The moon is offically called “S/2011 (134340) 1″. The moons are named like that with the discovery year on they Provisional designation. 134340 is the minor planet number of (134340) Pluto.

Many minor planets have names that start with the same alphabet (and some do not have a name at all yet) so their moons cannot be named same way as the planetary moons (year, planets names first alphabet, number that tell order that that moon was foud that year). One example: The moon of (243) Ida was known as “1993 (243) 1″ before it was named Dactyl.