New Species Of Freshwater Earthworms Discovered In Thailand

Researchers have discovered ten new species of the semi-aquatic earthworms in Thailand.

AsianScientist (Feb. 11, 2013) – The semi-aquatic earthworms in the genus Glyphidrilus live between the terrestrial and freshwater ecosystems of rivers, streams, and paddy systems. Remarkably, each species is endemic to a single water basin, carrying its own signature of evolution from their common origin.

In the journal ZooKeys, a new study describes ten newly discovered species of the genus Glyphidrilus in Thailand.

Among the interesting characteristics of these worms is a rounded body tip, while the end is square shaped. When twisted, the posterior end, which is normally above the soil surface, forms U-shaped channels. These are used to allow water circulation down the burrow.

Another peculiar feature is the so-called “wings,” or the expanded part of epidermis near the body tip. The function of the wings is still unknown to scientists, but it has been suggested that they evolved to assist breathing in such aquatic habitats. Because the wings are absent in sexually immature juveniles, a more conventional explanation might be that they are used to aid copulation rather than respiration.

The rice fields in Thailand serve as a reservoir and breeding ground for the animals. Here, the worms facilitate in the decomposition of organic matter to be a natural fertilizer, as well as improve the soil properties for better rice root system.

But the increased use of pesticides in agriculture puts these species in danger, says the paper’s co-author Dr. Somsak Panha, from the Animal Systematics Research Unit, Chulalongkorn University in Bangkok, Thailand.

“The worms will survive in areas using chemical fertilizers but not those using chemical pesticides. However, the worms did well in areas of organic farming and so are likely to be sensitive to modern agrochemical contamination of the environment. They may play an important role in organic rice farming,” he said.

The article can be found at: Chanabun R et al. (2013) The semi-aquatic freshwater earthworms of the genus Glyphidrilus Horst, 1889 from Thailand (Oligochaeta, Almidae) with re-descriptions of several species.


Source: Pensoft Publishers; Photo: Somsak Panha/Flickr/CC.
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