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1.
In four species of gobiid fish caught in Tagus estuary during 1996, the incidence of skeletal deformities ranged from 2 to 5%. Differences between sampling stations or between the two most abundant species Pomatoschistus minutus and Gobius niger were statistically not significant (p > 0.05). The type of deformity depended upon species. P. minutus and P. microps showed bone nodules at the inferior side of the abdominal vertebrae, whilst G. niger and G. paganellus had shortened caudal vertebrae (achondroplasia) and deformed ural plates. The possible role of pollution or other conditions in the Tagus estuary is discussed.  相似文献   

2.
Macroderoides minutus n. sp. is described based on specimens collected from the Florida gar (Lepisosteus platyrhincus) from Orange Lake, Alachua County, Florida. The new species is the ninth recognized species of Macroderoides and is morphologically closest to Macroderoides flavus and Macroderoides typicus. It differs from both species in having a smaller body, ventral sucker larger than the oral sucker, substantially lower body length to width ratio, fewer and larger eggs, and other characters. A comparison of sequences of nuclear rDNA (partial 18S, complete ITS region, and partial 28S) of the new species, with sequences of 5 other Macroderoides, convincingly supports the status of M. minutus as a new species. Molecular phylogenetic analysis, including all North American Macroderoides species except for Macroderoides parvus, has demonstrated the presence of 2 distinct clades, 1 including Macroderoides spinifer + (Macroderoides minutus n. sp. + Macroderoides texanus) and the other including Macroderoides trilobatus + (M. typicus + M. flavus). The tree topology suggests that the similarity in body proportions among M. minutus n. sp., M. typicus + M. flavus is not a result of close phylogenetic relationship. It has also revealed for the first time the phylogenetic affinities of M. flavus, which is the only North American member of Macroderoides that switched from holostean fishes to teleosts.  相似文献   

3.
Four Gyrodactylus species parasitising four closely related gobiid species in European coastal waters were studied and compared with G. arcuatus Bychowsky sensu Bychowsky & Poljansky (1953) from Gasterosteus aculatus . These were G. gondae n. sp. from Pomatoschistus minutus and P. lozanoi , G. flavescensis n. sp. from Gobiusculus flavescens , G. arcuatoides n. sp. from P. minutus and G. branchialis n. sp. from P. microps. Combined molecular and morphological analyses, as well as morphometric and statistical methods, were used. The ssrRNA V4 region and the complete ITS rDNA region were sequenced. Genetically the four new species are clearly distinct from G. arcuatus . From a morphological point of view, the haptoral hard parts of G. gondae n. sp., G. flavescensis n. sp. and G. arcuatoides n. sp. are related to those of G. arcuatus, while these parts of G. branchialis n. sp. are different, but related to those of G. quadratidigitus Longshaw, Pursglove & Shinn, 2003. For the latter two species, a new species group is formed. The V4 and ITS sequence analyses, however, indicate a close relationship between G. branchialis and the three G. arcuatus-like species.  相似文献   

4.
Invading and native species often interact directly, such as by predation, producing patterns of exclusion and coexistence. Less direct factors, such as interactions with the broader abiotic and biotic environment, may also contribute to such patterns, but these have received less recognition. In Northern Ireland, the North American Gammarus tigrinus has invaded freshwaters populated with the native Gammarus duebeni celticus , with intraguild predation between the two implicated in their relative success. However, these species also engage in day and night "drifting", an activity that subjects amphipods to intense predation from fish and wildfowl. Sampling of two rivers where the invader and native co-occur showed that, compared with the benthos, G. tigrinus was underrepresented and G. d. celticus overrepresented in the drift. In addition, G. tigrinus were free from parasites, whereas some G. d. celticus harboured the acanthocephalans Polymorphus minutus and Echinorhynchus truttae and the muscle wasting microsporidian Pleistophora sp. (new species). Compared with the benthos, G. d. celticus parasitized with P. minutus were overrepresented and unparasitized individuals underrepresented in the drift. The opposite pattern was found with Pleistophora sp . In laboratory experiments, G. tigrinus were less positively phototropic and less "active" than G. d. celticus (unparasitized animals). Polymorphus minutus increased G. d. celticus positive phototropism and activity, while Pleistophora sp. increased positive phototropism but decreased activity. Previous studies show that the invader G. tigrinus is more disadvantaged by intraguild predation from the native G. d. celticus than vice versa. However, the native appears more disadvantaged with respect to drift, parasitism and the interaction of the two. These factors may mitigate direct interactions and help explain complex patterns of coexistence between these invader and native species.  相似文献   

