Morphometric Approach Research Articles

Applying a geometric morphometric surface semilandmark-based approach for assessing sexual dimorphism in cranial bones

Traditionally, sex estimation in human skulls has been carried out applying non-metric and inter-landmark distance approaches. Such estimation has substantially improved with the introduction of geometric morphometric semilandmark-based registration, representing a useful tool for capturing the complex morphology of 3D surfaces, particularly in human skulls. Taking in account these improvements, the main purpose of this study is to show the benefits of these techniques for assessing by means of a quantitative, hypothesis testing approach the differential phenotypic expression of sexual dimorphism in human cranial traits, using the frontal bone, the mastoid process of the temporal bone, and the zygomatic bone as proxies. According to our main results: i) accuracy and precision of sex estimation is higher when the shape variable is included in the analysis than when it is not, ii) numerical classification tends to be more accurate in males than in females for both shape and size components of sexual dimorphism, and iii) a single trait or two traits in combination would be more successful in sex classification than the three traits taken as a whole. The introduction in the present study of a surface semilandmark-based approach for quantitatively assessing sexual dimorphism in human skull considerably improves the capture of sexual dimorphic signatures, corroborating the importance of the information carried by the surface of the frontal bone, mastoid process, and zygomatic bone. Our results suggest that shape and size components should be considered as relevant factors in making a differential, bone- dependent sex assessment in human crania.

A three-dimensional geometric morphometric analysis of the morphological transformation of Caiman lower jaw during post-hatching ontogeny.

Shape ontogenetic changes of the lower jaw in crocodylians are poorly understood. In order to answer some questions related to the inter- and intraspecific morphological variation of the mandible of two extant Caiman species, we performed a three-dimensional geometric morphometric approach. For this purpose, we used landmarks and semilandmarks on two ontogenetic mandibular series of 48 and 15 post-hatching specimens of C. yacare and C. latirostris, respectively. We have also examined the relationship between these anatomical transformations and ontogenetic shifts in diet. We performed a principal component analysis (PCA) for the two species, and regression and partial least squares (PLS) analyses for each species, separately. As a result, species were segregated along the PC1 with specimens of C. yacare showing more gracile mandibles, and specimens of C. latirostris more robust ones. The PC2 and regression analyses showed an age gradient and represented ontogenetic shape changes. Adult caiman mandibles are higher and wider than juvenile ones, and shape changes are more conspicuous in C. latirostris. The PLS analyses showed a significant relationship between shape and diet. Morphological changes of the PLS1 of block-1 match with those of the regression analysis for both species. We have detected morphological transformations in areas where the musculature in charge of mandibular movements is attached. Common morphological changes occurring during ontogeny seem to reflect the same mechanical properties required for crushing and killing in both species, driven by an ontogenetic shift in the diet from invertebrates to vertebrates. Additionally, interspecific differences were also found to be correlated to ontogenetic changes in diet and could be related to dissimilar feeding mechanical requirements (e.g., stiffness and toughness of the item consumed), and to different habitat preferences. Robust mandibles would be more suitable for shallow and fully vegetated environments, as it can be seen in C. latirostris, whereas slender jaws seem to be more suitable for more aquatic species such as C. yacare.

Morphology and Morphometry of the Magellanic Penguin (Spheniscus magellanicus) Trachea

Objective: This work aimed to describe the trachea of the Magellanic Penguin (Spheniscus magellanicus) through descriptive and morphometric approaches. Methods: ten adult male Spheniscus magellanicus were used, which were collected, fixed, and kept immersed in an aqueous solution of 10% formaldehyde. Results: the trachea of the penguin began caudally from the cricoid cartilage of the larynx, represented by 121.3±5.65 cartilaginous rings joined together, which extended to the syrinx (19.75±0.70 cm). Considering its five segments (I-V), the number of tracheal rings decreased in a cranio-caudal direction. The medial tracheal septum, which started caudally from the cricoid cartilage of the larynx, was approximately 2±0.08 cm and was formed by approximately 6.75±0.25 rings. The dimensions of the lumen of the trachea decreased cranio-caudally, with a statistical difference between segment I and the others (II to V). The syrinx of the tracheobronchial type presented 7.52±0.65 rings. Conclusions: these data will contribute to the understanding of the anatomy of this species, as well as to the diagnosis and treatment of possible tracheal pathologies found in it.

