Tuesday, April 12, 2016

A new tardigrade: Milnesium sandrae

Tardigrades are one of nature's smallest animals. They are never more than 1.5 mm long, and can only be seen with a microscope. They are commonly known as water bears. To date we have discovered about 900 species. Most feed by sucking the juices from moss, lichens and algae.

Tardigrades are notable for being perhaps the most durable of known organisms; they are able to survive extreme conditions that would kill nearly all other known life forms. They can withstand temperature ranges from −272 °C to about 150 °C, pressures about six times greater than those found in the deepest ocean trenches, ionizing radiation at doses hundreds of times higher than the lethal dose for a human, and the vacuum of outer space.

The new species was found on Hawaii and was named in honour of Dr. Sandra J. McInnes (Cambridge, United Kingdom), who helped the authors with the English in their manuscripts.

For the experts: Two new species of Milnesium are described, Milnesium minutum sp. n. from Sicily and Milnesium sandrae sp. n. from the Hawaiian Archipelago. The body size of Milnesium minutum is the smallest of the known species of the genus. The stylet supports are inserted on the buccal tube at 63–66% of its length and the claws have a [3-3]-[3-3] configuration. Milnesium sandrae has stylet supports inserted on the buccal tube at 58–60.5% of its length, a [3-3]-[3-3] claw configuration, and the percent ratio between the secondary claw and primary claw length on legs I–III (78.6%–85.5%) clearly higher than on legs IV (70.5%–71.4%). With the description of these two new species, the number of species in the genus is increased to 31.

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