**Acknowledgements**

We are grateful to all members from the Centre of Rickettsiosis and Arthropod-Borne Diseases, Hospital San Pedro-Centre of Biomedical Research (CIBIR), Logroño (La Rioja), Spain. We also thank to Dr. Shatrov and Dr. Stekolnikov from the Zoological Institute of the Russian Academy of Science, St.-Petersburg, Russia, and Dr. Takahashi from the Saitama Medical University, Saitama, Japan, for providing us the pictures and for their invaluable help. Financial support was provided in part by two grants (FOMENTA 2007/14 and PREDOC 2008/29) from "Con‐ sejería de Educación, Cultura y Deporte del Gobierno de La Rioja", Spain.
