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1.
We reconstructed the matrilineal phylogeny of Asian algae-eating fishes of the genus Capoeta based on complete mitochondrial gene for cytochrome b sequences obtained from 20 species sampled from the majority of the range and 44 species of closely related barbs of the genera Barbus s. str. and Luciobarbus. The results of this study show that Capoeta forms a strongly supported monophyletic subclade nested within the Luciobarbus clade, suggesting that specialized scraping morphology appeared once in the evolutionary history of the genus. We detected three main groups of Capoeta: the Mesopotamian group, which includes three species from the Tigris-Euphrates system and adjacent water bodies, the Anatolian-Iranian group, which has the most diversified structure and encompasses many species distributed throughout Anatolian and Iranian inland waters, and the Aralo-Caspian group, which consists of species distributed in basins of the Caspian and Aral Seas, including many dead-end rivers in Central Asia and Northern Iran. The most probable origination pathway of the genus Capoeta is hypothesized to occur as a result of allopolyploidization. The origin of Capoeta was found around the Langhian-Serravallian boundary according to our molecular clock. The diversification within the genus occurred along Middle Miocene-Late Pliocene periods.  相似文献   

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The Mecoptera are thought to be one of the most primitive groups in the Holometabola, but their embryology is rarely studied. By means of scanning electron microscopy, we studied the external features of the embryo of the scorpionfly Panorpa emarginata in middle and late development. The embryo remains in the superficial position until hatching. Embryonic development can be divided into 10 stages along with the first‐instar larva. The external features are described from the germ band to the first‐instar larva, with special reference to the components and segmentation of the head, the segmentation of abdomen and the formation of abdominal prolegs. Our results confirm that the head consists of an anterior‐most acron and six trunk segments: the labral, antennal, intercalary, mandibular, maxillary, and labial segments. The labrum is confirmed to derive from the paired appendages. Our observations also provide additional direct evidence that the abdominal prolegs are not serially homologous with the thoracic legs. The presence of the eleventh abdominal segment is clarified. J. Morphol. 2009. © 2009 Wiley‐Liss, Inc.  相似文献   

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The embryogenesis of Grylloblattodea, one of the most primitive of the polyneopteran orders, is described using Galloisiana yuasai with special reference to external morphology. The egg membranes are characterized by an endochorion crossed by numerous vertical aeropyles and a fairly thin vitelline membrane, features shared by Mantophasmatodea. The inner layer formation is of the fault type. Serosal elements in the amnioserosal fold differentiate into hydropylar cells, to function in water absorption together with specialized amniotic structures, i.e., an amniotic strand and a thickened amnion. The germ band is of the short germ type. The germ band immerses deep into the yolk after its full elongation along the egg surface, and in this respect blastokinesis closely resembles that of Mantophasmatodea. The embryological features, i.e., those on egg membranes and blastokinesis, may suggest a closer affinity of Grylloblattodea and Mantophasmatodea. Appendages, ectodermal invaginations, and sternal and pleural sclerites are discussed in the light of serial homology, to provide a new basis for elucidating the insect body plan. Appendages are divided into the proximal coxopodite and distal telopodite, the former being divided further into the subcoxa and coxa. Subcoxal and coxal elements are identified in the mandible as well as in the abdominal appendages. The subcoxa is divided into the epimeron and episternum by the pleural suture in thoracic segments. Likewise, in the abdominal segments the subcoxa is divided into two, although the homologs of the epimeron and episternum are not sclerotized, and in the labial segment the subcoxal derivative or the postmentum is divided into the submentum and mentum. Two coxal endites bulge out from the medial side of the gnathal appendages. The mandibular molar and incisor, maxillary lacinia and galea, and labial glossa and paraglossa are serially homologous with each other. In the thoracic segments the original embryonic sternum or "protosternum" is largely replaced by subcoxal elements, and merely remains as a small anterior presternum and a posterior spinasternum. A major part of the venter is represented by the derivatives of the episternum such as an extensive basisternum, katepisternum, and trochantin and the medial element of the epimeron. The pleuron is derived from the episternal elements or the anepisternum and preepisternum, which bears a spiracle in the mesothorax and metathorax, and the lateral element of the epimeron. The homolog of the preepisternum in the prothorax is the cervical sclerite, but with no spiracle developed. A median ventral invagination arises in the thoracic segments as a spina, and the homolog of the spina develops into the eversible sac in the first abdominal segment.  相似文献   

