Showing papers in "Zoomorphology in 2021"
TL;DR: It is hypothesize that the oxudercine gobies had been adapted to feeding microalgae in shallow water before expanding their niche onto land, and subsequently diverged to more specialized herbivorous and carnivorous groups (Periophthalmus and PeriPhthalmodon) feeding in higher intertidal habitats.
Abstract: Oxudercine gobies show not only a full spectrum of habitat transition from water to land, but also varying feeding habits from herbivory to carnivory. In this study, we compared the anatomy of the feeding apparatus of five oxudercine gobies, Boleophthalmus boddarti (moderately terrestrial, herbivorous), Oxuderces nexipinnis (nearly aquatic, herbivorous), Scartelaos histophorus (moderately terrestrial, omnivorous), Periophthalmus chrysospilos (highly terrestrial, carnivorous), and Periophthalmodon schlosseri (highly terrestrial, carnivorous), collected from a mudflat in Vietnam. B. boddarti and O. nexipinnis are characterized by a horizontal disposition of the dentary teeth, more densely spaced gill rakers on the posterior row of the third arch and both rows of the fourth arch, and large, ventrally curved pharyngeal plates bearing numerous fine teeth. Ps. chrysospilos and Pn. schlosseri have oral jaw bones with jaw-levers producing a greater biting force, rudimentary gill rakers, and pharyngeal plates studded with robust canine teeth. On the underside of the ventral plates, prominent ridges occur, onto which strong muscles attach. The jaw adductors are larger in these carnivorous mudskippers. S. histophorus shows an anatomical architecture which may be considered intermediate between these herbivorous and carnivorous species. On the basis of currently accepted relationships of oxudercine genera, their feeding habits, and the morphology of the feeding apparatus, we hypothesize that the oxudercine gobies had been adapted to feeding microalgae in shallow water before expanding their niche onto land, and subsequently diverged to more specialized herbivorous (Boleophthalmus) and carnivorous groups (Periophthalmus and Periophthalmodon) feeding in higher intertidal habitats.
8 citations
TL;DR: In this article, a parametric method based on discrete cosine transform (DCT) is proposed to serve as a morphometric tool for 3D open curves, which transforms real signal (coordinates) into a combination of cosine functions.
Abstract: Fourier transform methods are usually adopted to fit 2D closed curves representing samples’ profiles to be studied in morphometric analysis. As for problems concerning 3D open curves, landmark-based methods are widely used. In this paper, a parametric method based on discrete cosine transform (DCT) is proposed to serve as a morphometric tool for 3D open curves. DCT transforms real signal (coordinates) into a combination of cosine functions. DCT describes the shape of a curve with coefficients generated from the fitting curve. Four examples are introduced to be fitted with DCT. The first example is 3D spiral curves with different shapes, added random disturbances to make this model more general. A curve alignment is also utilized to eliminate the non-shape effect. The other three examples of suture curves abstracted from 3D human skulls on which semilandmarks and landmarks are aligned with General Procrustes Analysis (GPA) to eliminate the effect brought by location, size, and orientation. These 3D curves with different diagnoses are matched with DCT. Coefficients generated in the fitting result are analyzed with between-group principal component analysis (bgPCA) and one-way permutational multivariate analysis of variance (PERMANOVA). Different groups of four examples are separated and present significant differences in the results of one-way PERMANOVA. Statistical analyses demonstrate that DCT is promising in morphometric analysis of 3D open curves.
7 citations
TL;DR: The antennae of species in Pleidae exhibit at least 12 types of sensilla, all of which are documented for the first time for this family in this paper, and the antenna of N. striola and N. harnedi suggest that they are separate species and previous suggestions of synonymy are not supported.
Abstract: The antennae of species in Pleidae exhibit at least 12 types of sensilla, all of which are documented for the first time for this family. Representatives of all genera (Heteroplea, Neoplea, Paraplea, and Plea) of Pleidae are surveyed and their antennal sensilla documented. The antenna of Heteroplea shares characteristics with Helotrephidae, the sister family to Pleidae, suggesting that its antennal type may be useful in determining relationships between species currently placed in these two families. The antennae of N. striola and N. harnedi suggest that they are separate species and previous suggestions of synonymy are not supported.
6 citations
TL;DR: In taxa with a large crop, a flat facies articularis scapularis is likely to be associated with a reorganization of the pectoral musculature, whereas in procellariiform birds, the transition from a cotyla to a faciesArticularis appears to have been correlated with the capacity for sustained soaring without wing flapping.
Abstract: A survey is given of the morphological variation of the coracoscapular joint of neornithine birds. In Mesozoic stem group representatives, the coracoid exhibits a deeply concave cotyla scapularis, which articulates with a globose tuberculum coracoideum of the scapula. This morphology is likely to be functionally related to the development of a powerful supracoracoideus muscle and the formation of a triosseal canal as a pulley for the tendon of this muscle. In neornithine birds, the coracoid articulates with the scapula either via a concave cotyla or a flat facies articularis, with the latter largely restricting movements of the coracoid to the paramedian plane. Ancestral state reconstruction suggests that a cotyla scapularis is plesiomorphic for Neornithes and that a flat facies articularis scapularis evolved at least 13 times independently within the clade. For several lineages, the transition to a flat facies articularis scapularis can be traced in the fossil record, and the replacement of a cup-shaped cotyla by a flat articular facet seems to have been due to various functional demands. Often, a flat facies articularis scapularis is associated with reduced shafts of the furcula. A weakly developed furcula enables transverse movements of the coracoid and therefore enables a restriction of the mobility of the coracoscapular joint to the paramedian plane. In taxa with a large crop, a flat facies articularis scapularis is likely to be associated with a reorganization of the pectoral musculature, whereas in procellariiform birds, the transition from a cotyla to a facies articularis appears to have been correlated with the capacity for sustained soaring without wing flapping.
