Groups Of Snails Research Articles

Uncovering local endemism from southeastern Myanmar: description of the new karst-associated terrestrial snail genus Burmochlamys (Eupulmonata, Helicarionidae).

Salween River basin's karst ecosystems in southeastern Myanmar remain largely unexplored and are likely to harbour a high terrestrial snail diversity that are often associated with high levels of snail endemism. Here, an outstanding group of new karst-associated terrestrial snails, Burmochlamys gen. nov., are discovered. A study of the comparative morphological and anatomical data reveals that the reproductive tract and radula of this new genus are closely related to the helicarionid genus Sophina Benson, 1859 but shell morphology (shape, size, and sculpture) and mantle extensions are distinct from the latter genus. Burmochlamys gen. nov. now consists of four known nominal species, B.cassidula comb. nov., B.cauisa comb. nov., B.perpaula comb. nov., and B.poongee comb. nov., and five new species; B.albida sp. nov., B.fasciola sp. nov., B.moulmeinica sp. nov., B.versicolor sp. nov., and B.whitteni sp. nov. The highlight is that the members of the new genus show site-specific endemism, being restricted to karstic habitat islands of the Salween River basin. In addition, the discovery supports that the unique and complex structure of Salween River basin's karst ecosystems are habitats in which the terrestrial malacofauna have speciated and become endemic.

The reproductive response of Cornu aspersum to different hibernation conditions

ABSTRACT This study was conducted between February and May 2019 on mature Cornu aspersum in the Black Sea region, Turkey to investigate the effects of different hibernation situations on reproductive responses. Three snail groups were studied: NH (natural hibernation), ASH (artificial short hibernation) and ALH (artificial long hibernation). NH showed inactive behaviour and had no reproductive activity while ASH and ALH performed intensive reproduction. During the experiment, the mean spawning rate (SpR), egg number (EgN), hatching rate (HR) and offspring number (OfN) were 20.50 ± 1.69%, 100.10 ± 5.22, 85.63 ± 2.36 and 80.69 ± 5.44 in the ASH group; 23.43 ± 3.36%, 122.33 ± 7.62, 61.55 ± 10.76 and 70.26 ± 11.60 in the ALH group, respectively. In conclusion, the high temperatures in the winter months of 2019 may have caused NH snails to become reproductively inactive, or it could simply be a consequence of their life-history strategy. Snails in the ASH and ALH groups represented a resource allocation trade-off between fecundity and survival to carry the genetic information to the next generation. This study leads to a better understanding of land snail reproductive physiology and behavioural responses to different hibernation conditions.

Phylogeny and evolution of the land snail tribe Clausiliini (Gastropoda: Clausiliidae)

The phylogenetic relationships within the land snail group Clausiliini were analysed based on an almost complete taxon sampling (28 of 29 extant species) and a set of mitochondrial and nuclear markers. The phylogenetic analyses and character state reconstructions revealed several trends in the group that resulted in repeated convergences. The N-type closing apparatus was convergently transformed into a G-type clausilial apparatus in Graciliaria, Ruthenica + Micridyla and probably three times within Neostyriaca. There were parallel changes in the length of the male copulatory organs and repeated reductions of the basal keel in several lineages. Such trends resulting in repeated convergences are characteristic for several radiations of stylommatophoran land snails. They may reflect parallel adaptations of related lineages to similar environmental constraints. However, it is also possible that some of these transformations are not adaptive, but represent random changes in a restricted morphospace. We explored the timing of the Clausiliini radiation using different calibration strategies. Despite large numbers of fossils of Clausiliidae from Western and Central Europe, the results of these analyses and the fossil evidence for a Cretaceous origin of the Clausiliidae indicate that there are large gaps in the fossil record of the Clausiliini. Especially the origin and early evolution of the Clausiliini in Southeastern Europe is obscured by our insufficient knowledge of Neogene deposits there.

