首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 421 毫秒
1.
The early history of Panorpidae (Mecoptera) is poorly known due to sparse fossil records. Up to date, only nine fossil species have been described, all from the Paleogene, except the Early Cretaceous Solusipanorpa gibbidorsa Lin, 1980. However, we suggest S. gibbidorsa is too incompletely preserved to permit even family classification. A new genus with two new species, Jurassipanorpa impunctata gen. et sp. n. and Jurassipanorpa sticta sp. n., are described based on four well-preserved specimens from the late Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China. These two new species are the earliest fossil records of Panorpidae. The new genus is erected based on a combination of forewing characters: both R1 and Rs1 with two branches, 1A reaching posterior margin of wing distad of the forking of Rs from R1, and no crossveins or only one crossvein between veins of 1A and 2A. In all four specimens, long and robust setae ranging from 0.09 to 0.38 mm in length and pointing anteriorly, are present on anal veins of forewings. The function of these setae is enigmatic.  相似文献   

2.
Arctosmittia biserovi gen. n., sp. n. (subfamily Orthocladiinae) is described from a single male. The specimen was collected in the Novaya Zemlya Archipelago (Yuzhnyi (Southern) Island, Pankov Peninsula). The new genus is closely related to Mesosmittia Brundin in the structure of the head, thorax, anal lobe, and squamae, and the presence of a false anal appendage in the male genitalia, but differs from it in a low value of the antenna index (AR < 1), the structure of the wing veins (FCu situated at the same level with cross-vein RM; veins R 1 and R 4+5 with macrotrichiae), presence of SCI on Ta 1, and pseudospurs on Ta 2 in the middle and hind legs, and in the structure of the genitalia (gonostylus with large additional lobe).  相似文献   

3.
From rocks of Westphalian D age of Ibbenbueren in Westphalia/W-Germany a new taxon of the Omaliidae Handlirsch, 1906 -Kelleropteron kaelberbergense n. g., n. sp. — is described. It is represented by only one wing. The new genus is characterized by the following features: the subcosta ends on the costa; the radius is very prominent and runs far distantly from the anterior border of the wing proximally; the branches of the sector radii and the medialis are directed distally, not posteriorly; a connective vein between medialis and sector radii is present; the cross-veins are relatively dense and irregularly branched. The Omaliidae are redefined, the relationships of their genera are discussed. The genera are arranged in 3 groups (Fig. 1). In theHeterologies-group - as in the Paoliidae — the subcosta ends on the radius; in theCacurgus — group the subcosta ends on the costa, a connective vein between medialis and sector radii is not present; in theOmalia- group the subcosta also ends on the costa, but a connective vein between medialis and sector radii has evolved.Kelleropteron is a member of the last group, differing fromOmalia above all by its denser, more irregularly arranged cross-veins. The Omaliidae are confined stratigraphically to the Westphalian and geographically to the EuropeanNorthamerican region. They apparently are descendants of the Paoliidae Handlirsch, 1906. In both families a connective vein between medialis and cubitus is present, and the anterior branch of the medialis is lost. The most important difference between them is seen in the cross-veins: within the Paoliidae they are very dense, similar to the archedictyon of the Palaeodictyoptera, but within the Omaliidae they are more widemeshed and more prominent.  相似文献   

4.
Several new remains of fossil insects from the Late Carboniferous (Pennsylvanian: Namurian?B or C) of the Fr?ndenberg/Ruhr Region (Unna District, Western Germany) are described. They comprise seven wing fragments of Homaloneura berenice Brauckmann and Gr?ning, 1998 (Palaeodictyoptera: Spilapteridae), a species which is better and more completely known from the Konservat-Lagerst?tte Hagen-Vorhalle (Namurian?B: Marsdenian) with at least three specimens. Two additional wing fragments belong to Bechala sommeri gen. et sp. nov. (Megasecoptera: Bechalidae fam. nov.). Together with Brodioptera stricklani Nelson and Tidwell, 1987 (Brodiopteridae; earliest Namurian, Kinderscoutian; Utah, USA), Sylvohymen peckae Brauckmann, 1988 and S.?pintoi Brauckmann et?al., 2003 (both: Bardohymenidae; Namurian?B, Marsdenian, Hagen-Vorhalle, Germany), and Xenoptera riojaensis Pinto, 1986 (Xenopteridae; probably late Namurian or early Westphalian; Malanzán, La Rioja, Argentina) they belong to the most ancient members of the Megasecoptera. Both of these species from Küchenberg have a striking specific color pattern. The holotype of B.?sommeri gen. et sp. nov. exhibits both a very fine woven archedictyon and well-developed, cell-forming cross-veins. This combination is appraised to be very plesiomorphic. Additionally, one isolated wing fragment of Kochopteron hoffmannorum Brauckmann, 1984 (??basal Neoptera??) is preserved. The Fr?ndenberg wings were deposited in a mainly limnic/terrestrial environment and have been most probably transported by eolian and/or fluviatile processes.  相似文献   

