clause (3) Section 115BBC states the following:
(3) For the purposes of this section, “anonymous donation” means any voluntary contribution referred to in sub-clause (iia) of clause (24) of section 2, where a person receiving such contribution does not maintain a record of the identity indicating the name and address of the person making such contribution and such other particulars as may be prescribed.]
The words 'such Other particulars as may be prescribed' as stated in the section, would also mean that there is an requriement of PAN. Hence if PAN is not available then it would be treated as an anonymous donation.