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I think you cannot rule out Diptera (Nematocera) larva. At a first glance it looks a bit like a Bibionidae, but the anal end is too blurry to be sure. Mycetophilidae or Sciaridae may be possible too. You may have to check if there are some kind of (reduced) legs. Diptera larvae do not have legs, while many (to all?) Coleoptera-larva have some kind of leg(parts) with claws. It looks as if the thorax and many abdominal segments has stigmata (holopneustic/peripneustic?), so if it is a diptera than many families can be excluded. I'm not that much of an expert on terrestrial Coleoptera larva, but I don't know of any larva with prothoracic spiracles (but you may know that I only have field of expertise in the aquatic habitat).
It is definetely not a Dryomyzidae because it has a non-retractable head.