6 citations
TL;DR: A detailed morphological description of raptorial forelegs of Mantispa styriaca (Neuroptera), including musculature and the material composition in their cuticle is shown, and a possible catapult mechanism is identified as a driving force of the predatory strike in Mantispidae.
Abstract: The insect leg is a multifunctional device, varying tremendously in form and function within Insecta: from a common walking leg, to burrowing, swimming or jumping devices, up to spinning apparatuses or tools for prey capturing. Raptorial forelegs, as predatory striking and grasping devices, represent a prominent example for convergent evolution within insects showing strong morphological and behavioural adaptations for a lifestyle as an ambush predator. However, apart from praying mantises (Mantodea)—the most prominent example of this lifestyle—the knowledge on morphology, anatomy, and the functionality of insect raptorial forelegs, in general, is scarce. Here, we show a detailed morphological description of raptorial forelegs of Mantispa styriaca (Neuroptera), including musculature and the material composition in their cuticle; further, we will discuss the mechanism of the predatory strike. We could confirm all 15 muscles previously described for mantis lacewings, regarding extrinsic and intrinsic musculature, expanding it for one important new muscle—M24c. Combining the information from all of our results, we were able to identify a possible catapult mechanism (latch-mediated spring actuation system) as a driving force of the predatory strike, never proposed for mantis lacewings before. Our results lead to a better understanding of the biomechanical aspects of the predatory strike in Mantispidae. This study further represents a starting point for a comprehensive biomechanical investigation of the convergently evolved raptorial forelegs in insects.
6 citations
TL;DR: The gorgonocephalous pediceLLaria is a multi-valved, unstalked, crossed pedicellaria in basketstars and snakestars in the euryalid family Gorgonocephalidae, described and illustrated here with recommended morphological terminology to facilitate future studies on biomechanics, histology, paleontology, and phylogenetics.
Abstract: Echinoderm pedicellariae are groups of specialized opposable spines (valves) that articulate on a baseplate. The valves of a pedicellaria act together to grasp items for prey capture, surface cleaning, or defense. Pedicellariae have long been known to occur in sea urchins and seastars, and many types for different functions have been described. Here we describe a type of pedicellaria in basketstars and snakestars in the euryalid family Gorgonocephalidae. Valves of gorgonocephalous pedicellariae have been described and illustrated as independent “hooklets” since the 1800s. Aside from one illustration in 1930, baseplates have been illustrated only since the 1980s, after the advent of the scanning electron microscope. The structure, arrangement, and operation of valves on baseplates warrant their recognition as a pedicellaria, analogous to those of sea urchins and seastars. The gorgonocephalous pedicellaria is a multi-valved, unstalked, crossed pedicellaria. It is described and illustrated here with recommended morphological terminology to facilitate future studies on biomechanics, histology, paleontology, and phylogenetics.
5 citations
TL;DR: In this paper, the authors provided a comparative study of the head lateral line of the threespine stickleback, Gasterosteus aculeatus, and found no distinct difference in the pattern of the system between the three major ecotypes but significant differences in neuromast numbers.
Abstract: The mechanosensory lateral line of fishes is a flow sensing system and supports a number of behaviors, e.g. prey detection, schooling or position holding in water currents. Differences in the neuromast pattern of this sensory system reflect adaptation to divergent ecological constraints. The threespine stickleback, Gasterosteus aculeatus, is known for its ecological plasticity resulting in three major ecotypes, a marine type, a migrating anadromous type and a resident freshwater type. We provide the first comparative study of the pattern of the head lateral line system of North Sea populations representing these three ecotypes including a brackish spawning population. We found no distinct difference in the pattern of the head lateral line system between the three ecotypes but significant differences in neuromast numbers. The anadromous and the brackish populations had distinctly less neuromasts than their freshwater and marine conspecifics. This difference in neuromast number between marine and anadromous threespine stickleback points to differences in swimming behavior. We also found sexual dimorphism in neuromast number with males having more neuromasts than females in the anadromous, brackish and the freshwater populations. But no such dimorphism occurred in the marine population. Our results suggest that the head lateral line of the three ecotypes is under divergent hydrodynamic constraints. Additionally, sexual dimorphism points to divergent niche partitioning of males and females in the anadromous and freshwater but not in the marine populations. Our findings imply careful sampling as an important prerequisite to discern especially between anadromous and marine threespine sticklebacks.
4 citations
TL;DR: In this paper, the growth pattern of the five dermatocranial elements that construct the temporal region of the skull (the parietal, postorbital, jugal, quadratojugal, and squamosal) was found to be highly conserved during embryogenesis across cryptodiran turtles.