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Water and muscle tissue samples from two morphotypes of the African large barb Labeobarbus intermedius collected from three sites in Lake Hawassa in 2012–2013 were analysed for eight heavy metals, including Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn. Five metals (Cr, Cu, Mn, Ni and Zn) were detected in fish muscle samples, whereas only Cr, Cu and Ni were detected in water samples. Of the five metals detected in the muscle samples, Cu and Zn were present in higher concentrations in the golden morphotype, whereas Cr, Mn and Ni were found in higher concentrations in the silver morphotype. Bioaccumulation factor (BAF) values indicated that Cr, Cu and Ni have a tendency to accumulate in fish muscle in amounts exceeding those in water. In both morphotypes the highest concentrations of Zn and Mn were detected at the Hospital site, whereas the concentrations of Cr, Cu and Ni were highest at the Tikur Wuha site. Chromium, Cu and Ni concentrations recorded in fish muscle at all sampling sites exceeded the safe limits recommended by FAO/WHO and UNESCO, suggesting that water and fish from Lake Hawassa are contaminated with heavy metals originating from factories, a hospital and agricultural activities in proximity to the lake.  相似文献   

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The phylogeographical patterns and population genetic structures of Varicorhinus barbatulus in Taiwan were investigated based on genetic diversity of 34 allozyme loci and nucleotide sequences of 3' end of the cytochrome b gene, tRNA genes, D-loop control region, and the 5' end of the 12S rRNA of mtDNA. Allozyme and mtDNA analyses revealing evident geographical structuring suggest limited gene flow between populations (F(ST)=0.511 and 0.791, respectively). Low genetic variability within populations (P=5.56%; He=0.018) based on allozymes and significantly negative Tajima's D statistics based on mtDNA suggest that most populations in Taiwan may have originated from a small number of founders followed by demographic expansion. The gene genealogy of mtDNA identified six lineages corresponding to major drainages that were separated by the geological barriers due to vicariant events. A minimum spanning network based on nucleotide substitutions reflects divergence from populations of the Miao-li Plateau to northern and southern regions of the island. In contrast to a previous hypothesis that suggests an early invasion to eastern part of Taiwan prior to the lifting of central mountain range some one million years ago, the mtDNA genealogy and molecular dating reveal very recent colonization of the eastern population. Nested clade analyses revealing significant associations between genetic structure and geographical division identify past fragmentation and range expansion as major phylogeographical events that shaped the geographical distribution of this species in Taiwan.  相似文献   

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The karyotype and major ribosomal sites as revealed using silver staining of Anatolian leuciscine cyprinid fish Acanthobrama marmid were studied. The diploid chromosome number was invariably 2n = 50. Karyotype consisted of eight pairs of metacentric, 13 pairs of submetacentric and four pairs of subtelocentric to acrocentric chromosomes. The largest chromosome pair of the complement was subtelo-to acrocentric characteristically, which is a characteristic cytotaxonomic marker for representatives of the cyprinid lineage Leuciscinae. The nucleolar organizer regions (NORs) were detected in the telomeres of two pairs of medium sized submeta-to subtelocentric chromosomes. No heteromorphic sex chromosomes were found. The karyotype pattern of A. marmid is nearly identical to that found in most other representatives of the Eurasian leuciscine cyprinids, while the multiple NOR phenotype appears to be more derived as opposed to a uniform one, ubiquitous in this group.  相似文献   

