RESUMO
Ornithodoros (Alectorobius) amblus Chamberlin 1920, adults previously were described inadequately. Practically nothing was known regarding the identity, hosts, distribution, and biology of this species. We redescribe both sexes, describe the nymph and larva, and present criteria for differentiating these stages from those of other members of the O. (A.) capensis group in the Western Hemisphere. Samples were collected from 13 localities on the Pacific coast and on offshore islands of Peru. Hosts recorded are the Peruvian Brown Pelican, Peruvian Booby, Blue-footed Booby, Red-legged Cormorant, Guanay Cormorant, and Inca Tern. These birds are not long-distance migrants and more widely distributed species of the O. (A.) capensis group have not been found parasitizing them. The life cycle is characteristic of the O. (A.) capensis group; the first nymphal instar does or does not feed. Humans are attacked eagerly by O. (A.) amblus and suffer afterward from severe inflammation and "incredible" pruritus, and possibly from more severe illness. Viruses infecting this tick are Punta Salinas (Hughes serogroup, family unclassified) and Huacho (Reoviridae, genus Orbivirus, Kemerovo serogroup). Dense tick populations cause breeding birds to desert numerous nests; thus, O. (A.) amblus is economically important to the Peruvian guano industry. Certain spiders and lizards may prey on this tick.