based on a dense intra- and interspecific sampling of extant armadillo diversity. While allometric trajectories differ among distantly related species, they hardly do so among sister families. This suggests that phylogenetic distance plays an important role in explaining allometric divergences. Beyond trajectories, our analyses revealed pervasive allometric shape changes shared across variational levels and anatomical scales. At the entire cranial scale, craniofacial allometry (relative snout elongation and braincase reduction) is accompanied notably by variations of nuchal crests and postorbital constriction. Among cranial subunits, the distribution of allometry was highly heterogeneous, with the frontal and petrosal bones showing the most pervasive shape changes, some of which were undetected at a more global scale. Evidence of widespread and superimposed allometric variations raises questions on their determinants and anatomical correlates and demonstrates the critical role of allometry in morphological evolution.

Outline-based geometric morphometrics: Wing cell differences for mosquito vector classification in the Tanaosri mountain range, Thailand

Recent studies have revealed taxonomic signals within the wing cells of certain mosquito species. In our study, wing cell differentiation among mosquito vectors from the Tanaosri mountain range in Thailand was evaluated using the outline-based geometric morphometric (GM) approach. Our focus was on four specific wing cells for GM analysis: the wing contour (external cell), the second submarginal cell (internal cell 1), the first posterior cell (internal cell 2), and the third posterior cell (internal cell 3). Before proceeding with the GM approach, the identity of seven mosquito genera and 21 species was confirmed using molecular techniques. Our validated classification tests demonstrated that the performance of mosquito species classification varies according to genus. Notably, three Aedes species exhibited the highest accuracy for both internal cell 2 and internal cell 3, each registering a score of 93.20 %. In the case of two Mansonia species, the wing contour displayed a remarkable accuracy of 98.57 %. Consequently, we suggest the use of the outline-based GM approach, particularly focusing on the wing contour, for differentiating Mansonia annulifera and Mansonia uniformis. In contrast, the highest accuracy for classifying Culex species was found in internal cell 1, at 75.51 %, highlighting the challenges due to similarities in wing cells within this genus. These findings provide a guideline for future applications of the outline-based GM approach, focusing on wing cells, as an alternative method to classify mosquito vector species.

Geometric Morphometrics Applied to Cartography

The morphological differences between two geographical maps can be highlighted by a polycentric distance cartogram resulting from a bidimensional regression. Beyond the communicational interest of the transformations thus produced, the method makes it possible to reveal the differences in structure and therefore constitutes a real research tool. However, bidimensional regression can only compare the shape of two maps. Since the 1990s, geometric morphometrics has revolutionized the morphological analysis of natural structures (and others). It has since been applied in many fields of research but not in cartography. This article describes the theoretical and methodological bases of a method combining bidimensional regression with a geometric morphometrics approach to compare the shape of several geographical maps. Geometric morphometrics and bidimensional regression indeed share common approaches of the statistical shape analysis like homologous landmarks and interpolation grids. However, there is no software in geometric morphometrics capable of directly reading geographical data, which would facilitate the work of cartographers accustomed to GIS software. That is why we present MapMorphy, a tool specifically developed for this task. An example on ancient maps illustrates the method.

The relationship between wing morphology and foraging guilds: exploring the evolution of wing ecomorphs in bats

Abstract Different aspects of foraging strategies in bats have been studied to understand the evolution of flight in mammals. General descriptors of wing morphology associated with flight performance, such as aspect ratio and wing loading, allowed us to describe ecomorphs determined by the dietary preferences of bat species. However, the role of wing shape divergence in the evolution of bat foraging strategies remains little explored. We adopted a two-dimensional geometric morphometric approach to quantify the wing shape and size variation explained by phylogenetic relatedness (families) and to evaluate the covariance between foraging guilds and flight descriptors based on phylogenetic comparative methods in 69 Neotropical bat species. We tested whether wing morphology represents a reliable marker of the foraging guild, and we explored the rate of shape evolution among foraging guilds to describe divergent trends that could explain the morphological and ecological diversification. Our results suggest that the earliest bat ancestor was an aerial forager occupying the edge space, which is congruent with the observed evolution of wing shape from an edge space wing morphology. The relationship between wing shape and foraging space defines wing ecomorphs, which probably evolved early in bat ancestors; a process other than convergence could explain this association.

