Spatulate Tips Research Articles

On the taxonomy of Philyra sagittifera (Alcock, 1896) and P. concinnus Ghani & Tirmizi, 1995 (Decapoda, Brachyura, Leucosiidae), with description of a new genus from the Indian Ocean.

The identity of the leucosiid crabs, Philyra sagittifera (Alcock, 1896) and P. concinnus Ghani & Tirmizi, 1995, originally described from Pakistan is clarified. Redescription of the lectotype male of Philyra sagittifera (Alcock, 1896) and fresh material of both species collected from the Persian Gulf revealed that these two species show significant morphological differences from the generic characters of Philyra sensu stricto and other allied genera in possessing three broad tuberculated ridges united to form a "broad-arrow" pointing forwards on the carapace, and male G1 with apical process curved, with or without a spatulate tip. Therefore, a new genus Tirmilyra n. gen. is established to accommodate both species.

Revisiting the classification of squamate adhesive setae: historical, morphological and functional perspectives.

Research on gecko-based adhesion has become a truly interdisciplinary endeavour, encompassing many disciplines within the natural and physical sciences. Gecko adhesion occurs by the induction of van der Waals intermolecular (and possibly other) forces between substrata and integumentary filaments (setae) terminating in at least one spatulate tip. Gecko setae have increasingly been idealized as structures with uniform dimensions and a particular branching pattern. Approaches to developing synthetic simulacra have largely adopted such an idealized form as a foundational template. Observations of entire setal fields of geckos and anoles have, however, revealed extensive, predictable variation in setal form. Some filaments of these fields do not fulfil the morphological criteria that characterize setae and, problematically, recent authors have applied the term ‘seta’ to structurally simpler and likely non-adhesively competent fibrils. Herein we briefly review the history of the definition of squamate setae and propose a standardized classificatory scheme for epidermal outgrowths based on a combination of whole animal performance and morphology. Our review is by no means comprehensive of the literature regarding the form, function, and development of the adhesive setae of squamates and we do not address significant advances that have been made in many areas (e.g. cell biology of setae) that are largely tangential to their classification and identification. We contend that those who aspire to simulate the form and function of squamate setae will benefit from a fuller appreciation of the diversity of these structures, thereby assisting in the identification of features most relevant to their objectives.

Dorsal setae in Raoiella (Acari: Tenuipalpidae): Their functional morphology and implication in fluid secretion

The setae of mites are not regarded as secretory structures, yet in the flat mite genus Raoiella, each developmental stage presents droplets of fluid associated with the tips of their dorsal setae. To understand the origin of this fluid, the ultrastructure of the dorsal setae is investigated in females of Raoiella bauchani Beard & Ochoa and the invasive pest species Raoiella indica Hirst using scanning and transmission electron microscopy techniques.The dorsal setae are barbed along their entire length and have either a broadened plumose or a flat spatulate tip. Ultrastructurally, they present the typical features of mechanoreceptors, but have a “hollow” axis represented by a protoplasmatic core containing dendritic branches. This combination of ultrastructural characters indicates that the setae might be multimodal receptors: acting as both mechanoreceptors and contact chemoreceptors. The epidermal cells that underlie the setal sockets are columnar and have an ultrastructure that suggests they have a glandular function. Moreover, these cells present regular microvilli apically and form extracellular cuticular canals, containing epicuticular filaments, that are connected with the microvilli proximally and which open via pores onto the surface of the setal base distally. This arrangement indicates that the secretion from the microvilli passes into the canals and is then conducted to pores at the base of the seta, where it then accumulates and moves up the setal shaft, along the longitudinal grooves of the barbs. Based on similar arrangements in some insect taxa, the organization of the structures here observed in Raoiella suggests the passage of a non-polar, water insoluble, lipoid fluid through the cuticle, the function of which is still obscure.

The same but different: setal arrays of anoles and geckos indicate alternative approaches to achieving similar adhesive effectiveness.

