Han Meng-Qi is an expert on Petrocosmea in China, and photographed this nice example of P. barbata while on a research expedition. He reports that P. barbata is very similar to P. glabristoma, and that the most easily seen difference is in the degree and nature of yellow coloring in the throat. In P. barbata, any yellow color forms a single spot that does not extend into the throat. In P. glabristoma the yellow is in the form of two dots (sometimes merged) and typically extends into the throat. The overall flower shape is also somewhat different.