Tag Archives: Megalobulimidae

Interaction between alien and native species

Mirando & Pecora (2017) published an ecological study on the interaction between a native and an introduced species. “The Giant African Snail Achatina fulica is widely considered one of the most invasive species in the world. Megalobulimus paranaguensis is a snail endemic to the Brazilian Atlantic Rainforest. Data on possible interactions between A. fulica and terrestrial mollusc species are scarce. We tested whether the presence of A. fulica affects the behaviour of M. paranaguensis. We put three individuals of A. fulica and three individuals of M. paranaguensis in the same aquarium and quantified the time spent in seven behaviours, during three nights (n = 72 individuals for A. fulica and M. paranaguensis). We also tested the effect of sexual maturity, putting juvenile and adult individuals of both species in the same aquarium. We found behavioural differences between species, among individuals exposed to interspecific interactions and in interactions between these factors, but there was no difference in behaviour between juveniles and adults in the same species and between species. Achatina fulica changed its behaviour in interspecific interaction, becoming more active than usual, but M. paranaguensis did not change its behaviour in the presence of the alien species. Our results show that interspecific interaction has an effect on the behavioural patterns of the alien species, and the main factor negatively impacting Megalobulimus populations in Brazil is probably the non-specific control of A. fulica and the alteration and destruction of its habitats”.

This kind of studies, still rarely done, may become more important with the spread of introduced species (unfortunately too often happening). The study will be especially appealing to ecologists and conservationists.

Reference:
Miranda, M. & Pecora, I., 2017. Conservation implications of behavioural interactions between the Giant  African Snail and a Native Brazilian species. – Ethology Ecology and Evolution, 29 (3): 209-217.

Reproductive biology of a Megalobulimus species

Fontenelle & Miranda have just published a paper on Megalobulimus. Their abstract reads “We studied the reproductive biology of Megalobulimus paranaguensis (Pilsbry & Ihering, 1900), a large and long-lived land gastropod from the Atlantic Rainforest of Brazil. The study was conducted at an urban park in the city of Santos, state of São Paulo. For 4 years, we counted the egg postures and annual eclosion rate of 32 captive snails and looked for associations between egg posture and the climatical variables of the period. The annual mean posture of 8.7 eggs per snail obtained in our results is a small number, but typical of Brazilian macromollusks. The annual eclosion rate was 31%. The beginning of the annual activity period of snails occurred in the middle of March, and lasted 33.97±3.02 weeks. The dormancy period started in the beginning of November, and lasted 18.39±3.11 weeks. There were two egg posture peaks, a minor peak between March and May, and a major peak between August and November, with greater values in September. Megalobulimus paranaguensis has a well-defined seasonal reproductive pattern influenced by environmental temperature and temperature range. Furthermore, in this snail, reproduction is negatively influenced by temperature increasing and temperature range”.

Schermafbeelding 2017-04-06 om 20.55.36

Reference:
Fontenelle, J.H. & Miranda, M.S., 2017. Aspects of biology of Megalobulimus paranaguensis (Gastropoda, Acavoidea) in the coastal plain of the Brazilian southeast. – Iheringia, Zoologia, 107: e2017004 (5 pp.). DOI: 10.1590/1678-4766e2017004

New Megalobulimus from Peru

Borda & Ramirez (2016) have just published a new paper on Peruvian Megalobulimus species, in which they also describe two new species.

Schermafbeelding 2016-08-16 om 13.40.46

The abstract of their paper is: “A major taxonomic problem around the genus Megalobulimus Miller,1878, the largest land snails in the Neotropics, is plasticity of conchological characters. Here we re-describe Megalobulimus leucostoma (Sowerby, 1835) and describe two new species of Megalobulimus from Southern Peru, Megalobulimus tayacajus sp.nov. and Megalobulimus inambarisense sp.nov. These descriptions are based on both conchological and soft anatomical characters. Megalobulimus leucostoma is characterized by the presence of a retractor muscle with two insertions to the buccal mass, two small bulges on pre-rectal valve, and a geographical distribution appears limited to Cusco. Megalobulimus tayacajus sp.nov. is characterized by the presence of a retractor muscle that divides near the buccal mass, two lobed bulges on pre-rectal valve, and to date, has been found only in Huancavelica. Megalobulimus inambarisense sp.nov. is characterized by the presence of a retractor muscle with one insertion to the buccal mass, two big bulges on pre-rectal valve, and a distribution appears limited to Puno. The digestive system appears to serve as useful characters to discriminate these species and, when combined with shell and reproductive characters, may help to understand better the evolution and ecology of these snails”.

