The external and internal morphology of the female nuttallielid tick Nuttalliella namaqua is reviewed in relation to argasids and ixodids. External characteristics of Nuttalliellidae relating to Argasidae are the general integument structure, unarmed coxae, hypostome structure, and absence of porose areas. The anteriorly arised capitulum, presence of pseudoscutum (? true scutum), and structural similarity of dorsal and ventral integuments are ixodid characteristics. Unique features to Nuttalliellidae are 3-segmented palpi, pseudoscutum, ball and socket joints, and fenestrated spiracular plates. Internal characteristics of Nuttalliellidae relating to Argasidae are stomach lobe numbers and arrangement, number of Malpighian tubule loops, transverse position of the ovary, bilobed uterus, vaginal division into cervical and vestibular parts, absence of cervical chamber and seminal receptacle, and number of main tracheal trunks. Features relating to Ixodidae are unlobed rectal sac, connecting tube joining uterus with the cervical part of vagina, and presence of a valve between the two parts of vagina. Gene s organ saccular numbers and arrangement are unique to Nuttalliellidae. Thus, the external and internal morphology of Nuttalliellidae combines certain characteristics of the Argasidae, and Ixodidae and also has characters unique to this family. However, N. namaqua will stands as a mysterious tick species among biologists until data on its biology, histophysiology and life-cycle become available. Therefore, it is difficult at this time to determine whether Nuttalliellidae is closely related to Argasidae or Ixodidae.