I'd like to import gendarme reports into sonarqube.
A sonar-csharp-gendarme-plugin existed once for this purpose, but seems to have been abandoned.
Is there any replacement?
There is no replacement, and it is not supported. Gendarme is an inactive project for quite a while, and I really doubt its development will resume: Indeed, like FxCop, it does analysis based on the assemblies, not directly on the source code.
Now, with Visual Studio 2015, Roslyn analyzers are executed live as you type. This raised the bar of what people expect from code analyzers, and FxCop analyzers as well as Gendarme ones should be rewritten using Roslyn to improve the end-user's experience.
Now, if you really would like to, you still could develop a SonarQube plugin to integrate Gendarme results, but I don't think it is a good idea.