Tag Archives: bulimulus

Snails as snake prey

Several snake species are known to prey on molluscs, and in the Neotropics some examples are already known; e.g., in the recent book on Belizan land snails by Dourson et al. pictures are given of Sibon species consuming a Drymaeus.

By serendipity I found a paper by Sazima & Muscat (2016) on Dipsas snakes in Brazil, which are known to feed on snails and slugs. The first author had reported in the past about the challenges that these molluscs offer to their predator. Snails must be removed from their shell and slugs release plenty of mucus, making snail handling time-consuming and handling slugs poses the risk of sticking to the substratum. Most observations are based on laboratory conditions, but this paper describes how newly hatched snakes are feeding on snails under natural conditions.

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The (unwilling) victims in these cases were respectively Bulimulus tenuissimus (d’Orbigny, 1835) and Helicina angulata G.B. Sowerby, 1873. Both observations were made in Sao Paulo state in different forests.

Reference:
Sazima, I. & Muscat, E., 2016. Shelled baby food: Newly hatched goo‐eating snakes of the genus Dipsas (Squamata: Dipsadidae) prey on snails in nature. – Herpetologia Brasileira, 5 (3): 63-64. 

Fossil gastropods from Uruguay

Cabrera et al. published a paper on Late Cretaceous molluscs from Uruguay. Their abstract reads: “Paleoecological studies of continental gastropods give valuable information about the depositional environment of the fossil assemblages. In South America, these assemblages from the Late Cretaceous/ Paleocene are scarce and poorly studied. Most works focuses on taxonomy, but a paleoecological approach is still missing. We analyzed the assemblages present in the Queguay limestones from Uruguay. The total fossil content consists in freshwater and terrestrial gastropods, characean gyrogonites, ostracods, Neosauropoda eggshells, vegetable remains, insect nests, and pupal chambers. As the precise age and sedimentary environment of the Queguay limestones have been discussed for almost nine decades, a paleoecological study was conducted in order to answer these questions from this point of view. Diversity (Simpson, Shannon-Wiener, equitability) and similarity (Jaccard and Kulczynski) indices were calculated; the analyses showed a close relationship among all locations, and therefore we conclude that there are not differences in fossil content among the localities. Moreover, the data allows to consider them basically of the same environment and age. The presence of Neosauropoda eggshells in several outcrops indicate unquestionably a Late Cretaceous age, and establish the oldest record worldwide for Pupillidae, Orthalicoidea and Biomphalaria”.

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The fact that the fossils mentioned establish the oldest known facies for several genera (Pupoides, Bulimulus, Bahiensis, and Biomphalaria) is an important result of this study. This might be useful data for future use when one needs fossil species for calibrating  phylogenetic data.

Reference:
Cabrera, F. et al., 2018. Continental Late Cretaceous gastropod assemblages from Uruguay. Paleoecology, age, and the oldest record for two families and a genus. – Historical Biology, advance online. DOI: 10.1080/08912963.2018.1471478.

New Brazilian species

Recently published, Simone & Do Amaral studied snails collected on islands off the Brazilian coast and discovered new species.

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Their abstracts is as follows: “Three new species of Bulimulidae (Gastropoda, Pulmonata) are described, each one endemic to a different island off the São Paulo coast, showing a high degree of endemicity of these islands in terrestrial malacofauna. Drymaeus castilhensis occurs on Castilho Island, it is mainly characterised by the strong axial dark spots in the shell or in being totally pale beige, penis elongated, lacking any inner chambers or glands, and double ducts of albumen gland. Drymaeus micropyrus occurs on Queimada Pequena Island, it is mainly characterised by greenish-cream shell, with narrow axial spots, and single duct of albumen gland. Bulimulus sula is from Alcatrazes Island, its main features include a relatively cylindrical, featureless shell, bilobed penis and, mainly and remarkably, a genital appendix that looks like a small accessory penis. These three species are described and compared with similar species, and accounts on their biogeography”.

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The two species of Drymaeus, if presented as shells only and without locality data, are so similar that would have doubted them to be two different taxa. But the anatomical differences evidently show that cannot be conspecific. Also the Bulimulus species is anatomically peculiar with the reported “small accessory penis”.

Reference:
Simone, L.R.L. & Amaral, V.S. do, 2018. Insular life: new endemic species from São Paulo oceanic islands, Brazil (Pulmonata, Bulimulidae), as example of endemicity. – Journal of Conchology, 43(2): 167-187.

Bulimulus as potential host of nematods

Martins et al. just published two papers showing that also Bulimulus species can potentially act as intermediate host to nematods.

