18S RIBOSOMAL-RNA GENE-SEQUENCES AND PHYLOGENETIC-RELATIONSHIPS OF EUROPEAN HARD-TICK SPECIES (ACARI, IXODIDAE)

The complete 18S rRNA gene sequences of the following six European har d-tick species were obtained by direct PCR cycle sequencing and silver -staining methods: Rhipicephalus pusillus, Boophilus annulatus, Dermac entor marginatus, Hyalomma lusitanicum, Haemaphysalis punctata, and Ix odes ricinus. Differences observed in the sequence alignment of these sire species together with the 18S rRNA gene sequences of 13 other har d-tick species demonstrate that this gene is a good marker for suprasp ecific differentiation as well as genus grouping among hard ticks. Phy logenetic analyses strongly support that Hyalomma species share a comm on ancestor with Rhipicephalinae and, consequently, Hyalomminae should no longer be considered an independent subfamily. However, no definit ive conclusion could be reached to support or oppose the separation of the subfamilies Haemaphysalinae and Amblyomminae.