If I wanted to pay homage to a sci-fi author, could I use his or her species in my story? (For example, Andalites from Animorphs; Formics from Ender's Game; describing a species that looks like Yoda or E.T.) Could I mention that species by name in passing? Could I hint by description that I'm alluding to a particular species? Could I get an author's permission to feature a character who is a member of that species? At what point would I be crossing a line?
Using another author's created species is something fanfic authors do all the time. It is legally something of a grey area in Anglosphere legal systems (I don't know anything about the situation elsewhere) - but in the last ten years the amount of fanfic has exploded beyond the ability of anyone to police it, even if they wanted to. It's when and if you start to make any money out of your story that your legal problems may start.