Oncomelania hupensis
Encyclopedia
Oncomelania hupensis is a species
of very small tropical freshwater snail
, an aquatic
gastropod mollusk in the family Pomatiopsidae
.
island of Sulawesi
.
, operculum
etc. Phenotypically, Oncomelania hupensis can be separated into ribbed- and smooth- shelled morphotypes. In China, the typical morphotype of Oncomelania hupensis is ribbed-shelled, and its distribution is restricted to Yangtze River
basin. Smooth-shelled snails are also distributed in mainland China, but are considered as the same species and subspecies of Oncomelania hupensis.
Oncomelania hupensis reported in other Far East countries are smooth-shelled, and have been considered either as subspecies of Oncomelania hupensis or independent species in this genus.
There are 4 subspecies of Oncomelania hupensis in China: hupensis, robertsoni, tangi and guangxiensis.
Genetic confirmation of thsese four Chinese subspecies: Based on shell form, biogeographical and allozyme
data, Davis et al. (1995) distinguished 3 subspecies of the Oncomelania hupensis in mainland China. However, Zhou et al. (2008) separated the Oncomelania hupensis guangxiensis out from Oncomelania hupensis tangi based on allozymes and amplified fragment length polymorphism (AFLP), which was verified recently by Li et al. with internal transcribed spacer (ITS) and 16S fragments.
s in China, which have been used to control snails for about fifty years, might have imposed some effect on population genetics of these snails.
The complete mitochondrial genome of Oncomelania hupensis has been released in 2010.
species which lives in lakes and on marshy ground.
The habitats of Oncomelania hupensis in the middle and lower reaches of the Yangtze River include lake/marshland regions and hill regions, both of which have extensive physical connections with the Yangtze River through channels or in low floodplains beside the Yangtze River. With frequent floodings of the Yangtze River, snails in these habitats can be dispersed
and subsequently deposited widely in various localities. The accumulation of mixed sources of snails can then generate genetically diversified populations of snails, leading to the existence of various haplotype
s.
In Sichuan and Yunnan provinces in the upper reaches of the Yangtze River, Oncomelania hupensis robertsoni are distributed in mountainous areas, and are not subjected to flood influence as much as in the middle and lower reaches of the river. It is interesting to see that a relatively lower number of haplotypes were found in this region as compared with Oncomelania hupensis hupensis. It appears likely that there has been certain degree of isolation for these mountainous populations.
blood fluke parasite, and the paragonimus
lung fluke parasites.
Oncomelania hupensis is the unique intermediate host
of Schistosoma japonicum
, which causes schistosomiasis endemic in the Far East
, and especially in mainland China. Oncomelania hupensis largely determines the parasite's geographical range.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of very small tropical freshwater snail
Freshwater snail
A freshwater snail is one kind of freshwater mollusc, the other kind being freshwater clams and mussels, i.e. freshwater bivalves. Specifically a freshwater snail is a gastropod that lives in a watery non-marine habitat. The majority of freshwater gastropods have a shell, with very few exceptions....
, an aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
gastropod mollusk in the family Pomatiopsidae
Pomatiopsidae
Pomatiopsidae is a family of small mainly freshwater snails with gills and an operculum, aquatic gastropod mollusks in the superfamily Rissooidea ....
.
Distribution
Oncomelania hupensis has been found in China, and also in Japan, Philippines, and IndonesianIndonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
island of Sulawesi
Sulawesi
Sulawesi is one of the four larger Sunda Islands of Indonesia and is situated between Borneo and the Maluku Islands. In Indonesia, only Sumatra, Borneo, and Papua are larger in territory, and only Java and Sumatra have larger Indonesian populations.- Etymology :The Portuguese were the first to...
.
Description
Over the past a few decades, the taxonomy of Oncomelania hupensis has been a dispute due to the variation in morphological characters such as shell sculptureSculpture (mollusc)
The sculpture of a mollusc shell is the three-dimensional ornamentation on the outer surface, as distinct from the basic shape of the shell itself or colouration. Sculpture may be concave as well as convex. Sometimes it has microscopic detail. Sculpture refers to the calcareous outer layer, not the...
, operculum
Operculum (gastropod)
The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...
etc. Phenotypically, Oncomelania hupensis can be separated into ribbed- and smooth- shelled morphotypes. In China, the typical morphotype of Oncomelania hupensis is ribbed-shelled, and its distribution is restricted to Yangtze River
Yangtze River
The Yangtze, Yangzi or Cháng Jiāng is the longest river in Asia, and the third-longest in the world. It flows for from the glaciers on the Tibetan Plateau in Qinghai eastward across southwest, central and eastern China before emptying into the East China Sea at Shanghai. It is also one of the...
basin. Smooth-shelled snails are also distributed in mainland China, but are considered as the same species and subspecies of Oncomelania hupensis.