Morphological and Genetic Variability in Radix auricularia (Mollusca: Gastropoda: Lymnaeidae) of Lake Baikal, Siberia: The Story of an Unfinished Invasion into the Ancient Deepest Lake

This article aims to reconstruct the invasion of the ear-shaped pond snail, Radix auricularia (Linnaeus, 1758), to Lake Baikal, East Siberia. This species is widely distributed in the Palaearctic and Northern America, and since the early 20th century has formed abundant and sustained populations in Lake Baikal. The data provided on the morphological and genetic variability of R. auricularia help to better describe and delineate the species. With an integrative approach involving morphological and molecular data, we improved the knowledge of the intraspecific variability of R. auricularia in the most important characteristics used for its determination. Molecular sequences of nuclear spacer fragment ITS-2 and mitochondrial gene fragment cyt–b were obtained from 32 individuals of Radix (including seven outgroup Radix species) collected from various parts of Lake Baikal and adjacent waterbodies and compared with sequences of 32 individuals of R. auricularia from different regions of the Palaearctic as well as with individuals determinated as R. intercisa from Lake Baikal, R. iturupica from the Kurile Islands, R. ussuriensis from the Khabarovsk region, R. narzykulovi from Tajikistan, and R. schubinae from the Amur region. Molecular genetic analyses revealed that all specimens collected from Lake Baikal belong to R. auricularia. There are no genetically distinct groups of snails that would correspond to two morphospecies previously recorded in Lake Baikal (e.g., R. auricularia s. str. and R. intercisa). Variability of the characteristics that are commonly used for species identification (shell morphology, mantle pigmentation, shape and position of the bursa copulatrix, length and position of the bursa duct, length ratio of preputium to penial sheath) were found in individuals analysed with molecular genetics to be broader than recognised in the current literature. Some shells of R. auricularia collected from Lake Baikal resemble shells of another lymnaeid species, R. balthica, and without molecular assessment can be confused with the latter. Geometric morphometric analysis of more than 250 shells revealed no observed hiatus between Baikalian and non-Baikalian R. auricularia. The probable stages and pathways of R. auricularia invasion to Lake Baikal’s ecosystem are outlined and discussed. Factors such as global climate warming and human activity stimulated and facilitated the ongoing dispersal of ear pond snails within Lake Baikal.

An update to the 2014 nomenclator of Valvatidae.

This contribution is an update to the 2014 compilation of all supra- and (infra-) specific taxa of extant and fossil Valvatidae, a group of freshwater operculate snails near the base of Heterobranchia with a nearly worldwide distribution. This update includes corrections and many additions (two replacement taxon names, 21 mainly fossil taxa previously overlooked, and 37 invalid names) to the 2014 contribution and adds all newly described species (11) during the past eight years. The extensive reference list is directly linked, where possible, to the available electronic source of the cited papers.

The high diversity of trematode metacercariae that parasitize freshwater gastropods in Bangkok, Thailand, and their infective situations, morphologies, and phylogenetic relationships.

AbstractWe investigated diversity, infective situations, morphological features and phylogenetic relationships of the metacercariae in freshwater snails from Bangkok between March 2018 and February 2020. Crushing and dissection techniques were performed to explore the metacercariae in the snail hosts. Polymerase chain reaction was implemented to amplify the internal transcribed spacer 1 (ITS1), 5.8S ribosomal DNA and ITS2 regions of metacercarial DNA. A total of 3173 of all 21 707 snails showed infections with metacercariae, representing a relatively high infective prevalence (14.62%) compared to earlier research. All infected snails belonged to 14 species/subspecies. A group of viviparid snails exhibited the highest metacercarial infections (26.10–82.18%). We found metacercariae with seven morphological groups. Five of them can be stated as new records of the metacercariae in Thailand, indicating a broader spectrum of larval trematode diversity. Our phylogenetic assessments established that five of the seven morphological groups can be molecularly classified into different taxonomic levels of digenean trematodes. Echinostome A metacercariae revealed the highest infective prevalence (7.15%), and their sequence data were conspecific with a sequence of Echinostoma mekongki, which is a human intestinal fluke; this finding denotes the distribution and suggests epidemiological surveillance of this medically important fluke in Bangkok and adjacent areas. However, two groups of Opisthorchiata-like and renicolid metacercariae remain unclear as to their narrow taxonomic status, although their molecular properties were considered. For more understanding about trematode transmissions in ecosystems, both physical and biological factors may be further analysed to consider the factors that relate to and contribute to trematode infections.

