''Oncomelania hupensis'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of very small

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

freshwater snail, an aquatic gastropod

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

in the family

Pomatiopsidae Pomatiopsidae is a family of small, mainly freshwater snails, (some also occur in other habitats) that have gills and an operculum, aquatic gastropod mollusks in the superfamily Truncatelloidea (according to the taxonomy of the Gastropoda b ...

Distribution

''Oncomelania hupensis'' has been found in China,

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...

, and also in Japan, the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

, and on the

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

n island of Sulawesi. Oncomelania hupensis hupensis (PLoS)

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

sculpture Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable ...

, 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 The Yangtze or Yangzi ( or ; ) is the longest list of rivers of Asia, river in Asia, the list of rivers by length, third-longest in the world, and the longest in the world to flow entirely within one country. It rises at Jari Hill in th ...

basin. Smooth-shelled snails are also distributed in mainland China, but are considered 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.Davis G. M. (1979). "The origin and evolution of the gastropod family Pomatiopsidae, with emphasis on the Mekong river Triculinae". ''

Academy of natural Sciences of Philadelphia The Academy of Natural Sciences of Drexel University, formerly the Academy of Natural Sciences of Philadelphia, is the oldest natural science research institution and museum in the Americas. It was founded in 1812, by many of the leading nat ...

'', Monograph 20: 1–120.
at Google Books
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

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 lindoensis'' (Davis & Carney, 1973)—in Sulawesi, or as separate species ''

Oncomelania lindoensis ''Oncomelania'' is a genus of very small tropical freshwater snails, aquatic gastropod mollusks in the family Pomatiopsidae. These ''Oncomelania'' snails are distantly related to the marine periwinkle, and more closely related to the small mar ...

'' * ''Oncomelania hupensis nosophora'' (Robson, 1915)—it is

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and in ...

(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

Sichuan Sichuan (; zh, c=, labels=no, ; zh, p=Sìchuān; alternatively romanized as Szechuan or Szechwan; formerly also referred to as "West China" or "Western China" by Protestant missions) is a province in Southwest China occupying most of the ...

and

Yunnan Yunnan , () is a landlocked province in the southwest of the People's Republic of China. The province spans approximately and has a population of 48.3 million (as of 2018). The capital of the province is Kunming. The province borders the C ...

provinces. * ''Oncomelania hupensis tangi'' (Bartsch, 1936)—it has a smooth shell but with thick varix, is found in

Fujian Fujian (; alternately romanized as Fukien or Hokkien) is a province on the southeastern coast of China. Fujian is bordered by Zhejiang to the north, Jiangxi to the west, Guangdong to the south, and the Taiwan Strait to the east. Its cap ...

province and Guangxi autonomous region, separated geographically from 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''.Yi-Biao Zhou, Mei-Xia Yang, Gen-Ming Zhao, Jiang-Guo Wei & Qing-Wu Jiang. (2007). "''Oncomelania hupensis'' (Gastropoda: Rissooidea), Intermediate Host Of ''Schistosoma japonicum'' In China: Genetics and Molecular Phylogeny Based On Amplified Fragment Length Polymorphisms". ''Malacologia'' 49(2): 367–382.
abstract
/ref> Genetic confirmation of these 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.

Genetics

It may also be possible that continuous control efforts, such as routine

molluscicide Molluscicides () – also known as snail baits, snail pellets, or slug pellets – are pesticides against molluscs, which are usually used in agriculture or gardening, in order to control gastropod pests specifically slugs and snails which damag ...

s in China, which have been used to control snails for about fifty years, might have imposed some effect on

population genetic Population genetics is a subfield of genetics that deals with genetic differences within and between populations, and is a part of evolutionary biology. Studies in this branch of biology examine such phenomena as adaptation, speciation, and popu ...

s of these snails. The complete

mitochondrial genome Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial ...

of ''Oncomelania hupensis'' has been released in 2010.Zhao Q. P., Zhang S. H., Deng Z. R., Jiang M. S. & Nie P. (2010). "Conservation and variation in mitochondrial genomes of gastropods ''Oncomelania hupensis'' and ''Tricula hortensis'', intermediate host snails of ''Schistosoma'' in China". ''

Molecular Phylogenetics and Evolution ''Molecular Phylogenetics and Evolution'' is a peer-reviewed scientific journal of evolutionary biology and phylogenetics. The journal is edited by E.A. Zimmer. Indexing The journal is indexed in: * EMBiology *Journal Citation Reports *Scopus ...

'' 57(1): 215–226. .

Habitat

It is seasonally amphibious 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 haplotypes. 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 Vector most often refers to: *Euclidean vector, a quantity with a magnitude and a direction *Vector (epidemiology), an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematic ...

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...

infection in the tropics and subtropics. It can serve as vectors for two serious human diseases: the schistosomiasis blood fluke parasite, and the paragonimus lung fluke parasites. ''Oncomelania hupensis'' is the unique intermediate host of ''

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 prima ...

'', which causes schistosomiasis endemic in the

Far East The ''Far East'' was a European term to refer to the geographical regions that includes East and Southeast Asia as well as the Russian Far East to a lesser extent. South Asia is sometimes also included for economic and cultural reasons. The ter ...

, and especially in mainland China. ''Oncomelania hupensis'' largely determines the parasite's geographical range. Disinfesting Oncomelania hupensis, Japan has completely overcome Schistosoma japonicum.

References

This article incorporates CC-BY-2.5 text from references.Zhao Q. P., Jiang M. S., Littlewood D. T. J. & Nie P. (2010). "Distinct Genetic Diversity of ''Oncomelania hupensis'', Intermediate Host of ''Schistosoma japonicum'' in Mainland China as Revealed by ITS Sequences". '' PLoS Neglected Tropical Diseases'' 4(3): e611. .Zhao Q. P., Jiang M. S., Littlewood D. T. J. & Nie P. (2010) "Distinct Genetic Diversity of ''Oncomelania hupensis'', Intermediate Host of ''Schistosoma japonicum'' in Mainland China as Revealed by ITS Sequences"
Ribbed-shelled ''Oncomelania hupensis hupensis'' (Gredler, 1881)
. '' PLoS Neglected Tropical Diseases'' 4(3): e611. .

External links

* {{Use dmy dates, date=May 2017 Pomatiopsidae Gastropods described in 1881