That's far more significant than discovering a new species, if it's true.
While I was reading through the article, I spotted this sentence:
It has not escaped our notice that the characteristics of these novel sequences are consistent with the possibility that they come from a new (i.e., fourth) major branch of cellular organisms on the tree of life.That sentence really jumped out at me, because it echoes another very famous sentence in biological science:
It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.That second sentence is from the 1953 article by James D. Watson and Francis Crick that first described the "spiral staircase" structure of DNA, and showed how DNA might replicate. It's the Nobel Prize-winning article that set into motion almost all of our later discoveries about how life works. The famous short article is perhaps the most frequently analyzed text in science, and that is one of its most famous sentences -- in part because of its hypercautious understatement. They'd pretty clearly made an electrifying discovery, and rather than make a bold pronouncement, they said, in essence, "Oh, yeah, and over here there's this possible ramification, which would be interesting."
For comparison, imagine a priest walking into a landscape where he sees a giant ancient ship parked on a mountain top, a burning bush, and a guy in sandals standing on top of a lake. He writes an article in a religious magazine describing these observations, and then says, "It has not escaped my notice that these may have religious implications." He leaves it at that. That's the sort of understated conclusion that Watson and Crick drew.
By echoing that statement, the "fourth domain" researchers are sending a weird, mixed signal: They're echoing one of the most cautious, humble lines in scientific literature, so you might think they're being equally humble and cautious. But by using that language, they're also clearly associating themselves with some landmark, world-changing discoveries. Intentionally or not, they're implying that "We've found something on the scale of that DNA discovery."
If I had to guess, I'd say the echo of Watson & Crick is a deliberate signal to the community. It's saying, "Officially, on the record, we're not drawing conclusions, but we're letting you know that off-the-record, we think we're onto something huge." If that's the case, it's not remotely humble or cautious at all. It's just clever.