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straight or slightly convex; anterior and posterior margins straight, parallel. Segment 3 triangular, outer margin approximately twice as long as inner margin. Pal i ventr with segments 2 and 3 of al. most equal length, segment 3 earing a small triangular retrograde spu extending just beyond the apex of segment 2; segment 4 small, inserted in pit of segment 3; segment 1 forming a slight pedicle for palpi and hearing at its inner basal margin a slight knob with at least one bristle. stoma twice as long as wide, apical margin broadly rounded no ed medially; a dense corona present; dentition 5/5, with nine to eleven denticles in each file, files of equal length.

Scutu: Outline narrowly elongate with lateral margins par. allel, posterior margin bluntly rounded; lateral margins widening slightly over scapulae; anterior emargination deep. Posteromedian and amedian oves shallow, narrow, short, and indistifict, situa a eve o spiracular plates. Cervical grooves shallow but distinctly divergent to lateral margin posterior 0 eyes. Eyes on lateral margin at level of coxa 2; small but distinct, rounded and slightly raised. Suface of scutum smooth and shiny, with a narrow median field of few scattered puctations extending the full length of the scutum; a single row of twelve hairs along posterior margin and a few hairs aong posterior grooves; area between cervical grooves and lateral margins punctate and bearing scattered fine, long, white hairs; a row of hairs also situated on anterior margin between cervical grooves. Inte§uE§§t bulging around scutu from level of eyes posteriorly; s with reg. ularly scattered, dense, long, white, conspicuous hairs bordering scutum to level of spflraoular plates; thence these hairs more confined to narrow lateral surface of integuent around posterior margin of scutum, few or no hairs on dorsal surface in this area.


Spiéacular plate subcircular with one and a half rows of large go e s surrouding apertue. Genital a rtue situated at midlevel of coxa II, anterior and pos erior margins parallel,

lateral margins slightly converging posteriorly. Genital ooves extending from genital aperture to level of anus, Elightly giver. gent. Adanal shields commencing at anterior level of coxa IV and

extending B5yoEH level of anus almost to posterior margin of body (depending on degree of integumental stretching due to feeding), narrowly elongate, slightly expanded just anterior of anus,

tapering and bluntly rounded distally; divided fro each other by narrow area of integuent; unattached to integument posterior of anus; suface bearing a few scattered hairs distally. Accesso shields extending from level of anus to approximately same level as apex of adanal shields, tapering, bluntly rounded apically; narrower than adanal shields. Hairs on ventral surface fairly dense and evenly distributed but shtrter than those on lateral surfaces.


Le s with free segments appearing beaded due to width and constr c ion between several segments; length.width ratio of seg; ments variable but width of none equalling length of same segment; free segments with numerous long, fine hairs dorsally and ventral. ly. Tarsi apically extended into a downward projecting, spurlike point; IV also with a short ventral subapical spur; outline nar. rowly elongate; claws and pads arising from dorsal surface at apex; claws long, narrow, recurved at some distance beyond pads. Coxa I narrowly, elongately subtriangular and extending anterior. I; almost to anterior margin of basis capituli, visible from dorsal view; posteriorly deeply cleft to form a widely triangular outer spur and a narrower, tapered inner spur; other coxae sud» rectangular with rounded margins; posterior margins slightly cleft; all coxae with numerous hairs.

FEMALE (Figues 238, 239, 347 to 351); Unengorged specimens are very slightly larger than males; engorged specimens measure up to 6.2 mm. long but retain the linear, podshape appearance of boophilid females due to the severely parallel lateral margins of the body. Female characters recall those of the male but the leg' segments are less expanded and the palpi are more elongate with a slight constriction between the second and third segments.

Capitulum: Basis ca ituli from one and a half to twice as wide as ong; basfi margin erately concave and joined to lateral margins by slight expansions suggestive of cornua; lateral margins concave to widest point at anterior third, thence recuved to anterior margin; porose areas small, shallow, and indistinct, subtriangular or pear shaped; bearing four or five hairs lateral.

ly on dorsal surface. Pal i more elongate than those of male, segments 2 and 3 separattdgby a pediclelike constriction and of

1.q¢_-approximately equal length; segment 2 arising from pedicle, with _;;_<-straight outer margin, convex inner margin, and subparallel ante... ;_ ._:ior and posterior margins; segment 3 with lateral margins slightly '_,_=ponverging to bluntly rounded anterior margin, posterior margin ;_straight though forming a slight, more or less downcurved projec.. mfition at juncture with inner margin; segment 3 ventrally with ,3 ~__..short, broad spur reaching basal margin; segment 1 narrow, pediclelike, not observed to bear a ventral knob as in male; palpi with hairs as illustrated. gypgstome larger but otherwise

similar to that of male.


