Thank you,that was what I was trying to put across, you articulated it better than I.I think many of us know the difference between Herichthys carpintis and Herichthys cyanaguttatus.
A common name is what the fish is commonly called. Whether you like it or not, one of the common names for Herichthys carpintis is Texas cichlid. It is commonly called that even by those who are well aware of the differences between the 2 species. It has been called this by many, for at least 50 years.
Fish often have more then one common name. The names can be completely different from one place to another. Often, the names are not the same at all, in other languages. And they change over time. Many of the common names used for cichlids when I started in the hobby in the early '70's are completely different today! Through out the animal and plant kingdom, often a common name will refer to a whole group of species rather then just one.
And don't try to argue that because Herichthys carpintis doesn't come from Texas it can't be called a Texas cichlid. All kinds of common names can include countries or places that an animal or plant doesn't come from. Chinese algae eater, just one example of many. H. cyanguttatus is barely found in Texas. It's predominantly found in Mexico, as is H. carpinitis.
As was mentioned by Stanzzz7, many organisms can have the same common name. And most can have many more then just one. Use scientific names (both genus and specific name!) if you want to be clear and precise about what species you are referring to.