Abstract: Reptilian skull morphology is highly diverse and broadly categorized into three architectural patterns: anapsid, synapsid, and diapsid. The anapsid condition where the temporal region is completely roofed by bones is observed in both basal reptiles and turtles. According to recent phylogenetic studies, turtles are derived from diapsid reptiles, implying that the temporal fenestrae were secondarily closed in turtles. Although the repeated evolution of dermatocranial bone reductions in the skull’s temporal region of the anapsid skull and the biomechanical factors driving the evolution of the anapsid skull in turtles have been actively discussed, its developmental basis for the anapsid skull remains poorly understood. To investigate the developmental mechanisms underlying the morphological evolution of turtle skulls, here we describe the cranial osteogenesis of three cryptodiran turtle species with distinct skull morphologies: Chelonia mydas (Cheloniidae), Mauremys reevesii (Geoemydidae), and Pelodiscus sinensis (Trionychidae). Our interspecific comparison of embryonic cranial osteogenesis suggests that the growth pattern of skull bone elements is presumed to be highly conserved during embryogenesis across cryptodiran turtles. We found that the growth pattern of the five dermatocranial elements that construct the temporal region of the skull (the parietal, postorbital, jugal, quadratojugal, and squamosal) is highly conserved among turtle species, and that the morphological diversity of turtle skulls arises from slight differences in growth patterns. Our study also suggests that interspecific morphological differences in the cheloniid adult skulls may become apparent in the post-hatching growth period rather than during embryogenesis.
4 citations
TL;DR: In this paper, the authors investigated the effect of body mass on the macro-and microstructure of the compact bone in cows and sheep at the age of 4-10 years.
Abstract: The structure and geometry of bone depend on many biological and environmental factors. These factors affect the bone tissue's microstructure differently, and their interaction has not yet been fully elucidated. Our research investigated the effect of body mass on the macro- and microstructure of the compact bone. Therefore we analyzed the humerus and femur bones from females of 11 cows and 11 sheep at the age of 4–10 years. Both species have very similar dietary and locomotion patterns, but their body size and weight are very different. Within macroscopical analyzes of bones were observed ascending order of robustness index and bone diaphysis index. In both animals, plexiform and irregular Haversian bone tissues were identified in humerus and femur. Conversely, the dense Haversian tissue present only in cow above all in the femur. The most considerable interspecific osteonal difference between sheep and cow was in the osteon density, whose average value is 37% higher in the cow. The osteons of sheep humerus are almost circular, and osteons of cow femur are more elliptical. Within both species, the femoral osteons are elliptical than those of humerus. Despite the cow weighing more than 10 times the sheep, the measurements of osteons and Haversian canals, are very similar (the values of the ratio cow/sheep for these types are comprised from 1.04 to 1.86). Our findings indicate that the body mass does not affect the size of bone microstructure, probably more sensitive to other factors as a lifestyle and locomotor ability.
4 citations
TL;DR: Strong evidence is found for a functional grouping of the sensilla into receptors used on the ground or in flight, respectively and the placing of sensilla deserving protection in closeable cavities and the reduction in number and length of the external sensilla can be interpreted as adaptations to the fire habitat.
Abstract: The ‘Australian firebeetle’ Merimna atrata approaches fires in Eucalyptus forests for reproduction. Beetles stay on a postfire area as long as burning wood or hot ashes emit heat and smoke. Abdominal infrared receptors protect the beetles from landing on hot spots; however, until now fire-specific adaptations of the antennae have not been investigated in more detail. This affects the localization of olfactory sensilla used for the perception of smoke and in addition mechanisms to protect delicate sensilla against desiccation and pollution. Moreover, nothing was known about antennal thermo-/hygroreceptors in Merimna atrata. We found strong evidence for a functional grouping of the sensilla into receptors used on the ground or in flight, respectively. A first group comprises the outer visible sensilla, i.e. mechanosensory bristles, short gustatory sensilla and a small field of very short olfactory sensilla. They are used when the beetle is running around on the fireground on burnt bark or ashes. A second group of sensilla is hidden in closeable cavities on antennomeres 4–11. If the cavities are closed, the sensilla inside are fully protected. If the cavities are opened in flight, the beetles can make use of many multiporous basiconic sensilla and multiporous basiconic grooved peg sensilla for smoke detection. Minute modified sensilla coelocapitula occurring in small numbers in the cavities too, most probably serve as thermoreceptors. As a result the placing of sensilla deserving protection in closeable cavities and the reduction in number and length of the external sensilla can be interpreted as adaptations to the fire habitat.
4 citations
TL;DR: The present ultrastructural investigation using scanning and transmission electron microscopy as well as light and fluorescence microscopy describes in detail the attachment devices and tarsal gland of the bug Coreus marginatus (L.) (Hemiptera: Coreidae) and hypothesise a fluid emission mechanism based on changes of the hydraulic pressure inside the gland, due to the unguitractor tendon movements.
Abstract: The present ultrastructural investigation using scanning and transmission electron microscopy as well as light and fluorescence microscopy describes in detail the attachment devices and tarsal gland of the bug Coreus marginatus (L.) (Hemiptera: Coreidae). In particular, the fine structure of pulvilli reveals a ventral surface rich with pore channels, consistent with fluid emission, and a folded dorsal surface, which could be useful to enhance the pulvillus contact area during attachment to the substrate. The detailed description of the tarsal gland cells, whose structure is coherent with an active secretory function, allows us to consider the tarsal gland as the plausible candidate for the adhesive fluid production. Scolopidia strictly adhering to the gland cells are also described. On the basis of the fine structure of the tarsal gland, we hypothesise a fluid emission mechanism based on changes of the hydraulic pressure inside the gland, due to the unguitractor tendon movements. This mechanism could provide the fluid release based on compression of the pad and capillary suction, as demonstrated in other insects. The data here reported can contribute to understanding of insect adhesive fluid production, emission and control of its transport.
