Earlier this month we showed you a list of Sony devices that will be updated to Android 6.0 Marshmallow. At that time we did not know when it would happen and if before they would have their portion of Android 5.1 Nothing could be further from the truth, those Xperia devices that are on the list will be updated directly to Android 6.0 Marshmallow.
As you well know the Sony Xperia Z2, Z3 and Z3 Compact already have Android 5.1 L, but most of the Xperia phones that are going to upgrade to Android 6.0 Marshmallow will be upgrading from Android 5.0.
These are the Xperia phones that will receive Android 6.0 Marshmallow without going through Android 5.1
According to Sony's official website, the following Xperia devices will receive the latest version of Google's operating system without the need to receive Android 5.1: Xperia M4 Aqua, Xperia C4, Xperia C5 Ultra, Xperia M5, Xperia Z3 +, and Xperia Z4 Tablet.
We don't know the exact date in which these devices will be updated to Android 6.0 Marshmallow, although we can expect that in the coming months the expected updates will begin to reach users.
You'd expect Sony to jump straight from Android 5.0 to Marshmallow. Why compile the update to Android 5.1 if I can directly launch the latest version of Google's operating system?