Ithytrichia lamellaris: ‘Not observed in a hundred years’

In a little stream in Limburg, the southernmost province in the Netherlands, an apparently unknown animal was unexpectedly found by members of the Macrofauna Workgroup Green Hearth Leudal. During the determination an animal with a very remarkable shape was noticed in a partly transparent tube, which was no larger than 4 mm. The segments of the abdomen of the animal were lobed like bellows of an accordion. In addition, there was a drop-shaped appendix on each lobe. This had to be something very special. Internet gave little to no result. Until an article with a photo attracted attention. In the photo you could see an animal that looked like the captured one. The headline: ‘Not observed in a hundred years’, indicated that something strange might have been caught?

Something rare indeed. It was a caddisfly larva with the name Ithytrichia lamellaris. It lives in a casing made of spinning threads to protect the soft abdomen. The spots on the tube are probably caused by fungi or bacteria. The tube has an opening at both ends to allow a water flow, so that the animal can absorb oxygen through the skin. The lobed abdomen segments increase the skin surface for maximum oxygen contact. And if that is not enough, you can also see an outgrowth of a gill on every lobe. Perfection in a nutshell!

The larva had even more in store. Carrying the tube can be a problem if the larva encounters obstacles on its way. Navigating through it with his little house is sometimes impossible. How can this be solved? Simple, the larva turns around in his little house and continues its way in the opposite direction. The Ithytrichia is not found in the northern part of The Netherlands. Only in some places in Limburg. This animal is not uncommon there. Its presence stands for clean and oxygen-rich water.

Therefore, the headline, ‘Not observed in a hundred years’, does not fully cover the load, but this does not alter the fact that something special has been observed.

Thanks to Paul Lormans and the ‘Macrofauna Werkgroep Groen Hart Leudal’, Limburg.

https://www.groenhartleudal.nl/de-macro-fauna-werkgroep/#