In 1967, Vermeil and Marguet described Ornithodoros coniceps maritimus from larvae reared from larvae taken from marine birds on Dumet Island (Atlantic Ocean), Basse Bretagne, France. We collected O. (A.) coniceps Canestrini, 1890, from the type locality (Venice, Italy) and determined that the taxons coniceps and maritimus each require full species status. We selected a lectotype and paralectotypes for the taxon maritimus from the original Dumet Island material. The larva of maritimus is redescribed and the nymph, male, and female are described for the first time. Collection data are recorded from Dumet and other islands off France, Aegimures Islands off Tunisia, Puffin Island off northern Wales, and Great Saltee Island off Ireland. This tick infests nesting colonies of the common tern, roseate tern, sandwich tern, herring gull (northern and Mediterranean races), common cormorant, shag, razorbill, common murre, black-legged kittiwake, and probably other marine birds nesting nearby. Adults and nymphs (tentatively identified as maritimus but lacking associated larvae for full confirmation) were taken near nests of the little egret in Lake Tunis, Tunisia. Soldado virus was isolated from Puffin Island tick samples and a Soldado-like virus from Great Saltee Island tick samples. An experimental study of West Nile virus in the Tunisian tick population is reviewed. The birds species associated with maritimus in each collecting locality, and their nesting and resting habits and migration patterns in relation to tick and arbovirus survival and distribution, will be reported in the following paper in this series.