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Multiple infections of larval trematodes in one snail

Basch PF, Lie Kian Joe

Med J Malaya, 1965 Sep;20(1):59.
PMID: 4221421
Matched MeSH terms: Snails*
Occurrence of Physastra sumatrana (Mollusca : Pulmonata) in Malaysia

Sullivan JT, Dondero TJ, Palmieri JR, Palmieri MD

Southeast Asian J. Trop. Med. Public Health, 1977 Sep;8(3):408.
PMID: 607431
Matched MeSH terms: Snails*
Miracidial maze. Use of a free-choice system to test Echinostome miracidia in their relative attraction towards normal and abnormal snails hosts, living, dead, whole, and dissected snails

Heyneman D

Med J Malaya, 1966 Jun;20(4):354-5.
PMID: 4224364
Matched MeSH terms: Snails*
Fulltext A molecular and conchological dissection of the "scaly" Georissa of Malaysian Borneo (Gastropoda, Neritimorpha, Hydrocenidae)

Khalik MZ, Hendriks K, Vermeulen JJ, Schilthuizen M

Zookeys, 2018.
PMID: 30026659 DOI: 10.3897/zookeys.773.24878

The Bornean hydrocenids have so far been understudied compared to other non-pulmonate snails in this region. In the present study, we review a first group of minute land snail species belonging to the genus Georissa (Gastropoda, Hydrocenidae) from Malaysian Borneo. This group is restricted to the species with conspicuous scale-like sculpture on the shell. Based on materials from recent fieldwork, museums, and personal collections, Malaysian Borneo hydrocenids are more complex and diverse in shell characters than previously anticipated. Here, a molecular, conchological, and biogeographic study of this "scaly group" is presented. We recognise 13 species of which six are new to science, namely Georissa anyiensissp. n., Georissa muluensissp. n., Georissa bauensissp. n., Georissa silaburensissp. n., Georissa kinabatanganensissp. n., and Georissa sepulutensissp. n.

Matched MeSH terms: Helix (Snails); Snails
Fulltext Phylogenomic resolution of the root of Panpulmonata, a hyperdiverse radiation of gastropods: new insight into the evolution of air breathing

Krug PJ, Caplins SA, Algoso K, Thomas K, Valdés ÁA, Wade R, et al.

Proc Biol Sci, 2022 Apr 13;289(1972):20211855.
PMID: 35382597 DOI: 10.1098/rspb.2021.1855

Transitions to terrestriality have been associated with major animal radiations including land snails and slugs in Stylommatophora (>20 000 described species), the most successful lineage of 'pulmonates' (a non-monophyletic assemblage of air-breathing gastropods). However, phylogenomic studies have failed to robustly resolve relationships among traditional pulmonates and affiliated marine lineages that comprise clade Panpulmonata (Mollusca, Gastropoda), especially two key taxa: Sacoglossa, a group including photosynthetic sea slugs, and Siphonarioidea, intertidal limpet-like snails with a non-contractile pneumostome (narrow opening to a vascularized pallial cavity). To clarify the evolutionary history of the panpulmonate radiation, we performed phylogenomic analyses on datasets of up to 1160 nuclear protein-coding genes for 110 gastropods, including 40 new transcriptomes for Sacoglossa and Siphonarioidea. All 18 analyses recovered Sacoglossa as the sister group to a clade we named Pneumopulmonata, within which Siphonarioidea was sister to the remaining lineages in most analyses. Comparative modelling indicated shifts to marginal habitat (estuarine, mangrove and intertidal zones) preceded and accelerated the evolution of a pneumostome, present in the pneumopulmonate ancestor along with a one-sided plicate gill. These findings highlight key intermediate stages in the evolution of air-breathing snails, supporting the hypothesis that adaptation to marginal zones played an important role in major sea-to-land transitions.

