The beginning of the name Thesenvitz starts on the isle Ruegen in Baltic Sea. You will find a very small village 4km away from town Bergen. You can find here it on Google Maps.
On the isle Ruegen you will find a huge number of families with the surname Thesenvitz. You just need to take a look into the local telephone directory or here
The original meaning of Thesenvitz comes from Slavic word “Tesenovici” and stands for “people of Tesen” similar to the west Pomeranian town Thessenstorp (nowadays Testorf) and Tessenow.
The village Thesenvitz was founded in the 14th century by squires from Gagern selling their pensions to the abbey Marienkron in Stralsund.
Especially in the 18th century the village was strongly prospering to its actual size and population. More details you can find here and here in German language only.