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1.
Fumio Iwata 《Hydrobiologia》1997,365(1-3):199-213
The hoplonemertean Amphiporus parmiornatus Iwata,1957, from Sagami Bay, Japan, has beenredescribed and named Kameginemertes gen. n. asa member of the reptantic Polystilifera. Anatomicallythe new genus shows affinity to the genus Drepanophorus belonging to the EureptantiaAequifurcata, but because of differences in thecerebral sensory organs, nervous system,blood-vascular system, and rhynchodaeal wall, a newgenus is proposed for it.  相似文献   

2.
Fumio Iwata 《Hydrobiologia》1998,378(1-3):199-213
Two different tributyltin (TBT)-induced virilisation phenomena in prosobranch snails – intersex in Littorina littorea and imposex in Nucella lapillus – are compared in order to facilitate their simultaneous use in geographical large scale effect monitoring surveys. Imposex in dogwhelks is a more sensitive biomarker and should be used in areas that are only slightly or moderately contaminated with TBT (ambient TBT concentrations < 2.0 ng as Sn l-1). The assessment of intersex intensities in periwinkle populations has considerable advantages in areas with higher TBT concentrations and should be used also wherever dogwhelks are absent irrespective of the TBT exposure level. The intersex index (ISI) and vas deferens sequence (VDS) index are proposed as the most suited parameters for effect monitoring purposes. The geographical uniformity of intersex and imposex is analysed and proven for the coasts of Ireland, France, and Germany. A relative loss of TBT sensitivity in females can be found, but to a varying extent in both species. The implications of this result for biological TBT effect monitoring programmes are discussed in light of the fact that intersex and imposex have both been found to be irreversible. Because it is the objective of these programmes to assess current TBT contaminations and resulting biological effects, only relatively young specimens should be considered in the sampling strategy.  相似文献   

3.
Heintzichthys gouldii is redescribed based on new material from the Interstate 71 Paleontological Salvage Project (Cleveland Museum of Natural History, 1966-67). Phylogenetic analysis of brachythoracid arthrodires clearly shows the monophyly of Camuropiscidae and the aspinothoracid arthrodires. Heintzichthys gouldii and Gorgonichthys clarki are removed from Dinichthyidae and placed within aspinothoracid arthrodires. The remaining members in the family Dinichthyidae are united solely by plesiomorphic characters. A number of putative synapomorphies for the eubrachythoracid arthrodires are questioned; however, the validity of this taxon is supported by three synapomorphies.  相似文献   

4.
Two new genera and species of reptantic polystiliferous hoplonemerteans from the Great Barrier Reef province of Australia are described and illustrated. Urichonemertes pilorhynchus gen. et sp. nov. and Xenonemertes rhamphocephalus gen. et sp. nov. are both placed in the family Drepanophoridae (Polystilifera: Eureptantia: Aequifurcata).  相似文献   

5.
蝗虫分子系统学研究进展   总被引:7,自引:0,他引:7  
本文从遗传多样性、近缘种鉴别以及分子进化和系统发育重建 3个方面综述了蝗虫分子系统学的研究进展。  相似文献   

6.
7.
Collagen and albumin were extracted from subfossil bones of the extinct rodent Malpaisomys insularis; the radiocarbon age of the sample was at least 1.73 Ka. Electrophoretic and immunological techniques indicate the preservation of albumin while collagen is revealed as degraded fragments. Immunological comparisons between Malpaisomys albumin and albumin antisera of four extant rodents indicate that Malpaisomys is more closely related to Mus than to Acomys and Uranomys and that Cavia is the most divergent taxon studied. The branching order of the fossil and the extant rodents is discussed with respect to the relationships derived from morphological criteria.  相似文献   

8.
New characters based on the arrangement and morphology of dermal denticles show that sawfishes can be divided into two distinctive groups. The first group, comprising the knifetooth sawfish Anoxypristis cuspidata , is characterized by tricuspid denticles variably located on both dorsal and ventral parts of the body. The second group is represented by species of the genus Pristis , showing an uniform and homogenous dermal covering of monocuspidate denticles on both dorsal and ventral sides of the body and within the buccopharyngeal cavity. Pristis is further divided into two subgroups: the first comprises species with denticles lacking any keels and furrows (the smalltooth sawfish Pristis pectinata , the green sawfish Pristis zijsron and the dwarf sawfish Pristis clavata ); the second comprises species with denticles presenting keels and furrows well differentiated on their anterior part (the common sawfish Pristis pristis , the largetooth sawfish Pristis perotteti and the greattooth sawfish Pristis microdon ). This investigation of the dermal covering provides results which agree with studies that separate the same two species groups of Pristis on the basis of other morphological data.  相似文献   

