Archachatina puylaerti

[Kevin]

I received some unknown Archachatina from Gabi, that I thought may have been degneri, or possibly ventricosa or purpurea. I have been in contact with an author on a book on giant snails, I asked him what he thought they were, he explained that they are Archachatina puylaerti, a species first described by Dr Mead in 1998, they are found in the wild in Togo and Benin, and are very similar to Archachatina degneri, he explained that true Archachatina degneri are only found in Ghana. He sent me this picture to show Archachatina puylaerti (bottom) and a Archachatina degneri (top)



This is one of them,

[Deleted]

so how does one tell the difference between degneri and purpurea?

[Kevin]

lotsofsnails said:

so how does one tell the difference between degneri and purpurea?

I have been given this information, on the differences of degneri and purpurea.

A.purpurea has a granulose coarse sculpture on the shell like
A.ventricosa, A.degneri has a smooth shell.
The shape of the degneri shell is broad an big, A.purpurea is a small species with a slender shell. The eggs of
A.purpurea are smaller than of the other Archachatinas.

[Paul]

I have just received that info also.

Purpurea are easier to discount because they have a very textured shell, much like ventricosa. Rhodostoma are the smoothest.

Having looked at the new puylaerti species defined by Mead, I still think Lucy's are degneri. For the following reasons:

The shape and shell ratio is that of degneri (1:1.6) rather than puylaerti (1:1.8). The size of the sub-sutural band matches that of the degneri in the picture earlier, although in that article it seems to suggest puylaerti usually have thicker subsutural banding. The soft-body is also light, like the degneri pictured but obviously there is much variation in snails. My snails also have a bright pink columella from very early on, whereas the article suggests that puylaerti at 5.5 whorls only have a thin ridge of pink developing and I'm fairly sure the columella groove was closed by this size. The puylaerti seems slender, whereas mine are very ventricose. I will do some whorl measurements. It is unfortunate that there is no guaranteed, distinctive difference, without dissection.

It seems that without dissection, locality is the deciding factor, the rest are just hints and not decisive. And since we haven't got that information we can only guess.

I've not had time to fully digest and understand Mead's info and it isn't an easy read, but I'm gonna look into it more throughly and compare with the one's I have.

[Deleted]

oops sorry, I meant to say

what is the difference between degneri and puylaerti?

In that picture I can't see much difference...


and what's a sub-sutural band?

[Paul]

According to Mead there is no distinctive identification feature between them and therefore no way of telling them apart externally. They have to be dissected to tell the difference because outward appearance is almost identical. See picture at the top of the thread.

There are hints that can help point to one or the other, as mentioned in my earlier post.

Sub-sutural band is the area of shell below (if apex is north) the sutures.