A phylogeographic assessment redefines the distributions of Truncilla species (Bivalvia: Unionidae) in Texas

ABSTRACT Truncilla macrodon¸ the Texas Fawnsfoot, is currently considered to be restricted to the Brazos and Colorado river drainages in central Texas, USA. Subfossil specimens resembling T. macrodon from shell middens in the Trinity river drainage have raised questions about its presumptive range. Extant Truncilla populations occupying the Trinity river drainage are believed to be Truncilla donaciformis, the Fawnsfoot, but the species identity has not been assessed using molecular techniques. In this study, we set out to use phylogeographic and morphometric approaches to resolve the distribution of Truncilla spp. in Texas, with an emphasis on assessing species identity of Truncilla in the Trinity river drainage. Our molecular analyses indicated individuals from the Trinity river drainage are T. macrodon rather than T. donaciformis, and morphometric analyses using ratios of shell length, width and height supports this finding and showed differentiation among T. macrodon, Truncilla cognata and T. donaciformis. These combined findings suggest the range of T. macrodon is larger than previously recognized and includes the Colorado, Brazos and Trinity river drainages. The status of Truncilla spp. in the San Jacinto river basin remains unclear due to lack of information on historical or extant populations, but we recommend conservationists consider T. macrodon as part of the mussel fauna since the drainage shares an embayment with the Trinity river drainage. Molecular data also indicated the Trinity population of T. macrodon is distinct from, and more genetically diverse than, the Brazos and Colorado populations. This difference suggests the Trinity River population should be treated as a separate management unit from the Brazos and Colorado River populations to facilitate effective conservation and recovery planning. Our study adds to the growing body of literature highlighting the utility of molecular data in conservation and management of freshwater mussels.

A landmark-based geometric morphometric approach to quantify deviations from bilateral symmetry in polyplacophorans

The class Polyplacophora (chitons) represents a dorsoventrally flattened mollusk group that has an oval-shaped body covered with eight overlapping sclerites providing bilateral symmetry. Chitons show abnormalities (teratologies) that are characterized by symmetry deviations between the right and left sides of their bodies. As these deviations do not result in damage that affects vital functions, chitons are able to reach adult stages. In this study, we quantify the asymmetric condition of the species Chiton articulatus using a landmark-based geometric morphometric approach to assess variation in shape and bilateral symmetry. A geometric configuration of 22 landmarks and 50 semi-landmarks was created to evaluate shape variation in abnormal and deformed specimens compared to normal Chiton articulatus specimens. Vectors of change in the body shape configurations of chitons indicate that the greatest change occurs in the anterior part of the body, with less change in the middle and posterior parts. This gives chitons a widened appearance and provides anatomic compensation to restore the bilateral symmetry of the body scleritome. The diverse abnormalities and deformities had little impact on shape variations and confirmed that the coalescence condition is an intermediate step between a normal condition and the abnormal conditions of hypomerism or hypermerism. The low levels of fluctuating asymmetry expressed in C. articulatus indicate that despite living in areas of high stress, such as the rocky intertidal coast, this species maintains stability in its development and shape. Our results can serve as a model for studying bilateral symmetry deviation in polyplacophorans.

Physical training promotes remodeling of the skeletal muscle extracellular matrix: An ultrastructural study in a murine model of Down syndrome.

Down syndrome (DS) is a genetically based disease caused by triplication of chromosome 21. DS is characterized by multi-systemic premature aging associated with deficit in motor coordination, balance, and postural control. Using a morphological, morphometrical, and immunocytochemical ultrastructural approach, this study investigated in vastus lateralis muscle of Ts65Dn mouse, a murine model of DS, the effect of an adapted physical training on the extracellular matrix (ECM) characteristics and whether the forecasted exercise-induced ECM remodeling impacts on sarcomere organization. Morphometry demonstrated thicker basement membrane and larger collagen bundles with larger interfibrillar spacing as well as irregularly arrayed myofibrils and lower telethonin density on Z-lines in trisomic versus euploid sedentary mice. In agreement with the multi-systemic premature aging described in DS, these ECM alterations were similar to those previously observed in skeletal muscle of aged mice. Adapted physical training induced remodeling of ECM in both trisomic and euploid mice, that is, enlargement of the collagen bundles associated with hypertrophy of collagen fibrils and reduction of the interfibrillar spacing. A re-alignment of the myofibrils and a higher telethonin density on Z-line was found in trisomic mice. Altogether, our findings suggest that physical training is an effective tool in limiting/counteracting the trisomy-associated musculoskeletal structural anomalies. The current findings constitute a solid experimental background for further study investigating the possible positive effect of physical training on skeletal muscle performance. RESEARCH HIGHLIGHTS: Vastus lateralis muscle of trisomic mice shows aging-like alterations of extracellular matrix. Training promotes extracellular matrix remodeling. Training may be an effective tool to counteract trisomy-associated alterations of skeletal muscle.