The functional morphology of squamate fibrillar adhesive systems has been extensively investigated and has indirectly and directly influenced the design of synthetic counterparts. Not surprisingly, the structure and geometry of exemplar fibrils (setae) have been the subject of the bulk of the attention in such research, although variation in setal morphology along the length of subdigital adhesive pads has been implicated to be important in the effective functioning of these systems. Adhesive setal field configuration has been described for several geckos, but that of the convergent Anolis lizards, comprised of morphologically simpler fibrils, remains largely unexplored. Here, we examine setal morphology along the proximodistal axis of the digits of Anolis equestris and compare our findings to those for a model gecko, Gekko gecko. Consistent with previous work, we found that the setae of A. equestris are generally thinner, shorter, and present at higher densities than those of G. gecko and terminate in a single spatulate tip. Contrastingly, the setae of G. gecko are hierarchically branched in structure and carry hundreds of spatulate tips. Although the splitting of contacts into multiple smaller tips is predicted to increase the adhesive performance of a fiber compared to an unbranched one, we posited that the adhesive performance of G. gecko and A. equestris would be relatively similar when the configuration of the setal fields of each was accounted for. We found that, as in geckos, setal morphology of A. equestris follows a predictable pattern along the proximodistal axis of the pad, although there are several critical differences in the configuration of the setal fields of these two groups. Most notably, the pattern of variation in setal length of A. equestris is effectively opposite to that exhibited by G. gecko. This difference in clinal variation mirrors the difference in the direction in which the setal fields of anoles and geckos are peeled from the substrate, consistent with the hypothesis that biomechanical factors are the chief determinants of these patterns of variation. Future empirical work, however, is needed to validate this. Our findings set the stage for future comparative studies investigating the functional morphology of these convergent adhesive apparatuses. Such investigations will lead to an enhanced understanding of the interactions between form, function, and environment of fibril-based biological adhesive systems.

Schistonchus macrophylla (Nematoda: Aphelenchoididae): an enigmatic taxon from sycones of Ficus section Malvanthera in eastern Australia, with description of a new subspecies

Summary Over a period of 15 years, Schistonchus was collected from sycones of Ficus subgenus Urostigma section Malvanthera in eastern Australia, and was found to occur widely. Here, Schistonchus macrophylla macrophylla is redescribed from F. macrophylla and F. superba, and a new subspecies, Schistonchus m. lightfooti subsp. n., from F. rubiginosa and F. superba. Schistonchus m. lightfooti subsp. n., is characterised by having a long post-vulval uterine sac (PUS) with thickened walls and a narrowly rounded or pointed distal tip, procorpus which is usually longer than the stylet length, pyriform metacorpus, trapezoid-shaped head capsule, papillae arranged as one large pair adcloacal, a large pair at mid-tail length, and a small pair near the tail tip, no caudal alae, and a spatulate tail tip in females; and was collected from Sydney in New South Wales (NSW) to southern Queensland. Schistonchus m. macrophylla is characterised by having a procorpus shorter than or equal to the stylet length, an ovoid metacorpus, rectangular-shaped head capsule, long PUS with thickened wall only at its distal tip, caudal alae, and papillae arranged as one pair precloacal, one small pair adcloacal, and a large pair at mid-tail length. It was collected in NSW.

Bisonic Mechanical Wing Songs and Complex Kinematics in Aerial Displays of the Subtropical Doradito (Pseudocolopteryx acutipennis).

