Is that it?

I've seen 26 episodes. That's how many are listed here on IMDB.

Weird how they stopped at 9/10. They showed that entire batch at the beginning of 2012, the next twelve at the end of 2012 and the four newest ones at the end of last year, after the four episodes of The Young Montalbano.

I wouldn't be surprised if they made four more of each last winter (as the beach outside his house is too busy spring-autumn) and BBC4 has them up their sleeve for airing sometime starting in October.