Morphological integration and shape covariation between the trapezium and first metacarpal among extant hominids.

The shape of the trapezium and first metacarpal (Mc1) markedly influence thumb mobility, strength, and the manual abilities of extant hominids. Previous research has typically focused solely on trapezium-Mc1 joint shape. Here we investigate how morphological integration and shape covariation between the entire trapezium (articular and non-articular surfaces) and the entire Mc1 reflect known differences in thumb use in extant hominids. We analyzed shape covariation in associated trapezia and Mc1s across a large, diverse sample of Homo sapiens (n = 40 individuals) and other extant hominids (Pan troglodytes, n = 16; Pan paniscus, n = 13; Gorilla gorilla gorilla, n = 27; Gorilla beringei, n = 6; Pongo pygmaeus, n = 14; Pongo abelii, n = 9) using a 3D geometric morphometric approach. We tested for interspecific significant differences in degree of morphological integration and patterns of shape covariation between the entire trapezium and Mc1, as well as within the trapezium-Mc1 joint specifically. Significant morphological integration was only found in the trapezium-Mc1 joint of H. sapiens and G. g. gorilla. Each genus showed a specific pattern of shape covariation between the entire trapezium and Mc1 that was consistent with different intercarpal and carpometacarpal joint postures. Our results are consistent with known differences in habitual thumb use, including a more abducted thumb during forceful precision grips in H. sapiens and a more adducted thumb in other hominids used for diverse grips. These results will help to infer thumb use in fossil hominins.

Application of Morphometric Ranking Approach using Geospatial Techniques for Flash Flood Susceptibility Modelling in District Shangla, Pakistan

Every year, disaster strikes, and led to thousands of casualties and deaths around the world. A meteorological disaster such as a flash flood is a multifaceted hydro-meteorological phenomenon that can cause a huge loss of human life and can create severe economic problems. In this study, techniques based on Geographic information systems and Remote sensing were used to get the flood susceptibility map for District Shangla, Pakistan. For the susceptibility of flash floods, geo morphometric ranking model was used. Various causative factors were considered including; topography, river pattern, and flow accumulation. ALOS PALSAR digital elevation model was used for calculating the required causative factors. Eleven different sub-basins were delineated in the Shangla basin. A total of eighteen morphometric parameters were studied. The morphometric ranking approach (MRA) score was determined with a range of 1 to 5. Rank 5 represents high risk while rank 1 exhibits low risk. The results of the model were categorized into five flood vulnerability classes; very low, low, moderate, high and very high. The total population of Shangla district is 757,810 with a population density of 480 persons per sq km2, and results from this study revealed that 23 % of the total geographic area (364.11 km2) of the district is vulnerable to high flash floods.

Geological Substrate Effects on Teucrium montanum L. (Lamiaceae) Morphological Traits: Geometric Morphometrics Approach.

The shape-environment relationship in plants refers to the ways in which the physical characteristics and structures of plants are influenced by their environment. Plants have evolved a remarkable ability to adapt to their specific habitats, and their shape and form play a crucial role in determining their survival and reproductive success. This study aimed to examine differences in size and shape between morphological traits in mountain germander (Teucrium montanum L.) from different geological substrates (calcareous and serpentinite). For this study, 400 individuals of T. montanum from 20 populations (ten populations from the serpentinite and ten from the calcareous substrate) were selected. Using the geometric morphometrics approach, it was shown that the degree of phenotypic variation in the size and shape of the corolla, leaf, and stem of T. montanum depends on the type of substrate. The main differences between the populations are the narrower part of the lower lip of the corolla, the narrower leaf, and the wider central part of the vascular system stem from serpentinite populations. The results of this study will contribute to a better understanding of the morphological variability of T. montanum in relation to edaphic conditions. In addition, the results confirm that certain morphological differences play an important role in the adaptive response in relation to substrate composition, especially for substrates with increased metal content, such as serpentinite. The shape-environment relationship in plants could define diversity and complexity in plant life, and underscores the importance of shape as a key factor in their survival and success in different habitats.