Loud mechanical sounds with a communication role are called sonations. Male Subtropical Doraditos (Pseudocolopteryx acutipennis) exhibit five conspicuously modified primaries suspected of sonating. Here we (1) describe feather modifications, (2) describe three different territorial/aggressive contexts for these sounds: one-perch aerial displays (1PADs), two-PADs, and Chukrut pursuits, (3) investigate the kinematics of the most common display (1PADs) and the physical mechanisms of sonation using synchronized high-speed video and audio, and (4) assess the roles of modified wing feathers in all contexts by experimental manipulation in four individuals. Primaries p3-p7 were modified in adult males but not in females: p3 was pointed with a reduced distal third to the outer vane; p4 and p5 were slim and falciform with pointed tips curved outwards; p6 was broad, massive, and subtly S-shaped, with a spatulate tip; and p7 was large with the distal third of the outer vane abruptly reduced, and the inner vane with a shallow concave sub-apical emargination. One-PADs consisted of perched short nasal introductory syllables accelerating until the bird performed a super-rapid circular flight of ∽15 cm in diameter from and to the same branch, during which two syringeal syllables and three mechanical syllables were given (chik… chik…. chik-chik frrrottt). The syllables were produced during rapid downstrokes by fluttering feathers and were bisonic, being conformed by two simultaneous main tonal, flat, narrow band sounds: a low-pitched note (f0 ∽1 kHz) and a high-pitched note (f0 ∽3.7 kHz). Primary p7 is the necessary and sufficient sound source of the low-pitched note (removal of p7 caused the sound to disappear) and p3 is the sound source of the high-pitched note, being necessary but perhaps not sufficient (removal of p3 caused the sound to disappear); the other modified feathers seem involved in different roles related to either producing the sonation (p4 and p5 interacting with p3) or allowing it (p6 raising dorsally letting p7 flutter freely; removal of p6 did not affect sound production). The specialized shape of p6 might be compromised to allow sonation of p7 without losing flight functionality. Sonations in Subtropical Doraditos occupy the position of the vocal flourish in the songs of other Pseudocolopteryx suggesting the evolutionary replacement of vocal by mechanical sounds. We propose that wing songs in flying birds may be constrained to occur in temporally broken patterns due to intrinsic features of flapped flight and structurally constrained by the demands of creating an airfoil.

Continuous and scalable fabrication of bioinspired dry adhesives via a roll-to-roll process with modulated ultraviolet-curable resin.

A simple yet scalable strategy for fabricating dry adhesives with mushroom-shaped micropillars is achieved by a combination of the roll-to-roll process and modulated UV-curable elastic poly(urethane acrylate) (e-PUA) resin. The e-PUA combines the major benefits of commercial PUA and poly(dimethylsiloxane) (PDMS). It not only can be cured within a few seconds like commercial PUA but also possesses good mechanical properties comparable to those of PDMS. A roll-type fabrication system equipped with a rollable mold and a UV exposure unit is also developed for the continuous process. By integrating the roll-to-roll process with the e-PUA, dry adhesives with spatulate tips in the form of a thin flexible film can be generated in a highly continuous and scalable manner. The fabricated dry adhesives with mushroom-shaped microstructures exhibit a strong pull-off strength of up to ∼38.7 N cm(-2) on the glass surface as well as high durability without any noticeable degradation. Furthermore, an automated substrate transportation system equipped with the dry adhesives can transport a 300 mm Si wafer over 10,000 repeating cycles with high accuracy.

Experimental evidence for friction-enhancing integumentary modifications of chameleons and associated functional and evolutionary implications

The striking morphological convergence of hair-like integumentary derivatives of lizards and arthropods (spiders and insects) demonstrates the importance of such features for enhancing purchase on the locomotor substrate. These pilose structures are responsible for the unique tractive abilities of these groups of animals, enabling them to move with seeming ease on overhanging and inverted surfaces, and to traverse inclined smooth substrates. Three groups of lizards are well known for bearing adhesion-promoting setae on their digits: geckos, anoles and skinks. Similar features are also found on the ventral subdigital and distal caudal skin of chameleons. These have only recently been described in any detail, and structurally and functionally are much less well understood than are the setae of geckos and anoles. The seta-like structures of chameleons are not branched (a characteristic of many geckos), nor do they terminate in spatulate tips (which is characteristic of geckos, anoles and skinks). They are densely packed and have attenuated blunt, globose tips or broad, blade-like shafts that are flattened for much of their length. Using a force transducer, we tested the hypothesis that these structures enhance friction and demonstrate that the pilose skin has a greater frictional coefficient than does the smooth skin of these animals. Our results are consistent with friction being generated as a result of side contact of the integumentary filaments. We discuss the evolutionary and functional implications of these seta-like structures in comparison with those typical of other lizard groups and with the properties of seta-mimicking synthetic structures.

