Hard ticks are found in all six zoogeographic regions, but the distribution of the species in different genera is not uniform. The genus Ixodes has the widest distribution, occurring across the six zoogeographic regions; 32 species (13 %) occur in more than one zoogeographic region. Seven species of Ixodes have a broad distribution because they are established in three or more zoogeographic regions or, in the case of I. kerguelenensis, in the Australasian Region and on islands in the Atlantic, Indian and Pacific Oceans, while I. uriae has a circumpolar distribution, including adjacent islands and continental lands. Members of this genus are remarkable for parasitizing Aves on remote islands and around the poles. The Afrotropical Region contains the greatest number of Ixodes (63 species or 26 % of the total for the genus), followed by the Palearctic Region with 44 (18 %) found exclusively there. A total of 138 species (57 %) are currently known only from lands that constituted the ancient continent of Gondwana; this percentage increases to 69 % for the 169 species established exclusively and non-exclusively in these lands. On the other hand, 74 species (30 %) are exclusively found in lands derived from the ancient continent of Laurasia.