Dimidiata vs Immaculata

[Deleted]

last year i asked about the second one and the bloke complained about he was moving house he cudnt get all the books organised etc. etc.

ive got a few books

the british snail book

the book about GALS care

a notepad i made with descriptions of my snails

some really really obscure leaflet by da Costa from 1904 about new snails from costa rica or something

[Paul]

I'm thinking of scanning any books I can get my hand on that are out of print, so everyone can get a copy. We should all do this if you have the means to do it. I mean, if anyone is annoyed then tough shit, they can publish them again

Also, it'd be for non-profit reasons so I could never be accused of profiteerring.

[Deleted]

i cud scan the book about tropical american snails if u want, its in latin though and theres only about 5 species, but it might help?

[Paul]

Sounds great! I will add it to my document section. It may only have 5 species in but it is probably of use to somebody. I mean, you got it didn't you?

[Deleted]

yeh from ebay. i'll scan it tonight and put it on the internet when i can... ;D

[Deleted]

i just seen theres a variant of dimidiata called 'volkensis' that lives near Kilimanjaro

www.biologie.uni-ulm.de/cgi-bin/query_all/details.pl?id=50631&stufe=7&typ=ZOO

so dimidiata cant be a variant if it has variants of itself....its too confusing

the website also mentions a detailed list of lots of obscure achatinidae species.

www.biologie.uni-ulm.de/systax/daten/taxa/details/zoo_1.html

kind regards

mike

[Paul]

When I said variant I meant dimidiata and immaculata could end up proving to be variants of each other, as has happened with a number of species and will no doubt occur again. However at the moment as this isn't the case I think they are separate and both do exist as species. But I personally think people are confusing dimidiata with some sort of immaculata, possibly because of locale or features such as columella colour. Or perhaps even the other way round.

[Deleted]

Eric, could I possibly use that picture u got from the museum for my website?

[eric2]

of course why not

eric

[Deleted]

thank you

updated my african snails section of my website with a paragraph on dimidiata

www.freewebs.com/worldofsnails/giantafricansnails.htm

[Paul]

I've resurrected this old chestnut because I have some new information.

I have discovered that Achatina balteata can have a pink columella and one of the photos (black and white unfortunately) in the book looks like one of these two-toned snails. It is the variant infrafrusca that updated A. dimidiata v. Martens (1889).

Germain is quoted as saying...

"However, some medium sized specimens (95 mm. long, 50 mm. in greatest width, 42 mm. in lesser width) retain the pale yellowish-chestnut color with the violaceous columella"

Bequaert never got chance to study types of these in the Paris Museum when he visited. I'll take a photo of the shell and post it here when I've recharged the cameras batteries.

I'm not sure exactly how this helps, since Fredrik did get his specimens from a South African dealer and balteata doesn't feature there. But perhaps it may help explain these pale immaculata, because I can't seem to get reliable locale info for this species. One site says South Africa, others say West Africa and some East Africa.

I was really hoping the South African snail book would solve this. I think it would be a good idea to contact the author and ask him. I did have some correspondence with him whilst ordering and I did ask, but he never answered (perhaps he was worried I wouldn't need to buy the book ) but he has been helpful generally so I'll pop an email over as soon as my book arrives and I can reference it so he knows I am not wasting his time. Even if the book doesn't cover the same locale, you'd think he'd have ways to find out for us or people he could ask.

[Paul]

I have been talking to Raphael over at Achatinidae.com and we think we have solved this problem pretty much once and for all.

And that is that dimidiata is not a species at all, they are a variant of immaculata.

Historically there have been 2 dimidiatas:

Achatina dimidiata, v. Martens, 1889 (French Congo).

Bequaert identified it as Achatina balteata var. infrafusca v. Martens. Even though these can have a pink columella, we know that Fredrik definitely obtained his from South Africa so we can rule this one out.

Archachatina dimidiata, E. A. Smith, 1878 (South Africa) with subsp. schencki v. Martens, 1889.

The picture from the BNHM is an Archachatina, that much is clear, just take another look. If that is true to the form which I assume it is, it does indeed have a two-tone shell. So it is obvious why the two have been mistaken. I mean, it was a long time before people recognised that Achatina and Archachatina were different. So, because the two-tone immaculata look similar to another South African snail somewhere along the line they were mixed up.

Of course, I'm not saying the malacologists got it wrong, far from it. I'm suggesting either the exporters or the importers got it wrong. Simpler mistakes get made all the time. we all know that!

So in my opinion Mike was correct that his are indeed immaculata, but I was also correct that the two are the same. Now they are different to the nominate species so I would suggest that until we know more about immaculata, we call them Achatina immaculata var. dimidiata so everyone knows what we are talking about. The immaculata issue is a very tricky one, as a lot of malacologists think they are really panthera (including A. Mead). But we'd have to wait for reliable geographic information and a sex organ study.

The only possible spanner in this theory is if we can get a picture of both known subspecies of Archachatina dimidiata, only to find that neither look remotely like the one from the BNHM. (Arno....Has that book got pictures? Mine still hasn't arrived grrr). In which case, what the hell have the BNHM got listed as dimidiata? As far as I know they labelled it A.dimdiata, and it is clearly an Archachatina. They failed to say explicity whether it was Arch.dimidiata or A.dimidiata but it is obvious. And a lot of references do say A.marginata for example.

So I would say that is the problem as solved as we are gonna get it. Any colour, shell variance is just normal polymorphism. I wonder how we would go about confirming this or finding a name for this subspecies seeing as I doubt we would get taken seriously if, should one not already exist, we proposed one?

[Arno]

The book has got pictures(i'll scan them later)and lists two know forms:the typical dimidiata and burnupi which is more uniform olive-yellow to reddish-brown.
About the immaculata issue :the book states that A.panthera is a narrow form of immaculata...

[Deleted]

YAY

[Paul]

So Arno, if the typical form is two-tone, do you think the theory is correct?

As for the immaculata/panthera issue, that seems a weird way round to me because panthera don't seem that narrow to me, I'd say they have a more rounded spire. Perhaps it means the body-whorl.

[section8angel]

So instead of saying Achatina dimidiata, I now have to say Achatina immaculata var. dimidiata all the time?

Confusing Lol

immaculata/panthera .... Don't confuse me even more! lol

[Kevin]

So what are my immaculata then? they are from Italy, not the ones from Sweden.

[Arno]

admin said:

So Arno, if the typical form is two-tone, do you think the theory is correct?

As for the immaculata/panthera issue, that seems a weird way round to me because panthera don't seem that narrow to me, I'd say they have a more rounded spire. Perhaps it means the body-whorl.

Info from the book:

[Paul]

A picture beats a 1000 words as they say! I think it is fair to say "case closed....."

Kevin, not sure what yours are, they don't look like the nominate form to me, but I've never seen baby pictures. They look kind of like var. dimidiata to me. Either way, there is no reason to doubt they are immaculata if you were told they were and they have a pink columella.

[Kevin]

admin said:

Kevin, not sure what yours are, they don't look like the nominate form to me, but I've never seen baby pictures. They look kind of like var. dimidiata to me. Either way, there is no reason to doubt they are immaculata if you were told they were and they have a pink columella.

They do have a pink columella, its quite hard to see it though, they're only about 2cm, and havent grown much since I've had them, they eat the same as my other snails though, they're starting to develop dark stripes.

[Deleted]

WHAAAT? i dont get it? whats this archachatina dimidiata?

so theres no such thing as achatina dimidiata someone just got confused with arch. dimidiata?