Subdigital and subcaudal microornamentation in chamaeleonidae-A comparative study

Locomotion on horizontal and vertical substrates requires effective attachment systems. In three clades of arboreal and rupicolous Iguanidae, Gekkota and Scincidae adhesive systems consisting of microscopic hair-like structures (setae) have been evolved independently. Also the substrate contacting sites on toes and tails of chameleons (Chamaeleonidae) are covered with setae. In the present comparative scanning electron microscopy study, we show that representatives from the chamaeleonid genera Calumma, Chamaeleo, Furcifer, and Trioceros feature highly developed setae that are species-specific and similar on their feet and tail. These 10 μm long, unbranched setae rather resemble those in anoline and scincid lizards than the larger and branched setae of certain gecko species. In contrast to the thin triangular tips of other lizards, all examined species of the genera Furcifer and Calumma and one of the five examined species of the genus Trioceros have spatulate tips. All other examined species of genera Trioceros and Chamaeleo bear setae with narrowed, fibrous tips. Unlike the setae of other lizards, chamaeleonid setal tips do not show any orientation along the axis of the toes, but they are flexible to bend in any direction. With these differences, the chameleon's unique microstructures on the zygodactylous feet and prehensile tail rather increase friction for arboreal locomotion than being a shear-induced adhesive system as setal pads of other lizards.

New artiopodan arthropods from the early Cambrian Emu Bay Shale Konservat-Lagerstätte of South Australia

The Emu Bay Shale Konservat-Lagerstätte (Cambrian Series 2, Stage 4) on Kangaroo Island, South Australia, is the source of two new non-biomineralized artiopodan arthropods.Squamacula buckorumn. sp. is the first record outside of China of a genus otherwise known only from its type species,S. clypeata, from the Chengjiang biota. The Australian species displays the long cephalic doublure and spiniform exopod setae that are apomorphic for this genus, provides new information on the alimentary tract and midgut glands (the latter preserved as three-dimensional, permineralized structures), and indicates interspecific variability in trunk segment numbers. The distribution ofSquamaculastrengthens the biogeographic connections between early Cambrian “Burgess Shale-type” biotas of Australia and South China.Australimicola spriggin. gen. n. sp. represents a monotypic genus resolved in a cladistic analysis of Cambro-Ordovician artiopodans as most closely related to or within Conciliterga (a clade containingHelmetia,Kuamaia,Kwanyinaspis,Rhombicalvaria,Saperion,Skioldia, andTegopelte). Compared with other members of this clade from Chengjiang and the Burgess Shale, the new genus is diagnosed by an elongate trunk with 23 thoracic tergites having spatulate pleural tips and a small pygidium possessing a single, elongate pair of pleural spines, with specimens also showing a hypostome attached to an anterior (or prehypostomal) sclerite, antennae, short endopods, an annulated alimentary tract, and a series of three-dimensional, permineralized midgut glands. An alternative relationship betweenAustralimicolaand the Early Ordovician–Early Devonian Cheloniellida explains the shared anterior flexure of trunk pleurae but forces dubious homologies in other characters, such as dorsally-articulated furcae versus spines.

Surface roughness effects on attachment ability of the spider Philodromus dispar (Araneae, Philodromidae)

The morphology of the tarsal attachment system of the running spider Philodromus dispar Walckenaer 1826 (Araneae, Philodomidae) was studied using scanning electron microscopy and its performance was experimentally tested in traction force measurements. Each pretarsus bears a hierarchically built hairy adhesive pad that consists of a dense array of flattened setae covered with numerous microtrichia on the substrate-facing side. Microtrichia carry spatulate end tips that allow close contact with the substrate. Forces were estimated on tethered living specimens on rough epoxy resin surfaces (asperity size 0.3, 1, 3, 9 and 12 μm) and on a smooth surface as a control. A strong reduction in adhesion was observed for substrates with an asperity size of 0.3 and 1 μm. Comparison of the present data with previous results of different organisms demonstrates that the difference in force reduction on rough substrata depends on the dimensions of terminal contact elements (spatulae).

