"The Tiger" usage in the above examples is correct.
Explanation: We can also use the definite article with a singular countable noun to refer to the entire class that the noun belongs to. This is often done with species of animals, inventions, or musical instruments:
Example: The honey possum of Australia is the only mammal that lives exclusively on nectar.
- Now we look into the usage of "a feline species."
Species is both a singular and plural noun.
Examples: A new species of this plant has been discovered.
(Notice the "has" indicating species as singular here)
Many new species of this plant have been discovered.
(Many and have are establishing species as a plural here.)
Also, species is an arbitrary example of the many species that exist in this world (Not like the earth, sun, or atmosphere which is unique). With arbitrary nouns, we use the indefinite article. For example, "An elephant is a mighty animal". Here, animal is an arbitrary noun as there are several animals that exist.
So the correct one should be "The tiger is an example of a feline species."
We use 'a' in this example as feline is a word (adjective) that starts with a consonant. Take another example, Black Rhinos are an endangered species. Here 'an' comes because of the vowel sound of the adjective.