Claim: The longest reigning Princess of Thurn and Taxis was Margarethe Klementine of Austria, and the longest-serving Countess was Countess Anna of Horne, on the other hand, the shortest reigning Princess of Thurn and Taxis was Charlotte Louise de Lorraine, Countess de Lambesc.
Evidence: Margarethe Klementine of Austria 15 July 1890 22 January 1952
husband's death Countess Anna of Horne 6 February 1650 13 September 1676
husband's death Charlotte Louise de Lorraine, Countess de Lambesc 22 March 1745 6 January 1747 1695
husband's creation as Prince 13 November 1701 21 November 1703 21 September 1711 21 February 1714
husband's ascession 8 November 1739
husband's death 21 September 1750 4 June 1772 17 March 1773
husband's ascession 1776
divorce 13 November 1805
husband's ascession 15 July 1827
husband's death 24 August 1828 14 May 1835 24 January 1839 10 November 1871
husband's death 22 January 1952
husband's ascession 12 January 1970 26 April 1982
husband's ascession 14 December 1990
husband's death 5 May 1612
husband's accession 7 July 1624
husband's death 7 July 1624
husband's accession 23 May 1628
husband's death 24 March 1678 1695
husband's creation as Prince