TL;DR: In this article, the male reproductive system and sperm morphology of three species, including Bothrophorella nigra, Sixeonotus brasiliensis, and Pycnoderes incurvus, were described.
Abstract: The reproductive system and sperm morphology provide informative (but not so usual) characters in the systematic analysis, also it is still scarce for most of the insect taxa. Miridae is the largest family of Heteroptera, moreover, lower systematic relationships are still contentious, especially for the Bryocorinae subfamily. Due to the lack of data concerning Eccritotarsini (Bryocorinae), we described the male reproductive system and sperm morphometry of three species, including Bothrophorella nigra, Sixeonotus brasiliensis, and Pycnoderes incurvus. Our results showed that a single follicle per testis could be the typical follicular number for Eccritotarsini. To Miridae, the pair of medial accessory glands is often shorter than the lateral ones, as indicated by the gland morphology in Bryocorinae and Mirinae. A single pair of glands in B. nigra suggests it to be an autapomorphy in this taxon. We notice that a subdivided seminal vesicle is described only for Mirinae and no other heteropteran so far. There is a continuous sperm production in P. incurvus in the adult by the presence of cysts at distinct developmental stages. Also, sperm morphometry was unique for each species, and the total length in B. nigra (282 µm) was nearly twice that found for P. incurvus (174 µm) and S. brasiliensis (135 µm).
TL;DR: It has been found that, as expected, animal species is the factor contributing most to variation in the test parameters, but the degree of differences between species has been not always proportional to genetic distances between them.
Abstract: The levels of interspecific and intraspecific variation in morphometric parameters of spermatozoa have been studied in seven wild rodent species of the families Cricetidae and Muridae and inbred CBA mice. The study of intraspecific variability of parameters included an analysis of within-population age-related variation and variation among individuals within a population. It has been found that, as expected, animal species is the factor contributing most to variation in the test parameters, but the degree of differences between species has been not always proportional to genetic distances between them. The proportion of within-population age-related variation is not significant and, hence, can be ignored in population studies on male reproduction. In contrast, the contribution of individual variation in the parameters of spermatozoa to their overall variation in each species is significant and should be taken into account when forming the samples and analyzing the results. The levels of intraspecific variation in the morphometric parameters of spermatozoa in wild rodents and inbred mice are similar to each other.
TL;DR: Outgroup comparison indicates that an antennal heart with a M. interampullaris is the plesiomorphic character state among Embioptera and the likely ground pattern of the taxon Eukinolabia, supporting the view that Australembiidae are the sister group of the remaining Embiopters.
Abstract: The morphology of the antennal hearts in the head of Phasmatodea and Embioptera was investigated with particular reference to phylogenetically relevant key taxa. The antennal circulatory organs of all examined species have the same basic construction: they consist of antennal vessels that are connected to ampullae located in the head near the antenna base. The ampullae are pulsatile due to associated muscles, but the points of attachment differ between the species studied. All examined Phasmatodea species have a Musculus (M.) interampullaris which extends between the two ampullae plus a M. ampulloaorticus that runs from the ampullae to the anterior end of the aorta; upon contraction, all these muscles dilate the lumina of both ampullae at the same time. In Embioptera, only the australembiid Metoligotoma has an M. interampullaris. All other studied webspinners instead have a M. ampullofrontalis which extends between the ampullae and the frontal region of the head capsule; these species do not have M. ampulloaorticus. Outgroup comparison indicates that an antennal heart with a M. interampullaris is the plesiomorphic character state among Embioptera and the likely ground pattern of the taxon Eukinolabia. Antennal hearts with a M. ampullofrontalis represent a derived condition that occurs among insects only in some embiopterans. These findings help to further clarify the controversially discussed internal phylogeny of webspinners by supporting the view that Australembiidae are the sister group of the remaining Embioptera.
TL;DR: The hemipenial morphology of Epictia vellardi (Epictinae, Leptotyphlopidae) is described based on 16 organs belonging to eight specimens and two general morphological patterns for the genus are identified.
Abstract: Scolecophidia (Squamata, Serpentes), commonly known as blindsnakes, wormsnakes or threadsnakes comprises a group of small snakes, with relatively few systematic and morphological studies when compared to Alethinophidia. Since the external morphology is very conserved amongst scolecophidians, internal morphological studies—such as the hemipenial morphology—are useful to unravel several systematic issues within the group. We aimed to describe the hemipenial morphology of Epictia vellardi (Epictinae, Leptotyphlopidae) based on 16 organs belonging to eight specimens. The organ is unilobed, with the body conspicuously narrower than the base and with the apex slightly expanded, without any macroscopic ornamentation. The comparison of the hemipenial morphology of E. vellardi with other hemipenes of Epictia spp. allowed us to identify two general morphological patterns for the genus, which are proposed and discussed in detail in the present study. The results found herein may be extremely relevant for future hemipenial descriptions. In addition, independent characters found in Types I and II (such as ornamentation, shape of base, body and apex) should be regarded for future systematic and evolutionary morphology studies within Leptotyphlopidae, in addition to assisting in the taxonomy and identification of species of the genus.
TL;DR: The ontogenetic changes that occur in this species are described, therefore facilitating the correct ex situ handling practices during incubation and serving as a basis for phylogenetic studies among the Kinosternidae.
