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1.
The intrauterine eggs of the pleurogenid trematode Brandesia turgida ( Brandes, 1888), exhibiting advanced stages of miracidial differentiation and fully formed, ciliated miracidia, were examined by means of transmission electron microscopy (TEM). Each embryonated egg is composed of a mature miracidium surrounded by a four-layered egg wall: (1) an outer, anucleate layer external to the eggshell, which forms a thick cocoon; (2) the operculate egg-shell; (3) a small remnant of the compact, granular cytoplasm of the outer embryonic envelope (sensu stricto); and (4) a relatively distinct cellular remnant of the inner embryonic envelope. Layers enveloping the egg apparently play an important role in the protection, metabolism and storage of nutritive reserves for the developing miracidium. The outer, anucleate layer, or cocoon, situated externally to the eggshell and composed of a transparent, electron-lucent substance with numerous dense, osmiophilic islands attached to its peripheral membrane, has never previously been seen in TEM studies of the eggs of parasitic platyhelminths. The origin, formation, functional ultrastructure and chemical composition of this peculiar layer remain enigmatic, although its function appears to be protective. The thick, electron-dense eggshell resembles that of other trematodes, exhibiting a characteristic fissure zone around the operculum. The very small, indistinct remnants of the outer embryonic envelope appear in the form of a very thin, compact, granular cytoplasm closely attached to the inner surface of the eggshell. Conversely, the inner embryonic envelope is frequently apparent at one or both poles of the developed egg as a syncytial envelope formed by the fusion of mesomeres. This envelope, even in eggs containing a fully formed miracidium, still has the features of a metabolically active layer with an energy storage capability. Lysosome-like structures observed in some eggs may be involved in the autolysis of the embryonic envelopes.  相似文献   

2.
Summary The larval integument of the midge, Chironomus riparius Mg., is unusually thin although it conforms with the normal insect pattern. The cuticle of the post-cephalic segments is about 3 m thick and overlies an epidermis which has an irregular basal plasma membrane resulting in spaces occurring between it and the basement membrane. The ventral tubuli have a similar epidermis but the cuticle is somewhat thinner. The anal papillae have the thinnest cuticular covering with a uniquely folded epicuticle of variable thickness, and their epidermis has the characteristics of a transporting epithelium. No evidence of pore canals could be found in the cuticle of any part except the head capsule which has a remarkably smooth epicuticle and a distinct layer which may represent the exocuticle. There are no spaces between the basement membrane and basal plasma membrane of the epidermis in the head. Ultrastructural evidence would suggest that gaseous exchange can occur across most of the post-cephalic integument.The author is indebted to Mrs. L. Rolph and Mr. R.L. Jones for their technical assistance  相似文献   

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4.
The genus Leptopulvinaria Kanda is revised and placed in the tribe Pulvinariini as understood by Hodgson. The species L. kawaii sp. nov., which has been misidentified as Pulvinaria camelicola or P. floccifera by several researchers, is recognized as a second species of the genus, in addition to the type species L. elaeocarpi Kanda. Adult females of L. elaeocarpi and L. kawaii are redescribed and a key to the species is presented.  相似文献   

5.
The ultrastructure of the epidermis and the protonephridia of the free-living rhabdocoel Mesoscastrada führmanni is described. The epidermis consists of polarized cells, the nucleus located in the basal part of the cell and the mitochondria in the apical part. The surface is entirely covered by cilia anchored in the cytoplasm by horizontal and vertical striated rootlets. Cilia of the flame bulbs also have horizontal and vertical striated rootlets. The weir apparatus of the cyrtocyte is composed of a single row of ribs connected by a thin “membrane” of extracellular material. Bundles of microtubules, located in the ribs originate in the centrioles. Epidermal cells and flame bulbs of M. führmanni closely resemble those of the other Typhloplanoida examined so far.  相似文献   

6.
The paired, electrotonically coupled neurosecretory Canopy Cells (CC) of the pond snail Lymnaea stagnalis were microiontophoretically injected with horseradish peroxidase (HRP). Whole mount preparations and ultrathin sections of injected CC were studied to describe in detail the morphology of the CC, their axon tracts and neurohaemal areas. The CC release their secretory product at three different sites, viz. from the soma and from axon terminals in the intercerebral commissure and in the median lip nerve. Neural control over the CC occurs by few synapses found exclusively on the CC axon, not on the cell body. One type of "en passant" synapse was identified. Two morphologically distinct types of synapselike structures (SLS) are numerous. The site of electrotonic coupling between the two CC is most probably located in the cerebral commissure. Serial sectioning showed that the axons contact each other over more than 130 micrometers. The contact is very intimate and the axon membranes interdigitate in a complex manner. Gap junctions, which are often described as the sites of electrotonic coupling, were not found.  相似文献   