Intraspecific allometric shift in an endemic and endangered marine mollusc: A new minimally intrusive tool to capture shell shape in the field

AbstractPatella ferruginea (Gastropoda, Patellidae) is an endemic and endangered marine invertebrate species from the Western Mediterranean that presents two ecomorphotypes. Currently, there is no objective and nonmanipulative method to determine these ecomorphotypes in the field. The present study uses the geometric morphometrics approach to investigate variation in the shell‐shape allometric trajectories of both ecomorphotypes. In addition, we propose a new manipulation‐free tool to assign ecomorphotype in the field. A total of 190 shells, 123 from the lamarcki (20.0 to 86.7 mm) and 67 from the rouxi (25.3 to 95.9 mm) ecomorphotypes, were analyzed using three different 2D landmark and semilandmark configurations capturing the lateral, internal, and dorsal shell views. We provide compelling graphical and analytical evidence that these ecomorphotypes differ in allometric growth patterns. However, the findings of the current study do not support that lamarcki and rouxi correspond to different ontogenetic states of P. ferruginea. We hypothesize that the difference in the allometric trajectories between the rouxi and the lamarcki ecomorphotypes could be due to environmental constraints, but it might also be due to currently undetected genetic factors. Since the allometry‐free shape lateral view presented the most significant reliability in assigning ecomorphotypes, we evaluate an easy and inexpensive tool to assign individuals in the field to each ecomorphotype using a contour gauge and a simple landmark configuration (only three landmarks). Cross‐validated classification indicated that ecomorphotype assignations for lateral contour present total reliability calculated at 93.15%. Therefore, we encourage it to be implemented in future research to avoid sacrificing or manipulating specimens of this endangered species.

Diversity of cranial shape in European Woodpecker species (Picidae)

Abstract The woodpecker family (Picidae) includes numerous species that vary in size and plumage colouration, but which share many easily recognisable external features. These birds possess pronounced anatomical adaptions that enable them to exploit arboreal habitats and live in niches that are inaccessible to most other birds. The aim of this study was to increase our knowledge on the relationships between skull shape, habitat preference, pecking abilities and foraging habits of 10 European woodpecker species. A geometric morphometric approach was used to analyse two-dimensional cranial landmarks. We used principal component (PC) analyses on those measurements that may be related to habitat preference and foraging habits. The PCs resulted in descriptions of the relative length and width of the bill, variation in its relative size, orientation of the nostrils variation in the elongation of the neurocranium, the relative size and position of the palatine bone, length of the rostrum, and the thickness of the mandible bone. The analysis showed and confirmed the presence of some cranial elements that are strongly associated with habitat preference, pecking behaviour and excavation abilities.

Morphometrics of waterlogged archaeological seeds give new insights into the domestication and spread of Papaver somniferum L. in Western Europe.

Domesticated opium poppy Papaver somniferum L. subsp. somniferum probably originated in the Western Mediterranean from its possible wild progenitor, Papaver somniferum L. subsp. setigerum and spread to other European regions. Seeds of opium poppy have been identified in different European regions since the Early Neolithic (from the 6th millennium cal. BC onwards) period. However, until recently, the absence of morphological identification criteria has prevented the discrimination between wild and domestic morphotypes. New morphometric approaches to distinguish modern subspecies have been proven to be applicable to waterlogged archaeological remains, opening the possibility of understanding the process of domestication of the plant in both time and space. This paper applies seed outline analyses, namely elliptic Fourier transforms, combined with size and number of cells to archaeological waterlogged Papaver seeds throughout the Neolithic period in the NW Mediterranean and the surroundings of the Alps. Furthermore, one example from the Late Bronze Age (LBA) was added to see what kind of differences appeared during the >1000 years between the end of the Neolithic and the LBA. The aim of the study is to classify the archaeological seeds as domestic or wild morphotypes and observe morphometric changes in connection to geographical and chronological patterns that can explain the spread and domestication process(es) of this important crop. A total of 295 archaeological seeds coming from 10 waterlogged sites dating between 5300-2300 cal. BC (Neolithic), and one LBA site dating to 1070 cal. BC were analysed. The results indicate the presence of seeds, similar to the wild morphotype, in the Mediterranean sites and larger seeds, similar to the domestic morphotype, in the regions surrounding the Alps. The number of cells mainly increased during the Late Neolithic (3300 to 2300 cal. BC) and, finally, in the Late Bronze Age (ca. 1050-800 cal. BC), larger, morphologically domesticated seeds are clearly predominant. A change in the shape of the seeds is only clearly visible in the LBA material. Altogether our results suggest that opium poppy seeds show no sign of domestication in the early periods of the Neolithic, despite the fact that the plant was very probably already cultivated at that time in the western Mediterranean region.

