Major props to whichever Pathfinder author brought the nuno into the game. It’s a Philippine monster (short for nuno sa punso, "old man of the mound") that Bestiary 5 gave a mushroom makeover and a branch on the gremlin family tree. Best of all, B5 managed to translate many of the nuno’s original folkloric elements into game mechanics, such as the Nuno’s Curse (Su) and the delightfully one-of-a-kind Wax Locator (Su) vulnerability. (In fact, my only quibble is that I think the Bestiary team should have added termites to the nuno’s Ant Affinity (Su) description—I recommend you house-rule that one.)
It’s notable that while nunos are gremlins, unlike their kin they don’t go out of their way to proactively wreak havoc on others. Instead they save their spite for those who disturb their homes…but those who suffer their unkind attentions will have no doubt that a nuno can be as spiteful as any jinkin. You can also be sure that any villagers who live near a nuno will have a number of traditions to make sure they stay on the gremlin’s good side (as well as folk remedies to cope with any curses hurled their way).
Perhaps because they are more solitary creatures, some nunos become ascetics. Most likely become geokineticists or psychics, but rare individuals might become mediums (if their mound is located near a place of power) or even spiritualists (the phantom likely coming from a corpse the mushroom-like nuno once fed upon to learn its secrets). Nuno ascetics even get to customize their curses, which gives each one an individual signature. (Revealing the extra details about a well-known nuno ascetic to PCs who take the time to make nice with the locals is a good in-game pat on the back.)
One final note: The mound the nuno’s full name refers to of course means an ant or termite mound…but faerie mounds of quite another sort are also part of the legends of British Isles faerie stories. And this happy accident of language is a great excuse to mash both traditions together.
Adventurers come across a young tanuki in the throes of agony after having disturbed a nuno’s mound. If the adventurers can alleviate his suffering—most likely by dispatching the gremlin, but other means might be found—the tanuki will reward them with his grandmother’s magical cloak of transformation. Of course, he doesn't have the grandmother’s permission to offer up such a treasure, which may get the party into trouble with an entire village of sake-enraged raccoon-dog-folk.
A group of youths become adventurers after a giant ant abducts one of their sisters. A nuno took a fancy to her and wants her to sit for a portrait, so that he may have her image in his lair forever…but he thought nothing of sending one of his giant ant servitors to fetch her, rather than just asking.
At the winter solstice, the trooping faeries come to the faerie mound of Dun Gallar. Led by the bronze-clad sidhe lords (treat as elves with the fey creature template), the fey circle around the mound three times until it rises up and opens to greet them. There they remain for a week, before vanishing into the Underworld to return to their homes by spring. The rest of the year Dun Gallar is guarded by the Old Man of the Mound. This powerful nuno ascetic is said to draw power from the keepsakes of all the mortal heroes who have died beneath his faerie mound when they foolishly challenged the sidhe for one reason or another.
—Pathfinder Bestiary 5 132
The fact that I came down with fever yesterday afternoon as I was writing this was all that saved you from timely puns about the Nuno, the Pinta, and the Santa Maria. You’re welcome.