As far as I understand, this is a buff-tailed bumble bee (Bombus terrestris). It was collected (dying) inside my house in Santiago, Chile. The species was intentionally introduced not far away, for agriculture, some years ago.
Looking for descriptions, I see it is huge for its species, queens reportedly being 20-22 mm (1, 2). I also learned that workers span a wide range of sizes, depending on age (but not this large, supposedly.)
Now, for the caste/sex, I'm stuck due to lack of experience. This site suggests looking at pollen baskets in the hind legs for females (I think I see one, but can't be sure since I don't know exactly what to look at, despite browsing some example photos), but then hairy hind legs (again, I think I might see them, but I'm much less confident) and facial hair for males (I don't really have a point of comparison, but it has some short, black hair in the frons: see expanded photo). Common descriptions also suggests buff color for the tails for queens, but I have seen white-tailed queens around too.
I'd really like to acquire the experience needed.
Is this an old worker, or something else?