Each of these groups contain one or more separate species.

However, it has been considered a separate species since 2001.

They would be on their way to becoming separate species.

It was not recognized as a separate species until 1991.

The two are now usually considered to be separate species.

Why do you talk as if they are two separate species?

They seem to regard us as a separate species, not really human at all.

It was not realized that they were a separate species until the 1920s.

Later, when more remains were found, it was realized they could have been a separate species.

It was not described as a separate species until 2002.