Tarsal Segments Research Articles

Maconellicoccus hirsutus

<i>Maconellicoccus hirsutus</i>

The enigmatic Dacochile microsoma Poinar &amp;amp; Brown: Tanyderidae or Bruchomyiinae?

An examination of character states in a second Burmese amber specimen of Dacochile microsoma Poinar &amp; Brown from the type locality confirms the original placement of this species in the family Tanyderidae and not the Bruchomyiinae, as proposed by Woodley (2005). Of special interest are a row of heavily sclerotized processes shaped like rose thorns and positioned on the inside of the hind tibiae and first two tarsal segments. These processes, which point upward towards the body, suggest that at least the females of Dacochile supported themselves from vegetation by their hind legs, similar to the behavior of some present-day tanyderids.

Corydasialidae fam. n. (Megaloptera) from Baltic amber

AbstractA new family of the order Megaloptera from Baltic amber is suggested: Corydasialidae fam. n. The type species is Corydasialis inexspectatus gen. &amp; sp. n. The new family is characterized by some autapomorphic traits: 4th tarsal segments of the legs are bilobed, underside of the 4th tarsal lobes with a brush of sucker disc-shaped hairs, in forewings Sc and R1 are not fused and both CuA and CuP distinctly forked.

A New Subgenus of &lt;I&gt;Rhithrogena&lt;/I&gt; from China, with Description of a New Species (Ephemeroptera: Heptageniidae)

Abstract Imagos of Rhithrogena (Tumungula) unica subgen. n., sp. n. from Yunnan and Guizhou provinces, China, have a series of unique characteristics. Male imagos have a hypertrophied foreclaw and a first tarsal segment ≈1.5 times the length of the second. The male styliger plate has two sharp projections, and the penis lobes are divergent without titillators but with spiny median lobes. Nymphal characters are those of the genus as presently defined: three caudal filaments and gills modified to form an adhesive disc.

Diabrotica virgifera

<i>Diabrotica virgifera</i>

28 ハマダラカAn.engarensis成虫雄における脚白帯によるAn.sinensisとの鑑別

28 ハマダラカAn.engarensis成虫雄における脚白帯によるAn.sinensisとの鑑別

Evolution of locomotory attachment pads in the Dermaptera (Insecta)

This contribution is the first comparative SEM study of tarsal and pretarsal structures of 18 dermapteran species, including epizoic Hemimeridae, rare Apachyidae, as well as basal Pygidicranidae. Our data reject the apparent uniformity of this taxon and show that representatives of Dermaptera have independently evolved both types of attachment mechanisms: hairy and smooth. Dermaptera possess a wide spectrum of attachment devices: arolia, euplantulae, tarsal surfaces covered with specialised tenent setae and other types of cuticular outgrowths. The groundpattern of the pretarsal and tarsal attachment structures was reconstructed by mapping their characters onto a cladogram, generated without tarsal characters. In the groundpattern of recent Dermaptera, the tarsus consists of three tarsomeres. Presumably, the last common ancestor of the Dermaptera possessed an arolium, since this structure occurs in the most basal taxa: Diplatyidae, Karschiellidae (partim, adults), Pygidicranidae partim, and Apachyidae. The absence of arolium in two of the pygidicranid taxa is probably due to a secondary loss. The arolium seems to be reduced in the ‘higher Dermaptera’ and amongst them, only the Geracinae, which belong to the Spongiphoridae and, hence, to the well supported Eudermaptera [European Journal of Entomology, 98 (2001), 445], evolved this structure convergently. The character state distribution for euplantulae suggests their evolution being similar to that of the arolium. All species of Tagalina possess a specialised tarsus with a strongly dilated second tarsomere. The same applies to the Forficulidae. However, their relatively remote phylogenetic position to Tagalina burri is a convincing reason to assume convergent evolution of this character. The Chelisochidae, with a slender, elongated second tarsomere, possess a unique structure, which supports their monophyly. The special, heart shaped structure of the second tarsal segments in the Forficulidae suggests their monophyly. The attachment structures of Hemimerus vosseleri are highly derived and probably autapomorphic for this taxon.