Paper 1 was published in the Journal of Invertebrate Pathology. “The terrestrial gastropod Bulimulus tenuissimus is widespread in South America. It is an intermediate host of many parasites, but there are no records of infection of this snail by Angiostrongylus cantonensis, despite the occurrence of this parasite and angiostrongyliasis cases in the same areas in which B. tenuissimus occurs. For this reason, it is important investigate the susceptibility of B. tenuissimus to A. cantonensis-infection, since it can be used as intermediate host of A. cantonensis, increasing the list of terrestrial gastropods that infect wild and domestic animals and humans with this parasite. The purpose of this study was to evaluate the susceptibility of B. tenuissimus to experimental infection with L1 larvae of A. cantonensis. The snails were exposed to 1200 L1 larvae and it was possible observe many developing larvae in the cephalopedal mass and mantle tissues, with intense hemocyte infiltration and collagen deposition, but no typical granuloma structures were formed. The glucose content and lactate dehydrogenase activity in the hemolymph varied, indicating an increase of anaerobic energy metabolism in the middle of infection, but with a tendency to return to normal values at the end of pre-patent period. This was corroborated by the marked reduction in the glycogen content in the cephalopedal mass and digestive gland in the first and second week after exposure, followed by a slight increase in the third week. The content of pyruvic acid in the hemolymph was 14.84% lower at the end of pre-patent period, and oxalic acid content was 41.14% higher. These results indicate an aerobic to anaerobic transition process. The [periodic acid Schiff] PAS reaction showed a large amount of glycogen inside the developing larvae and muscular tissues of the cephalopedal mass, indicating that despite the high consumption of this polysaccharide by the parasite, the snail is able to maintain its energy metabolism based on carbohydrates. The results reveal that B. tenuissimus is a robust host, which can live with the developing larvae of A. cantonensis and overcome the metabolic damages resulting from parasitism”.

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This laboratory study shows that the snail can act as a robust host and thus in the wild might be considered as potential intermediate host for this nematod under the right conditions.

Paper 2 is to appear in the Brazilian Journal of Biology. Their full abstract: “Snails are essential to complete the life cycle of the metastrongylid nematode Angiostrongylus cantonensis, the causative agent of infections in domestic and wild animals, mainly rodents, and also of neural angiostrongyliasis or eosinophilic meningitis in humans. There are many reports of mollusks that can act as intermediate hosts of this parasite, especially freshwater snails and the African giant Achatina fulica. The terrestrial gastropod Bulimulus tenuissimus is widely distributed in Brazil and other species of the same genus occur in Brazil and other countries, overlapping regions in which there are reports of the occurrence of A. cantonensis and angiostrongyliasis. In spite of this, there are no records in the literature of this species performing the role of intermediate host to A. cantonensis. The present study analyzed the experimentalinfection with first-stage larvae of A. cantonensis, under laboratory conditions, of B. tenuissimus, by using histology and electron microscopy techniques. Three weeks after exposure to L1 larvae, it was possible to recover L3 larvae insmall numbers from the infected snails. Developing larvae were observed in the cephalopedal mass (foot), ovotestis, and mantle tissues, being located inside a granulomatous structure composed of hemocyte infiltration, but there was no calcium or collagen deposition in these structures in significant amounts. In the third week post exposure, it was possible observe a sheath around the developing larvae. The infected snails presented reduction in the fibrous muscular tissuein the foot region, loss of the acinar organization in the digestive gland, with increase of amorphous material inside theacini and loss of epithelial pattern of nuclear organization in the acinar cells. However, the ovotestis seemed unaffected by the infection, since there was a large number of developing oocytes and spermatozoa in different stages of formation.The digestion of infected snails allows us the third-stage recovery rate of 17.25%, at 14 days post exposure to the L1. These L3 recovered from B. tenuissimus were used to infect rats experimentally, and 43 days post infection first-stage (L1) larvae of A. cantonensis were recovered from fresh feces. The results presented constituted the first report of the role of B. tenuissimus as an experimental intermediate host to A. cantonensis and shed some light on a possible problem, since the overlapping distribution of B. tenuissimus and A. cantonensis in Brazil and other countries where different species of Bulimulus occur enables the establishment and maintenance of the life cycle of this parasite in nature, with wild rodents as reservoirs, acting as a source of infection to humans, causing neural angiostrongyliasis”.

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Although this is a laboratory study, the results are quite alarming. It is already known that the exposure of Achatina fulica is a health problem in some countries, and Bulimulus tenuissimus may be seen aa a model species for smaller snails. Luckily the human contact with these smaller species are a minimal risk (provided that they are not eaten!).

References:
Martins, F.G. et al., 2018. Bulimulus tenuissimus (mollusca) as a new potential host of Angiostrogylus cantonensis (nematoda), a histological and metabolic study. – Journal of Invertebrate Pathology, 154: 65-73.
Martins, F.G. et al., 2018. First record of Bulimulus tenuissimus (Mollusca) as potential experimental intermediate host of Angiostrongylus cantonensis (Nematoda). – Brazilian Journal of Biology: [11 pp., ahead of print] https://doi.org/10.1590/1519-6984.188914

Bulimulus as host for nematods

Today I was alerted of a citation of my paper on Bulimulus phylogeny, and when I looked up the citation I found a paper by Martins et al. which will appear in the Journal of Invertebrate Pathology.