5.
Summary

Recently, a specimen of Glossogobius callidus was collected in the Marico Oog, a major source of the Limpopo River in the western Transvaal. This locality is some 1500 km from the river mouth. Earlier taxonomic confusion of Glossogobius giuris and G. callidus has resulted in the omission of G. callidus from identification keys published before 1979. As a result, that species has not been recorded from the Limpopo system. A previously published record of G. giuris from that system, at a locality about 950 km from the sea, is now shown to be based on a misidentification of G. callidus specimens.  相似文献   

6.
介绍了近年从进口竹藤检疫中多次截获的5种竹长蠹:双窝竹长蠹 Dinoderus bifoveolatus (Wollaston)、小竹长蠹D. brevis Horn、日本竹长蠹D. japonicus Lesne、竹长蠹D. minutus Fabricius及小点竹长蠹D. ocellari Stephens,分别介绍了头、前胸背板、鞘翅、腹面及足的主要鉴别特征,并编制了这5个近似种的检索表.  相似文献   

7.
Gobioid fishes collected in Nha Trang and Van Phong bays (Vietnam) represented by 44 species, including 30 species continuously associated with soft bottoms in the open parts of the bays with normal marine conditions are reviewed. A new species, Navigobius khanhoa sp. n., is described. This species differs from other species of the genus in much higher number of rays in the second dorsal fin (26), smaller size of the mouth, teeth on the jaws arranged in a single row, and other characters. Four species from the genera Acentrogobius, Eviota, Favonigobius, and Gnatholepis have not been identified to the species, and, most likely, some of them are new for science. Nine species are recorded in the fauna of Vietnam for the first time: Aulopareia unicolor, Bathygobius hongkongensis, Egglestonichthys bombylios, Glossogobius circumspectus, Oplopomops diacanthus, Oxyurichthys auchenolepis, Tomiyamichthys ex gr. russus, Tryssogobius porosus, and Valenciennea immaculata. An occurrence of Glossogobius olivaceus in the fauna of Vietnam is confirmed. Three species, G. olivaceus, Oligolepis acutipennis, and Periophthalmus kalolo, are recorded in the Cai River delta for the first time. A new synonymy is established: Eviota gurjanovae (Prokofiev, 2007) = E. prasina (Klunzinger, 1871). The current state of knowledge of Gobiidae fauna of Vietnam is discussed, and the updating of the species composition of Gobiodontini of Nha Trang Bay is presented in addition to the species list published earlier (Prokofiev, 2007).  相似文献   

8.
Gyrodactylus rugiensis was originally described as a parasite occurring on the marine gobies Pomatoschistus minutus and Pomatoschistus microps. In our preliminary survey this species was also frequently found on Pomatoschistus pictus and Pomatoschistus lozanoi. Subsequent molecular analysis of the internal transcribed spacers rDNA region revealed that this parasite actually represents a complex of two apparently cryptic species, one restricted to P. microps and the other shared by P. minutus, P. lozanoi and P. pictus. Morphometric analyses were conducted on 17 features of the opisthaptoral hard parts of specimens collected from all four host species. Standard discriminant analysis showed a clear separation of both genotypes by significant differences in marginal hook and ventral bar features. Statistical classifiers (linear discriminant analysis and nearest neighbours) resulted in an estimated misclassification rate of 4.7 and 3.1%, respectively. Based on molecular, morphological and statistical analyses a new species, Gyrodactylus rugiensoides is described. This species seems to display a lower host-specificity than generally observed for Gyrodactylus species as it infects three sympatric host species.However, seasonal and host-dependent morphometric variation is shown for G. rugiensoides collected on P. pictus. Host-switching and gene flow might be important factors preventing speciation on closely related and sympatric host species. The presence of host associated species complexes in this Gyrodactylus-Pomatoschistus system is also confirmed by the presence of two host-dependent genotypes within G. micropsi found on P. minutus and P. lozanoi, and P. microps, respectively. By comparing host and parasite phylogeny, phylogenetic and ecological factors influencing host-specificity are discussed.  相似文献   