Climate, not Quaternary biogeography, explains skull morphology of the long-tailed macaque on the Sunda Shelf

Sundaland, comprising the low-lying Sunda Shelf, the major islands of Borneo, Sumatra, and Java, as well as many smaller surrounding islands, formed a contiguous landmass through much of the Pliocene and Pleistocene. Subsequent late-Pleistocene rising sea levels have often been invoked as major zoogeographic barriers to gene flow and associated phenotypic and taxonomic divergence of Sundaic mammals. However, previous examinations of mammalian biogeography have painted a complex picture, suggesting that mammalian diversification in the region cannot easily be explained by a single overarching biogeographical phenomenon. Instead, it may be that the significant climatic changes and their concomitant impacts on local environments were the more significant control. In this context, we study adult skull morphology of a widely distributed primate in insular and continental Southeast Asia, the long-tailed macaque (Macaca fascicularis), using a 3D geometric morphometric (GM) approach. We used principal component analysis and linear discriminant function analysis to analyze the associations between morphological divergence and island biogeography, taxonomy, and phylogeny. Reduced rank regressions (RRR) were employed to investigate associations with climate of the present and last interglacials and the last glacial maximum (LGM). There was very poor morphological divergence and discrimination among specimens from different biogeographical zones. There was also large overlap between M. fascicularis subspecies in skull size and shape, with M. f. fascicularis occupying the largest range of size and shape variation, consistent with its wide geographical distribution. Nonetheless, sundaic M. f. fascicularis and M. f. philippinensis, restricted to the Philippines, were successfully discriminated on size and shape, supporting the latter as a valid subspecies. There was moderate morphological differentiation associated with the deepest split in mitochondrial DNA lineages (M. f. aureus versus the rest) in skull size and shape. Contrary to biogeography, we detected strong associations between skull morphology and climate. Skull form (size and shape combined) was better explained by climate closer to present conditions and correlated most strongly with the current interglacial, even though past climatic conditions do show correlations with cranial morphology. We found no strong evidence that cranial and mandibular variation in M. fascicularis consistently tracks insularity caused by Quaternary sea level change. Instead, the morphological overlap evident in our sample indicates connections between subspecies and is consistent with the history of Sundaland as a single landmass for large portions of the Quaternary.

Otoliths of Caspian gobies (Teleostei: Gobiidae): Morphological diversity and phylogenetic implications.

Otoliths (ear stones) of the inner ears of teleost fishes, which develop independently from the skeleton and are functionally associated with hearing and the sense of equilibrium, have significantly contributed to contemporary understanding of teleost fish systematics and evolutionary diversity. The sagittal otolith is of particular interest, since it often possesses distinctive morphological features that differ significantly among species, and have been shown to be species- and genus-specific, making it an informative taxonomic tool for ichthyologists. The otolith morphology of the Caspian Sea gobiids has not been thoroughly studied yet, with data available for only a few species. The aim of the present paper is to examine the qualitative and quantitative taxonomic and phylogenetic information in the sagittal otoliths of these species. A total of 118 otoliths representing 30 gobiid species (including 53.5% of the Caspian gobiofauna) in three gobiid lineages (i.e., Gobius, Pomatoschistus, and Acanthogobius) and 11 genera (i.e., all Ponto-Caspian gobiid genera except Babka) were analysed at taxonomic levels using an integrated descriptive and morphometric approach. The results indicated high taxonomic efficiency of otolith morphology and morphometry at taxonomic levels for the Ponto-Caspian gobiids. Our qualitative and quantitative otolith data also (i) support the monophyly of neogobiin gobies, (ii) along with other morphological and ecological data, offer a new perspective on the systematics of Neogobius bathybius, (iii) suggest the reassignment of Hyrcanogobius bergi to the genus Knipowitschia, and (iv) question the phylogenetic integrity of the four phenotypic groups previously defined in the tadpole-goby genus Benthophilus; however, more studies are needed to complete these evaluations and confirm our otolith study findings.

