Are you talking about species description where new found species are given a name by the one describing them in an scientific article for the first time?

In that case: The author describing the species is free in his choice of a scientific name and may use Latin, Greek or any other language (or a fantasy name) they see fit. Within certain boundaries of course (for example a species must have a name with two parts that is written in Latin letters etc)

http://www.iczn.org/iczn/index.jsp

Here is the exact code if you're interested further