Sunday 4 November 2018

Macrobiotus hannae: A new species of Tardigrade from Podlasie Province, Poland.

Tardigrades, or Water Bears, are a distinctive group of small (usually less than 1 mm) invertebrates related to Arthropods, Nematodes and Velvet Worms. They have a simple segmented body with four pairs of limbs, and are remarkably resilient to environmental stress, being able to withstand extremely high and low temperatures, complete desiccation and even exposure to vacuum. To date about 1200 species of Tardigrade have been described, from marine, freshwater and terrestrial environments, with about a dozen more being described each year.

In a paper published in the Turkish Journal of Zoology on 28 March 2018, Bernadeta Nowak and Daniel Stec of the Institute of Zoology and Biomedical Research at Jagiellonian University, describe a new species of Tardigrade from Podlasie Province in northern Poland.

The new species is named Macrobiotus hannae, in honour of Hanna Tutaj, a PhD student at the Institute of Environmental Sciences at Jagiellonian University. The species is described from 139 individuals and 146 eggs, raised in culture from an initial sample collected from some ground-covering Moss in a deciduous forest in Podlasie Province. Adults of this species ranged from 341 to 760 μm in length, were white in colour and hermaphroditic. Juveniles are transparent and eggs white.

Macrobiotus hannae in dorsoventral view. Scale bar is 50 μm. Nowak & Stec (2018). 

The new species is very similar in appearance to the previously described Macrobiotus joannae, which was first identified in Australia in 1983, and has subsequently been reported in Russia and Italy, though the two species could be distinguished using genetic methods. This leads Nowak and Stec to question whether the European reports of Macrobiotus joannae are in fact erroneous, and are really specimens of Macrobiotus hannae.

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