Evaluation of age variation changes in cervical vertebrae: 2-Dimensional (2D) geometric morphometrics approach

Age estimation in adults is a complicated task because of various external factors occur concurrently with increasing age. The geometric morphometric method (GMM) is an approach that focuses on shape analysis and is widely recognized for its high reliability and reproducibility. The aim of this study was to explore the variation of cervical vertebrae among different age groups of the Malaysian population by GMM. Lateral skull radiographs of 432 subjects comprising four adult age groups; young adult age group (20–30 years old), early middle age group (31–40 years old), late middle age group (41–50 years old) and, elder adult age group (51–60 years old) were selected. Fifty-three 2-dimensional (2D) landmarks were applied to the digitalized radiographs by TPSDig2 (Version 2.31) software. Geometric morphometric analysis was performed by MorphoJ software. Results showed that the first three principal components (PC) contributed to 47.71 % of the cervical vertebrae variation and were shown in both lollipop and wireframe graphs. Procrustes ANOVA indicated that the shape was significantly different among different age groups. Canonical variate analysis revealed significant differences of both mahalanobis and procrustes distances among age groups with substantial individual overlap within groups. Discriminant function analysis (DFA) showed a correct classification rate for 61.5 % of cases respective to age groups. In conclusion, this study found significant differences in the shape of cervical vertebrae among different age groups of the Malaysian population using the GMM.

Three-dimensional changes in the cranial base associated with soft-diet feeding.

Masticatory activity affects the morphology of the maxillo-mandibular complex, however, its influence on the cranial base remains to be elucidated. The recent integration of quantitative morphometric analysis with 3D imaging enabled a comprehensive and high-resolution morphological characterization of the craniofacial complex. We aimed to investigate the influence of masticatory activity on the morphology of the growing cranial base by three-dimensional (3D) geometric morphometric approach using micro-CT. The micro-CT data was reanalyzed to illustrate the 3D shape of the cranial base, and wireframe models were generated by connecting landmarks on the images. In the original study, mice were fed a soft diet (SD) of powdered pellets or a conventional hard diet (HD) for 6 weeks from 3 to 9 weeks of age, immediately after weaning. A principal component (PC) analysis analyzed shape variations and assessed their significance, while canonical variate (CV) analysis facilitated the comparison and differentiation of groups based on shape, unveiling meaningful shape distinctions. Three PCs were extracted that significantly separated the SD and HD groups among those explaining variations in shape. These PCs were related to the length of the sphenoid bone, the width of the anterior part of the sphenoid bone, and the length of the cranial base. Furthermore, one CV effectively distinguished SD from HD, and CV analysis showed that the sphenoid was shortened in the length and narrowed at the border of the temporal bone in SD mice. Masticatory loading affects the skeletal development of the cranial base. The morphology of the sphenoid bone was affected in both the sagittal and transverse axes.

Comparative Skull and Mandible Geometric Morphometrics of Two Species of Mice, Mus domesticus and Mus macedonicus (Muridae, Rodentia) in Turkey

Using a geometric morphometrics approach, we examined shape and size variations of skull and mandible bone of two evolutionarily distantly related mice from Turkey: Mus domesticus and Mus macedonicus. PCA analyses revealed overlap in dorsal cranium and mandible shapes of both species, consistent with previous traditional morphological methods. The skull of M. macedonicus seems to be larger in size than M. domesticus according to box-plot analyses of centroid size values, however there is no obvious difference for the mandible. No difference was observed between sexes in either of the characters. We suggest that future studies focus on dental characteristics and also consider the variation among local populations and ecological variables.

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.

Head morphology reflects the introduction history in a globally invasive carnivore—the small Indian mongoose

Abstract Species displaced outside their native range may face new pressures resulting from both environmental gradients and important differences in ecosystem structure. We investigated how this may impact the morphological variation of a globally introduced carnivoran, the small Indian mongoose. Previous research showed size variations in several introduced populations, suggesting that these differences resulted from character release in response to the absence of competition from native species. Here, we contrasted the morphological evolution of indigenous and introduced populations using geometric morphometric approaches on the head system of a large sample of specimens belonging to several regions. Our analyses revealed that differences in size and shape between introduced and native populations do not support hypothesis of character release. These results suggest that morphological variations in introduced populations may reflect the introduction history of the species, rather than evolutionary processes resulting from changes in ecosystem composition.

Reed bamboos drive skull shape evolution in bush frogs of the Western Ghats, Peninsular India.