9.
The acanthocephalan parasite Polymorphus minutus is a manipulator of its intermediate host Gammarus roeseli, which favours its transmission to the final host, a water bird. In contaminated environments, G. roeseli have to cope with two stresses, i.e. P. minutus infection and pollutants. As P. minutus survival relies on its host's survival, we investigated the influence of P. minutus on the antitoxic defence capacities and the energy reserves of G. roeseli females after cadmium exposure. In parallel, malondialdehyde, a toxic effect biomarker, was measured in G. roeseli females and in P. minutus. The results revealed that infected females displayed higher cell damage than uninfected ones, despite an apparent increase in reduced glutathione and metallothionein production. In fact, the increase of these antitoxic systems could be counterbalanced by carotenoid intake by the parasite, so that the overall defence system seemed less efficient in infected females than in uninfected ones. In addition, we demonstrated that cadmium induced cell damage in P. minutus, probably linked with cadmium accumulation in the parasite. Altogether, we observed a paradoxical pattern of responses suggesting that P. minutus increases cadmium toxicity in G. roeseli females although (i) it tends to increase several host antitoxic defence capacities and (ii) it bears part of the pollutant, as reflected by cell damage in the parasite.  相似文献   

10.
Carotenoid compositions of two freshwater Gammarus species (Crustacea: Amphipoda) and of their common acanthocephalan parasite Polymorphus minutus were characterized. The effect of carotenoid uptake by the parasite was addressed by comparing the carotenoid content of uninfected and infected female hosts. Using high-pressure liquid chromatography (HPLC), co-chromatography of reference pigments and electron ionization mass spectrometry of collected HPLC fractions (EI-MS), several xanthophylls and non-polar compounds were identified. Seven kinds of carotenoids, mainly xanthophylls, were identified in gammarids. Astaxanthin was predominant, amounting to 40 wt.% of total carotenoid in both uninfected G. pulex and G. roeseli. By contrast, we found only non-polar compounds with a predominance of esterified forms of astaxanthin in P. minutus larvae. No significant effect of infection on carotenoid content was evidenced in G. pulex and G. roeseli females. Our study highlights the use of a Matrix Solid Phase Dispersion as an efficient extraction method of both xanthophylls and non-polar pigments in small samples, including lipid-rich ones as P. minutus parasite. We discuss on the presumptive pathway leading to the formation of free astaxanthin in gammarids via hydroxy compounds, and on the accumulation of esters of astaxanthin in parasites.  相似文献   

11.
Abstract. Investigation of the chromosomes has revealed a Helophorus species from Central and Eastern Europe, and West Siberia, here described as H.paraminutus sp.n., which often closely resembles minutus F., though some specimens are larger and resemble lapponicus Thomson. The chromosomes of paraminutus are clearly distinct from those of minutus but closely resemble those of lapponicus. In the laboratory first generation hybrids were obtained between minutus and paraminutus, lapponicus and paraminutus, and lapponicus and minutus, but in no case was it possible to breed from these hybrids. Thus there can be no doubt that these three species are distinct. Recognition of paraminutus as a distinct species, despite the fact that study of its morphology alone could suggest introgressive hybridization between lapponicus and minutus, requires the recognition of limbatus Motschulsky as a species separate from H. lapponicus and necessitates the revision of the Helophorus minutus group of species which, as here defined, includes minutus, paraminutus, hilaris Sharp, lapponicus, limbatus, mervensis Semenov, rinki Angus, fulgidicol-lis Motschulsky and asturiensis Kuwert. Types and synonymies are discussed, and a key to these species given. Two old, imperfectly known, names are discussed to clear them from the synonymy: granulans var. rufipennis Hubenthal is identified as brevipalpis Bedel, and a lectotype designated; H. griseus var. lateralis Dalla Torre is left as incertae sedis and is classed as a nomen oblitum.  相似文献   

