First Minister Alex Salmond's parliamentary aide has issued an apology to MSPs for showing disrespect to parliament.
Backbench MSP Joan McAlpine failed to turn up in the chamber during her ministerial questions slot.
She was spotted having lunch with Mr Salmond in the parliamentary restaurant shortly before Presiding Officer Tricia Marwick issued her rebuke.
Ms McAlpine has previously missed chamber speaking appearances.
Ms McApline's previous breaches of the parliamentary etiquette total six occasions including failing to be present in the Holyrood chamber to ask a question and not being present during full debates in which she was due to speak.
The Scottish Parliament said that Ms McAlpine had failed to lodge or ask parliamentary questions on a total of four occasions.
She was also written to by the presiding officer regarding her absence during two parliamentary debates on Scottish studies and architecture, at which she did speak.
The South of Scotland SNP MSP told the chamber she had "lost track of time" in the latest case and promised to reflect on her behaviour.
Ms McAlpine had been due in the chamber on Thursday afternoon to ask ministers about cases of osteoarthritis and its impact on the NHS, during themed question time.
But her failure to turn up resulted in a ticking off from the presiding officer, who demanded an apology.
For lunch in the parliamentary restaurant, Ms McAlpine was understood to have had smoked venison with Strathdon Blue cheese dressing and poached red wine pear, followed by breast of Scottish chicken with grilled asparagus chorizo, olives and parma ham.
The first minister had asparagus and soup.
Ms McAlpine told MSPs later: "I wish to apologise sincerely for my absence from the chamber at health and wellbeing question time this afternoon.
"I realise this is not the first time I've done this and I do understand the gravity of the matter.
"The fault is entirely mine, I'm afraid I completely lost track of time. I realise I've no excuse for not being present in the chamber when required.
"I apologise for showing such disrespect, not only to yourself presiding officer, but also to parliament and to my fellow MSPs.
"I take this as a salutary lesson which I will reflect on."
"Noting" Ms McAlpine's explanation, the presiding officer said: "It is a great privilege to be a member of the Scottish Parliament, and I expect all members to carry out their duties diligently, on behalf of the people who elected them.
"Let me make it clear that, as presiding officer, I will not tolerate discourtesy in this chamber or to this chamber."
The afternoon chamber session came after first minister's questions, where Mr Salmond again declined to say whether he had been the victim of phone hacking, and told MSPs that his evidence session before the Leveson Inquiry on media standards was the appropriate forum to address such issues.
Scottish Liberal Democrat leader Willie Rennie said: "Joan McAlpine shows as much respect for parliament as the first minister. His excuse is Leveson, hers is lunch."
A Tory spokesman added: "On this occasion, Ms McAlpine decided that having a lunch date was more important than parliamentary business. Ms McAlpine has treated parliament in a contemptuous manner."
Labour's Claudia Beamish said: "As a newspaper columnist and ministerial aide to the first minister, representing her constituents is clearly low down Joan McAlpine's list of priorities and she is making a habit of missing her appointments in the chamber.
"Rather than lunch dates and fine dining with the first minister, she should be doing the job she is paid to do and standing up for the people she is supposed to represent."
A spokesman for the first minister, said Ms McAlpine offered a "full and fair apology" to parliament, adding: "she will of course continue in her role as one of the first minister's parliamentary liaison officers, in which she does an excellent job."