7.
Morphometric and electrophoretic variation are analysed among Iberian and African populations of Cobitis (Cobitidae). Three discrete morphotypes are distinguished, showing a remarkable genetic differentiation among them. Each of the three morphotypes is judged to represent a species, one being described as a new species. Both approaches agree on the separate status of the Iberian populations from the Alagón drainage, Tagus basin of west central Spain. This population is described as a new species, Cobitis vettonica sp. nov., a sexually dimorphic spined loach was assigned to the subgenus Iberocobitis Bacescu, 1961. Morphometric and electrophoretic data placed this new species phenetically close to Cobitis maroccana Pellegrin, 1929 and Cobitis pahdica De Buen, 1930, but differs from these species in overall shape, male coloration pattern, shorter barbels and fins, posterior lamina of the cleithrum, seven branched rays on the dorsal fin and in having a unique alleles at sAAT-2*, EST-1* and MPI* loci. The new species range described in this paper is more restricted than that of C. pahdica. Both inhabit the Tagus basin but have not been reported to be sympatric.  相似文献   

8.
The ultrastructure of merozoites, gamonts and oocysts of the neogregarine Mattesia dispora and their development in larvae of the flour moth Ephestia kuehniella were studied by electron microscopy. The apical complex of free macronuclear merozoites was very distinct in micrographs of sections, the polar rings being especially prominent. Two gamonts associated in head-to-head syzygy and the apical complexes served as the contact point during pairing. At this stage the rhoptries became reduced and the conoid widened. The gamonts had a foam-like appearance in the light microscope. Paired gamonts formed an envelope and developed into a gametocyst, within which the gamonts were separated by a distinct border. Four gametes and two residual cells developed inside the gametocyst. The gametes were covered with a single membrane. The gametes fused in pairs to form two spherical zygotes, each covered by two membranes and with one large nucleus. The external layer appeared more undulated than the inner one. A single membrane covered each residual cell. Walls were formed around both zygotes to produce two oocysts. Each mature oocyst was lemon-shaped with polar plugs and eight peripheral sporozoites, which had a pellicle similar to that of the merozoites, lay beneath the thick oocyst wall.  相似文献   

9.
A new species of the Indo-Australian Gagrellinae (Arachnida: Opiliones: Sclerosomatidae), Gagrella cauricrepa , is described from the Iron Range, Cape York Peninsula, Queensland, Australia. This represents the first definite indigenous Australian record of Sclerosomatidae, though the family has previously been known from Papua New Guinea and the Solomon Islands. The previous record of Zaleptus marmoratus Roewer 1910 from the Australian fauna is regarded as currently unconfirmable.  相似文献   

10.
Strophidon McClelland is a muraenid genus with characteristic appearance of a very elongated body, a large mouth cleft and anteriorly placed eyes. The nomenclature and taxonomic history of species within Strophidon are contentious and its members are easily misidentified. In the present study, species of the genus Strophidon are revised based on morphological and molecular data, and five species are considered valid, including S. dawydoffi Prokofiev, S. dorsalis (Seale), S. sathete (Hamilton), S. ui Tanaka and a new species, S. tetraporus. Strophidon tetraporus sp. nov. is described based on 15 specimens from Indonesia, the Philippines, Taiwan and Vietnam with the unique characteristic of the constant presence of the fourth infraorbital pore among species of Strophidon. The intraspecific variation of vertebral formula within S. dorsalis is discussed based on molecular data. Muraena macrurus Bleeker and Thyrsoidea longissima Kaup are synonyms of S. sathete that can be distinguished from the most similar congener S. ui by a longer tail, smaller eyes and more inner maxillary and inner dentary teeth. A key to identify species of Strophidon is provided. The distribution and maximum size of each species are also re-evaluated.  相似文献   

11.
Egg parasitoids of the genus Anagrus Haliday (Hymenoptera: Mymaridae) are natural enemies of many pests around the world. We used an integrative approach to characterize some species belonging to the Anagrus atomus group, using specimens reared from leafhoppers infesting some Lamiaceae. Starting from morphological identifications based on available keys, we carried out a multi-locus genetic characterization using phylogenetic and species delimitation analyses, and integrated it with biological and morphometric evidence. This approach revealed the existence of a new species, A. nepetellae sp. nov., here described along with its phenological traits. The approach also allowed us to characterize the expected taxonomic stability of other putative species within the group. We propose two new species groups called the atomus group sensu stricto and the vilis group, with the goal of streamlining the taxonomy of the atomus group. We also present a key for the identification of females of the European species of the atomus group sensu stricto. Some specimens show heterozygosity in 28S-D2 sequences, suggesting hybridization between A. atomus and A. nepetellae, which, if it is common between other species as well, could partly explain the taxonomic problems in the genus Anagrus. DNA sequencing of specimens reared by the same biofactory at different times suggests involuntary contamination leading to the displacement of a laboratory strain of A. atomus by A. nepetellae, which may have resulted from undetected partial reproductive compatibility.http://zoobank.org/urn:lsid:zoobank.org:pub:DFCD7654-5AA5-4E4F-AE48-24377BAACEFE  相似文献   