Fine structure of adhesive devices of Strepsiptera (Insecta)

Legs and other body parts of males, females and first instar larvae of almost all recognised families of Strepsiptera (Insecta) were examined. Descriptions of tibial, tarsal and pretarsal adhesive structures for each family are presented. These and attachment devices not associated with the legs are discussed. Strepsiptera evolved two strictly different types of tarsal attachment structures: hairy surfaces in the males and smooth flexible pads in the first instar larvae. Additional adhesive devices are present in several subgroups: mushroom-shaped microtrichia on the maxillary palp of males of Bohartillidae and acute pointed tibiae, or tarsal segments of males in different families. First instar larvae have evolved adhesive hairs on the ventral side of the body and on the podomeres. Specialised adhesive hairs are absent in the groundplan of adult males of Strepsiptera, but have evolved with the adoption of permanent endoparasitism of females. The most elaborate attachment structures, both in males and first instar larvae, are present in parasites of fast flying hymenopteran hosts (Aculeata).

Bowl is required downstream of Notch for elaboration of distal limb patterning.

In the Drosophila leg, activation of Notch leads to the establishment of the joints that subdivide the appendage into segments. We find that mutations in bowl result in similar phenotypes to Notch, causing fusion and truncations of tarsal segments (tarsomeres) and, like its close relative Odd-skipped, Bowl is produced in response to Notch signalling at a subset of segment boundaries. However, despite the fact that bowl mutant clones result in fusion of tarsomeres, Bowl protein is only found at the t1/tibial and t5/pretarsal boundaries, not at tarsomere joints. One hypothesis to reconcile these data is that bowl has a role at an earlier stage in tarsal development. We therefore investigated the effects of bowl mutations on the expression of leg 'gap' genes that confer regional identity on the developing leg. Several of these genes have altered expression in bowl mutant cells. For example, bric-a-brac2 is normally expressed in the central part of the tarsus domain but expands into distal and proximal regions in bowl clones. Conversely, ectopic bowl leads to a reduction in bric-a-brac2, with a concomitant expansion of proximal (t1) and distal (t5) tarsomere fates. The bowl gene is therefore required for the elaboration of pattern in the tarsus and its effects suggest a progressive model for the determination of P/D identities. This mechanism might be important in the diversification of arthropod limbs, because it explains how segmented tarsomeres could have arisen from an ancestral limb with an unsegmented tarsus.

The odd-skipped family of zinc finger genes promotes Drosophila leg segmentation

Notch signaling controls formation of joints at leg segment borders and growth of the developing Drosophila leg. Here, we identify the odd-skipped gene family as a key group of genes that function downstream of the Notch receptor to promote morphological changes associated with joint formation during leg development. odd, sob, drm, and bowl are expressed in a segmental pattern in the developing leg, and their expression is regulated by Notch signaling. Ectopic expression of odd, sob, or drm can induce invaginations in the leg disc epithelium and morphological changes in the adult leg that are characteristic of endogenous invaginating joint cells. These effects are not due to an alteration in the expression of other genes of the developing joint. While odd or drm mutant clones do not affect leg segmentation, and thus appear to act redundantly, bowl mutant clones do perturb leg development. Specifically, bowl mutant clones result in a failure of joint formation from the distal tibia to tarsal segment 5, while more proximal clones cause melanotic protrusions from the leg cuticle. Together, these results indicate that the odd-skipped family of genes mediates Notch function during leg development by promoting a specific aspect of joint formation, an epithelial invagination. As the odd-skipped family genes are involved in regulating cellular morphogenesis during both embryonic segmentation and hindgut development, we suggest that they may be required in multiple developmental contexts to induce epithelial cellular changes.