Matched MeSH terms: Snails/genetics
Morphological and allozyme studies of small terrestrial snails (Opeas sp., Subulina sp. and Huttonella bicolor) collected from Peninsular Malaysia

Choh MS, Yap CK, Tan SG, Jambari HA

Genetika, 2006 Jan;42(1):49-57.
PMID: 16523665

Shell morphological characters and allozyme electrophoresis were used to study the relationships among six geographical populations of land snails collected from Peninsular Malaysia. Allozyme electrophoresis was used to study the genetic variations to complement the morphological features studied that included shell lengths, numbers of whorls and shell colour. Ten loci coding for six enzymes (MDH, LAP, ALP, PGM, G6PDH and EST) could be reliably scored in samples from the six populations studied. The dendrogram showed two major clusters with one cluster comprising Subulinidae populations from Perak, Selangor, Johor, Terengganu and Pahang while the other cluster included only the Streptaxidae Huttonella bicolor (red) population. The Subulinidae populations were grouped into two subclusters: one subcluster included the Subulina sp. populations from Perak, Selangor an Johor while the other subcluster included the Opeas sp. populations from Terengganu and Pahang. Morphological features can identify the different families and therefore they can complement the allozyme genetic studies on the land snail populations. Like other reports in the literature, our results also underline the importance of a genetic approach in conjunction with a morphological approach, for discriminating land snail species. The present results suggest that small land snails, which were similar in colour but different in sizes, were not of the same family/genus.

Matched MeSH terms: Snails/anatomy & histology*; Snails/enzymology*; Snails/genetics
A description of a pleurolophocercous cercaria of Procerovum sp from the Haplorchis group of heterophyid trematodes

Surin J

Southeast Asian J. Trop. Med. Public Health, 1993 Dec;24(4):692-6.
PMID: 7939942

Freshwater snails, Stenomelania denisoniensis (Brot) from Tinaroo Dam, North Queensland, Australia were found to be infected with a heterophyid cercaria identified as Procerovum sp. The tail of the cercaria has finfolds which are bilateral anteriorly and dorso-ventral posteriorly, features which separate it from other genera in the Haplorchis-group. This group is differentiated from the cercariae of all the other heterophyid genera by the presence of the penetration glands that extend to the posterior end of the body lateral to the excretory bladder. This paper presents a full description of the cercaria, together with comparisons with other known species of Procerovum.

Matched MeSH terms: Snails/parasitology*
Preliminary report on new cercariae from Bellamya and Pila snails in Peninsular Malaysia

Lim HK, Colley FC, Ow-Yang CK

Southeast Asian J. Trop. Med. Public Health, 1974 Sep;5(3):458-9.
PMID: 4432110
Matched MeSH terms: Snails/parasitology*
Morphology and life cycle of Schistosoma sinensium Pao, 1959, from northwest Thailand

Greer GJ, Kitikoon V, Lohachit C

J Parasitol, 1989 Feb;75(1):98-101.
PMID: 2918446

Schistosoma sinensium Pao, 1959, was first isolated from an unidentified snail in Szechuan Province, China, and was described on the basis of adult worms and eggs recovered from experimentally infected mice. We discovered snails, Tricula bollingi Davis, and rodents, Rattus rattus (L.) and Crocidura attenuata Milne-Edwards, infected with S. sinensium near Fang in northwest Thailand. Adult worms were recovered from small veins immediately adjacent to the small intestine. Eggs first appeared in the feces of experimentally infected mice at 25 days postinfection. Cercariae first emerged from experimentally infected T. bollingi at 40 days postinfection. Shortly after emerging, cercariae were found at the water surface, their bodies flat against the meniscus and tails hanging free in the water column. Our morphometric results for adults and eggs from naturally infected hosts agree well with those presented in the original description. The occurrence of a lateral spine on the egg of this Asian schistosome has created some confusion as to the affinities of S. sinensium. A comparison of 8 character states, including snail hosts, cercarial behavior, geographical distribution, and morphology of life cycle stages, indicates that S. sinensium is more closely related to S. japonicum Katsurada than it is to S. mansoni Sambon.

