Finlay Carson has joined at least 20 other Conservative MPs and MSPs calling for Dominic Cummings to step down.
The Galloway & West Dumfries MSP described Mr Cummings' position as 'untenable', though says the decision is for the Prime Minister to make.
In a statement, Finlay Carson MSP said: "I understand, and indeed very much share with many, frustration at this situation.
"When the effort of all levels of government, and every one of us fortunate enough to serve in parliament, should be focused exclusively on dealing with the current crisis, there is simply no time for distractions such as this.
"While it is a matter for the Prime Minister to determine who advises him and for how long, my own view is that rules must be applied equally and without favour.
"My personal opinion is that Mr Cummings' position is untenable and should step down.
"We have come too far together over the last two months, and with such great personal sacrifice on the part of millions of ordinary people, for anything other to be the case.
"As MSP for Galloway & West Dumfries...my own focus will remain resolutely on the task at hand - to hold the Scottish Government to account in the Scottish Parliament and provide the principled and constructive opposition our country needs at this time, to help get us all through the Covid crisis."
In a statement, Mr Ross said: "I have never met Dominic Cummings so my judgement on this matter has always been open and I accept his statement on Monday afternoon clarified the actions he took in what he felt were the best interests of his family.
"However, these were decisions many others felt were not available to them."
He added: "I have constituents who didn't get to say goodbye to loved ones; families who could not mourn together' people who didn't visit sick relatives because they followed the guidance of the government.
"I cannot in good faith tell them they were all wrong and one senior advisor to the Government was right."
Following Mr Ross’ resignation, Scottish Secretary Alister Jack said: “I would like to thank Douglas Ross for his contribution as a minister at the Scotland Office.
“I know he will continue to be a dedicated and hard-working constituency MP for Moray.”
MP for Copeland and the Prime Minister's private secretary Trudy Harrison has defended Mr Cummings' actions on Tuesday afternoon. She said:
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