• The Korean Journal of Malacology
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• v.26 no.4
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• pp.275-283
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• 2010

Many freshwater snail taxa are difficult to identify using morphological traits due to phenotypic plasticity. However, using of molecular DNA marker in combination with morphological traits can provide a reliable means for discriminating among freshwater snail taxa including cryptic species. To discriminate among Korean freshwater snail taxa and resolve their systematic relationships, wesequenced a fragment of mtDNA cytochrome oxidase I (COI) gene from 82 specimens collected from ten different sites distributed along the Korean peninsula. We identified more than seven freshwater snail taxa including cryptic species in Korea. Whereas traditional shell morphology of freshwater snails offers only weak discriminatory power for recognizing 'good' taxa, DNA sequence data provided positive and reliable identification. In addition, a major Semisulcospira clade was clearly separated from the remaining lineages observed including cryptic species. However, a phylogenetic tree inferred from the COI gene data did not fully resolve systematic relationships among pleurocerid taxa in Korea. Establishing more robust shell characteristics for identifying taxa unambiguously and hence improving traditional key shell morphology characters for freshwater snail species is an urgent requirement and will require more rigorous examination of all nominal taxa. While molecular data generated here will be useful for species identification and for describing the systematic relationships among Korean freshwater snails, further analysis will be required.

• Parasites, Hosts and Diseases
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• v.56 no.3
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• pp.247-257
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• 2018

The aim of this study was to conduct a freshwater snail survey in Mae Lao agricultural basin to assess the diversity with a focus on habitat types and their larval trematode infections. Snails were collected and examined in 14 sites of Mae Lao agricultural basin from August 2016 to October 2017. A total of 1,688 snail individuals were collected and classified into 7 families, 8 genera, and 12 species. Snail diversity and habitat types were higher in rice paddies than irrigation canals and streams. The most abundant species was Bithynia siamensis siamensis, representing 54.6% of the sample. Three species of snails act as first intermediate host were found with cercarial infections. They were Filopaludina sumatrensis polygramma, B. s. siamensis, and Melanoides tuberculata. The cercariae were categorized into 7 types; echinostome, monostome, gymnocephalous, virgulate, parapleurolophocercous, pleurolophocercous and megalurous cercariae. Parapleurolophocercous cercariae constituted the most common type of cercariae recovered, contributing 41.2% of all infections in snails. Echinostome metacercariae infections were found in 6 snail species with 7.6% prevalence. In addition, the metacercaria of avian trematode, Thapariella sp. were found in Filopaludina spp. snails and B. funiculata with a prevalence of 0.5%. This is the first report for Thapariella metacercariae in the snail host, B. funiculata, and also confirmed that viviparid and bithyniid snails act as the second intermediate hosts of this trematode. This work will provide new information on the distribution and intermediate host of trematode in this area.

• The Korean Journal of Malacology
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• v.15 no.2
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• pp.93-104
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• 1999

A histochemical and ultrastructural study on the salivary gland of a freshwater snail Radix auricularia coreana was conducted .The epithelial cells of the salivary gland are composed of 9 types of cells. Two types out of them work as frame cells supporting the epithelium and the secretory cells embedded within the epithelium Seven types of secretory cells are classifiable depend on their histochemical reactions and ultrastructures. The materials secreted by the secretory cells are neutral mucopolysaccharide, acid mucopolysaccharide, and glycogen.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.411-416
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• 2011

We investigated the nutritional status of the melania snail (Semisulcospira gottschei) using RNA/DNA ratios to evaluate the effect of feeding conditions (artificial versus natural) on the reaction times of the snails in a time course following starvation. In the short experiments (48 h), the RNA/DNA ratios of the artificial feeding groups were significantly higher than those of the natural groups. While two RNA/DNA ratio peaks were observed in the artificial food group during daytime, the natural food group showed a higher ratio at night. Under starvation conditions, the RNA content decreased whereas the DNA content was constant. The RNA/DNA ratios of the freshwater snail in both groups dramatically decreased after starvation and remained constant until the end of the experiment. We verified that the RNA/DNA ratio serves as an index of nutritional condition with respect to the effect of dietary differences. These results are important for understanding optimized aquaculture rearing conditions for this important commercial freshwater snail.

• The Korean Journal of Ecology
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• v.11 no.1
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• pp.37-53
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• 1988

The most medically important snail species of Korea is Parafossarulus manchouricus, a member of the freshwater prosobranch family Bithyniidae. The human parasite that this snail transmits is Clonorchis sinensis, the "Chinese live fluke". On the other hand, this snail has physiological characteristics that reduce the turbidity of freshwater by its filiter feeding activity. However, a few basic studies have been carried out so far. The present studies were attempted to know 1) the possibility of culturing the snails and 2) allozyme variations among 5 local populations of this bithyniid snails. As the results of the studies, P. manchouricus was able to be cultivated in the lavoratory and showed considerable allozyme variations especially in the Chongpyung and Paldaing populations out of those collected from 5 localities in Korea. It is quite suggestive that the endemicity of clonorchiasis might be related to the allozyme variability.