Matched MeSH terms: Snails/parasitology
A survey of snail hosts and larval trematodes collected by peninsular Malaysia and Singapore from 1972 to 1977

Palmieri JR, Sullivan JT, Ow-Yang CK

Southeast Asian J. Trop. Med. Public Health, 1977 Jun;8(2):275-7.
PMID: 918717
Matched MeSH terms: Snails/parasitology*
Paragonimus in West Malaysia

Joung SK, Jeyarassasingam U

Med J Malaya, 1968 Mar;22(3):230.
PMID: 4234365
Matched MeSH terms: Snails*
Infection of single snails with two different trematodes. I. Simultaneous exposure and early development of a schistosome and an echinostome

Basch PF, Joe LK

Z Parasitenkd, 1966;27(3):252-9.
PMID: 5990058
Matched MeSH terms: Snails*
Fulltext Land snail fauna in Gunung Kuang Limestone Hill, Perak, Malaysia and its conservation implications (Mollusca, Gastropoda)

Phung CC, Yong YZ, Said MAM, Liew TS

Zookeys, 2018.
PMID: 29988791 DOI: 10.3897/zookeys.769.25571

This paper presents the first land snail species checklist for Gunung Kuang (Kuang Hill), a limestone hill located next to Gunung Kanthan that is recognised as one of the most important limestone hills for its diverse land snail fauna in Kinta Valley. Samplings were carried out at five plots in Gunung Kuang. This survey documented 47 land snail species, in which six species were identified as unique to Gunung Kuang. Approximately half of the land snails from Gunung Kanthan were found in Gunung Kuang. In addition, one of six unique species from Gunung Kanthan was also found in Gunung Kuang. These rich land snail species in Gunung Kuang are similar to other hills in Kinta Valley, but it is relatively lesser than the adjacent Gunung Kanthan. In view of Gunung Kuang's unique land snail species, and its location closest to disturbed Gunung Kanthan, Gunung Kuang should be considered in the conservation management plan for Gunung Kanthan.

Matched MeSH terms: Helix (Snails); Snails
Distributions of heavy metal concentrations in different tissues of the mangrove snail nerita lineata

Yap C, Cheng W

Sains Malaysiana, 2013;42:597-603.

This study focused on the distributions of Cd, Cu, Fe, Ni, Pb and Zn in the various tissues (shell, operculum, muscle, digestive cecum, foot, cephalic tentacles, mantle, radular and remainder) of the mangrove snail nerita lineata collected from Sungai Janggut, Selangor. Copper and Zn levels in all soft tissues were found to exceed those in the sediment, indicating bioaccumulation of these metals. Fe levels in all soft tissues of the snails were found to be lower than those in the sediment even though Fe is the most abundant metal among the six metals investigated. Cd and Pb levels in
soft tissues were also found to be lower than those in the sediment but opposite trends were observed for Cd and Pb levels in the shells. Ni, Cd and Pb levels in the shells were significantly (p< 0.05) higher than those in the soft tissues and sediment. However, digestive cecum and remainder showed higher Ni level as compared with sediment. The biota sediments accumulation factor (BSAF) has identified that the shell and operculum were macroconcentrators for Cd, Ni and Pb while all the soft tissues of n. lineata were macroconcentrators for Cu (except for muscle) and Zn. The findings indicated that the differences in metal distribution could be attributed to the differences in tissue physiology and metal handling, storage and detoxification strategies.

Matched MeSH terms: Helix (Snails); Snails
Molecular phylogenetic analysis of mudflat snails (Gastropoda: Euthyneura: Amphiboloidea) supports an Australasian centre of origin

Golding RE

Mol Phylogenet Evol, 2012 Apr;63(1):72-81.
PMID: 22210412 DOI: 10.1016/j.ympev.2011.12.016

Amphiboloidea is a small but widespread group of snails found exclusively, and often abundantly, in mudflat and associated salt marsh or mangrove habitat. This study uses molecular data from three loci (COI, 16S and 28S) to infer phylogenetic relationships in Amphiboloidea and examine its position in Euthyneura. All but two of the named extant species of Amphiboloidea and additional undescribed taxa from across Southeast Asia and the Arabian Gulf were sampled. In contrast to the current morphology-based classification dividing Amphiboloidea into three families, analysis of molecular data supports revision of the classification to comprise two families. Maningrididae is a monotypic family basal to Amphibolidae, which is revised to comprise three subfamilies: Amphibolinae, Phallomedusinae and Salinatorinae. Sequence divergence between Asian populations of Naranjia is relatively large and possibly indicative of species complexes divergent across the Strait of Malacca. Salinatorrosacea and Salinator burmana do not cluster with other Salinator species, and require generic reassignment. In addition, sequences were obtained from an undescribed species of Lactiforis from the Malay Peninsula. Reconstruction of ancestral distributions indicates a plesiomorphic distribution and centre of origin in Australasia, with two genera subsequently diversifying throughout Asia. Increasing the sampling density of amphiboloid taxa in a phylogenetic analysis of Euthyneura did not resolve the identity of the sister taxon to Amphibolidae, but confirmed its inclusion in Pulmonata/Panpulmonata.