Abstract: Few studies have been conducted on the reproductive biology and embryology of Kinosternon scorpioides. Determining the development of embryonic stages is essential for studies on comparative anatomy and phylogenetic relationships. The aim of this research was to examine the macroscopic embryonic development of K. scorpioides. At least three eggs were collected at incubation intervals of 5 days. After morphometry, embryos in stages 9–12 were classified in relation to the presence of pharyngeal arches, optic and otic vesicles, as well as sequential changes in both the forelimbs and hindlimbs. Embryos from stages 13 to 17 were identified through evident eye pigmentation, limb morphology, carapace appearance, and urogenital protuberance. From stages 19 to 22, the presence of digits on digital plates and pigmentation of the body were used for defining each of the stages. From stages 23 to 26, the digits and dense pigmentation on the body were used to define the stages and the disappearance of the urogenital protuberance and umbilical hernia. These results describe the ontogenetic changes that occur in this species, therefore facilitating the correct ex situ handling practices during incubation and serving as a basis for phylogenetic studies among the Kinosternidae.
TL;DR: There is a concern that continued anthropogenic pressures, changing land use, and increased droughts are resulting in a skewed size-class bias towards older, larger, more resilient adult individuals.
Abstract: Little is documented on the population demographics and morphometrics of wild freshwater turtles (hereafter terrapins) in South Africa. From February 2016 to October 2019, we trapped and recorded morphometric and biological data for serrated hinged terrapins Pelusios sinuatus (n = 97) and marsh terrapins Pelomedusa galeata (n = 51) in KwaZulu-Natal Province, South Africa. We visited two areas (Ndumo Game Reserve and Tala Private Reserve) regularly during the study period. Data were also intermittently obtained from eight other study areas across the province. We recorded age class, and morphometrics (including carapace length, carapace width, body mass and sex) for each terrapin caught, and also noted injuries. We uniquely marked all captured terrapins on the peripheral scutes around the hindleg region of the carapace, so to record any recaptures. A size-class bias was observed, with most individuals being large mature adults. Juveniles for P. sinuatus only accounted for 11 of the total 97 individuals (11.3%). Juveniles for P. galeata only accounted for 4 of the total 51 individuals (7.8%). There were significant differences in the three main morphometric variables between the adult male and female P. sinuatus, whereas there were no morphological differences between the adult male and female P. galeata. We recaptured only one P. sinuatus and two P. galeata. There is a concern that continued anthropogenic pressures, changing land use, and increased droughts are resulting in a skewed size-class bias towards older, larger, more resilient adult individuals.
TL;DR: Fine structures of the statocyst revealed that the statolith developed after hatching, and it was hypothesized that geotactic ability needs the following conditions: a sufficient concentration of calcium salt in theStatocyst; stc must work as afferent neurons; and a ventral polar cell, which is present outside the capsule, must be a sensory cell stimulated by the lithocyte.
Abstract: Acoel statocysts are fluid-filled chambers formed by two parietal cells underlying basal lamina as a capsule and contain a movable statolith cell called a lithocyte. The statocyst is needed for geotaxis; however, the mechanism of the gravity receptor system has not been elucidated. We focused on the geotactic ability of the acoel Praesagittifera naikaiensis, acquired during the development of the statocyst and its nervous system after hatching, and examined the three-dimensional relationship between the statocyst and its nervous system. Acoel geotactic ability was acquired between 0 and 7 days after hatching. No major changes in neural structures, namely a commissural brain, nerve cords, and commissures, were observed between juveniles and adults. The statocyst-associated commissure (stc), a commissural brain component, was circular and was located ventral to the statocyst but was not observed in neural connections to the capsule’s lumen. Fine structures of the statocyst revealed that the statolith developed after hatching. We hypothesized that geotactic ability needs the following conditions: (1) a sufficient concentration of calcium salt in the statolith; (2) stc must work as afferent neurons; and (3) a ventral polar cell, which is present outside the capsule, must be a sensory cell stimulated by the lithocyte.
TL;DR: In this article, the authors show inconsistencies with regard to the identification and naming of the shoulder joint muscles in frogs and toads (Amphibia: Anura) were revealed and resolved by assessing the ontogenetic development, innervation, and adult morphology of selected anuran species representing ancient lineages and two major neobatrachian groups.
Abstract: Previous myological studies show inconsistencies with regard to the identification and naming of the shoulder joint muscles in frogs and toads (Amphibia: Anura). Those inconsistencies were revealed and resolved by assessing the ontogenetic development, innervation, and adult morphology of selected anuran species representing ancient lineages and two major neobatrachian groups. To do so, digital dissections of volumes acquired by histological serial sectioning, episcopic microtomy, and contrast-enhanced micro-computed tomography scanning were performed and three-dimensional reconstructions were derived. Muscle units crossing the shoulder joint were defined, their ontogenetic development was described, their homology across species was established, and a consistent nomenclature was suggested. The mm. anconaeus, dorsalis scapulae, latissimus dorsi, and the group of scapulohumeralis muscles were ontogenetically derived from the dorsal pre-muscle mass present in all tetrapods. The ventral pre-muscle mass gave rise to the mm. cleidohumeralis, episternohumeralis, supracoracoideus, coracoradialis, subcoracoscapularis, coracobrachialis, and pectoralis. The results indicate that the mm. anconaeus, dorsalis scapulae, latissimus dorsi, coracoradialis, and the portionis sternalis and abdominalis of the m. pectoralis have consistently been recognized and denoted in previous studies, whereas the names for the muscle units commonly denoted as m. coraco-brachialis longus and as parts of the m. deltoideus are misleading with regard to the ontogenetic origin of these muscles. The mm. scapulohumeralis profundus anterior and posterior, although present, have been overlooked in some studies. The mm. cleidohumeralis, supracoracoideus, and coracobrachialis are present with two parts or portions in some species, these portions have previously not always been recognized and assigned correctly.