Long-term effects of contrasting pCO2 levels on the scope for growth in the carnivorous gastropod Concholepas concholepas

We evaluated the effect of contrasting pCO2 levels: lower (390 μatm), moderate (700 μatm) and extreme (1000 μatm), on the scope for growth of the keystone snail Concholepas concholepas over an exposure period of 6 months. Juvenile snails were collected from rocky intertidal habitats and acclimated for 5 months to those pCO2 levels. Subsequently, three groups of snails were randomly taken (n = 7 for each treatment) and reared for an additional 1 month for each of the three pCO2 levels. Physiological traits related with energy gain and energy expenditure were quantified. The scope for growth index decreased significantly with increases in pCO2, yielding negative values throughout the experimental period for the snails exposed to 1000 μatm pCO2, probably due to the extra energy required to maintain their metabolic functions in balance. This suggests that future climate change scenarios with elevated pCO2 levels could threaten the growth and other basic functions of juvenile snails of this species.

Production of Specific Polyclonal Antibody against the Larvae of Corallivorous Gastropod Drupella fragum for Prediction of Outbreaks

The term corallivorous gastropod refers to a group of snails that feeds on coral and inhabits coral communities worldwide. Outbreaks of these species cause serious damage to coral communities. There are various reasons behind the outbreaks; however, further clarifications are needed. It may be possible to predict outbreaks by measuring the number of floating larvae of corallivorous gastropods in seawater. Drupella fragum is the most damaging species in Japan, so we produced antibodies against D. fragum larvae in order to easily detect this species in the field. Antibody specificity analysis in aquarium-hatched corallivorous gastropods showed a higher specificity against D. fragum compared to D. cornus. A field study using the antibody showed that many D. fragum larvae were detected from June to November at all stations. The larvae at the Shirigai station were collected in June and July in large numbers compared to the other stations. Large groups of D. fragum were collected around the sampling point in Shirigai in September 2016. Our results imply that there is a possibility that outbreaks could be predicted using this antibody.

Ecological Linkages Between Snails and Litters In Mount Gandang Dewata, West Sulawesi

Mount Gandang Dewata in West Sulawesi was recently granted National Park status. Exploration of land snails in Taman Nasional Gandang Dewata (TNGD) has never been carried out. Therefore, a study of land snails in the National Park was conducted in April 2016 to examine the composition of land snails in different habitats, namely primary and secondary forests. Overall, 43 specimens (21 species from 8 families) were found from eight study sites. Snails are not found in steep areas, on moderate slopes 1-10 snails are found, and in flat areas 8-13 snails are found. The analysis was carried out by the principal components (PCA). According to the PCA, three groups of snails were formed. Environmental factors such as litter, altitude, humidity, calcium (Ca), nitrogen (N), and sodium (Na) are discussed in relation to snails. In this paper, litter factors are discussed in greater depth than other environmental factors. Snails and litter interact in an ecological relationship in the forest ecosystem of Mount Gandang Dewata.

Integrated rearing system proposal for Cantareus aspersus in experimental orchards: Growth models.

An integrated rearing system for Cantareus aspersus under environmental conditions in an experimental orchard is proposed. In this study, the natural behaviour, circadian rhythms and suitable rearing conditions of the edible snail were optimised to produce homogeneous growth and low variability. The growth was standardised, and growth pattern fit was assessed with various models. One thousand fry were cultured in the orchard, and a random sample of 100 snails were measured weekly for 23 weeks. The rearing system had the following characteristics: snails and earthworms were included in the experimental rearing orchard; a homogeneous group of juvenile snails of the same age and size and high rearing density (500 snails/m2) was used; snails were fed with layers mash ad libitum; and mixed and fringes vegetation was planted in the orchard. A commercial size of 60% of snails was achieved in 21 weeks and 95% in 23 weeks. The different models showed a good fit, and the quadratic model obtained the best fit. This experimental snail orchard proposal can be extended to other areas, although it must be corrected according to different environmental conditions and fit to other species of interest. This experimental model could constitute a viable alternative to traditional models of animal experimentation with mammals, and given its high adaptability, it could be applied in different fields of science.