5.
Polygenic modifiers of the L4 and L5 wing veins in Drosophila simulans were used to study the degree of genetic independence of veins within the same developmental compartment. The L4 and L5 were selected for opposite changes in length. Whole-chromosome assays of heterozygous effects showed that the L4 and L5 polygenic modifiers were associated with differences both in chromosomes and in interchromosomal interactions. A comparison of selection responses confirmed that, though some modifiers had strictly vein-specific action, others acted either upon all veins within the posterior compartment or upon all veins in the wing. The results support the idea that some genes control pattern formation in the wing as a whole, others regulate structures within a single compartment, and still others are limited to a single element within a compartment.  相似文献   

6.
Miconia rondoniensis occurs in secondary upland (terra firme) moist open forest in the Brazilian states of Rondônia, Mato Grosso and Amazonas. It can be recognized by the tree habit, large leaves with rounded to obtuse or subcordate bases and 5+2 basal veins (five main veins plus a faint submarginal pair), large inflorescences with proximal paraclades bearing quaternary branches and distal paraclades bearing tertiary branches, persistent hemi-elliptic bracteoles, short persistent calyx lobes, and capitate stigmas. The most striking feature of this new species is the thick pubescence on the branches and petioles, composed of trichomes having a long axis and short arms at the base, but inflated and lacking arms at the apex, resulting in a sorus-like surface covered with globose structures.  相似文献   

7.
Cavicchi S  Guerra D  Giorgi G  Pezzoli C 《Genetics》1985,109(4):665-689
The effects of environmental temperature on wing size and shape of Drosophila melanogaster were analyzed in populations derived from an Oregon laboratory strain kept at three temperatures (18°, 25°, 28°) for 4 yr. Temperature-directed selection was identified for both wing size and shape. The length of the four longitudinal veins, used as a test for wing size variations in the different populations, appears to be affected by both genetic and maternal influences. Vein expression appears to be dependent upon developmental pattern of the wing: veins belonging to the same compartment are coordinated in their expression and relative position, whereas veins belonging to different compartments are not. Both wing and cell areas show genetic divergence, particularly in the posterior compartment. Cell number seems to compensate for cell size variations. Such compensation is carried out both at the level of single organisms and at the level of population as a whole. The two compartments behave as individual units of selection.  相似文献   

8.
The mucilage of Opuntia ficus-indica and a partially degraded mucilage have been investigated by methylation analysis and periodate oxidation. The results show that the mucilage is composed of 1,4-α-D-galactopyranosyluronic acid and 1,2-β-L- rhamnopyranosyl residues to which are attached short chains of 1,6-β-D-galacto-pyranosyl residues at position 4 of all of the rhamnopyranosyl residues. Most of the galactosyl residues in the side chains carry branches at O–3, while some are also branched at O–4. The branches are mainly composed of 1,5-linked arabinofuranosyl, end-group arabinofuranosyl, and end-group xylopyranosyl residues.  相似文献   

9.
The angular dependence of scattered light from amylopectin and its β-limit dextrin, the mean square radius of gyration and the molecular weights Mw and Mn have been calculated on the basis of the cascade branching theory for the homogeneously branched model by Meyer &; Bernfeld (1940) (Model I) and for the two heterogeneously branched structures suggested by French (1972) (Model II) and by Robin et al. (1974, 1975) (Model III). The calculations take into account the particularities of topology in branched molecules and the experimentally determined ratio of the number of A- and B-chains, A/B = 1. Furthermore, an average branching density of 4% and an interconnecting chain length of ovbar|ni2 = 22, found by gel permeation chromatography (GPC) after debranching, were used. The constraints lead to the conclusion that amylopectin is heterogeneously branched. Densely branched clusters containing 3·22 branching units are interconnected by longer chains of 22 units in length. Comparison of the calculated angular dependence of light scattering with measurements from a maize amylopectin β-limit dextrin in 1 n NaOH solution gives strong evidence for a modified Robin-Mercier model. The modification consists of the conclusion that the interconnecting chains are preferentially B-chains, such that these chains carry on the average 1·4 clusters, while Robin and Mercier assume exactly 2 clusters. Our result is in agreement with the distribution of chain length found after debranching the amylopectin β-limit dextrin.  相似文献   