TL;DR: A comprehensive and comparative myoanatomical study of three putatively, distantly related worm-like species: Cateria styx, Franciscideres kalenesos and Zelinkaderes yong, suggesting that a flexible, slender body evolved at least twice independently as an adaptation to the interstitial environment.
Abstract: Aberrant kinorhynchs show several modifications deviating from the typical kinorhynch body plan, including a modified introvert with very elongated and flexible scalids, a weakly developed neck, and a slender trunk with less distinct segmentation. How these aberrant external features are reflected in the inner anatomy and how their aberrant body plan evolved are not understood. Here, we provide a comprehensive and comparative myoanatomical study of three putatively, distantly related worm-like species: Cateria styx, Franciscideres kalenesos and Zelinkaderes yong. Despite the weak external segmentation of the trunk, the studied species show a distinct segmental arrangement of the musculature. However, this arrangement is shifted posteriorly with respect to the external segmentation, because the extremely thin and flexible cuticle is lacking the apodeme-like cuticular thickenings (pachycycli) where the longitudinal muscles usually attach. The muscular arrangement in the three species is overall similar, yet, C. styx shows most resemblance to the allomalorhagid F. kalenesos, whereas the cyclorhagid Z. yong differs in several ways. This suggests a closer relationship of C. styx to Allomalorhagida. Whereas most kinorhynchs prefer muddy sediments, both the allomalorhagid and cyclorhagid worm-like kinorhynchs are mainly found in sandy environments, suggesting that a flexible, slender body evolved at least twice independently as an adaptation to the interstitial environment.
TL;DR: The present study describes a clasper pocket, a male-specific groove to “stow” claspers close to the body, as a novel example of such modifications in sharks with a thunniform body plan.
Abstract: The evolution of thunniform swimming in sharks involves many morphological modifications that enhance the energetic efficiency of aquatic locomotion. The present study describes a clasper pocket, a male-specific groove to “stow” claspers close to the body, as a novel example of such modifications. According to observations in two lamnoid species, Lamna ditropis and Isurus oxyrinchus, the groove becomes drastically deeper along with clasper elongation through ontogeny. The clasper pocket was found in sharks with a thunniform body plan, so far only observed in Lamnidae and Cetorhinidae. The number of acquisitions of clasper pockets during lamniform phylogeny assessment ranges from one to two, depending on the interpretation regarding the phylogenetic relationships between Lamnidae and Cetorhinidae in the phylogenetic tree is used in the analysis.
TL;DR: In this article, specimens of Anemonia viridis and Aiptasia couchii from the North Adriatic Sea were collected to acquire data about cnidae from different tissues (i.e., column, tentacles, actinopharynx, mesenteries, and acrorhagi/acontia).
Abstract: Although the biometric investigation of the cnidome represents an essential diagnostic feature to successfully identify cnidarian species, further efforts are needed to fully characterize eventual differences. Important model actiniarians, such Anemonia viridis and Aiptasia spp., are commonly used for scientific purposes; however, their identification is often difficult, and the description of their cnidome is, therefore, essential. To contribute to this necessity, specimens of Anemonia viridis and Aiptasia couchii from the North Adriatic Sea were collected to acquire data (i.e. length, width, size range, length/width ratio) about cnidae from different tissues (i.e. column, tentacles, actinopharynx, mesenteries, and acrorhagi/acontia). Four types of cnidae were observed in each species. A. viridis shows microbasic b-mastigophores, microbasic p-mastigophores, holotrichous isorhizas, and spirocysts, whereas A. couchii harbored basitrichs, microbasic p-mastigophore, microbasic p-amastigophore and spirocysts. Molecular and phylogenetic analyses were also performed using three mitochondrial markers to confirm the correct classification of the specimens here analysed.
TL;DR: In this paper, the ontogenetic trajectories of balanocrinin species were investigated using SEM observations. And the authors concluded that the most advanced synarthries shared by distant crinoid taxa mainly represent a homoplasy under morphofunctional constraints and should be abandoned as a major character in the classification of Isocrinida.
Abstract: Ontogeny of non-muscular brachial articulations in extant species of Balanocrininae, i.e., Neocrinus decorus, Neocrinus blakei and Hypalocrinus naresianus (Crinoidea, Isocrinida), is described using SEM observations. All three species share embayed synarthries and symplexies (previously only known in crinoid stalks) showing a radiating crenularium pattern in their proximal arms but differ in several important ways. Neocrinus decorus has a shallow simple symmorphy affecting symplexies, and embayed synarthries. During the latest ontogeny of embayed synarthries, irregular syzygial ridges appear on the aboral segment of the fulcral ridge. Neocrinus blakei and H. naresianus share a peculiar sharp deep symmorphy superimposed on symplexies, and synarthries with a more complete single fulcral ridge that only appears late in ontogeny. Comparison with other crinoid taxa that have more advanced arm axial synarthries shows that this ontogenetic trajectory is restricted to paedomorphic stages in extant balanocrinins. An embayed synarthry seems to be derived from the earliest developmental stage of the radiating symplexial crenularium via hypermorphosis of a single crenula. An embayed synarthry is, therefore, a symplesiomorphy based on paedomorphic stage of development; it thus lacks phylogenetic significance, and should be abandoned as a major character in the classification of Isocrinida. The most advanced brachial synarthries shared by distant crinoid taxa mainly represent a homoplasy under morphofunctional constraints. However, they could result from different ontogenetic trajectories, which have only rarely been investigated. Another distinctive articulation feature, the peculiar sharp deep symmorphy observed in extant balanocrinins is a derived character known in a few fossil isocrinids beginning in the Middle Jurassic. We question its phylogenetic significance and suggest that it has developed repeatedly via iterative evolution in Isocrinida. Therefore, because these three extant balanocrinin species share the same ontogenetic trajectories of arm and stalk ligamentary articulations, and differ only in various states of heterochronic development of a few characters, we treat them as belonging to the same genus. We, therefore, consider Hypalocrinus as a junior synonym of the genus Neocrinus.