Matched MeSH terms: Snails/classification*; Snails/genetics
The convoluted evolution of snail chirality

Schilthuizen M, Davison A

Naturwissenschaften, 2005 Nov;92(11):504-15.
PMID: 16217668

The direction that a snail (Mollusca: Gastropoda) coils, whether dextral (right-handed) or sinistral (left-handed), originates in early development but is most easily observed in the shell form of the adult. Here, we review recent progress in understanding snail chirality from genetic, developmental and ecological perspectives. In the few species that have been characterized, chirality is determined by a single genetic locus with delayed inheritance, which means that the genotype is expressed in the mother's offspring. Although research lags behind the studies of asymmetry in the mouse and nematode, attempts to isolate the loci involved in snail chirality have begun, with the final aim of understanding how the axis of left-right asymmetry is established. In nature, most snail taxa (>90%) are dextral, but sinistrality is known from mutant individuals, populations within dextral species, entirely sinistral species, genera and even families. Ordinarily, it is expected that strong frequency-dependent selection should act against the establishment of new chiral types because the chiral minority have difficulty finding a suitable mating partner (their genitalia are on the 'wrong' side). Mixed populations should therefore not persist. Intriguingly, however, a very few land snail species, notably the subgenus Amphidromus sensu stricto, not only appear to mate randomly between different chiral types, but also have a stable, within-population chiral dimorphism, which suggests the involvement of a balancing factor. At the other end of the spectrum, in many species, different chiral types are unable to mate and so could be reproductively isolated from one another. However, while empirical data, models and simulations have indicated that chiral reversal must sometimes occur, it is rarely likely to lead to so-called 'single-gene' speciation. Nevertheless, chiral reversal could still be a contributing factor to speciation (or to divergence after speciation) when reproductive character displacement is involved. Understanding the establishment of chirality, the preponderance of dextral species and the rare instances of stable dimorphism is an important target for future research. Since the genetics of chirality have been studied in only a few pulmonate species, we also urge that more taxa, especially those from the sea, should be investigated.

Matched MeSH terms: Snails/anatomy & histology*; Snails/genetics
Population structure and coil dimorphism in a tropical land snail

Schilthuizen M, Scott BJ, Cabanban AS, Craze PG

Heredity (Edinb), 2005 Sep;95(3):216-20.
PMID: 16077741

Tree snails of the subgenus Amphidromus s. str. are unusual because of the chiral dimorphism that exists in many species, with clockwise (dextrally) and counter-clockwise (sinistrally) coiled individuals co-occurring in the same population. Given that mating in snails is normally impeded when the two partners have opposite coil, positive frequency-dependent selection should prevent such dimorphism from persisting. We test the hypothesis that a strong population structure with little movement between tree-based demes may result in the fixation of coiling morphs at a very small spatial scale, but apparent dimorphism at all larger scales. To do so, we describe the spatial structure in a Malaysian population of A. inversus (Müller, 1774) with 36% dextrals. We marked almost 700 juvenile and adult snails in a piece of forest consisting of 92 separate trees, and recorded dispersal and the proportions of dextrals and sinistrals in all trees over a 7-day period. We observed frequent movement between trees (155 events), and found that no trees had snail populations with proportions of dextrals and sinistrals that were significantly different from random. Upon recapture 1 year later, almost two-thirds of the snails had moved away from their original tree. We conclude that population structure alone cannot stabilise the coil dimorphism in Amphidromus.

