Bulinus
| Bulinus | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Bulinus wrighti |
||||||||||
| Systematics | ||||||||||
|
||||||||||
| Scientific name | ||||||||||
| Bulinus | ||||||||||
| OV Müller , 1781 |
Bulinus is a rather small to mittelwüchsige screw genus from the family of planorbidae (Planorbidae) used for the subordination of the basommatophora within the lung worm is expected (Pulmonata). It includes numerous species in tropical to warm temperate waters, some of which serve as intermediate hosts for parasitesthat can cause schistosomiasis (schistosomiasis)in humans. There is no generally recognized German name for this genus. One species ( Bulinus truncatus ) is also found in warmer regions of Europe.
features
- morphology
The housing measure in adult animals mm between about 4 and 25, are spirally wound and more or less oblong-shaped, between species but quite variable. Sometimes the mouth appears greatly enlarged (e.g. in B. welwitschi ), sometimes it is rather inconspicuous (e.g. in B. nasutus ). The species of the genus can be confused externally with other Planorbidae and with representatives of the bladder snails .
- Karyology
While the basic number of the haploid chromosome set in bulinus species is n = 18, this number is multiplied in some species: In some species one finds tetraploidy ( i.e. n = 36), in some cases even hexaploidy (n = 54) and octoploidy (n = 72). Octoploid shapes seem a. occur more frequently at higher altitudes.
- Molecular Characteristics
In order to recognize the individual species and genetic lines (strains) , which can represent intermediate hosts for certain types of parasites and thus can be significant in human medicine, the methods of morphology and karyology are not sufficient, but are expanded by molecular genetic features. DNA barcoding is being discussed as a suitable method for the future .
Reproductive biology
Like all aquatic snails, bulinus is hermaphroditic . In the case of Bulinus truncatus , which also occurs in Europe, two sexual expressions (sexual morphs) have been determined, namely individuals with a normal development of their hermaphroditic reproductive organs (euphallic individuals) and individuals who lack the male copulatory organ (aphallic individuals) and are therefore only considered to be during copulation Females can act. The two sexual forms can occur together in the same population. Both forms can reproduce through self-fertilization as well as through bisexual reproduction. The meaning of these different expressions of the sexual organs is not clear; however, the phenomenon also occurs in other species of the pinnacle family.
Medical importance
The snails serve species of the pair leech (genus Schistosoma from the class of flukes (trematodes)), which are pathogenic for humans or domestic animals, as intermediate hosts. In Africa it is especially the species Schistosoma haematobium and Schistosoma intercalatum , which are dangerous for humans , in the eastern Mediterranean region it is the species Schistosoma haematobium .
distribution and habitat
The species of the genus Bulinus are widespread in Africa and the Middle East. They can tolerate a wide range of temperatures between about 10 and 35 ° C; however, they avoid salty and acidic water. They also develop in temporary water reservoirs in arid areas, e.g. B. the Sahel. The population densities and the transferability of the parasites can vary greatly depending on the level of precipitation and water level in the water. The individuals, which sometimes only survive in dry periods, can quickly reach a high population density after rain. Since the snails often serve as intermediate hosts for parasites, they are controlled. On the one hand, molluscicides are used for this purpose ; In addition, attempts are being made to reduce or destroy the snail populations by drying out or removing the vegetation required for spawning.
Systematics
- External system
Within the Planorbidae, the Bulinus species are placed in their own subfamily Bulininae and / or in their own tribe Bulinini.
- Internal system
Currently 36 to 37 recent species are differentiated, but the separation into monophyletic taxa is difficult and has not yet been solved satisfactorily. In total, significantly more (around 1000) nominal species and subspecies have been scientifically described, but these are now largely regarded as varieties or genetic lines of species or groups of species that are difficult to separate.
