I was just finishing up a normal throdama's pheromones, and was blocked completly from an island. I have had this happen before and it didnt really bother me because I have other pets who are strong and would have no hassle with this problem. But I can imagine players taking average pets or new pets and suffering horribly. Not sure if this is a bug at all but I would hope the bosses blocking island access can be moved away or removed.

I've had this happen before with all of the species. I don't believe what you're calling a boss is actually a boss, that monster only has the one form, whether it's guarding a chest or not, but that's irrelevant. It's rather frustrating when going out with weaker pets and getting stuck, especially if it's right off from the portal. I once was on an island where I had to fight 4 monsters in a row who were blocking me from reaching the main island. Luckily I had a strong enough pet out for that.

I think it is a boss because the fire salamander guys are tougher than the rest of them. This throdama can breeze through any of the normal monsters but the bosses not so much, especially this one who just wouldnt go down.

I definitaly didnt smush the salamander's icon on my computer screen in an attempt to magically squash it.

Good thing your pet was able to make it through the four in a row. For a really weak pet that would of been end of exploration. Seems like the monsters are randomly placed...hrm hrm I may go test something when I get some islands back.

It's not a bug. Island shape is random, and creatures living there may decide to choose any place. Salamanders are normal full-powered monsters that aren't bound to the treasures and interested in the living territory itself. This is a feature of this particular monster type. There are no such monsters outside grasslands at this moment.