Matched MeSH terms: Snails/anatomy & histology*; Snails/physiology
Biology of Robertsiella kaporensis snails and Malaysian Schistosoma

Upatham ES, Kruatrachue M, Viyanant V, Khunborivan V, Kunatham L

Southeast Asian J. Trop. Med. Public Health, 1985 Mar;16(1):1-9.
PMID: 4023798

Studies on the bionomics and host-parasite relationship of Robertsiella kaporensis and Malaysian Schistosoma were investigated. The study was divided into 4 parts: cultivation of snails, R. kaporensis, and maintenance of Malaysian Schistosoma life cycle, daily cercarial shedding cycle in R. kaporensis, miracidial load and cercarial shedding pattern and the infectivity of Malaysian Schistosoma cercariae. R. kaporensis were cultured in the laboratory with the use of plastic container provided with fine sand. The snails were fed with diatoms and Saraca leaves. The development period for the snail eggs was about 20-30 days, the young grew to maturity in 14-15 weeks, and the average growth rate of snails was 0.23 mm per week. The daily cercarial shedding cycle of snails had shown that the peak emergence of cercariae of Malaysian Schistosoma occurred at night, between 6-10 pm. The miracidial load which yielded the best results in terms of percentage infection rates of snails and cercarial output was the miracidial concentration of 8 miracidia per snail. The study on infectivity of Malaysian Schistosoma cercariae has shown that there was a decrease in infectivity of the cercariae to mammalian hosts as the cercariae increased in age. The percentage infection rate of mice and numbers of worms recovered were highest in mice infected with cercariae of 0-1/2 hr. old. Infection of cercariae fell rapidly after the cercariae were 16 hr. old.

Matched MeSH terms: Snails/growth & development; Snails/parasitology*
Fulltext Recent range expansion of an intermediate host for animal schistosome parasites in the Indo-Australian Archipelago: phylogeography of the freshwater gastropod Indoplanorbis exustus in South and Southeast Asia

Gauffre-Autelin P, von Rintelen T, Stelbrink B, Albrecht C

Parasit Vectors, 2017 03 06;10(1):126.
PMID: 28264699 DOI: 10.1186/s13071-017-2043-6

BACKGROUND: The planorbid snail Indoplanorbis exustus is the sole intermediate host for the Schistosoma indicum species group, trematode parasites responsible for cattle schistosomiasis and human cercarial dermatitis. This freshwater snail is widely distributed in Southern Asia, ranging from Iran to China eastwards including India and from the southeastern Himalayas to Southeast Asia southwards. The veterinary and medical importance of this snail explains the interest in understanding its geographical distribution patterns and evolutionary history. In this study, we used a large and comprehensive sampling throughout Indo-Malaya, including specimens from South India and Indonesia, areas that have been formerly less studied.
RESULTS: The phylogenetic inference revealed five highly divergent clades (genetic distances among clades: 4.4-13.9%) that are morphologically indistinguishable, supporting the assumption that this presumed nominal species may represent a cryptic species complex. The species group may have originated in the humid subtropical plains of Nepal or in southern adjacent regions in the Early Miocene. The major cladogenetic events leading to the fives clades occurred successively from the Early Miocene to the Early Pleistocene, coinciding with major periods of monsoonal intensification associated with major regional paleogeographic events in the Miocene and repeated climate changes due to the Plio-Pleistocene climatic oscillations. Our coverage of the Indo-Australian Archipelago (IAA) highlights the presence of a single clade there. Contrary to expectations, an AMOVA did not reveal any population genetic structure among islands or along a widely recognised zoogeographical regional barrier, suggesting a recent colonisation independent of natural biogeographical constraints. Neutrality tests and mismatch distributions suggested a sudden demographic and spatial population expansion that could have occurred naturally in the Pleistocene or may possibly result of a modern colonisation triggered by anthropogenic activities.
CONCLUSIONS: Even though Indoplanorbis is the main focus of this study, our findings may also have important implications for fully understanding its role in hosting digenetic trematodes. The existence of a cryptic species complex, the historical phylogeographical patterns and the recent range expansion in the IAA provide meaningful insights to the understanding and monitoring of the parasites potential spread. It brings a substantial contribution to veterinary and public health issues.

Matched MeSH terms: Snails/parasitology*; Snails/physiology*
Discovery of a site of transmission and hosts of a Schistosoma japonicum-like schistosome in Peninsular Malaysia

Greer GJ, Ow-Yang CK, Singh KI, Lim HK

Trans R Soc Trop Med Hyg, 1980;74(3):425.
PMID: 7434446
Matched MeSH terms: Snails/parasitology*

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