It's just a twist to the left … or right

Just when you think that molluscs can't get any stranger … this weirdo turns up in Malaysia. Opisthostoma is a genus of microsnails renowned for its morphological exuberance but this one is out there even by those extreme standards.

I'll look at this in more depth when my GPS and I get back from Portland.

Thanks once again to the Budak for the links.

Universiti Malaysia Sabah

The Institute for Tropical Biology and Conservation at the Universiti Malaysia Sabah (UMS), Kota Kinabalu, specialises in research and education on rain forest and freshwater ecosystems. I spent some time there a few years ago, helping to curate their land snail collection. I thought you might like to see some photos from the trip. I'll put them up from time to time (sparingly).

UMS was constructing this huge mosque while I was there. I'd like to go back and see how the finished building looks. It's not going to be for a while, though.

New frog on the blog

I found this handsome fellow in a bathroom in Borneo. As you do. It's a four-lined tree frog (Polypedates leucomystax). This species is widespread in South East Asia, living in just about all habitats—including bathrooms. Polypedates is a relative of the flying frogs (Rhacophorus). Like them, it builds a foam nest from whipped-up mucus, in which it lays its eggs. The nest is usually attached to a leaf overhanging a body of water. When the tadpoles hatch, they drop and swim away.

This individual made no noise but the call was described to me as 'a big, watery fart'. So there's another reason to encourage wildlife in your house. Something else to blame.

Nothing succineids like success

Pulau Kapas might be covered in Amphidromus inversus, but that isn't the only snail on the island. This is an unknown species of succineid (I think).

Succineidae has a worldwide distribution. In Europe and North America, the family is associated with marshes and swamps, but elsewhere the snails might occur in any habitat. I found this Malaysian snail in rainforest. Australian succineids live in coastal heath, under eucalypt bark and on sand dunes. Tough little beggars.

They're difficult to identify. The shells all look pretty much the same (a few rapidly expanding whorls, no markings), as does the internal anatomy. There's nothing fancy about these snails.

So it's down to DNA to sort them out. Dr Rob Cowie and colleagues at the University of Hawaii are doing just that. They've already looked at thirteen species of Hawaiian succineids and found that the current taxonomic arrangement is all over the place like a mad woman's knitting. Almost everything is shoved into the open drawer marked Succinea, whether it should be there or not. Still, in which generic drawers those species should really go remains conjecture—until someone does a full-scale study of the family.

In the meantime, I've got no idea what species this is. If you can put a name on it, please let me in on the secret.


Read more

Rundell, R.J., Holland, B.S. & Cowie, R.H. (2004). Molecular phylogeography of the endemic Hawaiian Succineidae (Gastropoda: Pulmonata). Molecular Phylogenetics and Evolution 31: 246-255.

A twist in the snail

Pulau Kapas in the South China Sea is full of water monitors (Varanus salvator), which scavenge around the bins and pick off the odd rat. It's also absolutely chockers with snails. The trunks and branches of rainforest trees are covered in Amphidromus inversus, a large plain-coloured species of camaenid. It's a bit of an eye opener for Australian snail hunters. Over on this side of the Java Sea, finding native snails takes a major effort.

What's unusual about this species of Amphidromus (apart from their abundance) is they way their shells coil.

Most land snail shells coil to the right. (If you don't believe me, go out into the garden and pick up a snail. Hold it so the shell's apex is pointing away from you and the opening is facing up. On which side does that opening lie? The right! Told you so. But oh no ... you didn't believe me. Had to find out for yourself.) But not Amphidromus inversus. Most of them coil the other way.

Most. But not all. Populations of A. inversus are made up of a mixture of left- and right-handed individuals. (Cue Flanders and Swann.) This mixture of forms is even more peculiar among land snails.

Dr Menno Schuilthuizen and his colleagues looked at population structure of these snails on Pulau Kapas. The population was stable at 65% sinsistral (left-handed) and 35% dextral. Examining the line up of hypotheses, they discovered that the usual suspects could not explain the anomaly. The feckless snails showed 'a flagrant disregard for population genetics theory'.

Now, you might think that would cause a problem when snails try to mate. But, as you can see from these pictures, it doesn't seem to slow them down. Where's there's a will, there's a snail.

You can read more about Dr Schilthuizen's work at his excellent website.

Read more

Schilthuizen, M., Scott, B.J., Cabanban, A.S. & Craze, P.G. (2005). Population structure and coil dimorphism in a tropical land snail. Heredity 95(3): 216–220