Lutrai are a specific fictional race of otters created by Ollie Canal. They are chiefly distinguished from non-lutrai otters by their tribal aesthetic. Not all otters are lutrai, but all lutrai are otters.

I'm technically uncertain that we need a lutrai tag. The only thing that distinguishes them from normal otters are the presence of tribal aesthetics and in particular a characteristic pattern of tribal_markings (note that the tribal markings tag is a minor tag that is not reliably applied to lutrai images). Since lutrai are entirely defined as a race of tribal otters, a search for tribal and otter should turn up all correctly-tagged images which are unquestionably images of lutrai.

If retained, the lutrai tag should imply otter. If eliminated, it should be converted to an alias of otter.

Unlike many other fictional species, one being khajiit, there's no real way of distinguishing this race from what it was originally based on (in this case being otters). In my opinion, tag what you see should be applied here and lutrai should be aliased to otter. If not aliased, at least implicated.