Injured Ramsey not in Wales squad
Ramsey, 25, is nursing a hamstring injury and will miss the Euro 2016 semi-finalists’ opening Group D fixture against Moldova in Cardiff on September 5.
Real Madrid star Gareth Bale is included, but Crystal Palace playmaker Jonathan Williams is also injured and Nottingham Forest midfielder David Vaughan, 33, has retired from international football.
“When you’ve got a player as good as Aaron, take him out of any team and you are going to know about it,” Coleman told a press conference.
“He is irreplaceable. He makes a huge impact for us. He is a great player and it’s a shame he’s not here. He’s a loss to any team.”
Coleman described Vaughan, who made his international debut against the United States in May 2003, as “a great servant for Wales”.
Ramsey, Williams and Vaughan were the only absentees from the squad who reached the last four at Euro 2016 in France before falling to eventual champions Portugal.
Hal Robson-Kanu, one of Wales’s stars of the tournament, was called up despite being without a club following his departure from Reading.
Newcastle United full-back Paul Dummett, Cardiff City midfielder Emyr Huws and Leicester City striker Tom Lawrence have all been drafted in.
Wales will also face Austria, Serbia, the Republic of Ireland and Georgia in Group D as they bid to qualify for a first World Cup since 1958.
The Football Association of Wales recently rejected an approach for Coleman from Hull City and he said he was fully committed to the World Cup qualifying campaign.
“There was an approach, the FAW turned it down and that is the end,” Coleman said.
“I’m fully focused on what I have to do for my country, am looking forward to this next challenge and am ready to go.”
Goalkeepers: Wayne Hennessey (Crystal Palace/ENG), Danny Ward (Huddersfield Town/ENG, on loan from Liverpool/ENG), Owain Fon Williams (Inverness Caledonian Thistle/SCO)
Defenders: Ben Davies (Tottenham Hotspur/ENG), James Chester (Aston Villa/ENG), James Collins (West Ham United/ENG), Chris Gunter (Reading/ENG), Jazz Richards (Cardiff City), Neil Taylor (Swansea City), Paul Dummett (Newcastle United/ENG), Ashley Williams (capt, Everton/ENG)
Midfielders: Joe Allen (Stoke City/ENG), David Edwards (Wolverhampton Wanderers/ENG), Andy King (Leicester City/ENG), Joe Ledley (Crystal Palace/ENG), Emyr Huws (Cardiff City), George Williams (Milton Keynes Dons/ENG, on loan from Fulham/ENG)
Forwards: Gareth Bale (Real Madrid/ESP), Simon Church (Milton Keynes Dons/ENG), David Cotterill (Birmingham City/ENG), Tom Lawrence (Leicester City/ENG), Hal Robson-Kanu (unattached), Sam Vokes (Burnley/ENG)