Page images
PDF
EPUB

WEST AFRICA: "WEST AFRICA" (As H. savignyi impeltatum: Schulze and Schlottke 1930). RIO DE # (As H. impeltatum: Kratz 1940). FRENCH WEST AFRICA (As H. brumpti: # 1928, 1951, 1953B, and Williers 1955. Material from Mauritania in BMNH collections; H.H. det.). NIGERIA (As H. brumpti: Unsworth 1952. Material from Kano in BMNH collec#H.H. det.). IVCRY COAST (As H. brumpti: Rousselot 1948. Record not repeated by Rousselot but specimens checked by Theiler).

CENTRAL AFRICA CAMEROONS (All as H. brumpti: Delpy 1946A 1949A.E.T.Rageau I;51,1953). - 9

EAST AFRICA: SUDAN (As H. brumpti: Hoogstraal 1954B. As H- impertatum: Feldman-Muhsam 1952).

ERITREA (Specimens from near Karkobat in HH collection. ?As H. erythraeum: Tonelli-Rondelli 1932C; Niro 1935; and Stella ######see NOTE above). ITALIAN SOMALILAND (?As H. # Tonelli-Rondelli 1935 and Stella 1940; see NOTE above). SCMALILAND (Material in HH collection).

NOTE: H. marginatum balcanicum of Tonelli-Rondelli (1930A) from Eritrea, Somalia, and Ethiopia may refer to H. impeltatum; this name was also used by Stella (1938A, 1939A, 1940) for material from Italian Somaliland.

KENYA (Material in BMNH from sheep at Laisamis, Northern Frontier District; H.H. det.; collected by E. A. Lewis who had determined it as H. impressum albiparmatum. Numerous specimens in BMNH collections from cattle at Magadi and Shombole).

TANGANYIKA (Miss J. B. Walker has sent a large series of typical specimens for identification; material from a rhinoceros and wildebeest at Mto-wa-Mbu, a few miles north of Lake Manyara in northeastern Tanganyika, April 1952, A. C. Brooks

legit).

HOSTS

All domestic animals are attacked by adults of this tick. Available data does not indicate that among these animals H. impeltatum shows any marked host predilection. In Egypt a number of specimens have been taken feeding on personnel during field trips.

Wild animals known to be infested are gazelles in Egypt (HH), wild pig in Eritrea (HH), rhinoceros and wildebeest in Tanganyika (Walker records above), and caracal in French West Africa (Williers 1955).

Hosts of immature stages are rodents, hares, birds, and man. At Amara, on the Tigris River in Iraq, Lt. R. A. Buxton reared adults from nymphs taken from hares and from a redstart, P. phoenicurus (= Ruticilla pluvenicurus) (Nuttall lots 3239 #5.

In Egypt we have reared many adults from nymphs that have dropped from both the lesser and the greater Egyptian gerbils, Gerbillus g. gerbillus and G. P. amidum, and fewer from the foLIowing animals: "Tesser Egyptian jerboa, Jaculus J. jaculus; fat sandrat, Psammomys o. obesus; Egyptian hare, Légis C&penSls aegypticus; and man.

Although Rousselot (1948) reared this species, he furnished no data on the hosts of the immature stages either in the laboratory or in the field.

BIOLOGY Life Cycle Rousselot (1948) claimed that H. impeltatum (= H. brumpti) is a three-host species that in his # West Africa Taboratory completed its life cycle in about three months. Results of

studies in NAMRU-3 (Cairo) laboratories will be presented when completed.

Ecology

Although H. impeltatum is a tick of arid and semiarid regions, small populations # exist in certain African savannah areas. Biological and ecological characteristics and limitations of this species are still poorly known. As noted above, immature stages are found in common association with desert and desert-edge rodents

in Egypt.

In Nigeria, where H. impeltatum is almost entirely confined to the more arid northern provinces, it is sometimes the most common tick collected on cattle and appears to require a drier climate than do H. truncatum (= H. transiens), H. impressum, and H. ru

fipes (Unsworth TS52). Adults are found aro e anus and " #, and in the axillary regions of their hosts.

DISEASE RELATIONS

Apparently this tick is not a vector of Theileria annulata of cattle. Note, from Egyptian records, that nymphs and adults are known to feed on man in nature.

