Some specimens of this watermite species were caught in the Radewijker brook, a channeled stream near Hardenberg of medium size, that originates in Emlichheim (Germany) and converges with the river Vecht near Hardenberg (the Netherlands). They were caught at the edge of that brook, some other Piona species were caught in the same scoop.
At first sight the little red globules seemed like the very common Limnesia undulatoides to me, because they had large, dark palps and legs, that they moved vigorously. I wanted to neglect them, but but I was curious whether they were L. maculata or even L. fulgida. To my surprise, they only had two eyes, on their third pair of legs a hollow segment and the underside showed the unmistakable genital fields: they were males of Piona longipalpis. Among the specimen was one female. The males are relatively large, other species of Piona have males that are a lot smaller than the females.
Piona longipalpis is a watermite species that is rather rare in the Netherlands (Smit, 2018) and is known from a large part of the country. region were I found them. Their habitat: ditches and larger waters with a rather low nutrition concentrations.
According to Piersig (1897) these are lively and predatory watermites, that eat mostly small crustaceans (waterfleas and the like), but they also do not spare other watermites with a soft skin. Not surprising, seen the fact that these species has a superficial resemblance to L. undulatoides, which is as dangerous. On the picture below: the female specimen, with he long legs she has more the appearance of 'normal' Piona species.