on sand. The opportunities for dispersal of H. dromedarii over long camel routes may easily be imagined, but a large number of ticks undoubtedly perish in either the egg or larval stage along these wide and indefinite trails through barren deserts. Blanc, Martin, and Bruneau (1949) report females on camels that had ar rived, after a trek of longer than a week, across the Sahara, at Goulimine in southern Morocco from Mauritania, over a thousand kilometers away. In Egypt, similar infestations are found in the Cairo area on camels just arrived from the Sudan (these also bear other Sudanese but not Egyptian species of ticks) and in Siwa Oasis on camels from distant parts of Libya. In Egypt, unfed adults may be taken on the desert of the Mediterranean littoral at any time of the year. Unfed adults either come rushing at any potential host, including man, from under desert shrubs or are collected in rodent burrows before they depart in search of larger hosts. Engorged, ovipositing females may be observed in rodent burrows as well as under desert shrubs, in camel yards, and under stones. On the littoral desert unfed adults are seen at any time of the day in all sea sons. REMARKS In attempts to determine whether larvae produce an acquired immunity in the hosts, thus preventing subsequent larvae from engorging on the same animal, Brumpt and Chabaud (1947) fed this stage on rabbits with negative results. Differences in size of each stage and sex have been presented by Campana Rouget (1954). A capillary tube arrangement, which has proved successful for the artificial feeding of adults of H. dromedarii for physio logical and disease transmission studies, has been described by Chabaud (1950A). Parasitic wasps (Hymenoptera), Hunterellus hookeri, have been bred from nymphs of H. dromedarii H. asiaticum) in Russia by Bernadskaia (1939B). Integumentary sense organs, which are fixed in number and location and essentially similar in all stages, though more primitive in larvae, have been described and illustrated by Dinnik and Zumpt (1949). These are the organs that Delpy (1938) had previously referred to as spiracles ("stigmates respiratoires"). Pervomaisky (1949) was unable to rear a full F1 generation from parthenogenetic females of H. dromedarii. Abnormal specimens have been described by Pavlovsky (1940) and Alfeev (1948). The feeding of large numbers of this tick (= H. asiaticum) induces inflammation of the host skin that hinders normal engorge ment, especially of females that are likely to die as a result. When additional species compete for space, "a further antagonistic factor increases the obstacles" (Pavlovsky, Pervomaisky, and Chagin 1954). Warburton and Nuttall (1909, page 71) produced an excellent illustration of H. dromedarii (H. aegyptium) but the legend, inferring South Africa as the source, is misleading. Apparently the only specimen from South Africa is the abnormal one (figure 18), the identity of which is uncertain. "H. asiaticum", which Delpy considers to be a synonym of H. dromedarii, is still treated by Soviet workers (Pomerantzev 1950) as a separate species with several subspecies and with a wider geographical range than H. dromedarii. This form is less robust, smaller, and more slender, with a shorter posteromedian groove than in giant males typical of H. dromedarii. The fe males are more elongate than the typically robust female H. dromedarii and the length-width ratio of their palpi and of their scutum is longer. Such individuals are also encountered in African populations. Delpy (1946) first considered the short, wide palpal shape to be diagnostic but further studies indicated so much variation that "applied strictly to determination of isolated specimens, (this character) would have led to errors. (Also) the ratios that are true for a young, recently molted tick are no longer accurate when this tick has, aged and become engorged". The shortness of the posteromedian groove appears concomitant with the general lack of robustness in these smaller and more slender ticks. Feldman Muhsam (1954) states "The type specimens of H. drome darii asiaticum as well as H. asiaticum citripes differ from H. dromedarii and are not synonyms of H. dromedarii". Without further explanation, it is impossible to evaluate this remark. DISEASE RELATIONS MAN: A host and vector of Q fever (Coxiella burnetii). Experimentally, this tick can be infected with the virus of Russian spring-summer encephalitis, with the virus of mosquito borne autumn encephalitis from the Russian Maritime Province, and with the virus of a Japanese mosquito-borne encephalitis. CATTLE: Theileriasis (Theileria spp.). This tick (as H. asiaticum) is apparently not a carrier of brucellosis (Brucella spp.). CAMELS: Theileriasis (Theileria camelensis). IDENTIFICATION Males: Typical males are recognized by (1) large size (average length: 5.7 mm., range 5.2 mm. to 7.0 mm.; average width: 3.8 mm., range 3.0 mm. to 5.0 mm.), (2) distinct lateral displacement of the subanal shields, (3) short, deep lateral grooves limited to the posterior third of the scutum; and (4) few, large shallow punctations variously scattered over the surface and complete or almost complete absence of other puncta tions. Also distinctive is the deep, usually narrow, postero median groove extending from the distinct parma to the scutal midlength. This groove is bounded on either side by converging ridges; laterad of these ridges are deep, wide, often rugose paramedian grooves. The paramedian grooves are of variable length, and posteriorly delineate the two median pairs of festoons, which are often massive and which are larger than the more or less distinct three lateral pairs of festoons. Another pair of parallel ridges may be present between the paramedian grooves and the lateral grooves. Small Variations of the above characters are as follows: punctations may be present and rarely may be obtrusive enough to suggest H. impeltatum; also a line of large punctations extending anteriorly from the apex of the lateral grooves may suggest H. impeltatum. In engorged specimens, at least, differences in the posterior area of the scutum separate such specimens. In some specimens a dense field of small punctations may be present posteriorly, suggestive of H. excavatum. The subanal shields are sometimes divided into two pairs, but very few such specimens have been seen during the present study. In unengorged males, the subanal shields are closer to the central axis of the anal shields than otherwise, but their center is still exterior of the central axis of the adanals. Color varies from yellowish brown through dark brown to brownish black. The legs are usually paler than the scutum and the segments may be ringed by a paler band. (4 punc Females: Typical females may be recognized by (1) the narrowly elongate and triangular genital aperture, which in profile slopes gradually, (2) the comparatively wide scutal outline (length-width ratio about equal, (3) few, large, scattered pw tations and frequent rugosity of the scutal surface, and (4) large size. The palpi are usually twice as long as their com bined width. The color varies from yellowish brown to black; the legs are usually paler than the body and may be concolorous or ringed. The genital aperture is most distinctive and hardly variable. In newly molted females its outline is slightly concave sub apically, but in engorged specimens the lateral margins are usually straight. The narrowly triangular outline is apparent ly never lost. A narrow, raised integumental fold surrounds the apron, The scutal outline is widest just anterior of the eyes. The wide, deep, long cervical grooves are usually rugose as is also the scutal surface of most engorged specimens. From ten to twenty (average thirteen) large punctations are scattered over the central field and an equal number occur in each scapular field. Average newly molted specimens measure about 5.5 mm. long by 3.2 mm. wide, but engorged individuals may be 30.0 mm. long and 15.0 mm. wide. Scutal length is about 3.2 mm., width about 2.8 mm. |