REMARKS

The comparative size of each stage and sex has been noted by Campana-Rouget (1954).

The remarks below are based in part on specimens originally identified (as H. brumpti) by Dr. L. P. Delpy, on his remarks (correspondence) on # material, and on our further observations of additional collections consisting of some 2000 specimens.

IDENTIFICATION
Males. In TYPICAL specimens, (1) the exterior position of

the comparatively large subanal shields, (2) the lateral grooves that extend anteriorly at least to the scutal midlength, and (3)

the numerous, moderate size (few large), shallow, scutal punctations that are uniformly and widely distributed over most of the scutal surface, is a combination of characters easily separating males from those of all other species.

Variation in each of these characters are as follows: (1) In specimens that have fed, the subanal shields are always situated well exterior of the axis of the adanal shields; they are usually borne on a slightly rounded, elevated protrusion of the ventral integument, and usually extend posterior beyond the body margin. However, in unfed specimens, where the subanal shields are still closely appressed to the ventral integument, these shields may appear to be in line with the central axis of the adanal shields. Close observation reveals that the base of the subanal shields is in an exterior position but that the unique tilting of the subanal shields in a medially-directed position gives the first impression that they are situated directly posterior of the adanal shields. In fed males, the subanal shields are usually vertical and parallel. (2) The lateral grooves are usually well delineated and extend from the festoons in a progressively more shallow line almost to the eyes. In some specimens, they are more or less obscured, at the level of the scutal midlength and anteriorly, by scutal punctations; questionable specimens should be tilted towards the source of the light. In other individuals, the anterior extension of the lateral grooves consists chiefly of a distinct row of more or less contiguous punctations; such specimens may be confused with H. dromedarii, and, if the subanal shields are still closely appressed to the ventral integument, possibly even with H. excavatum. (3) Punctations are usually very slightly larger, deeper, and more dense posteriorly than elsewhere on the scutum. Punctations over the scutum are typically dense but not contiguous, regular, medium-size with a few scattered larger, deeper ones among them, and fairly shallow. The number and placement of these punctations is subject to considerable variation; in some specimens the central scutal area may be almost devoid of obvious punctations; this is especially true in engorged individuals.

Other characters are as follows: The area just anterior of

the festoons is almost always slightly depressed and contains a long, narrow posteromedian groove, and a pair of shorter, wider,

and deeper paramedian grooves. A parma, the color of which may be lighter or darker than the rest of the scutum, may be present, or may appear as a normal median festoon. Two definite pairs of festoons and two more or less fused pairs lie on either side of the parma or median festoon. Delpy states that the scutum is flat, actually it is usually more or less arched, especially in males that have fed.

The scutal color varies from dark brown to black; exceptional specimens, usually very small ones, may be lighter. The leg segments are usually pale anteriorly and posteriorly and darker centrally, but they may be entirely pale yellowish.

Female: The scutum posteriorly and centrally has numerous rather regularly spaced, moderate size, noncontiguous punctations. Scattered among them are several larger and deeper punctations in two parallel rows centrally. The moderate size punctations are usually mostly discrete, but exceptions to this are common. Anteriorly and in the scapular areas, punctations are large and deep; in the lateral fields punctations are absent or present. The deeply depressed cervical grooves are more or less rugose, and the punctations in them are more or less contiguous. The scutum of engorged specimens frequently has less distinct punctations and grooves. The scutum is generally dark brown in color. It is definitely longer than wide, but the ratio may be reduced in some newly molted, misshapen, or greatly engorged specimens.

The genital area is distinctive. The central genital apron is an elongate triangle much like that of H. dromedarii but shorter, wider, and usually not quite so narrowly pointed apically. In profile, it definitely bulges anteriorly and is depressed posteriorly. An important principal additional feature is that, in unmated specimens and in mated but not greatly engorged specimens, this genital apron is bordered on each side by a slight bulge that gives the genital area a trilobed appearance not found in any of the other species with which H. impeltatum may be confused. This characteristic is maintained # only slightly less distinctness in greatly engorged females.

Female body size, in all except runts, is always large. The legs are like those of the male.

« PreviousContinue »