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That the wide range of adult size and appearance (scutal smoothness, degree of punctation, depth of lateral grooves, pres. ence of hairs on basis capituli, presence of dorsal concavity of palpi, shape of adanal shields, presence of accessory shields, size and shape of tarsi and of porose areas, etc.) is due to variation in fullness of feeding of the immature stages has been convincingly presented by Nuttall (1913).

It appears, however, that no matter how variable this species may be, it is seldom difficult to distinguish from other species.

When making the rather sizeable collections of E. a endicu. latus at Kajo Kaji and Yei, in December of 1951, it was nota that specimens from the ears of cattle were consistently of rather uniform size and similar in structure and appearance. But spec. imens from sheep and goats varied considerably in size and structure, and many were malformed. Upon returning to Yei in December of 1952, additional specimens were obtained from cattle. Many of these were as variable and misshapen as the previous year's collections from goats and sheep. The factors behind these differences are too complex to allow conjecture over the reason, interesting as it might be to do so. It is suggested, however, that other reasons, besides immature stage nutrition, may drana. tically influence the parasite's well_being and should be inves_ tigated.

IDENTIFICATION

Males vary in overall length from l.8 m. to 4.4 mm.; "normal" males are 3.0 mm. or above in length. They are usually brownish or reddish_brown, but may be very dark; the legs are always red. dish.brown. The clearly_defined dorsal process of coxa I restricts this species to a rather small group among which it can be distinguished by the deep, long lateral grooves, peculiar scutal punctation, shape and rounded posterior margins of adanal shields, flat eyes, etc. Scutal punctations of moderate size are evenly spaced in the central area of the scutum but almost or entirely disappear in the lateral fields and outside of the lateral grooves. Posteromedian and paramedian grooves are narrow but distinct and the cervical fields are more or less reticulate, especially in large specimens. A caudal process is sometimes

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present. The characteristic elongate shape of the adaal shields with their slightly rouned angles is most distinctive after some series have been examined. Variation in shape of the adanal shields is illustrated (Figure 242). The basis capituli is some. what variable in that the lateral margins may be more or less angled, depending largely on the size of the individual.

Females are similar to males in color and quality of pucta. tions. The scutu has a distinctive outline (Figure 243) that may be slightly more narrowly rouded posteriorly than the spec. imen herein illustrated; it is as wide as or slightly wider than long. The lateral grooves are frequently short or poorly defined; the transition to the raised lateral border of the scutum may be gradual or abrupt; the lateral grooves are often picked out by a row of medium size punctations. The long cervical grooves that exted, albeit shallow, to the posterior margin of the scutum demarcate oval fields beside the central field, a characteristic aspect of this species; combined with it is the moderate density of small to moderate size punctations scattered over the scutu. In small females, the puctations are frequently less numerous an the scutal surface is not so markedly divided into a central and two oval fields within a raised lateral border. The porose areas vary with the size of the individual.

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Figure 245, 6', dorsal view. Figure A, adanal shield. Figure 246, Q, dorsal view. Figure 247, larva, dorsal view. Figure 248, nymph, dorsal view.

RHIPICEPHALUS ARNOLDI
[ After Theiler and Zumpt (1950) in Zurnpt (l95OA)_7

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L N 9 5‘ EQUATORIA PRUVINCE RECQDS l0 Ikoto Le us ca nsis crawsha ' Feb 1 Lotti Forest PraoE_E§IIEergi sdanensis Ap

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These are the only records of this species aside from the original collections from Transvaal and Cape Province, South Afri_ ca. Dr. Thei1er's identification of the larval specimen noted above is tentative.

DISTRIBUTION
The actual distributional picture of R. arnoldi, presently

known only from the Union of South Africa'§nd the Sudan, remains to be ascertained.

msr AFRICA: sum: (Hoogstraal 1951.13). sormmm AFRICA: UNION OF sourn muca (Theiler and Zumpt, in Zu1~t . nosrs

Hare, Le us sp.; and rock hare, Pronolagus sp. (Theiler and

Zumpt in Zumpt 950A Lepus ca nsis craws ayi and larva on Praomys tullbergi sudanensis (fiquatoria rovince records above).

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DISEASE RELATIONS

Unstudied.

REMARKS

The Sudan material was identified by Dr. G. Theiler. Santos Dias (195211) has compared this species with Q. serranoi.

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IDENTIFICATION

The following diagnosis is taken from the original description of this species.

Males are like those of R. mfihlensi in that they possess a well developed dorsal projection of coxa I and have literal grooves indicated only by punctations. They differ fro|§. muhlensi in that the scutal punctations are larger, the basis capit s broader ad has more acute lateral angles, the palpi are more compressed, and the adanal shields and spiracular plates are different. The middle festoons do not protrude; the posteromedian groove is narrow and long, the paramedian grooves are elongate_oval, and all the grooves are reticulate. Size is 2.25 m. to 3.00 m. long and 1.66 mm. wide; color light to dark brown; shape convex.

Female palpi are unusually triangular in combined appearance when the mouthparts are tilted downwards. The basis capituli, about twice as wide as long, converges strongly anteriorly in an extension of the same angle as the lateral margins of the palpi. The scutum is slightly longer than wide and posterior of the eyes is sharply narrowed to a comparatively long, nan. rowly pointed, posteromedian angle. No lateral grooves are present but the scutal periphery is raised and the cervical fields depressed; the cervical grooves converge from the deep anterior pits to the anterior third of the scutum and thence diverge as shallow grooves extending almost to the posterior margin. Scutal punctations are mixed, irregular, larger and denser than those of the male in the central area but fewer in lateral raised areas.

Theiler and Zumpt (log. git.) also described and illustrated the immature stages.

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