Oncomelania hupensis reported in other Far East countries are smooth-shelled, and have been considered either as subspecies of Oncomelania hupensis or independent species in this genus.
Subspecies
- Oncomelania hupensis chiui (Habe & Miyazaki, 1962) - in Taiwan
- Oncomelania hupensis hupensis (Gredler, 1881) - in China. It is the most widely distributed subspecies of Oncomelania hupensis and lives primarily at low altitude but a few populations live in hilly areas in the drainage area of the Yangtze RiverYangtze RiverThe Yangtze, Yangzi or Cháng Jiāng is the longest river in Asia, and the third-longest in the world. It flows for from the glaciers on the Tibetan Plateau in Qinghai eastward across southwest, central and eastern China before emptying into the East China Sea at Shanghai. It is also one of the...
in mainland China. It has varix, no matter whether the shell is smooth or ribbed, but most populations have ribbed-shell. Oncomelania hupensis hupensis has the same shell growth allometry as Oncomelania hupensis robertsoni but has a longer shell on average. - Oncomelania hupensis formosana (Pilsbry & Hirase) - in Taiwan
- Oncomelania hupensis guangxiensis (Liu, 1981)
- Oncomelania hupensis lindoesnsis (Davis & Carney, 1973) - in Sulawesi, or as separates species Oncomelania lindoensis
- Oncomelania hupensis nosophora (Robson, 1915) - it is EndangeredEndangered speciesAn endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
(type I, CR+EN) taxon in Japan. - Oncomelania hupensis quadrasi (Möllendorff, 1895) - in Philippines
- Oncomelania hupensis robertsoni (Bartsch, 1946) - It has a small, smooth shell but with no varix, is found in SichuanSichuan' , known formerly in the West by its postal map spellings of Szechwan or Szechuan is a province in Southwest China with its capital in Chengdu...
and YunnanYunnanYunnan is a province of the People's Republic of China, located in the far southwest of the country spanning approximately and with a population of 45.7 million . The capital of the province is Kunming. The province borders Burma, Laos, and Vietnam.Yunnan is situated in a mountainous area, with...
provinces. - Oncomelania hupensis tangi (Bartsch, 1936) - It has a smooth shell but with thick varix, is found in FujianFujian' , formerly romanised as Fukien or Huguing or Foukien, is a province on the southeast coast of mainland China. Fujian is bordered by Zhejiang to the north, Jiangxi to the west, and Guangdong to the south. Taiwan lies to the east, across the Taiwan Strait...
province and GuangxiGuangxiGuangxi, formerly romanized Kwangsi, is a province of southern China along its border with Vietnam. In 1958, it became the Guangxi Zhuang Autonomous Region of the People's Republic of China, a region with special privileges created specifically for the Zhuang people.Guangxi's location, in...
autonomous region, separated geographically from the Yangtze RiverYangtze RiverThe Yangtze, Yangzi or Cháng Jiāng is the longest river in Asia, and the third-longest in the world. It flows for from the glaciers on the Tibetan Plateau in Qinghai eastward across southwest, central and eastern China before emptying into the East China Sea at Shanghai. It is also one of the...
, and extensive control measures have brought this subspecies to near extinction.
There are 4 subspecies of Oncomelania hupensis in China: hupensis, robertsoni, tangi and guangxiensis.
Genetic confirmation of thsese four Chinese subspecies: Based on shell form, biogeographical and allozyme
Allozyme
Variant forms of an enzyme that are coded by different alleles at the same locus are called allozymes. These are opposed to isozymes, which are enzymes that perform the same function, but which are coded by genes located at different loci....
data, Davis et al. (1995) distinguished 3 subspecies of the Oncomelania hupensis in mainland China. However, Zhou et al. (2008) separated the Oncomelania hupensis guangxiensis out from Oncomelania hupensis tangi based on allozymes and amplified fragment length polymorphism (AFLP), which was verified recently by Li et al. with internal transcribed spacer (ITS) and 16S fragments.
Genetics
It may also be possible that continuous control efforts, such as routine molluscicideMolluscicide
Molluscicides, also known as snail baits and snail pellets, are pesticides against molluscs, which are usually used in agriculture or gardening to control gastropod pests like slugs and snails that can damage crops by feeding on them....
s in China, which have been used to control snails for about fifty years, might have imposed some effect on population genetics of these snails.
The complete mitochondrial genome of Oncomelania hupensis has been released in 2010.
Habitat
It is seasonally amphibiousAmphibious
Amphibious means able to use either land or water. In particular it may refer to:*Amphibious warfare, warfare carried out on both land and water*Amphibians, vertebrate animals of the Class Amphibia...
species which lives in lakes and on marshy ground.