Reed bamboo is a major ecological and economic resource for many animals, including humans. Nonetheless, the influence of this plant's evolutionary role on the morphology of animal species remains unexplored. Here, we investigated the significance of bamboo habitats as ecological opportunities in shaping the skull morphology of bush frogs (Raorchestes) from the Western Ghats, Peninsular India. We applied a three-dimensional (3D) geometric morphometric approach to capture the skull shape of 55 species of bush frogs. We visualized the skull shape variables in phylomorphospace with principal component analysis and performed phylogenetic generalized least-squares analysis to assess the impact of cranial size (evolutionary allometry) and habitat (bamboo or non-bamboo) on cranial shape. We quantified the morphological disparity between bamboo and non-bamboo bush frogs' skull shape, and employed RRphylo, a phylogenetic ridge regression method, to access the evolutionary rate and rate shifts of skull shape change. The phylomorphospace delineated bamboo and non-bamboo bush frogs. While cranial shape exhibited a significant but smaller association with size, its association with habitat type was non-significant. We detected, however, significant differences in skull shape between the two frog groups, with bamboo frogs showing higher morphological disparity and a remarkable shift in the evolutionary rate of skull shape diversification. These findings underscore the role of reed bamboo in the evolution of skull shape in the radiation of frogs, endemic to the Western Ghats. We demonstrate that the association between the members of two distinct endemic clades (bamboo reeds and bamboo frogs) is the outcome of a deep-time ecological opportunity that dates back to the Miocene.

Predictive use of modern reference osteological collections for disentangling the shape of Eurasian equid cheek teeth and metapodials in archaeological material

AbstractEquids have shaped past Eurasian societies in many ways. This applies in particular to domestic horses, donkeys, and their hybrids. Key to documenting modes of exploitation and cultural trajectories in past societies is the correct taxonomic classification of tooth and bone specimens found in archaeological sites. However, close osteomorphological resemblance of wild and domestic equids and their economically valuable hybrids, that is, mules and hinnies, complicates the identification of intentionally fragmented or naturally damaged archaeological specimens. Here, we apply geometric morphometrics (GM) to mandibular teeth and metapodials, two skeletal elements commonly found in archaeological collections and known for their diagnostic properties using traditional morphometric methods. We registered a statistically representative set of 2D and 3D coordinates on mandibular teeth (P3, P4, M1, and M2) and metapodials of 92 domestic horses (Equus caballus Linnaeus, 1758), 70 domestic donkeys (Equus asinus Linnaeus, 1758), 30 hybrids, and 63 Asiatic wild asses (Equus hemionus Pallas, 1775). Taxonomic classification of these 255 specimens considered both shape and form, applying linear discriminant analysis, k‐nearest neighbors algorithm, and artificial neural networks to seven combinations of taxa. We obtained correct classifications in over 87% and 80%, respectively, of the premolars and molars and in over 93% and 89%, respectively, of the metacarpals and metatarsals. This modern dataset was then used to classify equid specimens from three archaeological sites in the Middle East already analyzed morphologically. Taking into account the past zoogeography of wild equids and the historical distribution of their domesticated descendants and hybrids, the GM approach presented in this study offers the possibility to morphologically classify archaeological equids with far greater certainty than has been the case so far.

The harpoon stands yonder: Shape variation and functional constraints in Mesolithic complex weapon points from the circum-Baltic Sea area

Mesolithic harpoons are structurally complex weapon points and significant sources of archaeological information. Nonetheless, separating different types of information inherent in harpoon point shapes (e.g., aspects relating to mechanical performance, personal or group craft variation and chronology) using descriptive approaches is difficult. In this study, we employed an exploratory geometric morphometric approach to the analysis of 28 Mesolithic harpoon points, and 144 undated harpoon points from the circum-Baltic Sea area in order to retrieve both functional and spatiotemporal information. By analyzing harpoon structure statistically through (i.) a shape proxy (harpoon silhouette) and (ii.) harpoon sub-structures (barbs), we have been able to reveal information related to both variation in shape convention and functional constraints. Barb shape results revealed statistically significant chronological and geographical groupings with spatiotemporal barb-shape trajectories made visible and objective evaluation of how barb-shape conventions impacted functional variation. In addition, harpoon silhouette shape distributions were shown to have potential as sources for robust artifact classifications in relation to functional constraints and raw-material engagement. These results suggest that morphometric approaches similar to the ones we have employed offer promising ways of addressing specific archaeological questions in the context of harpoon point shapes and, more generally, other complex weapon point forms.

Geometric morphometrics of macro- and meiofaunal priapulid pharyngeal teeth provides a proxy for studying Cambrian “tooth taxa”

Priapulids are marine, benthic ecdysozoan worms that feed using a distinctive toothed pharynx. While only a handful of lineages have survived to the present day, the Cambrian priapulid stem group left behind a rich record of articulated body fossils and characteristic trace fossils in the form of burrows. Recently, the fossil record of isolated priapulid cuticular elements including pharyngeal teeth has gained increased attention as a means of revealing cryptic priapulid taxa otherwise unknown among macrofossils. In this study, we focus on the ecological implications of shape variation in the teeth of extant and extinct priapulids, which display substantial morphological differences between taxa and life stages. We define a landmarking scheme to capture shape variation in priapulid teeth and apply it to our dataset, which includes a breadth of tooth specimens from extant macrofaunal and meiofaunal lineages alongside numerous Cambrian priapulid teeth preserved as isolated small carbonaceous fossils. Through ordination of the principal components of shape, we explore the priapulid tooth morphospace and find evidence that its occupancy has expanded since Cambrian times, indicating a corresponding expansion of the group’s ecological niche. We also employ our geometric morphometric approach to make linear discriminant analysis-based taxon assignments based on tooth morphology, which can be helpful for classifying enigmatic “tooth taxa” known solely from fossil teeth. Finally, we use discriminant analysis to study tooth shapes from a functional perspective, considering known ecologies to characterize the ecological functions of unclassified isolated teeth.