10.
To better understand insect evolution, fossils – mainly known by their wings – must be used as terminals in phylogenetic analyses. Such analyses are, however, rarely performed because of a lack of consensus on the homology of venation in insects. Researchers do not agree with the current concept on the exact number and identity of the main veins. Here, we confirm the presence, which has been in question since the early 20th century, of an independent main postcubital vein (PCu vein) between the cubital and anal veins (29 fossil and extant examined orders; > 85% of observed insects). The PCu vein corresponds to the so-called vein 1A or first anal vein. It is easily identified by the unique shape of its bulla. It may have several branches and be partially fused with the cubital and anal veins. Once the PCu vein was identified, we reconsidered as an example the particular case of the Phasmatodea, showing that extant stick insects have a unique venation among insects, with a reduced median vein and a simple cubital vein adjacent or fused to the PCu vein. This study is a new approach towards resolving wing vein homology issues, crucial for future large-scale phylogenetic analyses in insects combining extant and extinct taxa.  相似文献   

11.
高原特有条鳅鱼类两新种在广西的发现及其动物地理学意义   总被引:16,自引:4,他引:12  
描述了采自广西都安县红水河水系的条鳅亚科鱼类2个新种:丽纹云南鳅yhnnanilus pulcherrimussp.nov.在侧线长度、鳞片分布、鳍条数目、尾型、吻须长度等方面与侧纹云南鳅yunnanilus pleurotaenia(Regan,1904)最为相似,但新种独特的斑纹和上下唇的长乳突可明显与之区别,二者在一些度量特征上也有区别。黄体高原鳅Triplophysa flavicorpus sp.nov.与同分布于西江水系的南丹高原鳅T.nandanensis Lan et al.较为相似,并以下列特征组合与高原鳅属所有已知种相区别:背鳍分枝鳍条10根、臀鳍分枝鳍条6~7根、体被细鳞、侧线完全、具6条宽横斑和1条沿侧线的细纵纹、尾鳍深分又、尾鳍基具1半圆形黑斑、尾鳍上下叶各具2条黑色横斑、腹鳍末端后伸超过肛门、腋部具发达的肉质鳍瓣、上唇中央完全中断等。云南鳅属和高原鳅属均是高原特有类群,前者仅分布于云南东中部地区,后者则集中分布于青藏高原。两个新种的分布地均远离这两个属的分布中心,而且呈间断分布。通过各自相近种谱系关系分析,推测这种特殊的分布格局是通过隔域分化形成的。  相似文献   

12.
In contemporary entomology the morphological characters of insects are not always treated according to their phylogenetic rank. Fossil evidence often gives clues for different interpretations. All primitive Paleozoic pterygote nymphs are now known to have had articulated, freely movable wings reinforced by tubular veins. This suggests that the wings of early Pterygota were engaged in flapping movements, that the immobilized, fixed, veinless wing pads of Recent nymphs have resulted from a later adaptation affecting only juveniles, and that the paranotal theory of wing origin is not valid. The wings of Paleozoic nymphs were curved backwards in Paleoptera and were flexed backwards at will in Neoptera, in both to reduce resistance during forward movement. Therefore, the fixed oblique-backwards position of wing pads in all modern nymphs is secondary and is not homologous in Paleoptera and Neoptera. Primitive Paleozoic nymphs had articulated and movable prothoracic wings which became in some modern insects transformed into prothoracic lobes and shields. The nine pairs of abdominal gillplates of Paleozoic mayfly nymphs have a venation pattern, position, and development comparable to that in thoracic wings, to which they are serially homologous. Vestigial equivalents of wings and legs were present in the abdomen of all primitive Paleoptera and primitive Neoptera. The ontogenetic development of Paleozoic nymphs was confluent, with many nymphal and subimaginal instars, and the metamorphic instar was missing. The metamorphic instar originated by the merging together of several instars of old nymphs; it occurred in most orders only after the Paleozoic, separately and in parallel in all modern major lineages (at least twice in Paleoptera, in Ephemeroptera and Odonata; separately in hemipteroid, blattoid, orthopteroid, and plecopteroid lineages of exopterygote Neoptera; and once only in Endopterygota). Endopterygota evolved from ametabolous, not from hemimetabolous, exopterygote Neoptera. The full primitive wing venation consists of six symmetrical pairs of veins; in each pair, the first branch is always convex and the second always concave; therefore costa, subcosta, radius, media, cubitus, and anal are all primitively composed of two separate branches. Each pair arises from a single veinal base formed from a sclerotized blood sinus. In the most primitive wings the circulatory system was as follows: the costa did not encircle the wing, the axillary cord was missing, and the blood pulsed in and out of each of the six primary, convex-concave vein pair systems through the six basal blood sinuses. This type of circulation is found as an archaic feature in modern mayflies. Wing corrugation first appeared in preflight wings, and hence is considered primitive for early (paleopterous) Pterygota. Somewhat leveled corrugation of the central wing veins is primitive for Neoptera. Leveled corrugation in some modern Ephemeroptera, as well as accentuated corrugation in higher Neoptera, are both derived characters. The wing tracheation of Recent Ephemeroptera is not fully homologous to that of other insects and represents a more primitive, segmental stage of tracheal system. Morphology of an ancient articular region in Palaeodictyoptera shows that the primitive pterygote wing hinge in its simplest form was straight and composed of two separate but adjoining morphological units: the tergal, formed by the tegula and axillaries; and the alar, formed by six sclerotized blood sinuses, the basivenales. The tergal sclerites were derived from the tergum as follows: the lateral part of the tergum became incised into five lobes; the prealare, suralare, median lobe, postmedian lobe and posterior notal wing process. From the tips of these lobes, five slanted tergal sclerites separated along the deep paranotal sulcus: the tegula, first axillary, second axillary, median sclerite, and third axillary. Primitively, all pteralia were arranged in two parallel series on both sides of the hinge. In Paleoptera, the series stayed more or less straight; in Neoptera, the series became V-shaped. Pteralia in Paleoptera and Neoptera have been homologized on the basis of the fossil record. A differential diagnosis between Paleoptera and Neoptera is given. Fossil evidence indicates that the major steps in evolution, which led to the origin first of Pterygota, then of Neoptera and Endopterygota, were triggered by the origin and the diversification of flight apparatus. It is believed here that all above mentioned major events in pterygote evolution occurred first in the immature stages.  相似文献   