12.
Several gammarid species serve as intermediate hosts for the acanthocephalan parasite Polymorphus minutus. This parasite influences gammarid behaviour in order to favour transmission to its ultimate host, generally a bird. We investigated this host manipulation in Gammarus roeseli, a gammarid species introduced in France 150 years ago which now coexists with several exotic species from different origins. In the field, vertical distribution of G. roeseli revealed a higher proportion of infected individuals close to the water's surface and the size distribution of infected gammarids revealed predation pressure on infected individuals. However, under laboratory conditions both infected and non-infected individuals remained benthic. The addition of a second gammarid, Dikerogammarus villosus, to the experimental device involved a vertical displacement of infected G. roeseli towards the water's surface. Dikerogammarus villosus, originating from the Ponto-Caspian basin, can be considered as an aggressive predator. The substitution of D. villosus with Atyaephyra desmarestii, a planktivore decapod, did not alter the gammarids' distribution, with both infected and uninfected G. roeseli staying benthic. Thus, biotic interactions between D. villosus and G. roeseli represent selective pressure encouraging the expression of manipulated behaviour in infected amphipods. Through manipulation, P. minutus was found to increase the survival of infected G. roeseli when faced with non-host predators and to make it more vulnerable to predation by the parasite's definitive host.  相似文献   

13.
Otolith and somatic mass of two Gadidae ( Merlangius merlangus and Trisopterus minutus ) were compared in order to analyse the sex-specific relationship between otolith and somatic growth at age. In the present study, otolith mass appeared a reliable indicator of age in both species. Otolith growth reflected somatic growth, but the relationship between these characters varied and differed between species and sexes.  相似文献   

14.
A series of 40 male and 40 female mites of the prostigmatid genus Eupodes from the maritime Antarctic were each scored for 58 morphological characters, and principal co-ordinate analyses were performed on each data set. The analyses produced three clusters of points, which were interpreted as representing three species. One of these species, identified as Eupodes minutus (Strandtmann), the only species of Eupodes currently known from the maritime Antarctic, is redescribed. The other two species, E. exiguus up. and E. parvus nsp., are described. Two subspecies are recognized for the latter species, E. p. parvus from the South Orkney Islands, and E. p. grahamensis nsp. from the Antarctic Peninsula and South Shetland Islands. The geographical distribution and habitat preferences of the four text are discussed, and a key to the species is presented.  相似文献   

15.
Small mammals were trapped on five islands for short periods during the summers of 1964 and 1965, with the following results:
Handa: Rattus norvegicus only, probably no other species present.
Muck: Sorex araneus, S. minutus, Apodemus sylvaticus and Microtus agrestis; R. norvegicus also present.
Pabay: S. minutus and Neomys fodiens ; probably no other species present.
Scalpay: S. araneus, S. minutus and M. agrestis.
Soay: S. araneus and S. minutus ; rodents almost certainly absent.
Ectoparasites (fleas and Acarina) collected from these small mammals are tabulated.  相似文献   

16.
The nucleotide sequences of the first and second internal transcribed spacers of nuclear ribosomal DNA were determined for adults of Cylicostephanus minutus from different geographical origins. The lengths of first and second internal transcribed spacer sequences ranged from 370 to 372bp and 215 to 216bp, respectively. Pairwise sequence comparisons revealed that some individuals of C. minutus had identical first and second internal transcribed spacer sequences, whereas others differed by 3.0% and 7.4% in their first and second transcribed spacers, respectively. Some individuals with sequence differences originated from the same host. The levels of difference within C. minutus were higher than that between the morphologically distinct species, Cylicostephanus goldi and Cylicostephanus longibursatus (0.8% for the first internal transcribed spacer and 3.8% for the second internal transcribed spacer). The data provide support for the proposal that C. minutus represents a complex of at least two species. In order to study the population genetic structure of C. minutus, a PCR-linked single-strand conformation polymorphism technique was also established.  相似文献   