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《Journal of morphology》2017,278(11):1469-1489
As the first step in the comparative embryological study of Blattodea, with the aim of reconstructing the groundplan and phylogeny of Dictyoptera and Polyneoptera, the embryonic development of a corydiid was examined and described in detail using Eucorydia yasumatsui . Ten to fifteen micropyles are localized on the ventral side of the egg, and aggregated symbiont bacterial “mycetomes” are found in the egg. The embryo is formed by the fusion of paired blastodermal regions, with higher cellular density on the ventral side of the egg. This type of embryo formation, regarded as one of the embryological autapomorphies of Polyneoptera, was first demonstrated for “Blattaria” in the present study. The embryo undergoes embryogenesis of the short germ band type, and elongates to its full length on the ventral side of the egg. The embryo undergoes katatrepsis and dorsal closure, and then finally, it acquires its definitive form, keeping its original position on the ventral side of the egg, with its anteroposterior axis never reversed throughout development. The information obtained was compared with that of previous studies on other insects. “Micropyles grouped on the ventral side of the egg” is thought to be a part of the groundplan of Dictyoptera, and “possession of bacteria in the form of mycetomes” to be an apomorphic groundplan of Blattodea. Corydiid embryos were revealed to perform blastokinesis of the “non‐reversion type (N)”, as reported in blaberoid cockroaches other than Corydiidae (“Ectobiidae,” Blaberidae, etc.) and in Mantodea; the embryos of blattoid cockroaches (Blattidae and Cryptocercidae) and Isoptera undergo blastokinesis of the “reversion type (R),” in which the anteroposterior axis of the embryo is reversed during blastokinesis. Dictyopteran blastokinesis types can be summarized as “Mantodea (N) + Blattodea [= Blaberoidea (N) + Blattoidea (R) + Isoptera (R)]”.  相似文献   

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The embryonic development of Zorotypus caudelli Karny (Zoraptera) is described with the main focus on its external features. A small heart‐shaped embryo is formed on the dorsal side of the egg by the fusion of paired blastoderm regions with higher cellular density. The orientation of its anteroposterior axis is opposed to that of the egg. This unusual condition shows the potential autapomorphy of Zoraptera. The embryo extends along the egg surface and after reaching its full length, it migrates into the yolk. After developing there for a period of time, it reappears on the surface, accompanied by a reversion of its anteroposterior axis, finally taking its position on the ventral side of the egg. The definitive dorsal closure completes, and the prelarva hatches after perforating the chorion with very long egg tooth formed on the embryonic cuticle. Embryological data suggest the placement of Zoraptera among the “lower neopteran” or polyneopteran lineage: features supporting this are embryo formation by the fusion of paired regions with higher cellular density and blastokinesis accompanied by full elongation of the embryo on the egg surface. The extraordinarily long egg tooth has potential synapomorphy with Embioptera or Eukinolabia (= Embioptera + Phasmatodea). Together with the results from our previous studies on the egg structure, male reproductive system and spermatozoa, the close affinity of Zoraptera with Eukinolabia appears likely, that is, a clade Zoraptera + (Embioptera + Phasmatodea). J. Morphol. 275:295–312, 2014. © 2013 Wiley Periodicals, Inc.  相似文献   

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The sperm of Marthasterias glacialis (Linnaeus) was studied by light and electron microscopy. It is a long uniflagellated cell of the “primitive” type. The head has a spherical shape and contains a nucleus with a spheroid acrosome lying in a cup-shaped anterior fossa. The acrosome is formed by an acrosomal vesicle surrounded by the periacrosomal material. The basal specializations of the acrosomal vesicle show a clear differentiation of its constituents resembling the structure of membrane. The midpiece contains a very large annular mitochondrion which encircles two perpendicular centrioles. The distal centriole is in close association with a pericentriolar radial complex. The tail, containing a common microtubular axoneme, is projected to a variable position.  相似文献   

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The pollen morphology of Gueldenstaedtia gansuensis. G. gracilis, G. henryi, G. monophylla. G. mutijlora, G. stenophylla. and G. verna and Tibetia liangshanensis, T. tongolensis, T. yadongensis. T. coelestis, and T yunnanensis are reported for the first time. The seed morphology of G. gracilis, G. maritima. G. monophylla, G. mutiflora, G. taihangensis, and G. verna and L coelestis, T. himalaica, T. yunnanensis, and T. yadongensis are firstly described here. In pollen morphology, the differences of pollen grains of Gueldenstaedtia and Tibetia are as follows: Gueldenstaedtia with pollen grains 3–colporate, psilate, and shapes spheroidal, sometimes subprolate, prolate or oblong; and Tibetia with pollen grains 3– and 4–colporate, perforate, shapes spheroidal, sometimes subprolate or prolate. These results, combined with the data of the basic chromosome number x=7 of Gueldenstaedtia and x=8 of Tibetia, support that the two genera should be recognized as two distinct genera, which are consistent with their morphological characters: Gueldenstaedtia with 2 upper lobes of calyx free, stipules free, adnate to petiole, and Tibetia with 2 upper lobes of calyx connate, stipules connate and opposite to leaves. In Tibetia, two types of pollen grains, 3– and 4–colporate pollen grains, are found. Regarding seed morphology: Gueldenstaedtia has circular depression, irregular circular depression or irregular circular reticulation on the surface; Tibetia has smooth surface. The differences in seed morphology of the two genera also support that they should be kept separate. The pollen morphology supports that G. gansuensis, G. gracilis, G. multiflora, G. stenophylla, and G. verna should be reduced into one species consistent with their morphological characteristics. The pollen grains of G. henryi are different from those of the other species in having wide colpi.  相似文献   

