Need help in Identifying this Snail

[Rolland Arriza]

I need help in identifying this snail. Sorry if I posted this on the wrong forum.



What I know is that the snail's shell covers the snail itself, but this snail is different. The snail itself covers its shell, but not fully.

Attachments:

[Evil Angel]

Due to the shell being covered by skin, I'd guess at Ratnadvipia Irradians?

[malacophile]

That's just too freakin' cool! Where's you find him?

[Rolland Arriza]

This was from Philippines, in Mindanao, South Cotabato.
We now have a lead that this could be a Megaustenia sp. (more similar to M. siamensis)

but still we're not sure.

[brunni]

Hi Rolland

Thanks for these interesting photos. Got any more ?

A large number of marine gastropods are in the habit of entirely covering their shell by the fleshy parts ( eg. Cypraeidae, Ovulidae, Naticidae ). Some land snails have developed in a similar way but are limited in habitat to humid tropical areas where they can support exposure of the soft tissue. As most of these species have an unobtrusive shell, the beauty of the living animal has been overlooked. They are a link between the snails and the slugs (many slugs bear internal shells).

The second image you have posted seems to originate here ( 17th. image down ) :
seashellhub.com/Ariophantidae.html
.......where it is identified as Megaustenia siamensis Haines, 1858 collected from Thailand.

On this site, the next species down looks very similar to the first photo you posted. However the animal is different so the name used is questionable. In fact the site owner wrote : Megaustenia c.f. praestans (Gould, 1843) - 230108 - C01 - 24,5 mm x 19,5 mm - Kanchanaburi, Thailand. - selfcollected - I am not sure of the ID. Please help me to id it. I say it is completely different, indicating a different family.

There has been another "Megaustenia sp." posted here :
www.achatschneckenvomwienerwald.de/viewtopic.php?f=37&t=396
This agrees better with species mentioned above from Thailand ( unfortunately no locality mentioned ). Both have striated sells, but otherwise the animals are distinct.

I would also rule out the identity of Ratnadvipia irradiansm which is illustrated online :
www.nhm.ac.uk/nature-online/species-of-the-day/collections/collecting/ratnadvipia-karui/taxonomy/index.html

For time being, I can not find a good name for your shell. I think the differences are clearer in this composite image ? It seems it has been collected in Mindanao, South Cotabato, Phillipines ?

[vallery]

What amazing looking snails. Does all their skin retract into the shell or is exposed at all times?

vallery

[Rolland Arriza]

Hey brunni, thanks for the links, and for the last image you posted ;D.
Here are the other images (alive & preserved):

Ohh, that black organism is unidentified too.



Obviously, these are different species.
Currently, our specimen was dead but was preserved. We're planning to recollect this "unknown snail" but we don't know when (we're still students).
And ohh, for the location, the snail was collected at South Cotabato, Philippines.
Thanks again.

[vallery]

Just found this on ARKive
www.arkive.org
Long- tailed Slug (ibycus rachelae)

[brunni]

@ Vallery : the animals will probably almost fully retract into the shells in time of stress.

@ Rolland : thanks so much for the new images !

Here is another link to an image of Megaustenia siamensis, also from Thailand ?
aquarium-ebooks.blogspot.com/2013/01/pic-of-day-megaustenia-siamensis.html

The classification roots : family Ariophantidae
Here you can find a listing of over 10 genera and 60 species belonging to this family ( only from Vietnam ! ).
shellsandsnails.info/index.php?option=com_content&view=article&id=179:vietnampulm&catid=8:phaunashells&Itemid=3

Your shell has a strong resemblance to the genus Microcystina Mörch, 1872 and several species are known from the Philippines. e.g.

M. saintjohni Godwin-Austen, 1891 found in Palawan : borneanlandsnails.lifedesks.org/pages/894

M. badia (Möllendorff, 1890) shells from Cebu : www.conchology.be/?t=34&u=543805&g=c0663042ffe954ac7837d59567d1f68d&q=3550290699419c578aa1d87d2ee6ca75

[vallery]

Hi Brunni ,

ARKive News has them classified as slugs. They have a great fact sheet. www.arkive.org Long-tailed slug.

[pinkunicorn]

That's a snug! (semi-slug). What a beauty. I've seen these guys in pictures and oh boy, would I want some! The beauty of a species evolving in action.

[brunni]

@ Rolland your new photos, at the moment I don't see any differences between the two ( i.e. preserved sp. and live sp. )

I am wondering what is the thing marked A that comes up through the leaf and touches the shell ? A grasshopper leg ?
AS in the anal slit, used to exit waste from the animal. It is a feature of the animal, not of the shell. The shell is a translucent khaki color.

@ Vallery Thanks for the info !!!
Ibycus rachelae Schilthuizen & Liew, 2008 has been described from Sabah, Borneo and is also in the family Ariophantidae ( see "Description" on www.arkive.org ) and very relevant to this topic.
Use of the common name "ninja slug" or "long tailed slug" may be misleading as true slugs are more considered to be within the families Veronicellidae, Rathouisiidae, Limacidae and Philomycidae. They are all terrestrial pulmonate gastropod mollusks, so where to draw the line between a snail and a slug ? As PU aptly put it, this is a snug.
I would use these features to distinguish I. rachelae from the one that is the topic of this thread :
- geographic range
- oval shell against a round shell
- length and color of tail

[malacophile]

That thing touching the snail looks like a leech, but might perhaps be a species of Platydemus, a parasite that preys on slugs and snails.

[vallery]

Yes It does explain in the fact sheet from ARKive News that 'it is a type of semi-slug, being somewhat intermediate in appearance between a snail and a slug.'
Lots more interesting info on it there as well.
vallery

Modified: Great Thread such an interesting creature.

[pinkunicorn]

Snug/semi-slug is the perfect category for everything that doesn't clearly fit under snail or slug. I think officially it means visible shell which may or may not be covered with mantle, but the animal cannot retract fully into it. Snugs come in so many forms... some have so tiny shells they can't fit in at all, some have mantle covering the shell and might be able to retract halfway and lots of other configurations!

[vallery]

They are so fascinating.
The skin that does not retract in must be very vulnerable.
They are gorgeous as well.
vallery

[Rolland Arriza]

Do you think this is a new species?