TL;DR: Providing guidelines for future sampling and measurements, this work encourages fellow researchers planning measurements to take into account the effect of specimen preparation techniques on the results, define landmarks, consider resolution, accuracy, precision, choose an appropriate sample size and report details on methodology.
Abstract: Mouthpart morphologies relate to diet range. Differences among or within species may result in resource partitioning and speciation. In plant-pollinator interactions, mouthpart length has an important role in foraging efficiency, resource partitioning and pollination, hence measuring nectarivorous insect mouthparts’ morphological variation is important. Most adult lepidopterans feed on nectars and participate in pollination. Although a vast range of studies applied morphometric measurements on lepidopteran proboscis (tongue) length, general recommendations on methodologies are scarce. We review available proboscis length measurement methodologies for Lepidoptera. Focusing on how proboscides have been measured, how accurate the measurements were, and how were these constrained by sampling effort, we searched for research articles investigating lepidopteran proboscis length and extracted variables on the aims of measurements, preparation and measurement methodology, and descriptive statistics. Different methods were used both for preparation and measurements. Many of the 135 reviewed papers did not provide descriptions of the procedures applied. Research aims were different among studies. Forty-four percent of the studies measured dead specimens, 13% measured living specimens, and 43% were unclear. Fifteen percent of the studies used callipers, 9% rulers, 1% millimetre scales, 4% ocular micrometers, 3% drawings and 14% photographs; 55% were non-informative. We emphasise the importance to provide detailed descriptions on the methods applied. Providing guidelines for future sampling and measurements, we encourage fellow researchers planning measurements to take into account the effect of specimen preparation techniques on the results, define landmarks, consider resolution, accuracy, precision, choose an appropriate sample size and report details on methodology.
TL;DR: It can be concluded that nuchal and dorsal organs are also identical in Orbiniidae, and despite general correspondence with spionids, convergent evolution in the two taxa appears to be the most parsimonious interpretation.
Abstract: Annelids and particularly polychaetes possess a great variety of sensory organs and respond to numerous sensory stimuli. Although eyes and nuchal organs are comparatively well studied, the so-called dorsal organs are among the lesser-known sense organs in aquatic annelids. Moreover, they are known to be restricted to only two out of approximately 80 families of polychaetes—Orbiniidae and Spionidae—which are not closely related. These organs have been regarded as segmentally repeated nuchal organs in the latter taxon, but in Orbiniidae, data are lacking, although it is known that the organs occur almost along the entire trunk except for the anterior-most segments. Furthermore, although the nuchal organ ultrastructure is known to be comparatively uniform for many polychaete species, a comparative investigation has not been conducted in Orbiniidae. To bridge this data gap, we examined an intertidal population of the widely distributed species Scoloplos armiger. Although not completely identical, nuchal and dorsal organs show a high degree of correspondence in the examined specimens. Moreover, both organs correspond to the general structure of nuchal organs. They comprise ciliated supportive cells and bipolar receptor cells and are innervated directly from the brain. The supportive cells form subcuticular spaces and olfactory chambers apically protected by specialized microvilli that house the sensory processes—cilia and microvilli—of the monociliated receptor cells. Therefore, it can be concluded that nuchal and dorsal organs are also identical in Orbiniidae. However, despite general correspondence with spionids, convergent evolution in the two taxa appears to be the most parsimonious interpretation.
TL;DR: The anatomical and histological features of the foveae in a gull, Larus michahellis, were investigated combining immunofluorescence and transmission electron microscopy.
Abstract: The anatomical and histological features of the foveae in a gull, Larus michahellis, were investigated combining immunofluorescence and transmission electron microscopy In an area of higher acuity, which extends in a band across the field of view, a central convexiclivate deep fovea was observed near of the pecten oculi Moreover, a shallow fovea was present in the dorsonasal region The central deep fovea was characterized by a remarkably and well-excavated pit containing extremely thin cones and a radial displacement of the cone axons and inner retinal layers Immunofluorescence demonstrated the absence of rods and the presence of violet and green/red sensitive cone opsins Ultrastructural analyses confirmed the lack of double cones, and specialized Muller cell processes forming a network that stabilizes the foveal structure This deep central fovea, which provides the highest resolution and colour discrimination, may be used for monocular sideways vision of distant objects and a binocular fixation The dorsonasal fovea was shallower and all retinal layers were present at the pit This fovea showed the same composition of photoreceptors than central fovea and could be implied in magnification of a wide monocular part of the retinal image The bifoveate condition of yellow-legged gull retina would allow the formation of three separate and distinct visual fields: two wide lateral monocular fields mediated by the dorsonasal and the central foveae, and a small binocular field mediated by the central deep fovea depending on ocular movements
TL;DR: A detailed description of the proboscis epithelium of females of B. viridis is provided in this article, where four zones of the stem can be distinguished: dorsal, ventral, and two lateral.
