In persona episcopi is a Latin expression used by the Roman Catholic Church

Roman Catholic Church

The Catholic Church, also known as the Roman Catholic Church, is the world's largest Christian church, with over a billion members. Led by the Pope, it defines its mission as spreading the gospel of Jesus Christ, administering the sacraments and exercising charity...

 to indicate a union of two or more dioceses in which the dioceses are administered by a single bishop but undergo no alteration to their diocesan structures (eg seminaries, cathedrals, curia officials). In its mildest form such a union can be temporary, but in other cases it can be an intermediate step towards a union aeque principaliter

Aeque principaliter

Aeque principaliter is a Latin term used by the Roman Catholic Church to indicate a merger of two or more dioceses in which - to avoid questions of predominance - the dioceses are all given equal importance...

or a full union.

Examples

• Diocese of Fossano and Diocese of Cuneo
• Diocese of Moosonee and Diocese of Hearst
• Diocese of Huesca
  Diocese of Huesca
  The Diocese of Huesca is located in north-eastern Spain, in the province of Huesca, part of the autonomous community of Aragón...
  
   and Diocese of Jaca
  Diocese of Jaca
  The Diocese of Jaca is located in north-eastern Spain, in the province of Huesca, part of the autonomous community of Aragón...