A screenshot guide to the location of the map data nodes in each zone.
I just ran through and found the map nodes, and figured I'd screenshot them and share. They're not particularly hard to find, but if you just want to get it out of the way, here you go. Minor spoilers ahead, obviously.
In the section near the slime door, facing the water on the left.
In the cave with the Rock Gordo, to the left of the exit to the north.
On a plateau to the west of the center section, behind a tree.
To the right of a platform that's to the right of the door leading to the last section before the hallways towards the Glass Desert teleporter.
In the section with the Tangle Gordo, beneath the platform, to the right of the northwest slime door.