Our Brigs are really diffusa ????

[badflash]

Check this paper:
http://www.pubmedcentral.nih.gov/articl ... id=1919357
My friend Mustafa who runs the petshrimp forum dropped that bombshell on me today.

From what this paper reads the snails in the US are not Brigs, but diffusa.

[PaulaO]

So instead of Pomecea bridgesii bridgesii, they could actually be Pomecea bridgesii diffusa?

[jonfr]

What is the diffrence ?

Do I have diffusa or brigs ?

[badflash]

So instead of Pomecea bridgesii bridgesii, they could actually be Pomecea bridgesii diffusa?

No, they were given a different species name and are not a sub-species. They are Pomecea diffusa.

[Donya]

I saw that paper a while back. Gotta say though that for some reason the diffusa looks different to me from the Pomacea "bridgesii" shells I've got. Could just be the individual shell of course, but there is also this:

Cowie and Thiengo [12] suggested that the latter might deserve full species status, and the two taxa have been confirmed as distinct species by genetic analyses

I don't see a reference as to which is the more common captive species, although also from our own site there's this (although the paper is more recent):

The bridgesii snails, available in the aquarium trade are Pomacea bridgesii effusa snails and eventually this these snails could turn out to be Pomacea effusa instead of a subspecies from Pomacea bridgesii.

[badflash]

They did not sample snails from the aquarium trade though. Donya, does anyone you know have the capability to genetically sequence some LSP's or DSP's? Mine get bigger than diffusa are supposed to get.

[Donya]

They did not sample snails from the aquarium trade though.

I realize that. That was part of my point actually - the diffusa cited in the paper were from South American collections. Stijn cites the bridgesii in the pet trade as perhaps being the bridgesii effusa subspecies, not the diffusa species. I see differences between the diffusa shell presented in the paper and the domestic bridg shells I have. Unless there is a source somewhere citing that effusa=diffusa (which I am not being able to find), it means that pet trade bridgs are not P. diffusa.

Donya, does anyone you know have the capability to genetically sequence some LSP's or DSP's?

Not without inflicting a reasonable amount of damage on the animals to get a tissue sample; that's why I've not gone that direction with my studies.


EDIT: I stand corrected on the shell collections and should have known that having read the paper before - I'm quite tired and misread. The collections are from Florida. However, there is still the effusa vs. diffusa issue.

...and a second edit because I can't seem to not make typos tonight. *sigh*

[badflash]

While I was at my Son's Karate class today I ran into one of the mothers that is a Biology Professor at a local college. She has access to a gene sequencer and thinks this would be a great project for her students.

I plan to supply snails that are on their last legs and should be euthanized anyway. I have hundreds of snails, so I just need to wait for the occational floater to present itself.

[Donya]

What are you planning to compare against?

[badflash]

I'm hoping we can link up with the folks that did the study, or maybe get a sample of the florida variiety. The paper gave collection locations. We might be able to enlist the help of a certain joker that lives down their...

[rpilla001]

You Talkin to me!
YOU TALKIN TO ME!
I don't see anyone else here, so you must be talkin to me!

Sorry, it's by best DeNiro

I saw alot of Paludosa eggs and shells in that article.

Go Flapples!!!

It looks like there is a large population in Palm Beach County. It is about an hour north of me. There is also some in West Dade, but the only way to get there is by airboat.

I do not forsee any freetime in the near future for such and adventure

[khayes]

Hi all,
Just wanted provide some relevant facts for the discussion of P. diffusa versus P. bridgesii, and about ongoing research with apple snails.