Tarsal movements in flies during leg attachment and detachment on a smooth substrate

In order to understand the attachment mechanism of flies, it is important to clarify the question of how the adhesive pad (pulvillus) builds and breaks the contact with the substrate. By using normal and high-speed video recordings, the present study revealed that pulvilli are positioned on the surface in a particular way. The pulvilli are apparently loaded or pressed upon the substrate after leg contact, as evidenced by splaying of the claws. Detachment of pulvilli from the substrate may be achieved in four different modes depending on the leg (fore-, mid- or hindleg): pulling, shifting, twisting, and lifting. Lifting is the only detachment mode depending on the claws’ action. Kinematics of the tarsal chain is studied in leg preparations, in which the tendon of the claw flexor muscle was pulled by tweezers and video recorded. The morphological background of tarsal movements during attachment and detachment is studied by scanning electron microscopy, fluorescent microscopy, and bright field light microscopy followed by serial semithin sectioning of pretarsal structures. Several resilin-bearing springs are involved in the recoil of the tarsal segments to their initial position, when the tendon is released after pull.

The Hox gene Ultrabithorax modulates the shape and size of the third leg of Drosophila by influencing diverse mechanisms

The developmental mechanisms that regulate the relative size and shape of organs have remained obscure despite almost a century of interest in the problem and the fact that changes in relative size represent the dominant mode of evolutionary change. Here, I investigate how the Hox gene Ultrabithorax (Ubx) instructs the legs on the third thoracic segment of Drosophila melanogaster to develop with a different size and shape from the legs on the second thoracic segment. Through loss-of-function and gain-of-function experiments, I demonstrate that different segments of the leg, the femur and the first tarsal segment, and even different regions of the femur, regulate their size in response to Ubx expression through qualitatively different mechanisms. In some regions, Ubx acts autonomously to specify shape and size, whereas in other regions, Ubx influences size through nonautonomous mechanisms. Loss of Ubx autonomously reduces cell size in the T3 femur, but this reduction seems to be partially compensated by an increase in cell numbers, so that it is unclear what effect cell size and number directly have on femur size. Loss of Ubx has both autonomous and nonautonomous effects on cell number in different regions of the basitarsus, but again there is not a strong correlation between cell size or number and organ size. Total organ size appears to be regulated through mechanisms that operate at the level of the entire leg segment (femur or basitarsus) relatively independently of the behavior of individual subpopulations of cells within the segment.

Ebbepterote, a new genus for the Australian 'Eupterote' expansa (T. P. Lucas), with a revised classification of the family Eupterotidae (Lepidoptera)

The single and endemic species of Eupterote Hübner recorded from Australia is shown not to possess the male genitalia typical of this genus, nor of any other genus of Eupterotidae, and it is consequently placed in a new genus, Ebbepterote Oberprieler, Nässig &amp; Edwards, as E. expansa (T. P. Lucas, 1891), comb. nov. Its genitalia are compared with those of many Asian and African genera of Eupterotidae, resulting in a revised classification and redefinition of the major eupterotid lineages. Five groups are defined: a probably paraphyletic 'basal' Ganisa-group and likely monophyletic subfamilies Janinae (including Tissanga Aurivillius and Hibrildes Druce), Striphnopteryginae, Eupterotinae and Panacelinae. Ebbepterote and the New Guinean 'Eupterote' styx Bethune-Baker species-complex are included in Striphnopteryginae, which is otherwise restricted to Africa. Cotana Walker is reassigned to Eupterotinae from Panacelinae and Sphingognatha Felder is resurrected from synonymy with Eupterote. The genitalia of Ebbepterote and several other critical genera are illustrated, demonstrating that the shape of the uncus does not constitute a suitable synapomorphy for defining the Eupterotidae as a monophyletic group. Another alleged eupterotid synapomorphy, the presence of a row of midventral spurs on the apical tarsal segment of the hindleg of the female, is shown to occur only sporadically in the family but also outside of it, in the lemoniid–brahmaeid–sphingid clade of Bombycoidea. As a result, the monophyly of the Eupterotidae currently rests only on a single, cryptic character of the mesoscutum of the imago and is in urgent need of substantiation.

The Drosophila Pox neuro gene: control of male courtship behavior and fertility as revealed by a complete dissection of all enhancers.

