From Germano- + -sphere, by analogy with Anglosphere.
Germanosphere
- The collection of German-speaking countries
2010 July 15, Panu <craoibhin66@gmail.com>, “Re: The name Mehserle”, in sci.lang[1] (Usenet):Anyway, both Messerli, Messerle, and Meserle (possibly even Mehserle with that very orthography) are demonstrably existing family names in the Germanosphere.