Ospreys lock James King and clubmate Eli Walker in a 35-man panel.
Walker's inclusion comes after yet another fine display at club level, with the young wing setting up Jonathan Spratt's late try in the Osprey's Heineken Cup draw with Leicester on Sunday.
Wales also welcome back Lions tight head Adam Jones and fellow prop Craig Mitchell in a squad captained by openside Sam Warburton.
Lee Byrne's impressive displays for Clermont Auvergne have won the 2009 Lions full back a recall after he was overlooked in the summer and the 31-year-old will now look to press his claims for a second successive adventure with Britain and Ireland's elite this June.
Ryan Jones and Richard Hibbard are both named despite a dislocated thumb and problematic shoulder respectively but locks Luke Charteris, Bradley Davies and Alun Wyn Jones were not considered for initial selection due to injury.
First-choice fly-half Rhys Priestland is also missing with what appears to be a season-ending injury, while last year's player of the tournament Dan Lydiate hasn't yet made his return from ankle surgery.
"We have put together a very experienced squad and complimented that by rewarding the in-form players with a call-up,"said Howley.
"The players in the squad have been playing really well and we have been pleased with their individual performances.
"We have a group of players who know how to win big matches and have experienced success. We are adding to that, players who have stood out and performed well for the regions this season."
Howley also announced the appointment of ex-Wales wing Mark Jones to his coaching staff for the duration of the Six Nations.
Jones, who is currently attack coach at his old side the Scarlets, had already been confirmed as part of the backroom staff for the summer tour of Japan but will now link up with the camp later this month before rejoining his region in March.
"Mark is an important addition to the coaching team," added Howley.
"He has played the game at the highest level and developed his coaching skills during his time with the Scarlets.
"He is a 'hands on coach' and understands how our environment works, which is important leading into the tournament.
"I'd like to thank Simon Easterby and the Scarlets for allowing Mark to join us and to start work immediately.
"We have always been an integrated coaching team and Mark will be a great addition alongside Robin (McBryde), Shaun (Edwards) and Neil (Jenkins)."
Forwards: Scott Andrews (Blues), Craig Mitchell (Exeter Chiefs), Adam Jones (Ospreys) Paul James (Bath), Gethin Jenkins (Toulon), Ryan Bevington (Ospreys), Richard Hibbard (Ospreys), Ken Owens (Scarlets), Matthew Rees (Scarlets), Ryan Jones (Ospreys) Lou Reed (Blues), Ian Evans (Ospreys), James King (Ospreys), Andrew Coombs (Dragons), Josh Turnbull (Scarlets), Josh Navidi (Blues), Aaron Shingler (Scarlets), Justin Tipuric (Ospreys), Sam Warburton (Scarlets), Toby Faletau (Dragons), Andries Pretorius (Blues)
Backs: Tavis Knoyle (Scarlets), Mike Phillips (Bayonne), Lloyd Williams (Blues), Dan Biggar (Ospreys), James Hook (Perpignan), Jonathan Davies (Scarlets), Jamie Roberts (Blues), Scott Williams (Scarlets) Alex Cuthbert (Blues), George North (Scarlets), Eli Walker (Ospreys), Leigh Halfpenny (Blues), Liam Williams (Scarlets), Lee Byrne (Clermont)