The Bowsers on the Nyrian habitat list.
The Bowsers habitat was one of the ninety-four environments found on board a Nyrian biosphere vessel in 2373.
A list of habitats was discovered by Tuvok which included the Bowsers as Kathryn Janeway accessed the Nyrians' computer systems. (VOY: "Displaced")
The name "Bowser" is most likely a reference to the main antagonist of Nintendo's Mario franchise.