Brain size and shape diversification in a highly diverse South American clade of rodents (Echimyidae): a geometric morphometric and comparative phylogenetic approach

Abstract Brain morphological variation is analysed through virtual endocasts in a highly diversified clade of caviomorph rodents belonging to the family Echimyidae. Diversification in brain size and shape is explored through geometric morphometrics and comparative phylogenetic analyses. The results indicate that brain shape is largely independent of general size and reveal different trends in brain size and shape. Fossorial Euryzygomatominae, arboreal Echimyini and the semi-aquatic Myocastorini Myocastor show high encephalization; the former with a greater contribution from the olfactory bulb and petrosal lobe, and the latter two with a larger surface area of neocortex. The Euryzygomatomyinae and Myocastorini of terrestrial habits show low encephalization with a low contribution of the neocortex. Phylogenetic comparative analyses suggest that endocranial morphological evolution would have been influenced by both phylogeny and locomotor habits. The concurrence of the best fit of the Ornstein–Uhlenbeck model and the significant phylogenetic signal in the datasets suggests the involvement of constraints on morphological diversification within the major clades, as expected under phylogenetic conservatism. This could be explained by an early establishment of a particular endocranial morphology in each major clade, which would have been maintained with relatively little change.

Molecular and morphometric differentiation of secondary filariasis vector Coquillettidia mosquitoes (Diptera: Culicidae) in Thailand.

Coquillettidia mosquitoes are important nuisance-biting pests and a vector of brugian filariasis in Thailand. However, comprehensive information about these mosquitoes remains unavailable such as molecular and morphometric differences among species. The lack of vector knowledge on Coquillettidia species could affect future disease control. This study aims to investigate differences in molecular variations based on mitochondrial cytochrome oxidase subunit I (COI) gene and wing geometric traits of three Coquillettidia species, namely Cq. crassipes, Cq. nigrosignata, and Cq. ochracea in Thailand. The results of molecular analyses revealed the differences among three Coquillettidia species. The genetic difference measure based on the Kimura two-parameter model among three Coquillettidia species showed low intraspecific distances (0%-3.05%) and large interspecific distances (10.10%-12.41%). The values of intra- and inter-genetic differences of three Coquillettidia species did not overlap which showed the existence of a barcoding gap indicating the efficiency of the identification based on the COI gene. As with molecular analysis, the landmark-based geometric morphometrics approach based on wing shape analysis indicated three distinct species groups which were supported by the high total performance score of cross-validated classification (97.16%). These results provide the first evidence of taxonomic signal based on molecular and wing geometric differences to support species identification and biological variations of Coquillettidia mosquitoes in Thailand for understanding these rare vector mosquitoes in depth and leading to effective further mosquito control.

Morphological surveys of the sagittal otolith of marine gobiid fish (Teleostei: Gobioidei)

Abstract The challenges fish face in intraspecific communication has resulted in adaptation in different parts of their sensory system, including the auditory system. Evidence suggests that the sensory capability is specific for each species. The otolith is a part of the auditory system of teleost fish, and plays an important role in maintaining balance and in hearing. According to previous research, the morphological variation of otoliths is a result of a synergy between genetic and environmental factors such as depth, diet, swimming, and substrates. In this research we focused to explain (1) morphological variations of the otolith of gobiid fish as an animal inhabiting both aquatic and terrestrial environments; (2) the use of this morphological variations for distinguishing gobiid fish; and (3) how communication systems adapt to the local environment. The sagittal otoliths of six species of gobiid fish were extracted and described. In the next step, we studied the sagittal otoliths using the geometric morphometrics method and shape indices. The most common characteristics of the sagitta in the studied gobies fish were the median and mesial sulcus and the absence of a clear rostrum and antirostrum. A comparison between the examined methods showed that the geometric morphometric approach was able to detect the subtle differences between gobies species. Moreover, it seems that lifestyle and vision could affect the efficiency of the auditory system, in particular the otolith shape. For example, it seems the specific otolith shape of Periophthalmus waltoni (a species that unlike other fish spends most of its time out of the water) perhaps is a result of adaptation to land and water.