We have dissected the entire cis-regulatory region of the Drosophila Pox neuro gene with regard to its enhancers, and have analyzed their functions by the selective addition to Pox neuro null mutant flies of one or several functions, each regulated by a complete or partial enhancer. We have identified at least 15 enhancers with an astounding complexity in arrangement and substructure that regulate Pox neuro functions required for the development of the peripheral and central nervous system and of most appendages. Many of these functions are essential for normal male courtship behavior and fertility. Two enhancers regulate the development of the penis, claspers and posterior lobes of male genitalia. Three enhancers, two of which overlap, control the development of chemosensory bristles in the labellum, legs and wings, some or all of which are required for the transmission of gustatory signals elicited by female pheromones. An additional enhancer regulates in the developing brain the connectivity of two specific neuronal clusters entrusted with processing olfactory pheromone signals from the antennal nerve. Finally, functions crucial for the ability of the male to copulate depend on an enhancer that activates Pox neuro expression in the embryonic ventral cord. In addition to these male courtship and fertility functions of Pox neuro, we have identified enhancers that regulate: (1) proper segmentation of tarsal segments in the leg disc and in homologous segments of the antennal disc; and (2) proper development of the wing hinge and hence the ability of the fly to fly.

CLADISTICS OF THE PANTROPICAL GENUS RHINOSTOMUS (COLEOPTERA: CURCULIONOIDEA: DRYOPHTHORIDAE), WITH NOMENCLATURAL NOTES

The dryophthorid genus Rhinostomus Rafinesque (=Yuccaborus LeConte, new synonym) is a monophyletic taxon, defined by a combination of the following characters: mandibles exodont, antennal scape passing hind margin of eye, postocular lobes absent, abdominal punctures present, tibiae usually dentate, and third tarsal segment bilobed. It belongs to the pantropical tribe Rhinostomini Kuschel and is comprised of eight species. A cladistic analysis was carried out using 28 characters from external morphology, body vestiture, and male genitalia. The analysis yielded a single most parsimonious cladogram, with 59 steps, consistency index of 0.61, and retention index of 0.75, which was stable to successive weighting. According to this cladogram, the species follow the sequence: R. frontalis (LeConte, 1874) [=R. frontalis sharpi (Casey, 1892), new synonym] new combination, R. thompsoni Vaurie, 1970, R. quadrisignatus (Boheman, 1845), R. meldolae (Pascoe, 1887), R. oblitus (Jacquelin du Val, 1857) plus R. scrutator (Olivier, 1807), and R. barbirostris (Fabricius, 1775) plus R. niger (Drury, 1773).

Description of Caenoephemera shangyuanensis, gen.nov., sp.nov. (Ephemeroptera), from the Yixian Formation

AbstractA fossil mayfly nymph Caenoephemera shangyuanensis, gen.nov., sp.nov., discovered in the lower part of the Upper Jurassic – Lower Cretaceous Yixian Formation of Jianshangou, Beipiao district, West Liaoning, China, is described. It has several archaic features typical of Paleozoic mayfly nymphs, such as 5 tarsal segments and hind wing pads not covered by fore wing pads, but also exhibits specialized modern features, such as a short metathorax, abdominal tracheal gills, and cerci. It appears to be intermediate in structure between Paleozoic and extant mayfly nymphs.

Distribution of the sensillae of the red palm weevil, Rhynchophorus Ferrugineus (Oliv.) (Coleoptera: Curculionidae)