Differences in foraging ecology determine variation in visual fields in ibises and spoonbills (Threskiornithidae)

Variations in visual field topography among birds have been interpreted as adaptations to the specific perceptual challenges posed by the species’ foraging ecology. To test this hypothesis we determined visual field topography in four bird species which have different foraging ecologies but are from the same family: Puna Ibis Plegadis ridgwayi (probes for prey in the soft substrates of marsh habitats), Northern Bald Ibis Geronticus eremita (surface pecks for prey in dry terrestrial habitats), African Spoonbill Platalea alba and Eurasian Spoonbill Platalea leucorodia (bill‐sweeps for prey in shallow turbid waters). All four species employ tactile cues provided by bill‐tip organs for prey detection. We predicted that the visual fields of these species would show general features similar to those found in other birds whose foraging is guided by tactile cues from the bill (i.e. bill falling outside the frontal binocular field and comprehensive visual coverage of the celestial hemisphere). However, the visual fields of all four species showed general features characteristic of birds that take food directly in the bill under visual guidance (i.e. a narrow and vertically long binocular field in which the projection of the bill tip is approximately central and with a blind area above and behind the head). Visual fields of the two spoonbills were very similar but differed from those of the ibises, which also differed between themselves. In the spoonbills, there was a blind area below the bill produced by the enlarged spatulate bill tip. We discuss how these differences in visual fields are related to the perceptual challenges of these birds’ different foraging ecologies, including the detection, identification and ingestion of prey. In particular we suggest that all species need to see binocularly around the bill and between the opened mandibles for the identification of caught prey items and its transport to the back of the mouth. Our findings support the hypothesis that sensory challenges associated with differences in foraging ecology, rather than shared ancestry or the control of locomotion, are the main determinants of variation in visual field topography in birds.

In‐frame deletion in FLNA causing familial periventricular heterotopia with skeletal dysplasia in males

Periventricular heterotopia (PH) is an etiologically heterogeneous disorder characterized by nodules of neurons ectopically placed along the lateral ventricles. Truncating and missense mutations of the FLNA gene have been identified in almost 100% of families and 26% of sporadic patients with PH. The otopalatodigital syndrome spectrum is caused by distinct FLNA missense mutations or in-frame deletions disrupting the development of craniofacial and long bones. We report on a clinical, neuroimaging, X-ray, and molecular study of a family in which classical bilateral PH appeared as an isolated anatomic feature in the mother and was associated with skeletal abnormalities and facial dysmorphisms in her two sons. Both boys exhibited PH associated with flat face and spatulate finger tips, short broad phalanx and metacarpus, and bowed radius with dislocated wrist joints. All three patients harbored the c.7865_7870del in-frame deletion (p.2622_2623delDK) in the carboxyl-terminal domain (repeat 24) of FLNA. The X-inactivation observed in the mother was skewed towards the mutant allele, resulting in the preferential expression of the wild-type allele. The in-frame deletion in the carboxyl-terminal domain of FLNA caused a phenotype in which PH was associated with skeletal features suggestive of the otopalatodigital syndrome spectrum in boys. There appears to be a continuum among allelic disorders due to FLNA mutations.

Shear induced adhesion: Contact mechanics of biological spatula-like attachment devices

Most biological hairy adhesive systems of insects, arachnids, and reptiles, involved in locomotion, rely not on flat punches on their tips, but rather on spatulate structures. Several hypotheses have been previously proposed to explain the functional importance of this particular contact geometry: (1) enhancement of adaptability to the rough substrate; (2) contact formation by shear force rather than by normal load; (3) increase in total peeling line due to the use of an array of multiple spatulae; (4) contact breakage by peeling off. In the present paper, we used numerical approach to study dynamics of spatulate tips during contact formation on rough substrates. The model clearly demonstrates that the contact area increases under applied shear force, especially when spatulae are misaligned prior to the contact formation. Applied shear force has an optimum describing the situation when maximal contact is formed but no slip occurs. At such equilibrium, maximal adhesion can be generated. This principle manifests the crucial role of spatulate terminal elements in biological fibrillar adhesion.