Abstract: Although Bonellia viridis is the best studied echiurid species, many features of its anatomy and ultrastructure are still unclear. Detailed data on the organisation of the proboscis may help us to understand the echiurid biology and some aspects of their feeding behaviour. In this study, a detailed description of the proboscis epithelium of females of B. viridis is provided. According to histological specificities, four zones of proboscis stem can be distinguished: dorsal, ventral, and two lateral. These zones differ from each other in ciliation and abundance of bonellin-producing and gland cells. Each zone provides certain functions: protective for dorsal, transport of food particles for ventral, and agglutination of food particles for lateral. Ciliated cells have been described in the epithelium of the dorsal side of the proboscis stem for the first time. These cells probably supply the slow ciliary movements of the proboscis. For the first time, the organisation of epithelial cells is described: these cells contain many pinocytotic vesicles, multivesicular bodies, and phagosomes, whose presence may provide evidence of the ability of epithelial cells to consume nutrients. The absence of continuous basal lamina under the ventral epithelium is ascertained and may be explained by the activity of bonellin-producing cells, which constantly penetrate between epithelial cells. In bonellin-producing cells, voluminous perinuclear space and the contribution of rough endoplasmic reticulum into the formation of bonellin-containing granules are detected for the first time. For the first time, the neurite bundles extending from lateral nerve cords to gland cells and bonellin-producing cells are discovered.
TL;DR: Body length variation across the family is mapped on an existing phylogeny, and some potential drivers of body size increase are explored: intrasexual competition between males, and mimicry patterns.
Abstract: Cimbicidae is a small family of Tenthredinoidea, containing the largest extant true sawflies. Body length variation across the family is mapped on an existing phylogeny, and some potential drivers of body size increase are explored: intrasexual competition between males, and mimicry patterns. Body length varies substantially within Cimbicidae, the largest species being found within the subfamily Cimbicinae. The smallest species occur in Corynidinae; this subfamily has experienced an overall decrease in body size. Initially, body size increase in Cimbicinae is correlated with males becoming larger than females, increase in relative mandible size in both sexes but especially in males, and increased hind femur width/length ratio in males only. Relative mandible size decreases in Cimbex spp. + Odontocimbex and hind femur width/length in male Leptocimbex spp., respectively. The record sizes obtained in Cimbex spp. + Odontocimbex are the result of a further increase in body size, coupled with increase in hind femur width/length ratio in males. Black and yellow body colouration and other potential mimicry patterns are observed in a number of genera of Cimbicinae, but are probably not ground plan features of the subfamily. Outside Cimbicinae, black and yellow body colouration is most frequent in Corynidinae, but it cannot be decided if it is a ground plan trait of this subfamily. Intrasexual competition seems to be more likely to have influenced size increase in Cimbicinae than adaptations to mimicry.
TL;DR: Based on the osteological data, it was concluded that the taxonomic status of the family could be increased to superfamily Congiopodoidea, and its subfamilies, respectively, to the rank of the families Congiopodidae and Zanclorhynchidae.
Abstract: A detailed study of the structure of bone elements of the neurocranium and pectoral girdle and of the structure of pelvis of all three genera of the family Congiopodidae: Congiopodus, Alertichthys, and Zanclorhynchus, was carried out in the present paper. It resulted in the discovery of new complex apomorphies of Congiopodidae s.l., which are an additional and very convincing confirmation of the separate position of this family in the suborder Scorpaenoidei. These include the features of the posterior neurocranium structure: location, shape, and size of the parietal and supraoccipital, location of these bones in relation to the anterior pterygiophores D1, position of the first vertebrae in relation to the neurocranium and the highly complex structure of the cleithrum. Based on the osteological data, it was concluded that the taxonomic status of the family could be increased to superfamily Congiopodoidea, and its subfamilies, respectively, to the rank of the families Congiopodidae and Zanclorhynchidae.
TL;DR: High-resolution images of fresh specimens of three teredinid species, representing three genera, are presented to show the different features of each organ of the digestive tract and intra- and inter-specific differences.
Abstract: Adult shipworms (Bivalvia, Teredinidae) have greatly elongate bodies, and thus, the organs have a different orientation than those of other bivalves. Studies on the anatomy of the digestive system have been carried out in a number of genera and species in the Teredinidae, but are now over 50 years old and most were carried in only a few preserved specimens. These studies contain descriptions and line drawings, but high-resolution images do not exist, except for Lyrodus pedicellatus that was recently studied using modern techniques. Thus, we present high-resolution images of fresh specimens of three teredinid species, representing three genera, to show the different features of each organ of the digestive tract and intra- and inter-specific differences. Most of our observations concur with, but some differ from previous descriptions. One observation in Teredo navalis showed, for the first time, the foot covered by a membrane with corrugated aspect, which the function is not yet understood. Another observation in the same species showed that the caecum and intestine have strikingly different colourations in specimens in overcrowded conditions when compared with those in uncrowded conditions. This may indicate that the former resort more to filter feeding to avoid the complete destruction of their habitat. In Psiloteredo megotara, the digestive gland seems to cover the caecum, as it does in Nototeredo norvagica and differing from a previous line drawing for the former species. Faecal pellets were observed in N. norvagica and P. megotara, which may indicate a more complete utilization of wood in these species.