Case 3838 – Helix plicaria Lamarck, 1816 (currently Hemicycla plicaria; Gastropoda, Eupulmonata, Stylommatophora, Helicidae): proposed conservation of the specific name

The purpose of this application, under Article 23.9.5 of the Code, is to conserve the specific name Helix plicaria Lamarck, 1816, a junior primary homonym of Helix plicaria Born, 1778. These names are currently in use for two different groups of land and freshwater snails, respectively, and have not been treated as congeneric since 1828. Helix plicaria Born, 1778 was first transferred to the genus Bulimus Scopoli, 1777 and subsequently to the genera Thiara Röding, 1798, Melania Lamarck, 1799, Melanoides Olivier, 1804 and Stenomelania Fischer, 1885. Helix plicaria Lamarck, 1816 has either been treated as belonging to Helix Linnaeus, 1758, Cochlea Da Costa, 1778 or has been included in Hemicycla Swainson, 1840. It is proposed that Helix plicaria Lamarck, 1816 be conserved by ruling it is not invalid by reason of being a junior homonym of Helix plicaria Born, 1778.

Weierstrassian Lévy walks are a by-product of crawling.

Weierstrassian Lévy walks are one of the simplest random walks which do not satisfy the central limit theorem and have come to epitomize scale invariance even though they were initially regarded as being a mathematical abstraction. Here, I show how these Lévy walks can be generated intrinsically as a by-product of crawling, a common but ancient form of locomotion. This may explain why Weierstrassian Lévy walks provide accurate representations of the movement patterns of a diverse group of molluscs-certain mussels, mud snails and limpets. I show that such movements are not specific to molluscs as they are also evident in Drosophila larvae. The findings add to the growing realization that there are many idiosyncratic, seemingly accidental pathways to Lévy walking. And that the occurrence of Lévy walks need not be attributed to the execution of an advantageous searching strategy.

Systematic review of the dextral Hemiplecta Albers, 1850 (Eupulmonata, Ariophantidae) from Thailand with description of a new species and list of all the Indochinese species.

The genus Hemiplecta is a group of large-sized land snails which have long been used as a food resource by Indochinese people. There are five dextral and four sinistral species currently recognized from Thailand. The dextral group is comprised of two previously recorded species (H. humphreysiana and H. distincta), two newly recorded species (H. funerea and H. esculenta), and one new species (H. nemorosasp. nov.) from northern Thailand is being proposed. We reassessed the diagnostic characters of the genitalia, mantle edge, and radula. Specimens were classified into the genus Hemiplecta on the basis of the penial verge and shell lobe, and on the characters of a bulbous gametolytic sac without a gametolytic duct. A complete species list, together with photographs of the name-bearing types or authenticated specimens and the taxonomic status of Hemiplecta s.l. that are known from Indochina including Peninsular Malaysia and Myanmar, is provided for the first time. In total, this species list contains 39 available nominal species names described from this area. Type or authentic specimens can be located for 37 nominal species names, of which 25 are illustrated herein and the other 12 were recently illustrated. However, two available species-level names could not be traced to any type specimens. In addition, lectotypes of H. funerea and H. pluto are designated herein to stabilize the names.

