In this score to the Barber of Seville, these rightward pointing triangles appear. I first thought that it may just be an unusual way of showing the accent mark > but this also appears. Does anyone know what these triangles mean?
I've never seen this symbol before, but according to Dolmetsch, this triangle indicates:
strongly accented then immediate diminuendo
It's worth nothing that the example they give is also from Rossini, in his overture to Il signor Bruschino:
And this discussion on a Finale forum indicates that Rossini makes triangles of many of his crescendo and decrescendo markings by adding a vertical line to the wide end of the mark. I've somehow never noticed this; perhaps my Rossini scores have been edited.
In any event, my guess is that this notation is relatively Rossini-specific.