Malaysian microjewels going extinct as they are discovered

Mar 25, 2014
This is a member of Plectostoma laidlawi (shell length ca. 2 mm) crawling in its natural habitat, microvegetation on limestone in Kelantan, Malaysia. Credit: Thor-Seng Liew

A Malaysian-Dutch team of biologists have catalogued all 31 species of the tiny, but oh so pretty snail genus Plectostoma from West-Malaysia, Sumatra, and Thailand. Ten species are new to science, but some of those are going extinct as they are being discovered.

The study was carried out by PhD student Thor-Seng Liew of Naturalis Biodiversity Center in Leiden, The Netherlands, and three colleagues. Liew, who is on study leave from Universiti Malaysia Sabah, spent four years studying the distribution, shell shape, and genetics of these minuscule snails. He is still working on the from Borneo, where Plectostoma is exceptionally diverse, but in the new paper, published in the open access journal ZooKeys, he first gets the species from the rest of Asia out of the way.

The snails are special for several reasons, says Liew. 'First of all, they flaunt all shell-coiling rules, by having very irregularly coiled and ornamented shells, making them look like microjewelry.' Liew used a so-called micro-CT-scanner, which produces three-dimensional X-rays of very tiny objects, to investigate the exact shapes of the shells. This allowed him to recognise 31 species, ten of which were new to science.

Another peculiarity is that they only live on limestone hills. In Southeast Asia, such hills are usually few and far between, and the snails that manage to colonise them are completely isolated. This, in turn, has caused a lot of "endemism": many Plectostoma species only occur on a single hill and nowhere else on earth.

This shows micro-CT-images of eight species of Plectostoma from Malaysia Credit: Thor-Seng Liew

But their endemism may also be their downfall, as Liew found out. Limestone hills are 'sitting ducks' for mining companies, and many are being quarried away for cement, taking their unique with them to their grave. One species, Plectostoma sciaphilum, is already extinct: its home was turned into concrete around 2003. Similar fates await at least six more species. One of these, P. tenggekensis (named and described in the new paper) occurs only on Bukit Tenggek, which the authors forecast to be completely gone by the end of 2014.

This is a member of Plectostoma salpidomon (shell length ca. 3 mm) crawling in its natural habitat, microvegetation on limestone in Pahang, Malaysia. Credit: Thor-Seng Liew

To highlight the plight of these unsung victims, the authors named several of the after conservationists and politicians who have fought for the preservation of Malaysia's endangered limestone hills.

Explore further: A stunning new species of dragon tree discovered in Thailand

More information: Liew T-S, Vermeulen JJ, bin Marzuki ME, Schilthuizen M (2014) A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1. DOI: 10.3897/zookeys.393.6717

add to favorites email to friend print save as pdf

Related Stories

Snail shell coiling programmed by protein patterning

May 27, 2013

Snail shells coil in response to an lopsided protein gradient across their shell mantles, finds research in BioMed Central's open access journal EvoDevo. In contrast the shell mantle of limpets, whose shells ...

Cone snails are for life and not just at Christmas

Dec 23, 2013

Those who fly to tropical shores this Christmas in search of sea and sun may be unaware that an exotic shell picked from the beach could potentially bring relief to many thousands of people suffering life-threatening ...

Recommended for you

Orb-weaving spiders living in urban areas may be larger

22 hours ago

A common orb-weaving spider may grow larger and have an increased ability to reproduce when living in urban areas, according to a study published August 20, 2014 in the open-access journal PLOS ONE by Eli ...

User comments : 0