Taxonomy, Conservation, and the Future of Native Aquatic Snails in the Hawaiian Islands

Freshwater systems are among the most threatened habitats in the world and the biodiversity inhabiting them is disappearing quickly. The Hawaiian Archipelago has a small but highly endemic and threatened group of freshwater snails, with eight species in three families (Neritidae, Lymnaeidae, and Cochliopidae). Anthropogenically mediated habitat modifications (i.e., changes in land and water use) and invasive species (e.g., Euglandina spp., non-native sciomyzids) are among the biggest threats to freshwater snails in Hawaii. Currently, only three species are protected either federally (U.S. Endangered Species Act; Erinna newcombi) or by Hawaii State legislation (Neritona granosa, and Neripteron vespertinum). Here, we review the taxonomic and conservation status of Hawaii’s freshwater snails and describe historical and contemporary impacts to their habitats. We conclude by recommending some basic actions that are needed immediately to conserve these species. Without a full understanding of these species’ identities, distributions, habitat requirements, and threats, many will not survive the next decade, and we will have irretrievably lost more of the unique books from the evolutionary library of life on Earth.

Modelling the production process of Roman snail using RIDGE and LASSO regression

This article is a continuation of a series of works on the study and modelling of the production process of the Roman snail (Helix pomatia L.). The paper considers the applicability of three models for simulating the average weight of groups of Roman snails based on the values of environmental parameters, snail’s ration and specific factors characteristic of molluscs. The main focus of the simulation is on two models: RIDGE and LASSO regression. It is proved that RIDGE regression gives the best results in modelling. The combination of qualitative and quantitative parameters (air temperature, relative humidity, nutrition and some specific factors characteristic of molluscs) is sufficient for modelling the production process of Roman snail.

The Effects of Using Chemicals to Remove Slime from African Giant Land Snails Flesh during Processing on Some Nutritional and Biochemical Parameters.

The effects of chemicals commonly used in Cameroon to eliminate slime from the flesh of the African giant land snail, Archachatina marginata, during processing on some nutritional and biochemical parameters were investigated. Groups of snails were processed with these chemicals at three different concentrations. Proximate analysis of all the treated snail groups was carried out, and groups with the highest concentration of each chemical were used to compose diets for experimental rats. Thirty weanling male Wistar albino rats (31.25 ± 3.09 g) aged 21days old were distributed into four groups and fed with 10% protein based diets of A. marginata named D1 (washed with only water), D2 (lime C-treated), D3 (alum C-treated), and D4 (salt C-treated). The crude protein contents of the treated groups reduced significantly when compared with the control (CW), with lime C-treated (LC) having the least here and in crude fiber, but higher (LC, LB, and LA) in dry matter. There was a significant reduction in the crude lipid of alum C-treated (AC) and salt A-treated (SA). In vivo studies showed a general decrease in food consumption, weight gained, efficiency of feed utilization (EFU), true protein digestibility (TD) (except D2), and hematological indices (RBCs (red blood cells), PCV (packed cell volume) of the treated groups (D2, D3, D4) when compared to the control (D1). On the other hand, an increase in the relative weight of the liver (RWL), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and total cholesterol was observed with some of the treated diets; meanwhile, protein efficiency ratio (PER), net protein ratio (NPR), relative weight of the kidneys (RWK), HDL cholesterol, and triglycerides were not affected by these diets. These chemicals should only be used at low concentrations or not at all because of its toxicity at high concentrations.

Reproduction of the Roman snail (Helix pomatia L.) from a local natural population in farm conditions and in a natural habitat

Abstract The aim of this study was to compare the quality of clutches and reproduction results of two groups of Roman snails (Helix pomatia) from the same local population, laying eggs simultaneously in semi-natural farm conditions and in a natural habitat. The study material were Roman snails aged 2 or more years which had entered the third phenological season of their life and thus the first season of sexual maturity. Observations were conducted at an earthen enclosure in a greenhouse belonging to the experimental farm for edible snails at the National Research Institute of Animal Reproduction in Balice near Kraków (Poland) as well as at a site where a local population naturally occurs in the uncultivated park surrounding the Radziwiłł Palace. In the June-July season, differences among such parameters as weight of clutch, number of eggs in clutch, mean egg weight, and hatchling percentage when compared to the total number of eggs in the clutch were compared. It was determined that clutches of eggs from the natural population laid in the greenhouse were of lesser weight (P<0.01), contained fewer eggs (P<0.05), and the mean weight of individual eggs was less (P<0.05) than in clutches laid simultaneously in a natural habitat. Both in the greenhouse and the natural habitat, in the first phase of laying eggs (June) the weight of the clutch and number of eggs its contained were greater than in the second phase (July). However, only for snails laying eggs in the greenhouse were these differences statistically significant (P<0.05) and highly significant (P<0.01), respectively. Statistically significant differences were not observed in hatchling percentage between eggs laid in the greenhouse and the natural habitat. The lower number of eggs laid in the farmed conditions of the greenhouse was successfully compensated for by the absence of mass destruction by rodents which occurred in the natural habitat.