There are currently four groups of species, all of which also contain species that can act as intermediate hosts for species of the pair of leeches. These four groups of species are:
- B. forskalii group: 11 species, slender and tall shells, distribution throughout Africa, including the Arabian Peninsula
- B. africanus group: 10 species, distribution in tropical Africa
- B. truncatus / tropicus complex: 14 species, some polyploid species and lines, distribution throughout Africa to the Middle East, southwestern Europe and Mediterranean islands
- B. reticulatus group: 2 species with restricted distribution: B. reticulatus and B. wrighty
Species selection in alphabetical order:
- Bulinus africanus CF Krauss, 1848
- Bulinus angolensis PA Morelet, 1866; Angola and Namibia, shell up to 14 mm
- Bulinus bavayi Dautzenberg, 1894; endemic to Madagascar, shell up to 12.5 mm
- Bulinus camerunensis Mandahl-Barth, 1957; endemic to Cameroon, considered to be threatened ("vulnerable")
- Bulinus cernicus Morelet, 1867; on Maritius and Réunion, is considered endangered ("lower risk near threatened")
- Bulinus crystallinus PA Morelet 1868; in Angola and Gabon, is considered to be threatened ("vulnerable")
- Bulinus forskalii , Africa, probably introduced into Madagascar
- Bulinus globosus PA Morelet, 1866
- Bulinus liratus Tristram, 1863; endemic to Madagascar
- Bulinus nasutus Martens, 1879; Kenya, Tanzania, Uganda, bowl up to 25 mm
- Bulinus nyassanus Smith, 1877; endemic to Malawi, considered threatened ("vulnerable")
- Bulinus obtusispira , Smith, 1882; endemic to Madagascar
- Bulinus reticulatus Mandahl-Barth, 1954; eastern and southern Africa, shell up to 7 mm
- Bulinus scalaris RW Dunker, 1845
- Bulinus senegalensis O. F. Müller , 1780 or 1781
- Bulinus transversalis E. v. Martens, 1897; Kenya and Uganda, considered threatened ("vulnerable")
- Bulinus tropicus CF Krauss, 1848
- Bulinus truncatus , JV Audouin, 1927; occurs in Europe as well as in Africa (Iberian Peninsula, Balearic Islands, France, Corsica, Sardinia, Sicily, Crete)
- Bulinus ugandae Mandahl-Barth, 1954
- Bulinus umbilicatus Mandahl-Barth, 1973
- Bulinus welwitschi ; Angola, shell up to 15 mm
- Bulinus wrighti Mandahl-Barth, 1965; Arabian Peninsula, shell up to 7 mm
Individual evidence
- ↑ CM Patterson, JB Burch: Chromosomes of pulmonate molluscs. Pp. 171-217, in: V. Fretter, J. Peake, Pulmonates . Vol. 2A, Academic Press, London (1978)
- Jump up ↑ D. Rollinson, J Russell Stothard, CS Jones, AE Lockyer, C. Pereira de Souza, LR Noble: Molecular characterization of intermediate snail hosts and the search for resistance genes. Memórias do Instituto Oswaldo Cruz 93, Suppl. I: 111-116 (1998)
- ↑ RA Kane, JR Stothard, AM Emery, D. Rollinson: Molecular characterization of freshwater snails in the genus Bulinus : a role for barcodes? Parasite Vectors 2008: 1:15. doi : 10.1186 / 1756-3305-1-15
- ↑ C. Doums, P. Jarne: The evolution of phally polymorphism in Bulinus truncatus (Gastropoda, Planorbidae): the cost of male function analyzed through life-history traits and sex allocation. Oecologia 106: 464-469 (1996)
- ^ Christian Albrecht, Kerstin Kuhn & Bruno Streit: A molecular phylogeny of Planorboidea (Gastropoda, Pulmonata): insights from enhanced taxon sampling. Zoologica Scripta, 36: 27-39, Oxford, 2007. doi : 10.1111 / j.1463-6409.2006.00258.x
- ↑ Archive link ( Memento of the original from March 28, 2007 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Bulinus camerunensis . 2006 IUCN Red List of Threatened Species.
- ↑ Bulinus cernicus . 2006 IUCN Red List of Threatened Species.
- ↑ Bulinus crystallinus . 2006 IUCN Red List of Threatened Species.
- ^ Bulinus nyassanus . 2006 IUCN Red List of Threatened Species.
- ^ Bulinus transversalis . 2006 IUCN Red List of Threatened Species.