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The developmental morphology of seedlings and shoots of Dalzellia zeylanica was examined with reference to the meristem in order to understand the dorsiventral, foliose shoot. In seedlings, no obvious primary shoot and no root are formed. Subsequent to disappearance of the vestigial primary shoot meristem, two shoot meristems are established in the axils of the cotyledons, one of which grows into a secondary shoot. Microtome and SEM examinations of mature plants show that the shoot meristem is complex, comprising three zones along the shoot margin. The organogenetic zone, equivalent to the shoot apical meristem, produces dorsal leaves proximally and much fewer marginal leaves distally. During development, the zone repeatedly changes into a dorsal zone, while a new organogenetic zone is formed in an area between developing marginal leaves, resulting in the alternation of the organogenetic and dorsal zones, which allowed development of the coenosomic structure of the shoot. The dorsal and ventral zones do not produce leaves, but contribute to shoot expansion. The ventral zone also forces the marginal leaves to shift to the lateral side of the shoot. The rosette with tufted leaves might be a modification of the short shoot (ramulus) of other Tristichoideae.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 289–302.  相似文献   

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Harold  Fox 《Journal of Zoology》1985,205(2):223-234
The skin of the paired tentacles of Ichthyophis consists of a cornified epidermis of 5–7 layers of epidermal cells, and a glandular dermis of ducted mucous glands, in association with collagen, blood vessels, fibroblasts, granulocytes, sparse melanophores and characteristic laminophores of unknown function. The epidermis is highly innervated at all levels below the stratum corneum by naked neurites, which originate as branches from large unmyelinated nerve bundles (and associated Schwann cells), located sub-epidermally, and which are part of the trigeminal cranial nerve. Myelinated nerves are also present below the epidermis, spatially associated with capillaries and glands. The study of the ultrastructure of the tentacle supports a concept of a sensory function, possibly tactile, though until further information from experimentation is available, any ideas on the specific nature of these sensory activities must remain speculative.  相似文献   

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Summary Pagurus rubricatus is predatory, detrivorous, macrophagous, and to a small degree, a suspension feeder. The crab searches for small invertebrates by digging shallow pits in the sediment. During this process it feeds on detritus obtained either directly from the sediment or scoured off gravel granules. Particles trapped by the dense setation of the 2nd and 3rd maxillipeds are brushed off and ingested.The distribution of the various types of setae on the mouthparts is mapped and structure of the mouthparts and their setae is correlated with function. Sediment collected by the pereiopods is brushed off by the endopodites of the 3rd maxillipeds and transferred to the inner mouthparts by the endopodites of the 2nd maxillipeds. The basipodites of the 1st maxillae form a filter screen through which particles of suitable size are pushed by the 2nd maxillae. Rejected particles are discarded by the exhalant stream via the currents generated by the exopodites of the maxillipeds. Specialized setae on the 2nd maxillae scour detritus from the surface of gravel granules applied to these appendages by the 2nd and 3rd maxillipeds. Interlocking setae from different appendages form a number of screens the main function of which is to retain material in the buccal region. The exopodite and endopodite of the 1st maxilliped and the endopodites of the 1st and 2nd maxillipeds form a channel which funnels the exhalant respiratory current away from the crab. The main grooming appendages are the endopodites of the 3rd maxillipeds, however, most of the other mouthparts have a self-cleaning function.  相似文献   

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The morphology and mode of action of the anal apparatus of membracid nymphs are described. The possible functions of the “whipping” action exhibited by the eversible tube which forms part of the anal apparatus are discussed and reasons why this seems most likely to be primarily a defensive reaction are given. Analogues of the structures are indicated.  相似文献   

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