You should be making sure you're an expert on all the fish you want to buy before you buy them, which includes IDing by common and scientific names, and IDing by how they look when they are not labelled. Expect to spend at least a few hours researching each species you want to consider. Do not ever trust a single source and do become accustomed to which ones are more reliable. I do 99% of my research online as I can't quite afford the species reference books I mentioned earlier (not top of my list to get, at the moment).
If you email Trimar with the common name they have listed, they will be able to tell you the scientific names and these will be enough for you to research the fish.. or get a list of scientific names for the species you want and send those to Trimar asking which common names they use or directly for prices. Do talk to your potential suppiers, good ones will take their time to talk and will be helpful. Don't trust everything someone who will get your money says.
Do not impulse buy fish you don't know about.. this is the most common reason for stocking problems.