Insignia of Italian restaurant two crayfish in Bologna - majolica

Which crayfish was referred the Oste, who about five hundred years ago advertised his "Good Gambari" in Bologna?
It is the now rare Austropotamobius pallipes italicus (the white-footed shrimp), the Italic crayfish.
Once very common in Italy, crayfish has been very rare in the last forty years due to pollution, mainly due to pollution caused by pesticides, and the destruction of the habitat in which it lives, until it becomes really rare.