9.
A review of the fundamental difference between single molecular-sequence positions, or numerical characters, and complex morphological characters is the subject of this study. It has been found that transformation series of single complex structures contain enough information to allow a priori determination of character order and that rooting of a dendrogram is possible without out-group comparison, while trees based on less-informative characters can usually only be rooted with out-group comparison. Furthermore, the quality of total information used is decisive in discriminating between hypotheses of relationships. Numerical methods for the inference of phylogenies have been found to be useful for high numbers of characters that have only a low information content, while the Hennigian procedure seems to be preferable for complex characters.  相似文献   

10.
A review of the fundamental difference between single molecular-sequence positions, or numerical characters, and complex morphological characters is the subject of this study. It has been found that transformation series of single complex structures contain enough information to allow a priori determination of character order and that rooting of a dendrogram is possible without out-group comparison, while trees based on less-informative characters can usually only be rooted with out-group comparison. Furthermore, the quality of total information used is decisive in discriminating between hypotheses of relationships. Numerical methods for the inference of phylogenies have been found to be useful for high numbers of characters that have only a low information content, while the Hennigian procedure seems to be preferable for complex characters.

Zusammenfassung


Ein fundamentaler Unterschied zwischen der einzelnen Sequenzposition oder auch numerischen Merkmalen und komplexen morphologischen Merkmalen ist ihr Informationsgehalt. Merkmalsreihen komplexer Strukturen enthalten meist genügend Information, um a priori die Bestimmung der Lesrichtung zu ermöglichen. Die Feststellung des Ursprunges eines Dendrogramms ist somit ohne kladistischen Außengruppenvergleich möglich, während Bäume (Topologien), die auf wenig informativen Merkmalen beruhen, allgemein nur mit dem kladistischen Außengruppenvergleich 'gewurzelt' werden können. Die Qualität der insgesamt verwendeten Information ist entscheidend für die Wahl zwischen alternativen Verwandtschaftshypothesen. Numerische Methoden der Rekonstruktion der Phylogenese sind nützlich bei Verwendung einer gro β en Zahl informationsarmer Merkmale; das Hennigsche Verfahren ist für komplexe Merkmale vorzuziehen.  相似文献   

11.
An electrophoretic study of genetic variation at 17 loci in ten serranids belonging to three subfamilies (Anthiinae, Epinephelinae and Serraninae) was carried out to assess their systematic relationships. A relationship dendrogram was constructed from the fenetic identities calculated b Nei's method for all pairwise cornarisons. These fishes were divided into three major welldefined groups: Anthiinae, Epinepielinae and Serraninae. Although the relationships among them appear slightly different from that deduced from morphological features; e. g., Serraninae are distant from Anthiinae and Epinephelinae biochemically, but are closer to Antiinae than to Epinephelinae morphologically. However, a tendency for an increase of the genetic distance in higher categories is obvious (Table 5).  相似文献   

12.
Abstract: Pleurotomaria species from lower Bajocian (Middle Jurassic) sediments of south‐western Luxembourg housed in the National Natural History Museum of Luxembourg are described. Seven species are recognized, one of which is new, Pleurotomaria faberi sp. nov. A more detailed definition of the diagnostic characters of the genus is proposed and the morphological continuity between Talantodiscus and Pleurotomaria is demonstrated, suggesting that the former cannot be considered as a distinct taxon. The palaeoecology, evolution and palaeobiogeographical history of Pleurotomaria are outlined. Pleurotomaria presumably first appeared in late Middle Triassic of New Zealand where it underwent a relative diversification up to the Hettangian (Early Jurassic). From early Hettangian, most of its evolutionary history took place in Europe and western Tethys. In the European epicontinental seas, Pleurotomaria experienced two important radiations. The first occurred in the Early Jurassic, with a peak in the late Pliensbachian, and was marked by an expansion of the distribution to the central part of western Tethys. After a collapse in species diversity, probably related to the early Toarcian anoxic event, a second radiation occurred. This culminated in the early Bajocian and was mainly confined in a region encompassing southern England, Paris Basin and southern Germany. Low‐spired species, formerly attributed to Talantodiscus, probably originated independently and iteratively during the history of Pleurotomaria. The facies and associated benthic faunas suggest that Pleurotomaria probably lived on shallow soft bottoms composed of mixed calcareous–siliciclastic sediments. The two main Early Jurassic and early Middle Jurassic radiations of the genus took place in these environments. Records of the genus in Jurassic carbonate platform deposits are very few and concern mainly post‐Bajocian species.  相似文献   

