Sir Malcolm MacGregor of MacGregor, convener of the Standing Council of Scottish Chiefs, said Tory hereditary backbench peer Lord Lucas of Crudwell and Dingwall's Equality (Titles) Bill to allow the elder female to inherit titles "is not in the interests of the clan system".
The Scottish chiefs back women inheriting titles if there is no male heir - there are 10 female clan chiefs - but said there should be a clause in the new law that they should retain the family name to help maintain continuity of the title and the clan chiefship.
Lands and castles could be disputed and families split through the new law, it was claimed.
Titles come under the heading of constitutional matters reserved for the Westminster Parliament and there are also about 65 chiefs out of 150 who hold titles within the peerage and the baronetage.
Sir Malcolm said instead of the Bill, which completed its second reading in the House of Lords in December and is at committee stage, existing special legal compensations to allow females to inherit where there are no males should be made easier to obtain.
This can be done through the Lord Chancellor, but is a difficult process.
The campaign for equality in the peerage, which calls for the same changes to succession that were introduced for the royal family last year, won the backing of more than 300 prominent figures from parliament, the arts and society including 38 MPs from all parties and the former Home Secretary David Blunkett.
Sir Malcolm said: "If hereditary titles go through the female line, there is greater risk that the title might be separated from any clan chiefship, or chieftainship, if the husband of a future female title holder is not willing to change his name, or to allow his eldest child to adopt the clan name.
"From a Scottish perspective it might have been sensible to have a provision in the Bill stating that any heir to a title is bound to adopt the surname linked to the title thus keeping the title with the chiefship.
"It can be seen how chiefships could easily become separated from traditional clan lands and titles."
Sir Malcolm added: "If Angus Macsporran younger of Macsporran had an elder sister, called Heather, he would no longer be the heir apparent.
"How would the situation be reconciled if Heather becomes clan chief, but lives out of Scotland and is married to Richard Dawnay from an old English family in Devon?
"She is Mrs Dawnay living in Devon. On the death of her father she becomes chief of the Macsporrans. Does she change her name to Mrs Macsporran of Macsporran? What if she refuses? Can a Mrs Dawnay be chief of clan Macsporran?"
A working group including Sir Malcolm and leading QC Sir Crispin Agnew of Lochnaw who is chief of the Agnews is lobbying the Lords.
Sir Malcolm added: "There are examples where the chiefship has been separated from the title, because the title was destined to the heir male, but if all titles go through the female line there is a greater risk of separation. That is not in the interests of the clan system.
"While one can fully sympathise with the equality aspects, and the clan system needs to be modern and up to date, the fact remains that by law many of these titles are reserved for males only."
Historians believe the first clans emerged in the Highlands around 1000 years ago, forged out of different groupings based on family ties.
The word clan comes from the Gaelic "clann ", which means children or descendants. There would always be a clan chief, who took on the responsibility of looking after the people in his area.
It is not the case that everyone in a clan belonged to the same family. The chief and his progeny would be the most important figures, but many other clansmen were not blood relations. They would simply be people who lived locally and looked to him for protection.