• The Korean Journal of Malacology
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• v.29 no.1
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• pp.83-85
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• 2013

Size-mass relationships were estimated for 4 species belonging to genus Semisulcospira from the Guem River, Korea. These 4 freshwater snail species: Semisulcospira libertina, Semisulcospira coreana, Semisulcospira gottschei, and Semisulcospira forticosta. Between June and November 2011, samples were caught by dredge (mesh size 10mm of multifilament nylon, total length 4.35 m) at depths of < 2 m. Estimates of for parameter b of the size-mass relationship (W = $aSH^b$) ranged between 2.0072 (Semisulcospira libertina) and 2.3463 (Semisulcospira gottschei).

• Korean Journal of Ecology and Environment
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• v.45 no.4
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• pp.453-458
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• 2012

The golden apple snail, Pomacea canaliculata, is a freshwater snail native to tropical and subtropical South America. The species was introduced into Korea as a human food source in 1983 and was first applied as a weed control agent for the paddy fields in 1992. As the snail is well known as an environmentally friendly biological control agent for weeds, the area of cultivation in which the golden apple snail is used for biological control has been enlarged substantially each year. Currently, the species is observed in open water courses. It is possible that the snail may overwinter in these open water courses and may become a serious pest, as is already the case in many Asian countries. In this study, we determined the status of the overwintering golden apple snail based on a literature survey and investigated the potential distribution area of the snail, as a result from global warming in Korea. The potential distribution area of the overwintering golden apple snail would be enlarged under the influence of global warming; ranging from 45.5% of South Korea's land area in the 2020s to 88.4% in the 2080s.

• The Korean Journal of Malacology
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• v.9 no.2
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• pp.57-67
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• 1993

A cladistic analysis for phylogenetic relationship among 3 freshwater planorbid snail species was carried out on the basis of their conchological and anatomical characteristics.The intestinal loop in the digestive systims was mainly distinguishable among 3 species of the planorbid snails. The loops in Hippeutis cantori and Segmentina hemisphaerula coiled around stomach, extended down to the distal part of the liver and finally connected with the anus, while the loop in Gyraulus convexiusculus was short and small, and connected directly to the anus after coiling around the stomach. However, the intestinal loop of Hippeutis cantori was the largest among those of 3 target snail species. In the main morpholohical differences of the riproductive systems, Gyraulus convexiusculus uniquely had a calcareous stylet in the penis sheath. Although there was no stylet in the penis sheath in the other snail species, the penis shesths connected with 1 and 2 flagella in Segmentina hemisphaerula and in Hippeutis cantori, respectively were different from each other. Two planorbid species, Hippeutis cantori and Segmintina hemisphaerula have a more recent phylogenetic ancestor out three species employed including Gyraulus convexiusculus.

• Parasites, Hosts and Diseases
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• v.39 no.3
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• pp.247-253
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• 2001

Three freshwater snail species of the family Lymnaeidae have been reported from Korea, Radix auricularia coreana, Austropeplea ollula and Fossaria truncatula. Out of 3 lymnaeid snail species, A. ollula was naturally infected with the Echinostoma cinetorchis cercariae (infection rate : 0.7%). In the experiments with the laboratory-bred snails, F. truncatula as well as A. ollula was also susceptible to the E. cinetorchis miracidia with infection rates of 25% and 40%, respectively. All of three lymnaeid snail species exposed to the E. cinetorchis cercariae were infected with the E. cinetorchis metacercariae. It is evident that A. ollula acts as the first molluscan intermediate host of E. cinetorchis in Korea, and F. truncatula may be a possible candidate for the first intermediate host of this intestinal fluke. Also, three lymnaeid snail species targeted were experimentally infected with E. cinetorchis metacercariae.

• The Korean Journal of Malacology
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• v.8 no.1
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• pp.21-28
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• 1992

Field investigations were made in 1991 and 1992 in Kwangju and the western and central Chonnam area to determine the distribution of Lymnaea viridis, the intermediate host of Fasciola hepatica, and to study their life history during the different seasons. It had a wide distribution, existing all over the places, and the principal habitats of the snail were rice paddies. The life cycle was determined by making frequent visits to a series of habitats. The snsils began to produce egg masses in April, and egg production was the highest in May and June. Egg laying was continued but decreased in summer. There was sudden decrease in egg production in October when the temperature was below 2$0^{\circ}C$. The number of snails in July. Under the unfavourble conditions the snail either crawle up on the snail to aestivation. At low temperature below 8$^{\circ}C$ the snails hibernated inthe mud of the habitat. It was found in some habitats thao the snails were loving together with L. auricularia and Physa s pp. which indicates the neccessity of differentiation among them.