"She was a wonderful asset to Aratoi. It will be much the poorer for her leaving."
Mr McLachlan said he understood Aratoi's financial position was sound and the museum had always had "a clear audit".
Marcus Boroughs, he said, was one of the top directors in New Zealand and was entitled to much of the kudos that the gallery received from the public.
Mayor Garry Daniell said he knew of the problem.
"I am aware there is some disquiet and I just hope we can resolve it as soon as possible so we can feel confident of Aratoi's potential development."
Mr Daniell said his council had requested a complete review of Aratoi before Christmas.
"We were curious about the adequacy of funding in the event of extensions to Aratoi," he said.
The new chair is barrister Kristy McDonald. Other members are retired police commissioner Robbie Robinson, Ian Grant, Barbara Roydhouse, Stephanie Turner and Paul Melser.
Mrs McDonald said problems at Aratoi were not personality clashes but were "in-house' at board room level.
She said the board "unanimously" backed a review and was committed to tightening governance and to "rigorous processes" that would ensure a proper oversight of the museum's operations.
She confirmed Fiona Reid had resigned.
Mrs Reid could not be reached for comment and Friends of Aratoi chair Penny Bunny would not comment.
Aratoi director Marcus Boroughs also declined to comment.
The museum receives a grant of $235,000 a year from Masterton District Council. Other principal funders are Carterton District Council, South Wairarapa District Council, Trust House, Lands Trust Masterton, and Prime Community Trust.