13.
Three basic proline-rich salivary proteins have been produced through the recombinant route. IB5 is a small basic proline-rich protein that is involved in the binding of plant tannins in the oral cavity. II-1 is a larger protein with a closely related backbone; it is glycosylated, and it is also able to bind plant tannins. II-1ng has the same polypeptidic backbone as II-1, but it is not glycosylated. Small angle x-ray scattering experiments on dilute solutions of these proteins confirm that they are intrinsically disordered. IB5 and II-1ng can be described through a chain model including a persistence length and cross section. The measured radii of gyration (Rg = 27.9 and 41.0 ± 1 Å respectively) and largest distances (rmax = 110 and 155 ± 10 Å respectively) show that their average conformations are rather extended. The length of the statistical segment (twice the persistence length) is b = 30 Å, which is larger than the usual value (18 Å − 20 Å) for unstructured polypeptide chains. These characteristics are presumably related to the presence of polyproline helices within the polypeptidic backbones. For both proteins, the radius of gyration of the chain cross-section is Rc = 2.7 ± 0.2Å. The glycosylated protein II-1 has similar conformations but the presence of large polyoside sidegroups yields the structure of a branched macromolecule with the same hydrophobic backbone and hydrophilic branches. It is proposed that the unusually extended conformations of these proteins in solution facilitate the capture of plant tannins in the oral cavity.  相似文献   

14.
The homology and nomenclature, as well as hypothesized pathways of the historical development of the clavus and jugal lobe of the beetle hind wings are discussed. The reconstructed plan of the clavus venation is largely similar to the venation patterns observed in some representatives of Corydalidae (Megaloptera). Its main apotypic characters are the following: the first anal cell was reduced at the wing base and the second anal or cuneiform cell appeared. This venation pattern is supposed to result from consolidation of the area around the claval furrow base at the earlier stages of the beetle wing evolution. In particular, longitudinal compressing the bases of RA, M, CuP, and 1A resulted in the development of a complex sclerite composed of the distal median plate and the bases of CuP and 1A. After this new reinforced connection between the remigium and the clavus appeared, the proximal parts of CuP and 1A were partly or completely reduced since they were no longer needed to maintain the structural integrity of the beetle wing.  相似文献   

15.
The pattern of wing venation varies considerably among different groups of insects and has been used as a means of species-specific identification. However, little is known about how wing venation is established and diversified among insects. The decapentaplegic (Dpp)/bone morphogenetic protein (BMP) signaling pathway plays a critical role in wing vein formation during the pupal stages in Drosophila melanogaster. A key mechanism is BMP transport from the longitudinal veins (LVs) to the posterior crossvein (PCV) by the BMP-binding proteins, short gastrulation (Sog) and twisted gastrulation2/crossveinless (Tsg2/Cv). To investigate whether the BMP transport mechanism is utilized to specify insect wing vein patterns in other than Drosophila, we used the sawfly Athalia rosae as a model, which has distinct venation patterns in the fore- and hindwings. Here, we show that Ar-dpp is ubiquitously expressed in both the fore- and hindwings, but is required for localized BMP signaling that reflects distinct wing vein patterns between the fore- and hindwings. By isolating Ar-tsg/cv in the sawfly, we found that Ar-Tsg/Cv is also required for BMP signaling in wing vein formation and retains the ability to transport Dpp. These data suggest that the BMP transport system is widely used to redistribute Dpp to specify wing venation and may be a basal mechanism underlying diversified wing vein patterns among insects.  相似文献   