First, the Rawlings et al. 2007 paper does not discuss the differences in detail simply because it was not the point of that paper. However, it has been long suggested, by Fred Naggs and others, that the true identity of the aquarium species was P. bridgesii diffusa, and that it might actually deserve species status (P. diffusa). The data for these suggestions primarily came from comparisons of type material and shells collected elsewhere. We have sampled what is called P. bridgesii from pet suppliers and established populations around the world including those in Florida, Texas, Hawaii, Rio de Janeiro, Panama, Singapore, Taiwan, Sri Lanka, India, Iran, Colombia and Australia. Also, we have purchased what has been labeled P. bridgesii (spike-topped apple snail, mystery snail, etc) from a number of online snail suppliers. All of these snails share a single mitochondrial haplotype, which is quite astounding given the wide geographic sampling. Our interpretation of these data is that the aquarium stock, including introduced populations established outside of South America all originated from a single source population. We then compared these sequences to samples collected from various locations in the Amazon Basin of Brazil, and it appears that geographic source of the “aquarium stock” is in the Brazilian state of Pará, near Belém. We also compared the shell morphology to type specimens of both P. bridgesii bridgesii and P. bridgesii diffusa from their respective museum collections in the UK and Germany. Finally, there are also a number of anatomical, behavioral and distributional differences among these taxa.

After comparison with 100’s of specimens from both introduced and native populations it is clear that there these taxa are two distinct species. Details of this work will be published over the next year or two, in the mean time there is another paper currently under review, and it covers the introduced species in SE Asia, including P. diffusa, P. scalaris, P. canaliculata and P. insularum. I hope it will be out in early 2008, and at that time I’ll be glad to provide a copy to anyone interested.

Over the next two years we will be publishing a number of papers describing the anatomical, behavioral, ecological, biogeographic and phylogenetic characteristics of the genus Pomacea, which we hope will help resolve the immense confusion over species identities, and provide some insight into the evolution of these fascinating snails. We are starting with the P. canaliculata group, since it is most wide spread, both naturally and anthropogenically. Once we’ve finished that group, we will move to the P. bridgesii group, which contains 6 different species, some that are actually cryptic.

As you are all aware, shell morphology can vary considerably within a single species, even within a single population (often influenced by environmental variables). This is particularly so within the genus Pomacea. For example, our work has found at least 11 species that belong within what is often called the P. canaliculata group, and these taxa do possess a number of synapomorphies which support their monophyly. Not surprisingly, in many cases the shell morphology is quite misleading, even for people that have spent the last 25+ years working with these snails in their native range.

One final comment, we have placed names on species only after extensive and careful work with numerous specimens from throughout their native ranges and introduced ranges (when applicable), as well as comparison with type material. To date, we have examined 100s of specimens from more than 50 taxa of New World Ampullariidae, and a number of Old World taxa (Pila. Lanistes, etc). Only after characterizing both inter- and intraspecific variation is it possible to clearly discern species differences, whether anatomical or genetic.

I’d be glad to answer questions about various details if anyone has any. Also, if any one has samples of hybrids (e.g. A. spixii x M. cornuarietus) or “unique” species (e.g. saltons) that they would like to send me for genetic analysis please get in touch with me.

All the best, Ken

P.S. – Badflash, if the college professor you wrote about would like to replicate some of our study, or have her students do genetic analysis of your specimens that would be great. Just have her get in touch with me and I can provide tissue samples from both the native and introduced ranges for comparison.

[khayes]

Just one more clarification. effusa should not be confused with diffusa, the two are not nomenclaturally related. The species effusa is actually considered a synonym of glauca, but was originally described as Nerita effusa Müller, 1774. However, no locality was given. Subsequently, Baker (1930) designated the Rio Yaracuy in Venezuela as the type locality. The distribution has been recorded as Suinam, French Guiana (Drouët 1859), Matinique (Saulcy 1854; Paetel 1887), Venezuela (Baker 1930) and Guyana (Pain 1950).

See Cowie & Thiengo 2003 for further references.

[badflash]

Thanks khayes! I will do that!

[flaringshutter]

i don't know if everyone else is as fascinated by this discussion as i am, but i wanted to thank you guys for doing all this research! this is incredibly interesting, and exciting! how lucky we snailers are to have such dedicated researchers helping us discover more about our aquatic friends.

so cool!