Monthly Archives: November 2018

Naesiotus in ethnological use

Recently a paper on the use and economic value of the snail Naesiotus quitensis was published in a not-so-common journal (at least for shell enthusiasts).

The abstract reads: “The terrestrial mollusks in Ecuador present a high abundance of endemic species with different categories of commercial and gastronomical uses. In this context, this study proposes documenting the value and current economic use given to the mollusk Naesiotus quitensis, in the Sangolqui population on the market “The Tourism”, based on semi-structured interviews performed on 20 persons in November 2017. As a result of the interviews it was shown that the origin of the eatable snails is Otavalo city, located in the Imbabura province, in the northern of the country. This information has been made evident in studies that point out that the climate diversification in the mountain range of the Andes allow to have a great variety of mollusks variety in these regions. Due to this abundance people collect the mollusks in their natural habitat (“helicicolecta”) for use as a commercial and economic good; in regard to the economic value, a major consumption was reported for the presentation of this mollusk cooked with lemon, in small bags. In the categorical approach of use, two new categories were registered: the ritualist which refers to delivering it as an offering in cemeteries and the playful one that is carried out as games between underage children of the sector. With these results we conclude that in spite of the parish of Sangolqui being a place that still preserves these traditions, the traditional heritage of consumption of this mollusk from the elderly towards the next generations is not evidenced. This might be due to little investigation and welcoming of this species of terrestrial snail in people of all ages; for this reason, it is difficult to know if there is an irrational exploitation of this species”.

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During my last visit to Ecuador I had seen the use of these snails as a snack food, but didn’t encounter the other uses. Although it interesting stuff for an ethnographer, I remain with what I have said before her: do not eat snails…

Reference:
Gutiérrez Cantuña, E.B. & Guainilla Maldonado, W.R. 2018. Uso y valor económico de Naesiotus quitensis (Pfeiffer, 1848) (Mollusca: Bulimulidae) como alimento tradicional en la parroquia urbana Sangolqui, Cantón Rumiñahui, Ecuador. – Ethnoscientia, 3: 1–6.

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.

Omalonyx unguis in Argentina

Recently, Guzmán et al. reported on this species with the following abstract: “Omalonyx unguis (d’Orbigny, 1837) is a semi-slug inhabiting the Paraná river basin. This species belongs to Succineidae, a family comprising a few representatives in South America. In this work, we provide the first record for the species from Misiones Province, Argentina. Previous records available for Omalonyx in Misiones were identified to the genus level. We examined morphological characteristics of the reproductive system and used DNA sequences from cytochrome oxidase subunit I (COI) gene for species-specific identification. These new distributional data contribute to consolidate the knowledge of the molluscan fauna in northeastern Argentina”.

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In the paper also figures of the shell and the genitalia are presented. The authors were likely unknown of the revisionary work of Vidigal et al. (2018), who showed that the correct name of this species is Omalonyx matheroni (Potiez & Michaud, 1835).

Reference:
Guzmán, L.B. et al., 2018. First record of the semi-slug Omalonyx unguis (d’Orbigny, 1837) (Gastropoda, Succineidae) in the Misiones Province, Argentina. – CheckList 14 (5): 705-712.

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

Holospira in Oaxaca

Guerrero-Arenas et al. (2018) published about their findings of a Holospira species in Oaxaca state, Mexico. Their abstract reads: “Holospira (Bostrichocentrum) goldmani Bartsch, 1906 is an urocoptid gastropod distributed throughout northwestern Oaxaca in southern Mexico. Since its original description, posterior records have been restricted to the Mixteca Baja region of Oaxaca. The purpose of this paper is to expand on the geographical distribution of this species, georeferencing six additional localities. Five of our sites are located in the Mixteca Alta region of Oaxaca. Holospira goldmani can survive in soil derived from non-calcareous rocks. Field observations of ecological preferences of H. goldmani suggest that they are more ecologically tolerant than previously thought”.

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The pictures of the localities where these snails were found show the volcanic rocks and several pine forest demonstrating that this species is indeed ecologically tolerant and may be found in habitats where snails usually are not very abundant.

Reference:
Guerrero-Arenas, R. et al., 2018. New occurrences of Holospira (Bostrichocentrum) goldmani Bartsch, 1906 (Gastropoda, Urocoptidae) in northwestern Oaxaca, southern Mexico. – CheckList, 14 (1): 107-112.

Bostryx voithianus

In an overlooked paper, Martinez de los Rios (2017) published new data on the distribution of this Chilean species. His abstract reads: “Bostryx voithianus (Pfeiffer, 1847) is reported, for the first time since its description, from northern Chile. In the origi-nal description, a particular type locality was not given for this species, but to it was described as collected in Chile by Thomas Bridges for the Hugh Cuming collection. Herein, the type locality is assigned to the Chilean Coastal Range between the places Cuesta La Arena (28.5721° S) and Quebrada Honda (29.5952° S), northern Chile”.

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These Chilean Bostryx species are still a relatively understudied group, despite some recent literature, and it is always good to have new reports on their occurrences.

Reference:
Martinez de los Rios, E., 2017. Rediscovery of Bostryx voithianus (Pfeiffer, 1847) (Gastropoda, Pulmonata) in northern Chile, with notes on the type locality. – CheckList, 13 (6): 1125-1129.

L / XL / XXL

In the latest Shell-O-Gram newsletter of the Jacksonville Shell Club, I found this article about record-breaking Euglandina shells:

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It would be interesting to know if there is any specific reason why in this population these snails become bigger than everywhere else. Plenty of food supply or just a gene going wild and producing mutants?