Monthly Archives: November 2012

Snail-eating snakes

Agudo-Padr??n (2012) recently published a brief overview of the preferences of snail-eating snakes in southern Brazil, belonging to the snake family Dipsadidae.

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Snails reported to be on the digest of these snails include Veronicellidae, Bulimulidae, as well as the invasive Bradybaena similaris.

Reference:
Agudo-Pad??n, I., 2012. Brazilian snail-eating snakes (Reptilia, Serpentes, Dipsadidae) and their alimentary preferences by terrestrial mollusks (Gastropoda: Gymnophila & Pulmonata): an preliminary overview. – Biological Evidence 2: 2-3. Online available at http://bio.sophiapublisher.com/core/files/journals/40/articles/490/public/490-1615-1-PB.pdf

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Ghost Bulimulus = Bulimulus sporadicus

There is a new invasive species in Florida, which has been reported for some time as the “ghost Bulimulus” or ‘Jacksonville Bulimulus‘. Thanks to the many efforts of Bill Frank and Harry Lee, and the ability of David Robinson to compare specimens with those that were previously reported as B. sporadicus (d’Orbigny, 1835) from Houston, we now know that the Florida populations belong to the same taxon. Some authors regard it as a subspecies of B. bonariensis (Refinesque, 1833).

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Bill Frank has made a summary of the data on his website http://www.jaxshells.org/gallery5.htm 

A history of (Brazilian) malacology

In a historical overview of malacology, the authors focus on the Americas and especially Brazil. They follow the sequences of the Unitas Malacologica (UM / WCM), where many well-known malacologists are mentioned. Also the history of CLAMA is treated. Present-day malacological activities in Brazil are focussing on applied malacology. The main text is in Portuguese, but an English abstract is provided.

The Mollusca phylum is the second largest zoological group known to science. Their representatives have conquered successful- ly almost all natural environments of the world and are critical to maintaining the ecosystem in which they live. The molluscs make up one of most evident among animals and closely related to human society from prehistory to the present days, being important as an economic resource and disease vectors. The Malacology, the science that deals with the study of molluscs, have advanced at the global level in recent decades, but in face of the diversity and importance attributed to the group, the knowledge about it can be considered still incipient. In Brazil there isn???t a priority area to be enhanced within the Malacology, the more urgent necessity for the development of this science in the country is the training of specialized personnel to maintain and coordinate researches and scientific collections.  

Reference:
Colley, E., Simone, L.R.L. & de Loyola e Silva, J., 2012. Uma viagem pele hist??ria de Malacologia. – Estudos de Biolog??a, Ambiente e Diversidade 34 (83): 175-190.

Second record for Thaumastus caetensis

Vasconcelos & Pena (2012) recorded the second specimen known for the rare Brazilian snail Thaumastus caetensis Pena, Salgado & Coelho, 2011. The specimen was found in de Serra da Piedade, Caet??, Minas Gerais and its presence in a protected area is important. This species is probably restricted to the ‘campos rupestres’ habitat. The (subadult) specimen was found alive, but preserved in formalin, which makes it unsuitable for DNA research. 

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Reference:
Vasconcelos, M. & Pena, P., 2012. Range extension of Thamastus caetensis  Pena, Salgado & Coelho, 2011 (Gastropoda: Orthalicidae: Bulimulinea) in the highlands of Minas Gerais, southeastern Brazil. – CheckList 8(3): 534-536. Available at http://www.checklist.org.br/archive

Snails and snakes

In past month’s newsletter from the Belize Foundation for Research and Environmental Education, a brief note appeared by Dan Dourson with observations on snail-eating snakes in Belize. See http://www.mynewsletterbuilder.com/email/newsletter/1411504614.

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Although the text doesn’t say, the observations seem to have been made in captivity, feeding a snake with different preys to see which were taken and which rejected. Drymaeus species were clearly a favorable bite for the Speckled Snailsucker Sibon nebulata.
There has been quite some research on predation of snails by snakes, mostly on S.E. Asian species (see the work of Masaki Hoso, currently post-doc in Leiden). See also Aydin Orstan’s post (http://snailstales.blogspot.nl/2007/02/evolution-of-jaw-asymmetry-in-snail.html).

Harry Lee followed up on the original posting to Dourson’s observation on the Conch-L list with:
“Apparently the evolution of jaw asymmetry is convergent (synapomorphic) in the two groups [see http://naherpetology.org/pdf_files/400.pdf]. As indicated by Aydin, sinstral snails seem to enjoy a selective advantage inasmuch as they are relatively refractory to predation by “right-handed” snakes. This may well account for the coevolution of chiral reversal in snail lineages (e.g., Bradybaenidae, Camaenidae, Ariophantidae, Dyakiidae) that share their ranges with the snail-eating snakes in Asia.

Speaking of synapomorphies and coevolution, the neotropical family Bulimulidae, separate (dextral) species of which are shown in the jaws of the two Sibon nebulata figured in Dan’s report, have evolved three sinistral taxa (and I consider them independent lineages):

Drymaeus inusitatus Fulton, 1900 Costa Rica and Panama.
Drymaeus semimaculatus perversus Pilsbry, 1926, type locality Garachino Province, Panama. [nominotypical subspecies dextral]
Drymaeus tropicalis (Morelet, 1849) type locality Campeche, Mexico, but my notes indicate that David Kirsh found a specimen on the grounds of Hotel Santa Maria de Ostuma, outside of Matagalpa, Nicaragua in August, 1983.

Perhaps the same snake-snail selective forces are at play in Central America as in E, S, and SE Asia.”

Thanks are due to David Kirsh and Harry Lee to bring up this subject on the Conch-L list.