The specific status of the Cape brown tick Rhipicephalus Koch, 1844, is not quite clear. Some authors (Neumann, 1905, 1907; Dias, 1953) divided into several subspecies which others subsequently synonymized (Zumpt, 1942, 1950; Theiler, 1943) or elevated to specific rank (Dias, 1951; FeldmanMuhsam, 1956). While studying some south African rhipicephalids (Feldman-Muhsam, 1956) it was noticed that material determined by several acarologists as was not homogeneous and showed marked variations in many characters. This concurs with Zumpt's (1942, p. 483) presumption that is an extraordinarily variable species. It appears, in fact, that if certain individual characters are considered separately, specimens determined generally as can be arranged in a continuous series of gradual variations. But if a complex of such variable characters is considered as a whole, the differentiation of types is feasible. Since these types are also found to be constant in one or more characters, particularly the genital aperture of the female, their elevation to specific rank seems to be justified. It may be noted that this state of affairs is quite common throughout the Ixodidae. The examination of the mounted genital aperture of the female of specimens considered to be showed that there are at least 2 distinct types with no transition forms. We thus came to the conclusion that includes 2 distinct species. These species are readily diagnosed by several macroscopic characters in the males as well as in the females. One type of is represented by medium-sized specimens, red-brown in color, with relatively long, wide, and expanding cervical grooves, generally quite distinct median and paramedian grooves, and with the so-called characteristic anal armature of the species (fig. 1,C). The second type of the so-called R. capensis is represented by smaller dark or light brown specimens, with short, deep, crescent-like cervical grooves, with less distinct median and paramedian grooves, and relatively small, rounded anal plates. After examining Koch's type specimen from the Berlin Museum (kindly sent to us for examination by Dr. W. Crome), we came to the conclusion that the first type represents the true capensis, whereas the second represents a distinct species and should be given a new name. We propose to call the new species gertrudae, in honor of Dr. Gertrud Theiler, through whose courtesy most of our material was obtained.