An account of the ticks of the northeastern of Spain (Acarina: Ixodidae).

The tick species commonly collected at the Northeast of Spain are reported in this paper. Data on hosts, temperature and humidity requirements, vegetation relationships, altitudinal distribution, and seasonal activity are included. R. sanguineus is commonly collected in areas with Mediterranean vegetation, esteppe, and semi-desertic esteppe, ranging from 190 to 1,000 meters above the sea level. R. sanguineus is related with sparse vegetal areas, and it is absent from areas with dense shrub or forests of every kind; sometimes, small populations may be collected in ecotones between Pinus spp. and esteppe formations. R. pusillus is closely related to areas of Mesomediterranean vegetation, sometimes subordinate to Pinus spp. and Quercus spp. The climate to which the species ally is always of continental type, with a hot and dry summer, and cold winter; although the species is commonly restricted to its main host, Oryctolagus cuniculus, several specimens have been collected from V. vulpes. Our data display the clear affinity of I. ricinus to the Supramediterranean vegetation (Aceri-Quercion faginae), places of Quercetum-Buxetum, as well as the Iberian Oromediterranean vegetation (Pinus sylvestris-Buxus sempervirens). Captures are scarce in forest of Fagus sylvatica, but data suggest that the species may be locally common on such places. Climate for the zones of collection of I. ricinus is Atlantic attenuated, with mild summers and humid winters. D. marginatus is strongly related to the xerophilic vegetation, widely spread through the Mediterranean, Supramediterranean, and hill levels, but does not colonize the true Oromediterranean vegetation. In our captures, the species is commonly collected in pubescent oak formations, but it does not penetrate in true forest associations.(ABSTRACT TRUNCATED AT 250 WORDS)