“The terrestrial gastropod Bulimulus tenuissimus is widespread in South America. It is an intermediate host of many parasites, but there are no records of infection of this snail by Angiostrongylus cantonensis, despite the occurrence of this parasite and angiostrongyliasis cases in the same areas in which B. tenuissimus occurs. For this reason, it is important investigate the susceptibility of B. tenuissimus to A. cantonensis-infection, since it can be used as intermediate host of A. cantonensis, increasing the list of terrestrial gastropods that infect wild and domestic animals and humans with this parasite. The purpose of this study was to evaluate the susceptibility of B. tenuissimus to experimental infection with L1 larvae of A. cantonensis. The snails were exposed to 1,200 L1 larvae and it was possible observe many developing larvae in the cephalopedal mass and mantle tissues, with intense hemocyte infiltration and collagen deposition, but no typical granuloma structures were formed. The glucose content and lactate dehydrogenase activity in the hemolymph varied, indicating an increase of anaerobic energy metabolism in the middle of infection, but with a tendency to return to normal values at the end of pre-patent period. This was corroborated by the marked reduction in the glycogen content in the cephalopedal mass and digestive gland in the first and second week after exposure, followed by a slight increase in the third week. The content of pyruvic acid in the hemolymph was 14.84% lower at the end of pre-patent period, and oxalic acid content was 41.14% higher. These results indicate an aerobic to anaerobic transition process. The PAS reaction showed a large amount of glycogen inside the developing larvae and muscular tissues of the cephalopedal mass, indicating that despite the high consumption of this polysaccharide by the parasite, the snail is able to maintain its energy metabolism based on carbohydrates. The results reveal that B. tenuissimus is a robust host, which can live with the developing larvae of A. cantonensisand overcome the metabolic damages resulting from parasitism.”

No phylogenetic related work thus, it seems that the citation was only used to support the wide-spread occurrence of Bulimulus species in different areas and the fact that some of these are easily imported and may act as alien species. I also found a (unjustified) citation in Martins et al. of a paper by Parent & Crispi dealing with the radiation of Galápagos Naesiotus species, which were misidentified as Bulimulus.

Although this seems a case of serendipity, it is interesting to know that Bulimulus tenuissimus is a potential host for Angiostrongylus cantonensis, given the fact that this is a potential health threat for humans. An update will be given once this paper is formally published.

Reference:
Martins, F.G. et al., 2018. Bulimulus tenuissimus (Mollusca) as a new potential host of Angiostrogylus cantonensis (Nematoda), a histological and metabolic study. – Journal of Invertebrate Pathology

 

Bulimulids introduced in the Pacific

Carl Christensen kindly sent me two papers which testify that two members of the Bulimulidae have been introduced to Pacific Islands.

The first one is an inventory of introductions in the Hawaiian Islands (Hayes et al., 2012). Bulimulus guadalupensis is reported from one of the islands.

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“This species originated in the Caribbean, where it is widespread, especially in disturbed habitats. It has been introduced to Florida, probably in association with agricultural or horticultural plants, and has been recorded in abundance in lawns and among ornamental plants in a residential area, as was the present material. It is likely that it was introduced via the horticultural trade. The only two localities at which the species has been found in the Hawaiian islands were close together and were also the only two localities at which Vallonia pulchella was found”.

In the second paper the occurrence of Drymaeus multilineatus (Say, 1825) is recorded on the island of Guam. According to Christensen, this species was introduced on that island before 1978, “likely inadvertently with cultivated plants” (Kerr & Bauman, 2013).

References:
Hayes, K.H., Yeung, N.W., Kim, J.R. & Cowie, R.H., 2012. New records of alien Gastropoda in the Hawaiian Islands: 1996-2010. – Bishop Museum Occasional Papers, 112: 21-28.
Kerr, A.M. & Bauman, S., 2013. Annotated checklist of the land snails of Mariana Islands, Micronesia. – University of Guam Marine Laboratory Technical Report, 148: i-vii, 1-72.

Bulimulus as world travelers

Some Bulimulus species can act as alien species, as has been reported here extensively with introductions in Florida (B. guadalupensis, B. aff. sporadicus), Costa Rica and Ecuador (both B. guadalupensis). As recent research has shown (Breure 2016 PeerJ in press), DNA can help to reveal the likely source of origin. However, this is only possible if there is sufficient reference data available, i.e. sequences from specimens adequately identified with good locality data.

KessnerV

Recently, a Bulimulus species was detected on containers originating from India, Thailand, southern China and Singapore in the port of Darwin, north Australia. Initially confused with a Cerastid species, several people now agree that it is likely a Bulimulid. However, which species? There is now speculation it is a species from Brazil or Argentina, which would place it in the Bulimulus sporadicus species-complex, extending from northern Argentina (B. bonariensis), Paraguay, Bolivia into southern Brazil. This species complex is insufficiently known, its morphological variation within its distribution is ill-documented, and with only one sequence from Paraguay as reference material the hope for a quick fix of this hitch-hiking snail is in vain. So before we might be able to solve this issue, the first action is to collect living specimens throughout the distribution range and sequence them. Work for local malacologists or a student in need for an interesting and an useful topic! Any takers?

Luckily, Bulimulus species can only be a nuisance, so far I have never heard of any real damage to the local fauna and flora.