17.
Protein variation at 20 loci was analyzed by starch gel electrophoresis in population samples of Ctenomys flamarioni, C. torquatus, C. sp., and C. minutus collected in 25 localities of Southern Brazil. Results show that these four species exhibit higher levels of genetic variability (He = 0.11-0.17) than those reported for most other fossorial rodents. Estimates of similarity coefficients indicate that C. minutus and C. sp. (S = 0.91) are the closest species, while C. flamarioni (S = 0.77) is the most distant from the others. The data presented here support the hypothesis of a relatively recent disjunction of C. minutus from C. sp. Within-species similarity indices are of the same order of magnitude as those found between species. The relatively high levels of heterozygosity observed are not in accordance with the view that subterranean taxa should be less variable than aboveground species due to the uniformity of their environment.  相似文献   

18.
Vicariant and climatic cycling speciation hypotheses of the 'sand gobies' belonging to the genera Pomatoschistus, Gobiusculus, Knipowitschia, and Economidichthys are tested using molecular phylogenies constructed of nuclear DNA (ITS1 locus) and mitochondrial DNA (12S and 16S fragments). These gobies are among the most abundant in the Eastern Atlantic-Mediterranean region, and play an important role in the ecosystem. Considerable ITS1 length differences, primarily due to the presence of several tandem repeats, were found between species and even within individuals. Therefore, phylogenetic analyses focused on fragments of the 12S and 16S mtDNA region that have been sequenced for 16 goby taxa. The 'sand gobies' clustered as a monophyletic group as proposed on morphological grounds. However, G. flavescens, E. pygmaeus, and K. punctatissima clustered within the Pomatoschistus species, pointing to a paraphyletic origin of these genera. Furthermore, the genetic divergence between P. minutus from the Adriatic Sea versus the Atlantic-Mediterranean region was as high as the divergence within the P. minutus complex, suggesting that P. minutus from the Adriatic Sea should be considered as a distinct species. The "star" phylogeny might suggest that these gobies evolved in a very short time period, possibly linked to the drastic alterations in the Mediterranean Sea during and immediately after the Messinian salinity crisis at the end of the Miocene. The freshwater life-style appeared monophyletic; equating its origin with the salinity crisis resulted in a molecular clock estimate of 1.4% divergence per million years. The last common ancestor probably occupied sandy bottoms and a coastal niche while several species subsequently adapted to new habitats (pelagic, freshwater or stenohaline). The origin of the shallowest clades dated back to the glacial cycling during the Pleistocene epoch.  相似文献   

19.
Analysis of the genetic structure (11 loci) of helminth populations (Monogenea, Diclidophora ), parasites of two teleost species (Gadidae, Trisopterus luscus and T. minutus minulus ) which are sympatric in the Atlantic, revealed the existence of two species which were specific to each of the two hosts. A strong genetic similitude was found between one of these species ( Diclidophora luscae ), a parasite of T. luscus and a monogenean population parasitizing a third Gadidae ( Trisopterus minutus capelanus ) in the Mediterranean. These results led to a re-examinination of the evolutionary systematics of the three host taxa of the genus Trisopterus. Genetic analysis showed differences between the two subspecies T. minutus minutus (Atlantic) and T. minutus capelanus (Mediterranean) at eight of the 16 loci studied. However, there was no significant genetic divergence between T. luscus and T.m. capelanus. A new phyletic structure in the genus Trisopterus is proposed and the evolutionary trends within the Gadidae/Monogenea system are discussed.  相似文献   

20.
Bourguignon T  Roisin Y 《ZooKeys》2011,(148):55-103
Recently, we completed a revision of the Termitidae from New Guinea and neighboring islands, recording a total of 45 species. Here, we revise a second family, the Rhinotermitidae, to progress towards a full picture of the termite diversity in New Guinea. Altogether, 6 genera and 15 species are recorded, among which two species, Coptotermes gambrinus and Parrhinotermes barbatus, are new to science. The genus Heterotermes is reported from New Guinea for the first time, with two species restricted to the southern part of the island. We also provide the first New Guinea records for six species of the genera Coptotermes and Schedorhinotermes. We briefly describe soldiers and imagoes of each species and provide a key based on soldier characters. Finally, we discuss the taxonomic and biogeographical implication of our results. A replacement name, Schedolimulus minutides Bourguignon, is proposed for the termitophilous staphylinid Schedolimulus minutus Bourguignon, to solve a question of secondary homonymy.  相似文献   

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