These are the standard for imitators and they imitate the R. variabilis. You may here them referred to as 'Standard,' or 'Green,' or other terms. I prefer the term 'Nominal.' They have been in the hobby the longest, and tend to be the most hearty, healthy, and visibly active.They also happen to be the cheapest of all the imitators sporting the color green with black dots and reticulated blue legs. While these are great imitators I admit their green makes them harder to to see in a vivarium, which may be one of the reasons they are the least expensive.
While there is no location specific information on where they come from, it is presumed they are from the Cainarachi Valley of Peru, since they are very similiar in appearance to R. imitator 'Cainarachi Valley.' While this is most likely correct, they should never be mixed with the location specific 'Cainarachi Valley.' This is simply because the resulting offspring could be a mix of different locations.
My group come from the Phil Tan line. Some lines of Nominals may appear very yellow and almost like Tarapotos, making you wonder where one imitator morph starts and the other ends. Remember that in the wild geographical locations are never completely isolated.