12.
《Journal of Asia》2022,25(1):101867
The genus Nuntiella Kuznetzov is reviewed. Nuntiella bidigitata sp. nov. is described as new with illustrations of adult male and female genitalia provided. The three previously described species are summarized with detailed references, distribution information, and diagnostic characters. A key to all the species of Nuntiella is given based on the characters of male genitalia.  相似文献   

13.
The genus Pseudaeginella is analysed herein by cladistic methods based on a morphological data matrix of 49 characters × 18 terminal taxa. Based on the results, we comment on the phylogenetic position of Paradeutella within Pseudaeginella, and we propose Pseudaeginella multispinosa comb. nov. and Pseudaeginella tanzaniensis comb. nov. Pseudaeginella freirei sp. nov. is described from the Abrolhos Bank, north-eastern Brazil. We provide an updated key to the Pseudaeginella species.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:F573E845-822E-41D6-8F58-FE54C5653A53  相似文献   


14.
15.
We studied spermatogenesis and spermiogenesis in Adalia decempunctata (L), a beetle of the Coccinellidae family. The spermatocyte exhibits two centrioles which elongate to form a pair of primary cilia. A novel structure, appearing in cross sections as a dense droplet, is observed near the long centriole during spermiogenesis, and is soon accompanied by a procentriole (PCL). PCL structure consists of singlet microtubules, a central tubule and an incomplete cartwheel. The PCL persists until the end of spermiogenesis, when it vanishes together with the dense droplet. The sperm has an exceptionally long basal body and the nucleus is disposed parallel to the flagellar components, a peculiar trait shared by other species of the coccinellid group. The presence of a procentriole suggested by the use of antibodies is discussed.  相似文献   

16.
郑哲民 《昆虫学报》2008,51(4):424-429
研究了分布于中国澳汉蚱属Austrohancockia的种类共10种,其中包括采自广西的1新种,即长背澳汉蚱Austrohancockia longidorsalis sp. nov.;并提供了分种检索表。新种模式标本保存于陕西师范大学动物研究所昆虫标本室。  相似文献   

17.
Hagfishes from New Zealand are reviewed and a phylogeny proposed using morphological and genetic data (DNA sequences of cytochrome c oxidase subunit I gene, COI, and the small subunit RNA, 16S). E ptatretus cryptus sp. nov. was previously confused with Eptatretus cirrhatus (Forster in Bloch & Schneider, 1801) because of their similar morphology, and is found from the Three Kings Islands to Stewart Island and in the eastern part of the Chatham Rise (at depths of 96–922 m). E ptatretus poicilus sp. nov. is endemic to the Three Kings Islands, where it is common and associated with soft sediment and deep‐sea coral‐sponge habitats (114–842 m). N eomyxine caesiovitta sp. nov. is a slender hagfish found along the east coast of the North Island south to the Chatham Rise (430–1083 m). A neotype is erected for E. cirrhatus (type locality: Breaksea Sound, Fiordland), occurring widely in New Zealand coastal, shelf, and slope waters (1–922 m), but not at the Three Kings Islands. Eptatetrus goliath Mincarone & Stewart, 2006, Neomyxine biniplicata (Richardson & Jowett, 1951), and Nemamyxine elongata Richardson, 1958 are further described using additional material. Rubicundus eos (Fernholm, 1991) is still only known from the holotype (type locality: Challenger Plateau). Genetic results showed that the New Zealand Eptatretus species form a monophyletic group within the subfamily Eptatretinae, indicating likely speciation from a single common ancestor within the area. E ptatretus poicilus sp. nov. is the sister species of E. cirrhatus, and E . cryptus sp. nov. is closely associated with the clade formed by these two species. Eptatretus goliath is most closely associated with Eptatretus minor Fernholm & Hubbs, 1981 (Gulf of Mexico), these two species basally diverging within New Zealand hagfishes. The endemic genus Neomyxine forms a well‐supported monophyletic group of as yet uncertain position within the phylogenetic tree. A key to the New Zealand hagfishes, fresh colour photographs, distribution maps, and in situ video recordings are presented. © 2015 The Linnean Society of London  相似文献   

18.
Morphological and genetic differentiation between populations of freshwater amphipods initially identified as Paramelita spinicornis are examined. Morphological data are analysed by means of cluster and discriminant functions analyses and genetic differentiation determined using starch gel electrophoresis. The 11 populations form two distinct groups, one of which corresponded to the described species, P. spinicornis , while the other is clearly recognizable as a new species, which is described here.  相似文献   

19.
Summary. This article describes two new species, Corticaria antonioi n. sp. and Corticaria lucasi n. sp., from the Iberian Peninsula. A key to the species of the sylvicola group is provided.  相似文献   

20.
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