Scutum three..fourths as wide as long; outline slightly convex an anterior of eyes, slightly converging from eyes to juncture of

I cervical grooves, abruptly converging posteriorly; anterior emsr.. ".’_.’ gination deep. Cervical ooves reaching lateral margins as in ; male and delimiting an anterolateral area that is hirsute and

T somewhat punctate as in male. Surface otherwise smooth except for 7“ a transverse row of hairs bordering anterior margin between cervical F‘ grooves and a few scattered hairs arising from punctations in cen.. "1 tral field. gas on lateral margins at scutal midlength, slightly

' convex.

in K-1



Spiracular plate of similar construction to that of male

but differing slightly in outline. Genital a ron a wide oval

at level of coxae II. Genital Eooves subparfifil to level of '9 spiracular plates, thence divergen 0 level of posterior margin E of anus. :2

-'~‘ Inte nt with numerous fairly regular_ rows of short hairs 1

on be ore and ventral surfaces; hairs more dense on posterior '5 margin between spiracular plates.

Legs similar to those of male except that the free segments 1 are narrower and tarsi more elongate; tarsus IV lacking ventral I subapical spur; anterior projection of coats I variable, as dis?» tinctly produced as that of male or more truncate.

NYMPH (Figures 352 to 358): Ca itulum. Basis capituli three times as wide as long, with straight basfi margin, rounded

junctures, and divergent lateral margins. Pal four times as long as wide; segment 1 forming a slight c e; segments 2 and 3 of approximately equal length and subrectangular; apex

more or less bllmtly rounded; segment 3 ventrally with a short,

wide spur not reaching basal margin of segment. gégstome similar to that of adults but with smaller corona and 3/3 an on in

files of eight denticles.

Scutum with length.width ratio approximately equal; outline grmiuzfifiiverging from scapulae to midlength, thence abruptly converging to narrow, bluntly rounded posterior margin. Surface lightly shagreened and with a few scattered hairs; cervical

grooves as in adults (not visible in all specimens); eyes small, indistinct or invisible.

S iracular late subcircular with six large goblets in a circle. IntegEm_e_z_1t with long hairs.

Le s with length.width ratio of free segments intermediate between those of male and females sexes; coxa I not so deeply

cleft and truncate anteriorly; tarsi short, robust, not tapered

downwards as in adults; dorsal margin gradually tapering; claws and pads as in adults.

LARVA: Unknown.


It appears well established that continental Africa is the place of origin and center of distribution of Rhi ce halus ticks. Of the L6 rhipicephalid species and subspecies that Zupt (l95OA) recognized in his preliminary generic revision, 39 (including the now cosmopolitan _s. sang-t_1%'neus) are endemic in the Ethiopian Faual Region; two are rien ; and five range from southern

Euope and northern Africa into Russia.

The genus Rhi ice halus comprises almost a third of the known Sudan tick faua 555 contains more than twice as many endemic

African species as any other ixodid geus in the Ethiopian Faunal Region.

King (1926) listed five forms of Rhi ice halus from the Su. dan. In addition, R. ca nsis has been apparently erroneously referred to the Sudan lzumpt 1942B). During the present study, seventeen species and two additional subspecies, or nineteen different forms, have been discovered in the Sudan.

Zumpt's (195011) maier eehti-ihutieh in bringing together the basic taxonomic data for this difficult genus will facilitate greatly the final revision of rhipicephalid species. Earlier, Theiler (l947,l949B,l950A,B) had comenced study of individual species, an effort that is still underway (Theiler and Robinson 1953B, Theiler, Walker, and Wiley 1956). Very careful and thor. ough studies are also in progress by Walker (1956), who has several further reports completed or in an advanced stage of preparation. Since Zumpt's classic preliminary work, Wilson (1954) described a new species, R. hurti, from Kenya and Santos Dias has provided a number of net names, the validity of which are uncertain. Obviously, new criteria must be sought to sep. arate many rhipicephalid species and subspecies. In an attempt to apply characters surrounding the female genital aperture, Feldman_Muhsam (1952A) has distinguished another species, §.

secundus among populations appearing to be E. E. sanvuineus. However,problems of morphological and biological criteria for

this genus are not likely to be solved until more exhastive field research and patient laboratory investigation have been devoted to them.

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