The Lord Of The Rings taught us that going through caves can often lead to unexpected encounters with spiders. Dr Marc Milne and colleague Elizabeth Wells had one of these encounters in Indiana. Luckily for them, the critter was not a giant monster but a tiny sheet-weaving spider. Oh, and it is translucent.

Many cave-dwelling creatures do in fact, over time, become translucent. Producing pigments requires energy, even the blandest color, so why waste precious energy when no one can see you?

As reported in the journal Subterranean Biology, the new spider is called Islandiana lewisi. It is the 15th species of the Islandiana genus to be discovered, which are mostly native to North America. The new creature was discovered in a Stygeon River Cave, located in southern Indiana. Only five of the Islandiana species live exclusively in caves.

The arachnid is tiny, only about 2 millimeters in length and, as the English name suggests, it builds its webs in a flat sheet-like structure. Its prey, the researchers suspect, is other smaller arthropods such as the springtail. They weave their web in small sheets spreading across the gaps between mud covered boulders. 

it was Dr Julian Lewis who first showed the spider to Dr Milne and acquired the permit to visit the cave, thus the spider is named after him. Milne, however, immediately thought the spider was quite peculiar.   

"I didn't know what the spider was at first, I just thought it was odd that so many were living within this dark cave with no other spider species around," Dr Milne, who is an assistant professor at the University of Indianapolis, said in a statement.

The specimen was collected in October 2016 and it took a while for Milne to realize that it was actually new. The first inspections showed similarities with two species Islandiana flavoides and Islandian cavelis, but a more detailed study after a few months showed unique characteristics not found in other species.

The cave it was found in is not exactly welcoming, either. It sits at the confluence of the Blue and Ohio rivers, and is subject to flooding. Although while humans might find it a bad place to live, or even dangerous, the Islandiana lewisi has carved a nice little niche for itself. Good for you, tiny spider.