Reference:
Borda, V. & Ramirez, R., 2016. The genus Megalobulimus (Gastropoda: Strophocheilidae) from Peruvian Andes: Re-description of Megalobulimus leucostoma and description of two new species. – American Malacological Bulletin 34: 15–27.

Population dynamics of a Megalobulimus species

The recent study by Miranda & Fontanelle (2015) is a welcome addition to our knowledge of Megalobulimus species.

ABSTRACT. The population dynamics of Megalobulimus paranaguensis (Pilsbry & Ihering, 1900), a large and long-lived land gastropod from Brazil’s Southeast (Atlantic Forest) was studied between 2006 and 2009, at an urban park in the city of Santos, state of São Paulo. The study included biometry, weighing, and marking and recapture of adult individu- als. The variables obtained from specimens were correlated with the environmental variables of the study period. The survival rate of the adult snail population was 96.7%. Recruitment showed several peaks during the year, and was concentrated between April and August, except in 2009, when there was only one peak in August. Specimen abun- dance progressively increased from 2006 on, with a trend towards relative stability during that period. The condition factor remained relatively stable as well, decreasing from December to February. The potential evapotranspiration and precipitation influenced the number of captures, and the mean temperature influenced the condition factor. Megalobulimus paranaguensis goes through a period of dormancy in the tropical summer, which is between November and February, but remains active in the winter. The survival rate of M. paranaguensis was high, and may be the result of having its annual cycle synchronized with the tropical climate of the Atlantic forest.

MirandaF15

Reference:
Miranda, M.S. & Fontenelle, J.H., 2015. Population dynamics of Megalobulimus paranaguensis (Gastropoda: Pulmonata) in the southeast coast of Brazil. – Zoologia 32 (6): 463–468.
Available at http://dx.doi.org/10.1590/S1984-46702015000600005

New species from Brazil

Thanks to the continuous effort of some Brazilian colleagues, the malacofauna of that country is enriched last year with several new taxa. I here briefly report on two contributions.

Fontanella et al. reported on shell mounds in Santa Catarina which remained from ancient times when Paleoamericans used shells to make ornaments and tools, or used them as a food source. One of the species discovered during archeological work on remains in Jaguaruna municipality is a new species of Megalobulimus, M. jaguarunensis.

Fontenelle 2014

Another paper describing a new species of Leiostracus was published by Salvador & Cavallari, based on a single shell in the Senckenberg Museum Frankfurt, without precise habitat and locality data.

Salvador&Cavallari14Leio

References:
Fontenelle J.H., Cavallari D.C. & Simone L.R.L. (2014) A new species of Megalobulimus (Gastropoda, Strophocheilidae) from Brazilian shell mounds. – Strombus 21: 30–37.
Salvador, R.B. & Cavallari, D.C. (2014) A new species of Leiostracus (Gastropoda, Pulmonata, Orthalicoidea) from Espirito Santo, Brazil. – Iheringia, Zoologia 104: 364–366.

Santa Catarina new records

Agudo et al. (2014) published nine new records for the fauna of the State Santa Catarina in Brazil.

The following taxa are concerned:
Family Helicinidae
Helicina schereri F. Baker, 1913
Family Assimineidae
Assiminea sp.
Family Subulinidae
Lamellaxis clavulinus (Potiez & Michaud, 1838)
Lamellaxis (Leptopeas) cf. mizius Marcus & Marcus, 1968
Family Bulimulidae [Amphibulimidae]
Plekocheilus (Eurytus) sp. [the specimen shown is mentioned as P. aff. rhodocheilus (Reeve, 1849) in my previous post]
Rhinus cf. longisetus (Moricand, 1846)
Family Amphibulimidae [both Rhinus and Simpulopsis are now placed in the Simpulopsidae sensu Breure & Romero, 2012]
Simpulopsis cf. ovata (Sowerby, 1822)
Family Megalobulimidae
Megalobulimus klappenbachi Leme, 1964
Family Charopidae
Zilchogyra cleliae Weyrauch, 1965

Agudo ea 2014f7

Reference:
AGUDO-PADRÓN, A.I.; LUZ, J.S.; FUNEZ, L.A.; ZERMIANI, A.E., 2014. Nine new records to inventory of continental mollusc species from Santa Catarina State, Central Southern Brazil. Brazilian Journal of Biology Sciences, 1(1): 15-20. Available at: http://revista.rebibio.net/v1n1/3543-4376-01-03.html