What does this upward dark triangle above the piano staff mean?

Question

What does the triangle in the notation mean. Looks like an accent, but I've never seen this symbol anywhere before, and couldn't find any info on the Internet.

The piece is Bartok's "Highwayman's Tune" from For Children (Sz. 42, No. 77 [or, Book 2, no. 35]).

Answer 1

It's just a variation on the more standard caret symbol, indicating a sharp — marcato — accent. It's typically interpreted as both accented and staccato, but in this case, since there's a tenuto mark, it's just a particularly accented accent, so to speak.

Here's the same measure from another edition:

_{(Image Source: IMSLP, Hungarian first edition)}

Masterclass.com has a good summary of accent symbols. Wikipedia's "Marcato" entry is also helpful.