The distribution of the types of sensillae in the adult red palm weevil, Rhynchophorus ferrugineus (Oliv.) (Coleoptera: Curculionidae), was studied using scanning electron microscopy. Five types of sensillae can be identified on the antenna, with no apparent differences between sexes. These are: multiporous peg sensillae, sensillae trichoïdea (I and II); sensillae basiconica (type I, II and III) and sensillae styloconica. The distal segment of the maxillary palp bears 22 sensillae basiconica in the female, 13 in the male.The upper and lower incisor cusps of the mandibles of the male are relatively longer and more rounded, with an angle of 45° or more where the inner margins of the cusps meet. In the female, the upper and lower cusps are slightly shorter, with an angle of about 45°. In the buccal cavity of females, groups of finger-like sensillae basiconica of various length and shape project toward the centre of the oral opening. In the male, multiporous peg sensillae are found. Sensillae trichoidea are present on the ventral and dorsal sides of the first, second and third tarsal segments distally. These are much denser on the male than the female. On the terminal (9th) abdominal segment of the ovipositor, sensillae are distributed on the dorsal plate, medial plate, ventral plate and anal leaflets (paired). Sensillae of four types occur on the anal leaflets.

Requirements of Lim1, a Drosophila LIM-homeobox gene, for normal leg and antennal development.

During Drosophila leg development, the distal-most compartment (pretarsus) and its immediate neighbour (tarsal segment 5) are specified by a pretarsus-specific homeobox gene, aristaless, and tarsal-segment-specific Bar homeobox genes, respectively; the pretarsus/tarsal-segment boundary is formed by antagonistic interactions between Bar and pretarsus-specific genes that include aristaless (Kojima, T., Sato, M. and Saigo, K. (2000) Development 127, 769-778). Here, we show that Drosophila Lim1, a homologue of vertebrate Lim1 encoding a LIM-homeodomain protein, is involved in pretarsus specification and boundary formation through its activation of aristaless. Ectopic expression of Lim1 caused aristaless misexpression, while aristaless expression was significantly reduced in Lim1-null mutant clones. Pretarsus Lim1 expression was negatively regulated by Bar and abolished in leg discs lacking aristaless activity, which was associated with strong Bar misexpression in the presumptive pretarsus. No Lim1 misexpression occurred upon aristaless misexpression. The concerted function of Lim1 and aristaless was required to maintain Fasciclin 2 expression in border cells and form a smooth pretarsus/tarsal-segment boundary. Lim1 was also required for femur, coxa and antennal development.

Echidnophaga suricatta (Siphonaptera: Pulicidae), a new species of flea from the Northern Cape Province, South Africa

Echidnophaga suricatta (Pulicidae), a new species of flea collected from the meerkat (Suricata suricatta Schreber, 1776) near Garies (30°22’S, 17°31’E) and Brandvlei (30°27’S, 20°29’E), Northern Cape Province, South Africa, is described. Based on chaetotaxy of the tarsal segments, this new species is most closely related to E. bradyta Jordan & Rothschild, 1906, E. iberica Ribeiro, Lucientes, Osacar & Calvete, 1994, E. macronychia Jordan & Rothschild, 1906, and E. ochotona Li, 1957. A key is provided for the 23 recognized species or subspecies in the genus Echidnophaga.

Identification of resilin in the leg of cockroach, Periplaneta americana: confirmation by a simple method using pH dependence of UV fluorescence

We have examined the tarsus (foot) and tibial segments of the cockroach leg to identify structures that contain the elastic protein resilin. The presence of resilin was tested using the conventional criteria of fluorescent emission at 420 nm under UV illumination and histological staining of wholemount tissues by toluidine blue. We have also developed a simple method of confirming identification of resilin through changes in its fluorescence that occur with alteration of pH of the surrounding medium. Using a commonly available excitation filter that only passes light at >330 nm, we found that the emission was present at neutral pH but was eliminated at low pH. It then reversibly reappeared when medium of higher pH was restored. This effect is attributable to a known shift in the absorption maximum of amino acids of resilin that occurs in acidic media (from 330 to 285 nm). The accuracy of this method of identification was confirmed by examination of ligaments of the wing hinge, which has previously been shown to contain resilin in a number of insects. Using these techniques, we have identified resilin in association with ligaments at the tibio-tarsal joint and in the articulation between the fourth and fifth tarsal segments of the leg. The anatomical arrangement of these ligaments suggests that they could aid in the generation of leg movements during walking by functioning as elastic antagonists to the actions of leg muscles. The method of identification we have devised could readily be applied to aid in the localization of resilin in other animals.