16.
Glycoproteins were extracted with water from leaves of Cannabis sativa grown from seeds of Thailand origin. By ion exchange chromatography the material was separated into a neutral and an acidic fraction. Both glycoprotein fractions contained arabinose, galactose, glucose, mannose and xylose, and in addition rhamnose and galacturonic acid were present in the acidic fraction. The carbohydrate moieties were investigated by methylation analysis and Smith-degradation, whereas the glycopeptide linkage was studied by alkaline hydrolysis in the presence of NaBH4 and Na2SO3, respectively. This linkage was shown to be of the serine-O-galactoside type. The carbohydrate structure is highly branched, the majority of branches terminating in arabinofuranose end groups. Arabinose is also present in the chain, predominantly (1 → 4)- and/or (1 → 5)-linked. Galactose makes up most of the main chain as (1 → 3)-linked residues but also constitutes end groups and branch points, as do mannose and/or glucose. Xylose and rhamnose are present as (1 → 4)- and (1 → 2)-linked units, respectively. Galacturonic acid is assumed to be (1 → 4)- linked with some branching at 3 position. The amino acid hydroxyproline, present in the glycoprotein of South African Cannabis leaves, was absent in the corresponding Thailand material.  相似文献   

17.
广西洞穴鱼类一新种(鲤形目:鳅科)   总被引:2,自引:0,他引:2  
本文记述了采自广西河池地区的洞穴鱼类一新种,并讨论了其分类地位。透明间条鳅,新种Heminoemacheilus hyalimus sp.nov.与同属种的区别主要表现在尾鳍分枝鳍条数目较少、须较短、眼睛完全退化、头较大和尾柄较细长等方面。  相似文献   

18.
Pseudophoxinus burduricus sp. n. is described from drainages of Salda and Burdur lakes, southwestern Turkey. It is distinguished from other Anatolian Pseudophoxinus by a combination of characters: lateral line incomplete, with 21–39 (commonly 26–37) perforated scales and 47–57+1-2 scales in lateral series; 10½–12½ scale rows between lateral line and dorsal fin origin, 3–4(5) scale rows between lateral line and the pelvic fin origin; dorsal fin commonly with 7½ branched rays; anal fin commonly with 6½ branched rays; 7–8(9) gill rakers on the first branchial arch; a faint and diffuse epidermal black stripe from eye to caudal fin base in alive and preserved individuals; mouth slightly subterminal, tip of mouth cleft on about level of lower margin of eye; snout rounded, its length greater than eye diameter. Comparison is given with all Pseudophoxinus species from western Anatolia.  相似文献   

19.

Background  

The Dermaptera belongs to a group of winged insects of uncertain relationship within Polyneoptera, which has expanded anal region and adds numerous anal veins in the hind wing. Evolutional history and origin of Dermaptera have been in contention.  相似文献   

20.
JH Dirks  D Taylor 《PloS one》2012,7(8):e43411
During the lifetime of a flying insect, its wings are subjected to mechanical forces and deformations for millions of cycles. Defects in the micrometre thin membranes or veins may reduce the insect’s flight performance. How do insects prevent crack related material failure in their wings and what role does the characteristic vein pattern play? Fracture toughness is a parameter, which characterises a material’s resistance to crack propagation. Our results show that, compared to other body parts, the hind wing membrane of the migratory locust S. gregaria itself is not exceptionally tough (1.04±0.25 MPa√m). However, the cross veins increase the wing’s toughness by 50% by acting as barriers to crack propagation. Using fracture mechanics, we show that the morphological spacing of most wing veins matches the critical crack length of the material (1132 µm). This finding directly demonstrates how the biomechanical properties and the morphology of locust wings are functionally correlated in locusts, providing a mechanically ‘optimal’ solution with high toughness and low weight. The vein pattern found in insect wings thus might inspire the design of more durable and lightweight artificial ‘venous’ wings for micro-air-vehicles. Using the vein spacing as indicator, our approach might also provide a basis to estimate the wing properties of endangered or extinct insect species.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号