The habitats of Oncomelania hupensis in the middle and lower reaches of the Yangtze River include lake/marshland regions and hill regions, both of which have extensive physical connections with the Yangtze River through channels or in low floodplains beside the Yangtze River. With frequent floodings of the Yangtze River, snails in these habitats can be dispersed
Biological dispersal
Biological dispersal refers to species movement away from an existing population or away from the parent organism. Through simply moving from one habitat patch to another, the dispersal of an individual has consequences not only for individual fitness, but also for population dynamics, population...
and subsequently deposited widely in various localities. The accumulation of mixed sources of snails can then generate genetically diversified populations of snails, leading to the existence of various haplotype
Haplotype
A haplotype in genetics is a combination of alleles at adjacent locations on the chromosome that are transmitted together...
s.
In Sichuan and Yunnan provinces in the upper reaches of the Yangtze River, Oncomelania hupensis robertsoni are distributed in mountainous areas, and are not subjected to flood influence as much as in the middle and lower reaches of the river. It is interesting to see that a relatively lower number of haplotypes were found in this region as compared with Oncomelania hupensis hupensis. It appears likely that there has been certain degree of isolation for these mountainous populations.
Parasites
This freshwater snail is significant medically, because it is an important vector of parasitic infection in the tropics and subtropics. It can serve as vectors for two serious human diseases: the schistosomiasisSchistosomiasis
Schistosomiasis is a parasitic disease caused by several species of trematodes , a parasitic worm of the genus Schistosoma. Snails often act as an intermediary agent for the infectious diseases until a new human host is found...
blood fluke parasite, and the paragonimus
Paragonimus
Paragonimus is an important genus of flatworms, or platyhelminths, that includes Paragonimus westermani, an infectious lung fluke endemic to Asia....
lung fluke parasites.
Oncomelania hupensis is the unique intermediate host
Intermediate host
A secondary host or intermediate host is a host that harbors the parasite only for a short transition period, during which some developmental stage is completed. For trypanosomes, the cause of sleeping sickness, humans are the primary host, while the tsetse fly is the secondary host...
of Schistosoma japonicum
Schistosoma japonicum
Schistosoma japonicum is an important parasite and one of the major infectious agents of schistosomiasis.This parasite has a very wide host range, infecting at least 31 species of wild mammals, including 9 carnivores, 16 rodents, one primate , two insectivores and three artiodactyls and therefore...
, which causes schistosomiasis endemic in the Far East
Far East
The Far East is an English term mostly describing East Asia and Southeast Asia, with South Asia sometimes also included for economic and cultural reasons.The term came into use in European geopolitical discourse in the 19th century,...
, and especially in mainland China. Oncomelania hupensis largely determines the parasite's geographical range.
See also
- Oncomelania quadrasi has a synonym: Oncomelania hupensis quadrasi (Davis, 1968). It lives in the Philippines.
Further reading
- Shi, C. H., T. Wilke, G. M. Davis, M. Y. Xia & C. P. Qiu. 2002. Population genetics, microphylogeography, ecology and susceptibility to schistosome infection of Chinese Oncomelania hupensis hupensis (Gastropoda: Rissooidea: Pomatiopsidae) in the Miao River System. Malacologia 44:2333–347.
- Tang C.-T., Lu M.-K., Guo Y., Wang Y.-N., Peng J.-Y., Wu W.-B., Li W.-H., Weimer B. C. & Chen D. (2009). "Development of Larval Schistosoma japonicum Blocked in Oncomelania hupensis by Pre-Infection with Larval Exorchis Sp.". Journal of Parasitology 95(6): 1321-1325. doi:10.1645/GE-2055.1.
- Wilke, T., G. M. Davis, C. E. Chen, X. N. Zhou, X. P. Zeng, Y. Zhang & C. M. Spolsky. 2000. Oncomelania hupensis (Gastropoda: Rissooidea) in eastern China: molecular phylogeny, population structure, and ecology. Acta Tropica 77:215–227. abstract
- Wilke, T., G. M. Davis, D. C. Qiu & R. C. Speak. 2006. Extreme mitochondrial sequence diversity in the intermediate schistosomiasis host Oncomelania hupensis robertsoni: another case of ancestral polymorphism. Malacologia 48:1–2143–157.
- Yang, Guo-Jing1; Utzinger, Jürg; Sun, Le-Ping; Hong, Qing-Biao; Vounatsou, Penelope; Tanner, Marcel; Zhou, Xiao-Nong 2007.Effect of temperature on the development of Schistosoma japonicum within Oncomelania hupensis, and hibernation of O. hupensis. Parasitology Research, Volume 100, Number 4, March 2007 , pp. 695–700(6). abstract
- Zhou, Y. B., Q. W. Jiang, G. M. Zhao & J. G. Wei. 2005. Analysis of morphological variation within Oncomelania hupensis population. Chinese Journal of Zoology 40:90–97.