Thank you for your suggestions! I did have L142 Baryancistrus topping my list of candidates, but now I'm leaning towards Hyp. contradens. Below is a picture of the mouth and belly - does that settle anything? Or are there any other parts I could get a picture of that could decide this for certain ...
This one was sold at my LFS as "L333 Snowball pleco" - and now that I have read up a little on the subject I would like to check with the experts (you guys!). I know it's not an L333, but it seems there are many, many different fish being labelled "snowball pleco ...