The Elaborate Courtship Behavior ofStenobothrus clavatusWillemse, 1979 (Acrididae: Gomphocerinae)*

The elaborate courtship behavior of the gomphocerine grasshopper Stenobothrus clavatus, endemic to a few mountains in Greece, incorporates acoustic signalling and visual display elements to prime the conspecific female. The courtship song, produced by rubbing hind legs against an elytral vein, can be divided into four consecutive phases. The basic movements of phases I, II and IV consist of simple up and interrupted downstrokes, with sound produced during the downstroke only. In contrast, phase III is characterized by a fast sound-producing elevation of the femora, a kick of the tibiae and other visual display elements, such as a fast raising of the antennae with their dark spatulate tips during each movement cycle. The latter is strongly pronounced and therefore a characteristic feature of this species. The stridulatory file of each hind leg consists of two parts. The proximal part bears a double row of little pegs, whereas the pegs in the distal part are regularly aligned in a single row. The proximal part of the stridulatory file is incorporated in sound production only during phase III. However, frequency spectra from different sound elements produced during phase III were similar. Nevertheless, differences are found between phase I/II and phase III/IV, which are ascribed to variations in contact pressure of the stridulatory file against the forewing, rather than to different portions of the stridulatory file being involved.

Enhanced friction of elastomer microfiber adhesives with spatulate tips

Previous studies have demonstrated that gecko foot-hair inspired elastomer microfibers with spatulate tips have significant adhesion enhancement compared to the flat elastomer surface. In this study, we report the friction enhancement of these highly adhesive fibers and analyze the relation between adhesion and friction of elastomer microfiber arrays with spatulate tips. Fabricated polyurethane fiber arrays with spatulate tips demonstrate macroscale static friction pressures up to 41N∕cm2 for a preload pressure of 1.5N∕cm2 on a 6mm diameter smooth glass hemisphere.

Biologically inspired polymer microfibers with spatulate tips as repeatable fibrillar adhesives

Being inspired by gecko foot hairs, microfibers with flat spatulate tips are proposed as repeatable adhesives. They are fabricated by molding a master template fabricated using deep reactive ion etching and the notching effect. Fabricated polyurethane fiber arrays with 4.5μm fiber and 9μm tip diameter demonstrated macroscale adhesion pressures up to 18N∕cm2 and overall work of adhesion up to 11J∕m2 on a 6mm diameter glass hemisphere for a preload pressure of 12N∕cm2. These results show around four times higher adhesion and five times higher overall work of adhesion as compared to the flat polyurethane surface.

Tecia solanivora

<i>Tecia solanivora</i>

The puerulus of the spotted spiny lobster, Panulirus guttatus (Latreille 1804) (Crustacea: Decapoda)

The puerulus of Panulirus guttatus is described from specimens collected at Florida reefs. Preliminary examination by scanning electron microscopy of the spatulate antennal tip of a P. guttatus puerulus revealed no qualitative features different than those previously described for the tapered antennal tip of P. cygnus. The unique combination of morphological characters of the P. guttatus puerulus requires minor adjustment to a recently proposed evolutionary classification of Panulirus based on pueruli.

Antennal Morphology In The Developing Polyphenics Of Liphaptis Erysimi (kalt.) (Hemiptera: Aphididae)

The present study revealed that the ratio of antennal to body length in Lipaphis erysimi (Kalt.) increased from 0.55:1.00 in the first instar to 0.75:1.00 in the adult alatae as compared to apterae, where the ratio stayed almost the same. The antenna showed specific growth regions i.e. first and fourth annuli, where the increase in size was more compared to other parts. Five morphologically distinct types of sensilla were recorded i.e. sensilla companiform. sensilla trichodea with enlarged spatulate tips, sensilla trichodea with tapering uniporous tips, plate organs and coeloconic pegs. The distribution pattern of these sensilla showed that the number of sensilla trichodea increased during the development, the increase was more in alatae compared to apterae. The secondary sensoria were restricted to adult alatae only, but could be seen under the cuticle in fourth instar alatae. In addition, the variation in the surface sculpturing in the form of scale-like projections were also observed on the antenna.