Hmm, there is something funky there. The construct is subdivided twice during renders, so it's very high-res. I just did a quick test using only the dome as a 30% white emitter, and the ground just plain white. I have used the "GPU High Quality" preset in Superfly, and has worked as expected. No lines showing up. I have reduced pixel samples all the way down to only 10, and it gets grainy, but still no lines.
I used to have issues with lines in the past, but only with Firefly, and those were caused by wrong params on the ambient occlusion settings. The lines would show because the AO bias size was big, to the point where FF was placing shadows at the wrong places, which caused the lines to appear. Adjusting the AO bias tolerance would fix this, and it was tricky because it depended on the background mesh density. But SF doesn't have such issues because it's not a biased renderer. I wonder why that happens in your renders.