Air carrier Captain reported the new transition taxi lanes at ORD airport are not clearly marked and cause confusion as to how to properly transition from the entry point to the intended taxi lane. Additionally; the transition lines are only available on the AMM and are not depicted on the airport pages.

Narrative

We were taxiing into the gate at ORD. As we approached Taxiway CS; we were cleared into the Ramp. Our instructions were to enter the Ramp via CS and then transition to the B taxi lane to the gate. While we were on CS; I saw on my Airport Moving Map (AMM) taxi chart that the B taxi lane diverts early to the right. As we were abeam the turn; I stopped the aircraft for clarification. We asked if we could take the C taxi lane and then transition to B to the gate due to the position of where our gate was located. The Ramp Controller approved our request. We arrived at the gate as scheduled. The reason why I am writing this report is mainly due to the new transition taxi lanes on the Ramp when you enter from the south port. These taxi lane lines can be confusing when having to transition from one taxi lane to the other. There are several transition taxi lines on the ground and they are not clearly marked in how they exactly transition from the entry point to the intended taxi lane. These transition lines are only available on the AMM and not depicted on the 20-9. I have had several occasions where you have to check the AMM multiple times to make sure you are transitioning from the Ramp entry point to the correct taxi lane due to multiple taxi lines going in multiple directions.