Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 27

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  freshwater snail
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Shell habitus and COI mitochondrial gene sequences of one freshwater snail from Khios and three from Rhodes islands were analysed. Both methods confirmed assignment of these specimens to the genus Daphniola Radoman, 1973. Genetic distance between individuals from these two islands is surprisingly low, strongly suggesting that they belong to the same species, still undescribed. Comparison of COI sequences with other known species of this genus shows that the closest relative of the Khios and Rhodes populations is D. louisi Falniowski et Szarowska, 2000 from Attica. The results are discussed in the context of geological and climatic history of the Mediterranean.
The list of freshwater gastropods of Bulgaria, with data on their distribution, ecology and conservation status, was based on a critical overview of all available sources and unpublished materials. The total number of freshwater snail species hitherto recorded from Bulgaria is 120. Three species are regarded as extinct, two species were found only as subfossil remains. The most diverse families are Hydrobiidae (67 species), Planorbidae (15), and Lymnaeidae (11). The remaining families are represented by 1 to 4 species. Zoogeographical, ecological and conservation data are discussed.
No freshwater snails were collected form the study area. The observed range of many physico-chemical factors was within the tolerance levels of the freshwater snails. The differences in the seasonal means of the parameters were not statistically significant. The absence of freshwater snails, including the snail vectors of schistosomiasis, was therefore attributed to the combined effect of the acidic nature of the water bodies and the low topographical terrain of the study area.
Out of the 39 various waterbodies studied, 31 (79,5%) harboured different species of freshwater snails. The six snail species collected were Pila ovata (Olivier), Bulinus forskali (Ehrenberg), B. globosus (Morelet), Lymnaea natalensis Krauss, Segmentorbis angustus (Jickeli) and Lanestes libycus (Morelet). Two snail species, L. natalensis and B. forskali, shed furcocercous and gymnocephalous cercaria respectively. The overall snail infection rate was 7.6%.
14
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

Abnormal shells Lymnaea (radix) peregra

84%
This review presents the results of studies on the freshwater snail-trematode associations, carried out in Europe since the beginning of the 20th century. The great number of synonyms of snail and trematode specific names has made the cooperation between malacologists and parasitologists difficult. Here we provide a survey of larval trematodes (cercariae) based on Central, North and Western European literature. Whenever possible, the valid species name is provided, accompanied by synonyms, or just provisional names are used making up the largest part of the list. Trematodes with a definitely unclear systematic status are indicated as species incertae sedis. These include mostly trematodes which were attributed obviously erroneous names with poor or no description of their morphology. Although the provisional names inflate the number of trematode species and there are still many identification problems, we believe that this is another step in assessing the trematode species composition in Europe which will help not only parasitologists but also malacologists and contribute to their closer cooperation.
Lymnaeid snails of the genus Radix serve as intermediate hosts of some schistosomes and fasciolids. In Europe, delineation of species within the genus Radix is unresolved and, therefore, spectrum of snail hosts susceptible to trematode infections is under discussion. We used and compared three criteria for species delineation using snails collected at 43 localities. (a) Sequence analysis of ITS-2 rDNA disclosed that the collected snails belong to four species — R. auricularia (Linnaeus, 1758), R. peregra (Müller, 1774), R. lagotis (Schrank, 1803) and R. labiata (Rossmaessler, 1835) (criteria and names are based on the work of Bargues et al. 2001). Occurrence of R. peregra in the Czech Republic was confirmed by molecular data for the first time. (b) Characterization of reproductive system disclosed differences in location, size and shape of bursa copulatrix and its ductus. Unfortunately, some R. labiata specimens shared morphological features of reproductive organs with R. lagotis. (c) Statistical analysis of shell morphology proved that significant differences exist among particular species. One prediction model showed that correct classification of species may be achieved in 82-84% of cases. However, identification of individual snails in the field (without knowledge of respective snail population and use of statistical tools) still remains a complicated issue due to overlaps of shell characteristics. Concerning the role in trematode transmission, R. lagotis, R. labiata and R. peregra are susceptible to Trichobilharzia regenti. Also, successful experimental infections of R. lagotis and R. labiata by Fascioloides magna were accomplished.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.