Molecular phylogeny of the Orthurethra (Panpulmonata: Stylommatophora)

AbstractWe have undertaken a molecular analysis of the Orthurethra, one of the major groups of stylommatophoran land snails and slugs. Approximately 4000 nucleotides of the rRNA gene cluster [5.8S, internal transcribed spacer 2 (ITS2) and almost the full-length large subunit (LSU; 28S) gene] were sequenced for 40 orthurethran genera belonging to 19 families. Our phylogeny recovers three well-supported clades within the Orthurethra; the Azecidae, Chondrinidae + Truncatellinidae, and a main clade comprising all remaining orthurethran families. The first division in the Orthurethra separates the Azecidae from all other orthurethran taxa. Of those families represented by more than one genus, the Achatinellidae, Azecidae, Cerastidae, Partulidae and Vertiginidae are recovered as strongly supported monophyletic units, whereas the Chondrinidae, Enidae, Pupillidae and Valloniidae are unsupported in the tree. Although there is relatively little support for the deep-level relationships among the main orthurethran groups, some groupings are strongly supported. The sister-group relationship of the Cochlicopidae with the Amastridae is strongly supported in our molecular analyses, and there is also some support for the grouping of the Orculidae with the Pyramidulidae, and the Draparnaudiidae with the Gastrocoptidae. The findings of our molecular analyses support dividing the Orthurethra into three superfamilies: the Azecoidea, Chondrinoidea and Pupilloidea.

Differences in the spermatozoa and ova of two species of giant African land snails (Archachatina marginata and Achatina achatina)

A comparative study of the gametes of two species of Giant African Land Snails; Archachatinu marginata and Achatina achatina was carried out. Three groups of snails weighing 80-100,101-150 and 151-250 g were used in a 3x2 factorial design, with 5 replicates, involving a total of 30 snails. Albumen gland, little hermaphrodite duct, spermotheca and ovo-testis were examined for the presence of ova and spermatozoa. The morphology of the spermatozoa and ova of both species Was studied. Ova were found in the albumen gland and ovo-testis. Spermatozou were only found in the little hermaphrodite duct. Spermatozoa head and tail lengths were not significantly (P>0.05) different between species, while the mid-piece length was significantly (P<0.05) different. Liveweight group 101-150 g had the highest number of spermatozoa and ova count in both species. Morphologically, spermatozoa head, collar and mid-piece crest differed between species Archachatina marginata spermatozoa had pointed head, longer collar and highest number of mid-piece crests compared to Achatina achatina. Ova seen in the ovo-testis of A. marginata were larger compared to those seen in A. achatina. It was concluded from the study that there are differences in the morphology and dimensions of their germ cells.

Tasmanian Museum and Art Gallery’s Expedition of Discovery II – The Flora and Fauna of Musselroe Wind Farm, Cape Portland, Northeast Tasmania

Flora and fauna surveys were conducted at the Musselroe Wind Farm property in 2018 and 2019 as part of the Tasmanian Museum and Art Gallery’s ongoing research, collection-building and nature-discovery program. The property was found to have significant ecological and nature conservation values and this survey program increases the number of vouchered taxa known for the area to 1336 primarily from the targeted groups of vascular plants, bryophytes, lichens, butterflies, moths, beetles, freshwater invertebrates, snails and slugs. Many threatened taxa were recorded and several of the taxa, chiefly lichens and invertebrates, are new to science or new records for Tasmania. This survey significantly expands our knowledge of the flora and fauna of the Cape Portland area and serves as a baseline for a property with a mix of farming and environmental conservation management.