13.
The Asian (nandid) and Afro‐Neotropical (polycentrid) leaffishes represent two superficially similar, but historically poorly diagnosed families – a situation resulting in a convoluted systematic history. Here, and including for the first time in a molecular study all leaffish genera, we generate a hypothesis of the phylogenetic history of both groups. We analyse a multilocus molecular data set encompassing 257 acanthomorph taxa, carry out a survey and assessment of selected osteological characters for the polycentrid leaffishes and also provide a reanalysis of previously published morphological data. Our results confirm: (1) that the Polycentridae and Nandidae are only remotely related, and hence, the classic leaffishes are diphyletic; (2) that the Polycentridae is monophyletic, with new skeletal synapomorphies being congruent with molecular data in placing the enigmatic Afronandus – a taxon that thus far has never been included in any molecular study – as sistergroup to the remaining genera; (3) the monophyly of the Nandidae + Badidae and their inclusion into a larger monophyletic group – along with the Pristolepididae, Anabantoidei and Channoidei – comprising the Labyrinthici sensu Rosen & Patterson. We also review the morphological and molecular evidence for both the conflicting placement of Pristolepis and the putative sistergroup relationship between the labyrinth fishes (Anabantoidei) and snakeheads (Channoidei).  相似文献   

14.
瓢虫科分类研究的现状   总被引:7,自引:1,他引:7  
庞虹 《昆虫知识》2002,39(1):17-22
本文总结了瓢虫科分类 2 0 0多年来的发展历程 ,以及中国瓢虫科分类研究的现状。另外还介绍了分子生物学技术在瓢虫科分类中的应用。  相似文献   

15.
16.
Kolbasov  Gregory A. 《Hydrobiologia》2000,438(1-3):185-191
A new species of the Lithoglyptes from the Seychelles is described. The external morphology of the mantle sac and the body were examined under SEM. The position of a new species within Lithoglyptes and the ultrastructural characters of different species of this genus are discussed.  相似文献   

17.
The female and male of Mesocyclops leuckarti (CLAUS , 1857) from a European population are redescribed in detail. New diagnostic characters are described which have passed unnoticed so far. All six naupliar stages of this species are studied as well. Characters of the adult and naupliar external morphology are discussed with respect to previous studies.  相似文献   

18.
From the stem bark of Fagaropsis angolensis (Rutaceae) three alkaloids and two limonoids were isolated. The alkaloids were identified as the 6-acetonyl derivatives of the benzophenantridines, dihydrochelerythrine, dihydrosanguinarine and dihydronitidine, the last of these being reported for the first time. The alkaloids did not appear to be artefacts of the corresponding benzophenanthridines. The limonoids were identified as rutaevin and limonin diosphenol. The significance of these compounds in resolving the confused taxonomic position of F. angolensis is discussed. Attention is drawn to the presence of a small group of taxa within the Rutaceae capable of synthesizing 1-benzyltetrahydroisoquinoline-derived alkaloids and the potential of these taxa as a starting point for visualizing biochemical evolution within the order Rutales, and putative relationships between the Rutales and Ranales are examined.  相似文献   

19.
Turbellaria Lecithoepitheliata: morphology,systematics, phylogeny   总被引:7,自引:7,他引:0  
A review of the literature on the world fauna of lecithoepitheliata and Prolecithophora and extensive observations by the author on species of the Prorhynchidae, including cosmopolitan species as well as some endemic to Lake Baikal, and on endemic species of Baicalarctiinae (Prolecithophora) show that the Prorhynchidae and Gnosonesimidae are properly classified in the Neoophora. The morphological similarity of the Prorhynchidae and Prolecithophora proves these taxa are closely related. A hypothesis relating the Lecithoepitheliata Prorhynchidae to primitive prolecithophorans appears to be the only tenable hypothesis on the phylogeny of Lecithoepitheliata. The question of whether the Lecithoepitheliata is monophyletic still needs investigation; more evidence on the phylogeny of the Gnosonesimidae is needed.  相似文献   

20.
Two morphological different species of hairtails, Trichiurus lepturus and T. japonicus were compared by starch gel electrophoresis. Isozyme patterns of eight metabolic enzymes and general muscle proteins using extracts of eye, muscle, liver and heart revealed 16 loci. The polymorphic loci were sAAT-1, GPI-A, GPI-B, IDHP-1 and PGM-2 for at least one of the two species. There were no fixed allelic isozyme patterns to differentiate among them. NEI's genetic identity (I) between the two species was calculated. An I index of 0.986 suggests that the two morphologically different hairtails belong to the same species, Trichiurus lepturus.  相似文献   

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