Developmental origin underlies evolutionary rate variation across the placental skull.

The placental skull has evolved into myriad forms, from longirostrine whales to globular primates, and with a diverse array of appendages from antlers to tusks. This disparity has recently been studied from the perspective of the whole skull, but the skull is composed of numerous elements that have distinct developmental origins and varied functions. Here, we assess the evolution of the skull's major skeletal elements, decomposed into 17 individual regions. Using a high-dimensional morphometric approach for a dataset of 322 living and extinct eutherians (placental mammals and their stem relatives), we quantify patterns of variation and estimate phylogenetic, allometric and ecological signal across the skull. We further compare rates of evolution across ecological categories and ordinal-level clades and reconstruct rates of evolution along lineages and through time to assess whether developmental origin or function discriminate the evolutionary trajectories of individual cranial elements. Our results demonstrate distinct macroevolutionary patterns across cranial elements that reflect the ecological adaptations of major clades. Elements derived from neural crest show the fastest rates of evolution, but ecological signal is equally pronounced in bones derived from neural crest and paraxial mesoderm, suggesting that developmental origin may influence evolutionary tempo, but not capacity for specialisation. This article is part of the theme issue 'The mammalian skull: development, structure and function'.

Dumbbell-shaped brains of Polish crested chickens as a model system for the evolution of novel brain morphologies.

The evolutionary history of vertebrates is replete with emergence of novel brain morphologies, including the origin of the human brain. Existing model organisms and toolkits for investigating drivers of neuroanatomical innovations have largely proceeded on mammals. As such, a compelling non-mammalian model system would facilitate our understanding of how unique brain morphologies evolve across vertebrates. Here, we present the domestic chicken breed, white crested Polish chickens, as an avian model for investigating how novel brain morphologies originate. Most notably, these crested chickens exhibit cerebral herniation from anterodorsal displacement of the telencephalon, which results in a prominent protuberance on the dorsal aspect of the skull. We use a high-density geometric morphometric approach on cephalic endocasts to characterize their brain morphology. Compared with standard white Leghorn chickens (WLCs) and modern avian diversity, the results demonstrate that crested chickens possess a highly variable and unique overall brain configuration. Proportional sizes of neuroanatomical regions are within the observed range of extant birds sampled in this study, but Polish chickens differ from WLCs in possessing a relatively larger cerebrum and smaller cerebellum and medulla. Given their accessibility, phylogenetic proximity, and unique neuroanatomy, we propose that crested breeds, combined with standard chickens, form a promising comparative system for investigating the emergence of novel brain morphologies.

Morphological variation during post-embryonic development in the centipede Lithobius melanops: traditional and geometric morphometrics approaches

Abstract Two modes of post-embryonic development, hemianamorphosis and epimorphosis, show a distinct pattern among extant centipede (Chilopoda) orders. Although studies on post-embryonic development in Lithobiomorpha date back to the 19th and the 20th century, many ambiguities referring to nomenclature of their post-embryonic stages still exist. In this paper coherent terminology of the post-embryonic stages in Lithobius melanops, which could be applied to other lithobiomorphs, is proposed. Additionally, morphological variability of selected morphological traits was analyzed using traditional and geometric morphometric approaches. We recognized five anamorphic (anamorph 0 to 4) and five epimorphic stages (agenitalis, immaturus, praematurus, pseudomaturus and maturus). Measurement and count of certain morphometric characters, detailed description of genital appendages, shape and size variation of the forcipular apparatus, the cephalic capsule and the terminal legs are given. Moreover, for the purpose of geometric morphometric analyses we separated specimens of epimorphic stages into three groups (agenitalis-, praematurus- and maturus-like) based on the level of differentiation of genital appendages. Sexual size dimorphism of the forcipular apparatus was observed only in the praematurus group. Also, significant inter-group forcipular size and shape differences are found between some tested groups. Furthermore, significant differences in size and shape were recorded for the cephalic capsule between all groups. Finally, significant size differences in ultimate legs are present between all epimorphic groups, while shape differences were detected only between agenitalis and maturus groups. Our results contribute to overcoming terminological disparities and provide guidelines for distinguishing stages via discrete and continuous changes during post-embryonic development of the anamorphic centipede.

