Tick Classification, External Tick Anatomy with a Glossary, and Biological Cycles

The superfamily Ixodoidea contains the families Argasidae (208 species), Ixodidae (722 species), and the African Nuttalliellidae (monotypic). Argasidae is formed by five genera with three present in the Southern Cone of America: Argas, Ornithodoros, and Otobius, while there are 12 extant genera of Ixodidae and 5 are established in the region: Amblyomma, Dermacentor, Haemaphysalis, Ixodes, and Rhipicephalus. Ixodidae is divided into Prostriata and Metastriata groups; the first group contains the genus Ixodes and the second the remainder genera. Main external morphological characters with relevance for genera and species differentiation are described and figured in a glossary for these main characters. The parasitic cycles of Ixodidae are one-, two-, or three-host cycles, while most species of Argasidae have a multihost life cycle but one species, Otobius megnini (present in the region) has a one-host cycle and another, Argas lahorensis (not established in the region), has a two-host cycle but the parasitic sequence of many species remains unknown.