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,
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 the same species and subspecies of Oncomelania hupensis.[1]
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.[1]
Oncomelania hupensis hupensis (Gredler, 1881)—in China.[3] 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 River 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.[1]
Oncomelania hupensis robertsoni (Bartsch, 1946)—it has a small, smooth shell but with no varix, is found in
Sichuan and
Yunnan provinces.[1]
Oncomelania hupensis tangi (Bartsch, 1936)—it has a smooth shell but with thick varix, is found in
Fujian province and
Guangxi autonomous region, separated geographically from the
Yangtze River, and extensive control measures have brought this subspecies to near extinction.[1]
There are 4 subspecies of Oncomelania hupensis in China: hupensis, robertsoni, tangi and guangxiensis.[6][7]
Genetic confirmation of these four Chinese subspecies: Based on shell form, biogeographical and
allozyme data, Davis et al. (1995)[8] distinguished 3 subspecies of the Oncomelania hupensis in mainland China.[1] However, Zhou et al. (2008)[9] 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.[10] with internal transcribed spacer (ITS) and 16S fragments.
Genetics
It is believed that continuous control efforts, such as routine
molluscicides in China, which have been used to control snails for about fifty years, might have imposed some effect on
population genetics of these snails.[1]
It is seasonally
amphibious species which lives in lakes and on marshy ground.[12]
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.[1]
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.[1] It is interesting to see that a relatively lower number of haplotypes were found in this region as compared with Oncomelania hupensis hupensis.[1] It appears likely that there has been certain degree of isolation for these mountainous populations.[1]
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
schistosomiasis blood fluke parasite, and the
paragonimus lung fluke parasites.
^
abYi-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". Malacologia49(2): 367–382.
doi:
10.4002/0076-2997-49.2.367,
abstract
^Davis G. M., Zhang Y., Guo Y. H. & Spolsky C. M. (1995). "Population genetics and systematic status of Oncomelania hupensis (Gastropoda: Pomatiopsidae) throughout China". Malacologia37: 133–156.
^(in Chinese) Zhou Y. B., Jiang Q. W., Zhao G. M. & Yuan H. C. (2007). "Subspecies differentiation of Oncomelania hupensis from mainland China". Chinese Journal of Schistosomiasis Control19: 485–487.
^Li S. Z., Wang Y. X., Yang K., Liu Q., Wang Q., et al. (2009). "Landscape genetics: the correlation of spatial and genetic distances of Oncomelania hupensis, the intermediate host snail of Schistosoma japonicum in mainland China". Geospatial Health3: 221–231.
^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 Evolution57(1): 215–226.
doi:
10.1016/j.ympev.2010.05.026.
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 Parasitology95(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.