New Data on the Distribution of the Bulgarian Spined Loach <i>Cobitis strumicae</i> (Teleostei: Cobitidae) in Turkey

This study reports the presence of Cobitis strumicae Karaman, 1955 in Terme Stream (Samsun-Black Sea-Turkey). Molecular and morphometric approaches were used together to prove the existence of the species in Terme Stream. The family Cobitidae represents a unique element of ichthyofauna. Even while sexual dimorphism can take many different forms, taxonomy studies have only used a small number of morphological features, leaving many concerns unanswered. In addition to the assessments of phenotypic traits (Gambetta’s longitudinal zones, Canestrini’s scales, suborbital spine morphology, barbel and mental lobe morphology), mitochondrial cytochrome b gene (cyt b) (1140 bp) sequence variation was studied in molecular analysis. We present the phylogenetic relationships of morphologically diagnosable subgenus Bicanestrinia from Asia Minor and Balkans in here. Samples from Terme (Accession Numbers: ON116344 and ON116345) and GENBANK were combined in the phylogenetic analysis. Our findings offered a significant distribution update of C. strumicae from Terme Stream, a southern coastal Black Sea drainage, and support the vicariance theory, according to the results of this study.

Sharpening the mesowear tool: geometric morphometric analysis of cusp shape and diet in ruminants

Mesowear is a dietary proxy that relates attritive wear and abrasive wear to the shape of worn tooth cusps of ungulates. Traditional mesowear methods categorize cusps according to relief and sharpness. A geometric morphometric approach has the potential to measure shape with higher precision and to discover unrecognized aspects of cusp shape, possibly improving the efficacy of mesowear. We quantified mesowear in extant Ruminantia, using a 2-D semilandmark outline technique on upper second molar metacones generated from photographs. Among the 91 species sampled, 65 were preassigned to dietary categories, browser, grazer, mixed feeder, and frugivore based on substantiated documentation of diet in the wildlife literature. Metacone cusp shape and metacone mesowear score were found to be independent of size. Principal component and discriminant function analyses of Procrustes transformed semilandmark coordinates revealed two diet-related components of cusp shape. The primary component is related to the traditional mesowear variables of cusp height and side steepness. The secondary shape component reveals variation in the mesiodistal symmetry of the metacone and may relate to a proal vector during the power stroke phase or the relative orientation of the cusps with respect to the chewing stroke vector. Discriminant function analysis of semilandmark data accurately classified the diets of species more frequently (67.2%) than the traditional mesowear method (56.1%). The semilandmark data successfully recognized the diets of grazing and browsing species with correct classification rates ranging from 69% to 95%. The diets of frugivorous and mixed feeding species were less frequently correctly recognized (33%–53%). Mixed feeding diets may be more difficult to recognize due to more heterogeneous diets when compared to browsers and grazers. Frugivores are more difficult to recognize because their rounded cusp apices resemble those of mixed feeders and grazers. We conclude that quantitative shape analysis improves the potential of mesowear. When used as a dietary proxy, we anticipate that mesowear analysis will correctly categorize the diets of most species. When misclassifications are made, they may most often be misclassifications of generalist mixed feeders and frugivores as either browsers or grazers.

Wing morphology variations in Culicoides circumscriptus from France.

The biting midge Culicoides circumscriptus Kieffer, 1918 is a European widespread vector of avian malaria throughout the continent and is a possible vector of Akabane virus and Bluetongue virus. This species populates a wide range of environments in contrasting ecological settings often exposed to strong seasonal fluctuations. The main goals of this study were to investigate C. circumscriptus phenotypic variation at three departments in France (Corsica Island, Moselle and Var) and to determine if its phenotypes vary with the environment. Culicoides circumscriptus wing phenotypes were analyzed using a geometric morphometric approach based on anatomical landmarks and outlines of the wing. Dendogram trees based on landmarks and the outlines-2 set (cell m4) showed similar topologies and separated populations of C. circumscriptus. In contrast, another set of outlines-1 (covering the r-m cross vein, M, radiale and arculus) presented a different hierarchical clustering tree. The phenotypic variation observed in C. circumscriptus indicated that these populations are exposed to environmental and ecological pressures. Our results suggest the presence of phenotypic plasticity in this species.