Why use the perfective "остаться" rather than the imperfective "оставаться" here?

Question

Кто бы мог представить, что в мире все еще остались такие уголки?

{instead of}: Кто бы мог представить, что в мире все еще оставались такие уголки?

I'd expected to see the imperfective verb here (in the sense of "still remaining"), so the use of the perfective verb (still remained) pulled me up short.

How exactly do the two verbs differ in meaning in this context?

Answer 1

Phrase #2 ("оставались") is in past tense. If the phrase #1 ("остались") is correct, then the phrase is supposed to be used in present tense, or, even if it talks about past, it is presumed that its meaning holds true in present as well.

Present tense for phrase #2 would be "остаются", which can be used interchangeably with "остались", but imperfective form implies that the process of disappearance is going on as we speak.

• "в мире все еще остались такие уголки" - there are (were) still places like that in the world (many disappeared, but some remain, and hold on);
• "в мире все еще оставались такие уголки" - there were places like that in the world (many disappeared, but some have remained, however by now they all might have gone)
• "в мире все еще остаются такие уголки" - there are still places like that in the world (many disappeared, but some are remaining, likely not for long)

Answer 2

Both are possible. You can't say either of them is incorrect.

"Кто бы мог представить, что в мире все еще остались такие уголки?" - more implies you are talking about today's world from the point of view of now (beatiful nooks, places still remain).

"Кто бы мог представить, что в мире все еще оставались такие уголки?" - makes sense if you are talking about the world in the past (or the world at a particular time in the past), and at that point 'some nice nooks, places WERE STILL REMAINING).

But in your sense (at present, still remain) the first variant is used.