No member of any planning commission and no member of any municipal agency exercising the powers of any planning commission, whether existing under the general statutes or under any special act, shall appear for or represent any person, firm or corporation or other entity in any matter pending before the planning or zoning commission or zoning board of appeals or agency exercising the powers of any such commission or board in the same municipality, whether or not he is a member of the commission hearing such matter. No member of any planning commission shall participate in the hearing or decision of the commission of which he is a member upon any matter in which he is directly or indirectly interested in a personal or financial sense. In the event of such disqualification, such fact shall be entered on the records of the commission and, unless otherwise provided by special act, replacement shall be made from alternate members pursuant to the provisions of section 8-19a, of an alternate to act as a member of such commission in the hearing and determination of the particular matter or matters in which the disqualification arose.